host-persist: content-addressed blob adapter — Blocker CLOSED

blob/put|get|has? backed by <root>/blobs/<cid>, CIDv1 (raw codec,
sha2-256 via Sx_cid/Sx_sha2). put idempotent; persist stores only the
{:cid :size :mime} ref. persist_durable_test.sh extended (8/8): blob
round-trip + content-address idempotency + bytes/ref surviving real
restart. Mock blob suite 14/0 on worktree binary. Durable-storage
Blocker now CLOSED.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

hosts/ocaml/bin/sx_server.ml

@@ -571,9 +571,12 @@ and cek_run_with_io state =
           Hashtbl.replace d "descent" (Number desc);
           Dict d
         | _ ->
-          let args = let a = Sx_runtime.get_val request (String "args") in
-            (match a with List l -> l | _ -> [a]) in
-          io_request op args
+          let argsv = Sx_runtime.get_val request (String "args") in
+          (match Sx_persist_store.handle_op op argsv with
+           | Some resp -> resp
+           | None ->
+             let args = (match argsv with List l -> l | _ -> [argsv]) in
+             io_request op args)
       in
       s := Sx_ref.cek_resume !s response;
       loop ()
@@ -1540,7 +1543,12 @@ let rec dispatch env cmd =
                | Some path -> load_library_file path | None -> ());
               Nil
             end
-          end else Nil (* non-import IO: resume with nil *) in
+          end else
+            (* durable-storage ops: service against on-disk store *)
+            let args = Sx_runtime.get_val request (String "args") in
+            (match Sx_persist_store.handle_op op args with
+             | Some resp -> resp
+             | None -> Nil (* non-import IO: resume with nil *)) in
           s := Sx_ref.cek_resume !s response
         done;
         Sx_ref.cek_value !s
@@ -3893,7 +3901,10 @@ let http_mode port =
       Dict d
     | "io-sleep" | "sleep" -> Nil
     | "import" -> Nil
-    | _ -> Nil);
+    | _ ->
+      (match Sx_persist_store.handle_op op args with
+       | Some resp -> resp
+       | None -> Nil));
   (* Response cache — path → full HTTP response string.
      Populated during pre-warm, serves cached responses in <0.1ms.
      Thread-safe: reads are lock-free (Hashtbl.find_opt is atomic for

hosts/ocaml/lib/sx_persist_store.ml

@@ -0,0 +1,293 @@
+(* sx_persist_store — host durable-storage adapter for lib/persist.
+   Production twin of `persist/serve` (lib/persist/durable.sx): it answers the
+   same `persist/...` IO ops, but backs them with real on-disk storage so writes
+   survive a process restart. Stateless-on-disk: every op reads/writes the
+   filesystem directly, so a fresh process recovers state with no warm-up — the
+   log on disk IS the state.
+
+   On-disk layout under the root dir (default ./persist-data, or $SX_PERSIST_DIR):
+     streams/<hex(stream)>.log   append-only, one SX-serialized event per line
+     streams/<hex(stream)>.seq   per-stream monotonic high-water counter (int)
+     kv/<hex(key)>               one SX-serialized value per key
+
+   Invariants honoured (see plans/persist-on-sx.md Blocker spec):
+   1. last-seq is a per-stream monotonic counter stored in .seq, SEPARATE from
+      the rows — it keeps climbing across truncate, so a compacted stream never
+      reassigns a seq.
+   2. append never renumbers — the event already carries its :seq (log.sx does
+      last-seq+1); the host only bumps the high-water mark to max(hw, seq).
+   3. read returns surviving events in append order with :seq intact.
+   4. streams is the set of streams that ever had an append — keyed off the .seq
+      file, which truncate never deletes, so it survives full compaction.
+   5. values round-trip structurally via the SX serializer/parser. *)
+
+open Sx_types
+
+(* ---- root dir ---------------------------------------------------------- *)
+
+let _root : string option ref = ref None
+
+let set_root dir = _root := Some dir
+
+let root_dir () =
+  match !_root with
+  | Some d -> d
+  | None -> (try Sys.getenv "SX_PERSIST_DIR" with Not_found -> "persist-data")
+
+(* ---- filesystem helpers ------------------------------------------------ *)
+
+let rec ensure_dir dir =
+  if dir = "" || dir = "." || dir = "/" || Sys.file_exists dir then ()
+  else begin
+    ensure_dir (Filename.dirname dir);
+    (try Unix.mkdir dir 0o755 with Unix.Unix_error (Unix.EEXIST, _, _) -> ())
+  end
+
+let streams_dir () = Filename.concat (root_dir ()) "streams"
+let kv_dir () = Filename.concat (root_dir ()) "kv"
+let blobs_dir () = Filename.concat (root_dir ()) "blobs"
+
+let read_file path =
+  let ic = open_in_bin path in
+  let n = in_channel_length ic in
+  let s = really_input_string ic n in
+  close_in ic;
+  s
+
+(* Atomic write: temp file in the same dir then rename over the target. *)
+let write_file_atomic path contents =
+  ensure_dir (Filename.dirname path);
+  let tmp = path ^ ".tmp" in
+  let oc = open_out_bin tmp in
+  output_string oc contents;
+  flush oc;
+  close_out oc;
+  Sys.rename tmp path
+
+let append_line path line =
+  ensure_dir (Filename.dirname path);
+  let oc = open_out_gen [Open_append; Open_creat; Open_wronly] 0o644 path in
+  output_string oc line;
+  output_char oc '\n';
+  close_out oc
+
+(* ---- name <-> filename (hex, reversible, fs-safe) ---------------------- *)
+
+let hex_encode s =
+  let b = Buffer.create (String.length s * 2) in
+  String.iter (fun c -> Buffer.add_string b (Printf.sprintf "%02x" (Char.code c))) s;
+  Buffer.contents b
+
+let hex_decode s =
+  let n = String.length s / 2 in
+  String.init n (fun i -> Char.chr (int_of_string ("0x" ^ String.sub s (i * 2) 2)))
+
+let stream_log stream = Filename.concat (streams_dir ()) (hex_encode stream ^ ".log")
+let stream_seq stream = Filename.concat (streams_dir ()) (hex_encode stream ^ ".seq")
+let kv_path key = Filename.concat (kv_dir ()) (hex_encode key)
+
+(* ---- value <-> SX text (round-trips through Sx_parser) ----------------- *)
+
+let escape_str s =
+  let len = String.length s in
+  let buf = Buffer.create (len + 16) in
+  for i = 0 to len - 1 do
+    match s.[i] with
+    | '"'  -> Buffer.add_string buf "\\\""
+    | '\\' -> Buffer.add_string buf "\\\\"
+    | '\n' -> Buffer.add_string buf "\\n"
+    | '\r' -> Buffer.add_string buf "\\r"
+    | '\t' -> Buffer.add_string buf "\\t"
+    | c    -> Buffer.add_char buf c
+  done;
+  Buffer.contents buf
+
+let rec serialize = function
+  | Nil -> "nil"
+  | Bool true -> "true"
+  | Bool false -> "false"
+  | Integer n -> string_of_int n
+  | Number n -> format_number n
+  | String s -> "\"" ^ escape_str s ^ "\""
+  | Symbol s -> "(quote " ^ s ^ ")"
+  | Keyword k -> ":" ^ k
+  | List items | ListRef { contents = items } ->
+    "(list" ^ (List.fold_left (fun acc v -> acc ^ " " ^ serialize v) "" items) ^ ")"
+  | Dict d ->
+    let pairs = Hashtbl.fold (fun k v acc ->
+      (Printf.sprintf ":%s %s" k (serialize v)) :: acc) d [] in
+    "{" ^ String.concat " " (List.sort String.compare pairs) ^ "}"
+  | _ -> "nil"
+
+(* Parse one serialized value back. Empty / blank -> Nil. *)
+let rec deserialize line =
+  let line = String.trim line in
+  if line = "" then Nil
+  else match Sx_parser.parse_all line with
+    | v :: _ -> eval_quote_lists v
+    | [] -> Nil
+
+(* serialize emits lists as `(list ...)` and symbols as `(quote s)` so the
+   parser yields data, not a call — but the parser leaves those as AST. Walk
+   the parsed AST and collapse `(list ...)`/`(quote s)` back to values. *)
+and eval_quote_lists v =
+  match v with
+  | List (Symbol "quote" :: x :: []) -> x
+  | List (Symbol "list" :: rest) -> List (List.map eval_quote_lists rest)
+  | List items -> List (List.map eval_quote_lists items)
+  | ListRef { contents = items } -> List (List.map eval_quote_lists items)
+  | Dict d ->
+    let d' = Hashtbl.create (Hashtbl.length d) in
+    Hashtbl.iter (fun k v -> Hashtbl.replace d' k (eval_quote_lists v)) d;
+    Dict d'
+  | other -> other
+
+(* ---- seq counter ------------------------------------------------------- *)
+
+let read_seq stream =
+  let p = stream_seq stream in
+  if Sys.file_exists p then (try int_of_string (String.trim (read_file p)) with _ -> 0)
+  else 0
+
+let write_seq stream n = write_file_atomic (stream_seq stream) (string_of_int n)
+
+let value_to_int = function
+  | Integer n -> n
+  | Number n -> int_of_float n
+  | _ -> 0
+
+let event_seq ev =
+  match ev with
+  | Dict d -> (match Hashtbl.find_opt d "seq" with Some v -> value_to_int v | None -> 0)
+  | _ -> 0
+
+(* ---- ops --------------------------------------------------------------- *)
+
+let do_append stream ev =
+  ensure_dir (streams_dir ());
+  (* bump the monotonic high-water mark; create .seq on first append so the
+     stream shows up in `streams` and survives later truncation. *)
+  let hw = read_seq stream in
+  let s = event_seq ev in
+  write_seq stream (max hw s);
+  append_line (stream_log stream) (serialize ev)
+
+let do_read stream =
+  let p = stream_log stream in
+  if not (Sys.file_exists p) then List []
+  else begin
+    let content = read_file p in
+    let lines = String.split_on_char '\n' content in
+    let evs = List.filter_map (fun l ->
+      if String.trim l = "" then None else Some (deserialize l)) lines in
+    List evs
+  end
+
+let do_last_seq stream = Number (float_of_int (read_seq stream))
+
+let list_dir_suffix dir suffix =
+  if not (Sys.file_exists dir) then []
+  else
+    Array.to_list (Sys.readdir dir)
+    |> List.filter (fun f -> Filename.check_suffix f suffix)
+    |> List.map (fun f -> hex_decode (Filename.chop_suffix f suffix))
+    |> List.sort String.compare
+
+let do_streams () = List (List.map (fun s -> String s) (list_dir_suffix (streams_dir ()) ".seq"))
+
+(* drop events with seq <= n; the .seq high-water counter is untouched. *)
+let do_truncate stream n =
+  let p = stream_log stream in
+  if Sys.file_exists p then begin
+    let evs = match do_read stream with List l -> l | _ -> [] in
+    let kept = List.filter (fun ev -> event_seq ev > n) evs in
+    let body = String.concat "" (List.map (fun ev -> serialize ev ^ "\n") kept) in
+    write_file_atomic p body
+  end
+
+let do_kv_get key =
+  let p = kv_path key in
+  if Sys.file_exists p then deserialize (read_file p) else Nil
+
+let do_kv_put key v =
+  ensure_dir (kv_dir ());
+  write_file_atomic (kv_path key) (serialize v)
+
+let do_kv_delete key =
+  let p = kv_path key in
+  if Sys.file_exists p then (try Sys.remove p with _ -> ())
+
+let do_kv_has key = Bool (Sys.file_exists (kv_path key))
+
+let do_kv_keys () =
+  if not (Sys.file_exists (kv_dir ())) then List []
+  else
+    List (
+      Array.to_list (Sys.readdir (kv_dir ()))
+      |> List.map hex_decode
+      |> List.sort String.compare
+      |> List.map (fun s -> String s))
+
+(* ---- blob store (content-addressed) ------------------------------------ *)
+(* Same pattern as the persist ops, but a SEPARATE adapter: large objects live
+   in a content-addressed directory keyed by a CIDv1 (raw codec, sha2-256).
+   persist only ever stores the returned ref ({:cid :size :mime}), never bytes.
+   blob/put is idempotent — identical bytes hash to the same cid + same file. *)
+
+let codec_raw = 0x55
+
+let blob_cid bytes =
+  let digest = Sx_cid.unhex (Sx_sha2.sha256_hex bytes) in
+  Sx_cid.cidv1 codec_raw (Sx_cid.multihash Sx_cid.mh_sha2_256 digest)
+
+let blob_path cid = Filename.concat (blobs_dir ()) cid
+
+let do_blob_put bytes =
+  let cid = blob_cid bytes in
+  let p = blob_path cid in
+  if not (Sys.file_exists p) then write_file_atomic p bytes;
+  String cid
+
+let do_blob_get cid =
+  let p = blob_path cid in
+  if Sys.file_exists p then String (read_file p) else Nil
+
+let do_blob_has cid = Bool (Sys.file_exists (blob_path cid))
+
+(* ---- dispatch ---------------------------------------------------------- *)
+
+let arglist = function
+  | List l | ListRef { contents = l } -> l
+  | Nil -> []
+  | v -> [v]
+
+(* Returns Some response if op is a persist op this store owns, None otherwise. *)
+let handle_op op args =
+  let a = arglist args in
+  let str = function String s -> s | v -> value_to_string v in
+  match op with
+  | "persist/append" ->
+    (match a with stream :: ev :: _ -> do_append (str stream) ev | _ -> ()); Some Nil
+  | "persist/read" ->
+    (match a with stream :: _ -> Some (do_read (str stream)) | _ -> Some (List []))
+  | "persist/last-seq" ->
+    (match a with stream :: _ -> Some (do_last_seq (str stream)) | _ -> Some (Number 0.0))
+  | "persist/streams" -> Some (do_streams ())
+  | "persist/truncate" ->
+    (match a with stream :: n :: _ -> do_truncate (str stream) (value_to_int n) | _ -> ()); Some Nil
+  | "persist/kv-get" ->
+    (match a with key :: _ -> Some (do_kv_get (str key)) | _ -> Some Nil)
+  | "persist/kv-put" ->
+    (match a with key :: v :: _ -> do_kv_put (str key) v | _ -> ()); Some Nil
+  | "persist/kv-delete" ->
+    (match a with key :: _ -> do_kv_delete (str key) | _ -> ()); Some Nil
+  | "persist/kv-has?" ->
+    (match a with key :: _ -> Some (do_kv_has (str key)) | _ -> Some (Bool false))
+  | "persist/kv-keys" -> Some (do_kv_keys ())
+  | "blob/put" ->
+    (match a with bytes :: _ -> Some (do_blob_put (str bytes)) | _ -> Some Nil)
+  | "blob/get" ->
+    (match a with cid :: _ -> Some (do_blob_get (str cid)) | _ -> Some Nil)
+  | "blob/has?" ->
+    (match a with cid :: _ -> Some (do_blob_has (str cid)) | _ -> Some (Bool false))
+  | _ -> None

hosts/ocaml/test/persist_durable_test.sh

@@ -0,0 +1,144 @@
+#!/usr/bin/env bash
+# hosts/ocaml/test/persist_durable_test.sh
+# Acceptance test for the host durable-storage adapter (Sx_persist_store).
+#
+# Exercises `persist/durable-backend` (REAL `perform`, not the mock) under the
+# WORKTREE-built sx_server.exe, and asserts:
+#   1. durable: writes land on disk and read back (the silent-data-loss repro
+#      from plans/persist-on-sx.md now returns correct values).
+#   2. last-seq is monotonic across truncate (compaction never reassigns a seq).
+#   3. kv ops round-trip and delete.
+#   4. recovery: a REAL process restart (write, exit, fresh process, replay)
+#      recovers state from disk.
+#
+# Run from repo root or anywhere; locates the worktree binary relative to itself.
+set -uo pipefail
+
+HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+ROOT="$(cd "$HERE/../../.." && pwd)"        # repo/worktree root
+cd "$ROOT"
+
+SX="hosts/ocaml/_build/default/bin/sx_server.exe"
+if [ ! -x "$SX" ]; then
+  echo "ERROR: worktree binary not found at $SX — build it first:" >&2
+  echo "  (cd hosts/ocaml && dune build bin/sx_server.exe)" >&2
+  exit 1
+fi
+
+DATADIR="$(mktemp -d)"
+trap 'rm -rf "$DATADIR"' EXIT
+
+PASS=0
+FAIL=0
+check() { # check <label> <got> <expected>
+  if [ "$2" = "$3" ]; then
+    PASS=$((PASS + 1)); printf '  ok   %-40s => %s\n' "$1" "$2"
+  else
+    FAIL=$((FAIL + 1)); printf '  FAIL %-40s got [%s] want [%s]\n' "$1" "$2" "$3"
+  fi
+}
+
+PRELUDE='(epoch 1)
+(load "spec/stdlib.sx")
+(load "lib/r7rs.sx")
+(load "lib/persist/event.sx")
+(load "lib/persist/backend.sx")
+(load "lib/persist/log.sx")
+(load "lib/persist/kv.sx")
+(load "lib/persist/durable.sx")
+(load "lib/persist/blob.sx")
+(epoch 2)'
+
+# run_eval <sx-expr-string>: prints the final (ok-len 2 ...) payload line.
+run_eval() {
+  local expr="$1"
+  printf '%s\n(eval %s)\n' "$PRELUDE" "$expr" \
+    | SX_PERSIST_DIR="$DATADIR" timeout 60 "$SX" 2>/dev/null \
+    | awk '/^\(ok-len 2 / {getline; print; exit}'
+}
+
+# escape an SX program into a single-line double-quoted SX string literal for
+# (eval "..."). The REPL reads one command per physical line, so newlines in the
+# program are collapsed to spaces.
+q() { printf '"%s"' "$(printf '%s' "$1" | tr '\n' ' ' | sed 's/\\/\\\\/g; s/"/\\"/g')"; }
+
+echo "== durable: append/read/last-seq round-trip on disk =="
+GOT=$(run_eval "$(q '(let ((b (persist/durable-backend)))
+  (begin
+    (persist/append b "s" "x" 0 {:v 1})
+    (persist/append b "s" "x" 0 {:v 2})
+    (list (persist/event-seq (persist/append b "s" "x" 0 {:v 3}))
+          (persist/count b "s")
+          (len (persist/read b "s")))))')")
+check "append/count/read" "$GOT" "(3 3 3)"
+
+echo "== last-seq monotonic across truncate =="
+GOT=$(run_eval "$(q '(let ((b (persist/durable-backend)))
+  (begin
+    (persist/append b "t" "x" 0 {})
+    (persist/append b "t" "x" 0 {})
+    (persist/append b "t" "x" 0 {})
+    (persist/truncate b "t" 2)
+    (list (persist/last-seq b "t") (persist/count b "t"))))')")
+check "last-seq survives truncate" "$GOT" "(3 1)"
+
+echo "== streams set survives compaction =="
+GOT=$(run_eval "$(q '(let ((b (persist/durable-backend)))
+  (sort ((get b "streams"))))')")
+check "streams" "$GOT" '("s" "t")'
+
+echo "== kv round-trip + delete =="
+GOT=$(run_eval "$(q '(let ((b (persist/durable-backend)))
+  (begin
+    (persist/kv-put b "k" {:a 1 :b "two"})
+    (persist/kv-put b "gone" 9)
+    (persist/kv-delete b "gone")
+    (list (get (persist/kv-get b "k") :b)
+          (persist/kv-has? b "k")
+          (persist/kv-has? b "gone"))))')")
+check "kv get/has/delete" "$GOT" '("two" true false)'
+
+echo "== recovery: state survives a REAL process restart =="
+# write in process A then let it exit; the next run is a brand-new process.
+run_eval "$(q '(let ((b (persist/durable-backend)))
+  (begin
+    (persist/append b "r" "ev" 0 {:n 1})
+    (persist/append b "r" "ev" 0 {:n 2})
+    (persist/kv-put b "survive" "yes")
+    (persist/count b "r")))')" >/dev/null
+# fresh process, same SX_PERSIST_DIR — must replay from disk.
+GOT=$(run_eval "$(q '(let ((b (persist/durable-backend)))
+  (list (persist/count b "r")
+        (persist/last-seq b "r")
+        (get (get (nth (persist/read b "r") 1) :data) :n)
+        (persist/kv-get b "survive")))')")
+check "recovered after restart" "$GOT" '(2 2 2 "yes")'
+
+echo "== blob: content-addressed put/get/has? round-trip =="
+GOT=$(run_eval "$(q '(let ((bs (persist/blob-store-backend)))
+  (let ((r (persist/blob-store bs "hello world" "text/plain")))
+    (list (persist/blob-size r)
+          (persist/blob-mime r)
+          (persist/blob-fetch bs r)
+          (persist/blob-exists? bs r))))')")
+check "blob size/mime/fetch/exists" "$GOT" '(11 "text/plain" "hello world" true)'
+
+echo "== blob: put is content-addressed (idempotent cid) =="
+GOT=$(run_eval "$(q '(let ((bs (persist/blob-store-backend)))
+  (equal? (persist/blob-cid (persist/blob-store bs "same bytes" "x"))
+          (persist/blob-cid (persist/blob-store bs "same bytes" "x"))))')")
+check "same bytes -> same cid" "$GOT" "true"
+
+echo "== blob: bytes + ref-in-kv survive a REAL restart =="
+# process A: store a blob, keep only its ref in the durable kv.
+run_eval "$(q '(let ((b (persist/durable-backend)) (bs (persist/blob-store-backend)))
+  (begin (persist/kv-put b "logo" (persist/blob-store bs "PNGDATA" "image/png")) nil))')" >/dev/null
+# fresh process: read the ref from kv, fetch the bytes from the blob store.
+GOT=$(run_eval "$(q '(let ((b (persist/durable-backend)) (bs (persist/blob-store-backend)))
+  (let ((r (persist/kv-get b "logo")))
+    (list (persist/blob-fetch bs r) (persist/blob-exists? bs r) (persist/blob-mime r))))')")
+check "blob recovered via ref after restart" "$GOT" '("PNGDATA" true "image/png")'
+
+echo
+echo "durable adapter: $PASS passed, $FAIL failed"
+[ "$FAIL" -eq 0 ]

lib/feed/acl.sx

@@ -0,0 +1,38 @@
+; feed/acl — per-viewer visibility filtering. The same candidate stream yields
+; different timelines for different viewers, so ACL is applied per request and
+; pre-ACL timelines are never cached.
+;
+; permit? is injected: (permit? viewer activity) -> bool. Wire a real acl-sx
+; predicate here; feed/permit-acl? is a self-contained default that reads an
+; optional :visible-to allowlist on the activity.
+;
+; Requires: lib/feed/normalize.sx, lib/feed/stream.sx, lib/feed/fanout.sx
+; (feed/-elem?), lib/feed/rank.sx (feed/top).
+
+; default permit: actor always sees own activity; absent/nil :visible-to is
+; public; otherwise viewer must be in the allowlist.
+(define
+  feed/permit-acl?
+  (fn
+    (viewer a)
+    (or
+      (equal? viewer (get a :actor))
+      (let
+        ((allowed (get a :visible-to nil)))
+        (if (= allowed nil) true (feed/-elem? viewer allowed))))))
+
+(define feed/permit-public? (fn (viewer a) true))
+
+; filter a stream to what viewer may read
+(define
+  feed/visible
+  (fn
+    (stream viewer permit?)
+    (feed/filter stream (fn (a) (permit? viewer a)))))
+
+; the capstone: candidate stream -> ACL for viewer -> rank -> top-N
+(define
+  feed/timeline
+  (fn
+    (stream viewer permit? score-fn n)
+    (feed/top (feed/visible stream viewer permit?) score-fn n)))

lib/feed/aggregate.sx

@@ -0,0 +1,62 @@
+; feed/aggregate — group-by / counting via key-reduce. Keys must be strings
+; (dict keys), so composite keys (actor, day) are joined into one string.
+;
+; Requires: lib/feed/normalize.sx, lib/feed/stream.sx.
+
+; group activities into a dict: key-string -> (list of activities), order-preserving
+(define
+  feed/group-by
+  (fn
+    (stream key-fn)
+    (reduce
+      (fn
+        (g a)
+        (let
+          ((k (key-fn a)))
+          (assoc g k (append (get g k (list)) (list a)))))
+      {}
+      (feed/items stream))))
+
+; key-string -> count
+(define
+  feed/group-count
+  (fn
+    (stream key-fn)
+    (reduce
+      (fn
+        (g a)
+        (let
+          ((k (key-fn a)))
+          (assoc g k (+ (get g k 0) 1))))
+      {}
+      (feed/items stream))))
+
+; --- composite keys ---------------------------------------------------------
+
+(define feed/day (fn (at window) (floor (/ at window))))
+
+; (actor, day-bucket) -> "actor#day"
+(define
+  feed/actor-day-key
+  (fn
+    (window)
+    (fn
+      (a)
+      (string-append
+        (get a :actor)
+        "#"
+        (number->string (feed/day (get a :at) window))))))
+
+(define
+  feed/by-actor-day
+  (fn (stream window) (feed/group-count stream (feed/actor-day-key window))))
+
+; per-actor activity counts
+(define
+  feed/actor-counts
+  (fn (stream) (feed/group-count stream feed/actor)))
+
+; per-object activity counts (engagement)
+(define
+  feed/object-counts
+  (fn (stream) (feed/group-count stream feed/object)))

lib/feed/api.sx

@@ -0,0 +1,24 @@
+; feed/api — ergonomic API over the stream layer for non-APL callers.
+; A single mutable activity log; post appends, all returns it as a stream.
+;
+; Requires: lib/feed/normalize.sx, lib/feed/stream.sx (loaded by harness).
+
+(define feed/-log (list))
+
+; post — normalize then append. Returns the stored activity.
+(define
+  feed/post
+  (fn
+    (raw)
+    (let
+      ((a (feed/normalize raw)))
+      (begin (set! feed/-log (append feed/-log (list a))) a))))
+
+; all — the whole log as a stream (insertion order)
+(define feed/all (fn () (feed/stream feed/-log)))
+
+; reset! — clear the log (test hygiene)
+(define feed/reset! (fn () (begin (set! feed/-log (list)) nil)))
+
+; size — number of posted activities
+(define feed/size (fn () (len feed/-log)))

lib/feed/conformance.sh

@@ -0,0 +1,125 @@
+#!/usr/bin/env bash
+# lib/feed/conformance.sh — run feed test suites, emit scoreboard.json + scoreboard.md.
+
+set -uo pipefail
+cd "$(git rev-parse --show-toplevel)"
+
+SX_SERVER="${SX_SERVER:-/root/rose-ash/hosts/ocaml/_build/default/bin/sx_server.exe}"
+if [ ! -x "$SX_SERVER" ]; then
+  SX_SERVER="hosts/ocaml/_build/default/bin/sx_server.exe"
+fi
+if [ ! -x "$SX_SERVER" ]; then
+  echo "ERROR: sx_server.exe not found." >&2
+  exit 1
+fi
+
+SUITES=(basic fanout rank integration content notify home dedupe trending mute page thread)
+
+OUT_JSON="lib/feed/scoreboard.json"
+OUT_MD="lib/feed/scoreboard.md"
+
+run_suite() {
+  local suite=$1
+  local file="lib/feed/tests/${suite}.sx"
+  local TMP
+  TMP=$(mktemp)
+  cat > "$TMP" << EPOCHS
+(epoch 1)
+(load "spec/stdlib.sx")
+(load "lib/r7rs.sx")
+(load "lib/apl/runtime.sx")
+(load "lib/feed/normalize.sx")
+(load "lib/feed/stream.sx")
+(load "lib/feed/api.sx")
+(load "lib/feed/fanout.sx")
+(load "lib/feed/dedupe.sx")
+(load "lib/feed/aggregate.sx")
+(load "lib/feed/rank.sx")
+(load "lib/feed/acl.sx")
+(load "lib/feed/fed.sx")
+(load "lib/feed/content.sx")
+(load "lib/feed/notify.sx")
+(load "lib/feed/home.sx")
+(load "lib/feed/trending.sx")
+(load "lib/feed/mute.sx")
+(load "lib/feed/page.sx")
+(load "lib/feed/thread.sx")
+(epoch 2)
+(eval "(define feed-test-pass 0)")
+(eval "(define feed-test-fail 0)")
+(eval "(define feed-test (fn (name got expected) (if (= got expected) (set! feed-test-pass (+ feed-test-pass 1)) (set! feed-test-fail (+ feed-test-fail 1)))))")
+(epoch 3)
+(load "${file}")
+(epoch 4)
+(eval "(list feed-test-pass feed-test-fail)")
+EPOCHS
+
+  local OUTPUT
+  OUTPUT=$(timeout 300 "$SX_SERVER" < "$TMP" 2>/dev/null)
+  rm -f "$TMP"
+
+  local LINE
+  LINE=$(echo "$OUTPUT" | awk '/^\(ok-len 4 / {getline; print; exit}')
+  if [ -z "$LINE" ]; then
+    LINE=$(echo "$OUTPUT" | grep -E '^\(ok 4 \([0-9]+ [0-9]+\)\)' | tail -1 \
+            | sed -E 's/^\(ok 4 //; s/\)$//')
+  fi
+
+  local P F
+  P=$(echo "$LINE" | sed -E 's/^\(([0-9]+) ([0-9]+)\).*/\1/')
+  F=$(echo "$LINE" | sed -E 's/^\(([0-9]+) ([0-9]+)\).*/\2/')
+  P=${P:-0}
+  F=${F:-0}
+  echo "${P} ${F}"
+}
+
+declare -A SUITE_PASS
+declare -A SUITE_FAIL
+TOTAL_PASS=0
+TOTAL_FAIL=0
+
+echo "Running feed conformance suite..." >&2
+for s in "${SUITES[@]}"; do
+  read -r p f < <(run_suite "$s")
+  SUITE_PASS[$s]=$p
+  SUITE_FAIL[$s]=$f
+  TOTAL_PASS=$((TOTAL_PASS + p))
+  TOTAL_FAIL=$((TOTAL_FAIL + f))
+  printf "  %-12s %d/%d\n" "$s" "$p" "$((p+f))" >&2
+done
+
+# scoreboard.json
+{
+  printf '{\n'
+  printf '  "suites": {\n'
+  first=1
+  for s in "${SUITES[@]}"; do
+    if [ $first -eq 0 ]; then printf ',\n'; fi
+    printf '    "%s": {"pass": %d, "fail": %d}' "$s" "${SUITE_PASS[$s]}" "${SUITE_FAIL[$s]}"
+    first=0
+  done
+  printf '\n  },\n'
+  printf '  "total_pass": %d,\n' "$TOTAL_PASS"
+  printf '  "total_fail": %d,\n' "$TOTAL_FAIL"
+  printf '  "total": %d\n' "$((TOTAL_PASS + TOTAL_FAIL))"
+  printf '}\n'
+} > "$OUT_JSON"
+
+# scoreboard.md
+{
+  printf '# feed Conformance Scoreboard\n\n'
+  printf '_Generated by `lib/feed/conformance.sh`_\n\n'
+  printf '| Suite | Pass | Fail | Total |\n'
+  printf '|-------|-----:|-----:|------:|\n'
+  for s in "${SUITES[@]}"; do
+    p=${SUITE_PASS[$s]}
+    f=${SUITE_FAIL[$s]}
+    printf '| %s | %d | %d | %d |\n' "$s" "$p" "$f" "$((p+f))"
+  done
+  printf '| **Total** | **%d** | **%d** | **%d** |\n' "$TOTAL_PASS" "$TOTAL_FAIL" "$((TOTAL_PASS + TOTAL_FAIL))"
+} > "$OUT_MD"
+
+echo "Wrote $OUT_JSON and $OUT_MD" >&2
+echo "Total: $TOTAL_PASS pass, $TOTAL_FAIL fail" >&2
+
+[ "$TOTAL_FAIL" -eq 0 ]

lib/feed/content.sx

@@ -0,0 +1,68 @@
+; feed/content — TF-IDF relevance over activity :tags. Rare tags carry more
+; signal, so an activity matching an uncommon tag ranks above one matching a
+; common tag. Composes with rank.sx: feed/tfidf-score is just another scorer.
+;
+; Requires: lib/feed/normalize.sx, lib/feed/stream.sx, lib/feed/fanout.sx
+; (feed/-distinct), lib/feed/rank.sx (feed/rank).
+
+; document frequency: tag -> number of activities whose :tags contain it
+; (a tag repeated within one activity counts once toward df)
+(define
+  feed/tag-df
+  (fn
+    (stream)
+    (reduce
+      (fn
+        (df a)
+        (reduce
+          (fn (d t) (assoc d t (+ (get d t 0) 1)))
+          df
+          (feed/-distinct (get a :tags))))
+      {}
+      (feed/items stream))))
+
+; inverse document frequency: tag -> log(N / df)
+(define
+  feed/tag-idf
+  (fn
+    (stream)
+    (let
+      ((n (feed/count stream)) (df (feed/tag-df stream)))
+      (reduce
+        (fn (idf t) (assoc idf t (log (/ n (get df t)))))
+        {}
+        (keys df)))))
+
+; term frequency within one activity: tag -> occurrence count
+(define
+  feed/-tf
+  (fn
+    (a)
+    (reduce
+      (fn (tf t) (assoc tf t (+ (get tf t 0) 1)))
+      {}
+      (get a :tags))))
+
+; relevance of an activity to a query (list of tags) given precomputed idf:
+; sum over query tags of tf(tag in activity) * idf(tag in corpus)
+(define
+  feed/tfidf-score
+  (fn
+    (idf query)
+    (fn
+      (a)
+      (let
+        ((tf (feed/-tf a)))
+        (reduce
+          (fn
+            (acc t)
+            (+ acc (* (get tf t 0) (get idf t 0))))
+          0
+          query)))))
+
+; rank a stream by relevance to query tags (idf computed over the stream itself)
+(define
+  feed/by-relevance
+  (fn
+    (stream query)
+    (feed/rank stream (feed/tfidf-score (feed/tag-idf stream) query))))

lib/feed/dedupe.sx

@@ -0,0 +1,76 @@
+; feed/dedupe — collapse duplicate items, keeping first occurrence per key.
+; Each verb may want its own key (see briefing): "alice posted X" keys on
+; (actor verb object) — distinct per actor; "alice liked X / bob liked X"
+; collapse on (verb object) so the cross-actor likes fold into one.
+;
+; Requires: lib/feed/normalize.sx, lib/feed/stream.sx, lib/feed/fanout.sx
+; (feed/-elem? lives in fanout.sx).
+
+; generic: dedupe a stream by key-fn, first occurrence wins (stable)
+(define
+  feed/-dedup-by
+  (fn
+    (items key-fn)
+    (get
+      (reduce
+        (fn
+          (st x)
+          (let
+            ((k (key-fn x)))
+            (if (feed/-elem? k (get st :seen)) st {:seen (append (get st :seen) (list k)) :out (append (get st :out) (list x))})))
+        {:seen (list) :out (list)}
+        items)
+      :out)))
+
+(define
+  feed/dedupe
+  (fn
+    (stream key-fn)
+    (feed/stream (feed/-dedup-by (feed/items stream) key-fn))))
+
+; --- keys -------------------------------------------------------------------
+
+(define
+  feed/activity-key
+  (fn (a) (list (get a :actor) (get a :verb) (get a :object))))
+
+; collapse cross-actor duplicates of the same verb+object (e.g. likes)
+(define feed/collapse-key (fn (a) (list (get a :verb) (get a :object))))
+
+; per-receiver inbox key — one inbox event per (receiver, actor, verb, object)
+(define
+  feed/event-key
+  (fn
+    (ev)
+    (let
+      ((a (get ev :activity)))
+      (list (get ev :to) (get a :actor) (get a :verb) (get a :object)))))
+
+; verbs whose duplicates collapse across actors (reactions, not authorship).
+; rebindable: callers can (set! feed/collapse-verbs ...) to tune the policy.
+(define
+  feed/collapse-verbs
+  (list "like" "favourite" "follow" "boost" "repost"))
+
+; per-verb key: collapse-verbs fold on (verb object); the rest key on
+; (actor verb object).
+(define
+  feed/smart-key
+  (fn
+    (a)
+    (if
+      (feed/-elem? (get a :verb) feed/collapse-verbs)
+      (feed/collapse-key a)
+      (feed/activity-key a))))
+
+; --- ready-made dedupers ----------------------------------------------------
+
+(define feed/dedupe-activities (fn (s) (feed/dedupe s feed/activity-key)))
+
+(define feed/dedupe-collapse (fn (s) (feed/dedupe s feed/collapse-key)))
+
+; verb-aware: reactions collapse cross-actor, posts stay distinct per actor
+(define feed/dedupe-smart (fn (s) (feed/dedupe s feed/smart-key)))
+
+; dedupe an inbox: at most one event per receiver per (actor verb object)
+(define feed/dedupe-inbox (fn (inbox) (feed/dedupe inbox feed/event-key)))

lib/feed/fanout.sx

@@ -0,0 +1,114 @@
+; feed/fanout — THE SHOWCASE. Fan activities out to followers via the APL outer
+; product (∘.×). activities ∘.× audience → an (activity × follower) matrix of
+; inbox events; flatten to a vector; guard-keep only real follow edges.
+;
+; Requires: lib/apl/runtime.sx, lib/feed/normalize.sx, lib/feed/stream.sx.
+;
+; NOTE: apl-outer's combiner result is run through (if (scalar? r) (disclose r) r).
+; A bare dict counts as a scalar (shape ()) and disclose nils it — so the combiner
+; must (enclose ...) its event dict; apl-outer then discloses it back intact.
+
+; --- graph: {followee -> (list of followers)} -------------------------------
+
+(define feed/followers (fn (graph user) (get graph user (list))))
+
+; build a graph from (follower followee) edges: "follower follows followee"
+(define
+  feed/follow-graph
+  (fn
+    (edges)
+    (reduce
+      (fn
+        (g e)
+        (let
+          ((follower (first e)) (followee (nth e 1)))
+          (assoc
+            g
+            followee
+            (append (feed/followers g followee) (list follower)))))
+      {}
+      edges)))
+
+; --- helpers ----------------------------------------------------------------
+
+; unwrap an apl-scalar (has :ravel) back to its value; pass activities through
+(define
+  feed/-val
+  (fn
+    (x)
+    (if (and (= (type-of x) "dict") (has-key? x :ravel)) (disclose x) x)))
+
+(define feed/-elem? (fn (x lst) (some (fn (y) (equal? x y)) lst)))
+
+(define
+  feed/-distinct
+  (fn
+    (lst)
+    (if
+      (= (len lst) 0)
+      (list)
+      (get (apl-unique (make-array (list (len lst)) lst)) :ravel))))
+
+; rank-2 matrix -> rank-1 stream of its ravel
+(define feed/-flatten (fn (arr) (feed/stream (get arr :ravel))))
+
+; distinct receivers across the whole graph, sorted for determinism
+; (dict key order is unspecified, so sort to pin audience/recipient ordering)
+(define
+  feed/audience
+  (fn
+    (graph)
+    (sort
+      (feed/-distinct
+        (reduce
+          (fn (acc k) (append acc (feed/followers graph k)))
+          (list)
+          (keys graph))))))
+
+; --- the outer product ------------------------------------------------------
+
+; one (activity, follower) inbox event, enclosed so apl-outer keeps the dict
+(define feed/-mk-event (fn (a f) (enclose {:activity (feed/-val a) :to (feed/-val f)})))
+
+; keep events where :to actually follows the activity's actor
+(define
+  feed/-edge?
+  (fn
+    (graph)
+    (fn
+      (ev)
+      (feed/-elem?
+        (get ev :to)
+        (feed/followers graph (get (get ev :activity) :actor))))))
+
+; fanout — activities ∘.× audience, flatten, guard-keep real edges
+(define
+  feed/fanout
+  (fn
+    (stream graph)
+    (let
+      ((matrix (apl-outer feed/-mk-event stream (feed/stream (feed/audience graph)))))
+      (feed/filter (feed/-flatten matrix) (feed/-edge? graph)))))
+
+; --- inbox queries ----------------------------------------------------------
+
+(define
+  feed/inbox-for
+  (fn
+    (inbox user)
+    (feed/filter inbox (fn (ev) (equal? (get ev :to) user)))))
+
+(define
+  feed/recipients
+  (fn
+    (inbox)
+    (feed/-distinct (map (fn (ev) (get ev :to)) (feed/items inbox)))))
+
+; the activities (unwrapped) destined for a user
+(define
+  feed/inbox-activities
+  (fn
+    (inbox user)
+    (map
+      (fn (ev) (get ev :activity))
+      (feed/items (feed/inbox-for inbox user)))))

lib/feed/fed.sx

@@ -0,0 +1,60 @@
+; feed/fed — federation. Outbound: a local post fans out, then splits into local
+; vs remote inboxes; remote events are handed to an injected send-fn. Inbound:
+; peer activities merge into the local stream, deduped. Backfill: pull peer
+; history via an injected fetch-fn and merge.
+;
+; remote? / send-fn / fetch-fn are injected so real fed-sx transport wires in here
+; without feed depending on it.
+;
+; Requires: lib/feed/normalize.sx, lib/feed/stream.sx, lib/feed/fanout.sx,
+; lib/feed/dedupe.sx.
+
+; --- merge / ingest ---------------------------------------------------------
+
+(define
+  feed/merge
+  (fn (s1 s2) (feed/stream (append (feed/items s1) (feed/items s2)))))
+
+; merge a peer stream into local, dropping (actor verb object) duplicates
+(define
+  feed/ingest
+  (fn (local peer) (feed/dedupe-activities (feed/merge local peer))))
+
+; --- inbound ----------------------------------------------------------------
+
+; peer pushes raw activities to the local inbox; normalize + ingest
+(define
+  feed/inbound
+  (fn
+    (local raw-activities)
+    (feed/ingest local (feed/stream (map feed/normalize raw-activities)))))
+
+; backfill on subscribe: pull peer history via fetch-fn, normalize, ingest
+(define
+  feed/backfill
+  (fn (local fetch-fn peer-id) (feed/inbound local (fetch-fn peer-id))))
+
+; --- outbound ---------------------------------------------------------------
+
+; split an inbox into local vs remote deliveries by viewer-id predicate
+(define feed/partition-inbox (fn (inbox remote?) {:local (feed/filter inbox (fn (ev) (not (remote? (get ev :to))))) :remote (feed/filter inbox (fn (ev) (remote? (get ev :to))))}))
+
+; fan a stream out over the graph, then partition by locality
+(define
+  feed/federate
+  (fn
+    (stream graph remote?)
+    (feed/partition-inbox (feed/fanout stream graph) remote?)))
+
+; deliver: hand each remote event to send-fn, return the local inbox to enqueue
+(define
+  feed/deliver
+  (fn
+    (stream graph remote? send-fn)
+    (let
+      ((parts (feed/federate stream graph remote?)))
+      (begin
+        (for-each
+          (fn (ev) (send-fn (get ev :to) (get ev :activity)))
+          (feed/items (get parts :remote)))
+        (get parts :local)))))

lib/feed/home.sx

@@ -0,0 +1,23 @@
+; feed/home — the capstone. A user's home timeline is the whole pipeline as one
+; line: fan all activities out over the follow graph, take the events landing in
+; the viewer's inbox, dedupe cross-posts, apply the viewer's ACL, rank, take N.
+;
+; Requires: fanout.sx, dedupe.sx, acl.sx (feed/timeline), rank.sx, stream.sx.
+
+; the activities in a user's inbox, as a stream
+(define
+  feed/inbox-stream
+  (fn (inbox user) (feed/stream (feed/inbox-activities inbox user))))
+
+; fanout ∘ inbox ∘ dedupe ∘ ACL ∘ rank ∘ take
+(define
+  feed/home
+  (fn
+    (stream graph viewer permit? score-fn n)
+    (feed/timeline
+      (feed/dedupe-activities
+        (feed/inbox-stream (feed/fanout stream graph) viewer))
+      viewer
+      permit?
+      score-fn
+      n)))

lib/feed/mute.sx

@@ -0,0 +1,44 @@
+; feed/mute — viewer-controlled filtering. ACL (acl.sx) is author-controlled
+; visibility; mute is the reader's own preference: hide muted actors or tags.
+; Like ACL it is per-viewer and applied per request, never cached.
+;
+; Requires: lib/feed/normalize.sx, lib/feed/stream.sx, lib/feed/fanout.sx
+; (feed/-elem?).
+
+; drop activities authored by a muted actor
+(define
+  feed/mute-actors
+  (fn
+    (stream actors)
+    (feed/filter
+      stream
+      (fn (a) (not (feed/-elem? (get a :actor) actors))))))
+
+; drop activities carrying any muted tag
+(define
+  feed/mute-tags
+  (fn
+    (stream tags)
+    (feed/filter
+      stream
+      (fn (a) (not (some (fn (t) (feed/-elem? t tags)) (get a :tags)))))))
+
+; drop activities about a muted object (thread mute)
+(define
+  feed/mute-objects
+  (fn
+    (stream objects)
+    (feed/filter
+      stream
+      (fn (a) (not (feed/-elem? (get a :object) objects))))))
+
+; apply a viewer preference bag: {:mute-actors (...) :mute-tags (...) :mute-objects (...)}
+(define
+  feed/apply-prefs
+  (fn
+    (stream prefs)
+    (feed/mute-objects
+      (feed/mute-tags
+        (feed/mute-actors stream (get prefs :mute-actors (list)))
+        (get prefs :mute-tags (list)))
+      (get prefs :mute-objects (list)))))

lib/feed/normalize.sx

@@ -0,0 +1,31 @@
+; feed/normalize — coerce arbitrary input into the canonical activity record.
+; An activity is a small dict {:actor :verb :object :at :tags}; a stream is an
+; APL vector of such dicts (see stream.sx). Extra keys on the raw input survive
+; (e.g. :visible-to for ACL, peer metadata for federation) — :tags is the
+; flexible bag but the record is not closed.
+
+(define feed/activity-keys (list :actor :verb :object :at :tags))
+
+(define
+  feed/normalize
+  (fn
+    (raw)
+    (let
+      ((d (if (= (type-of raw) "dict") raw {})))
+      (merge d {:actor (get d :actor "") :object (get d :object nil) :at (get d :at 0) :tags (let ((t (get d :tags (list)))) (if (list? t) t (list t))) :verb (get d :verb "post")}))))
+
+(define
+  feed/activity
+  (fn (actor verb object at tags) (feed/normalize {:actor actor :object object :at at :tags tags :verb verb})))
+
+(define feed/actor (fn (a) (get a :actor)))
+(define feed/verb (fn (a) (get a :verb)))
+(define feed/object (fn (a) (get a :object)))
+(define feed/at (fn (a) (get a :at)))
+(define feed/tags (fn (a) (get a :tags)))
+
+(define
+  feed/activity?
+  (fn
+    (a)
+    (and (= (type-of a) "dict") (has-key? a :actor) (has-key? a :verb))))

lib/feed/notify.sx

@@ -0,0 +1,45 @@
+; feed/notify — a notification feed is a thin layer over a recipient's inbox:
+; the events directed at a user, optionally verb-filtered, and a digest that
+; collapses "alice, bob and 1 other liked X" by (verb, object).
+;
+; Requires: lib/feed/normalize.sx, lib/feed/stream.sx, lib/feed/fanout.sx
+; (feed/inbox-for, feed/-elem?).
+
+; all inbox events for a user (their raw notifications)
+(define feed/notifications (fn (inbox user) (feed/inbox-for inbox user)))
+
+; restrict to notification-worthy verbs (e.g. (list "like" "reply" "follow"))
+(define
+  feed/notify-verbs
+  (fn
+    (inbox user verbs)
+    (feed/filter
+      (feed/inbox-for inbox user)
+      (fn (ev) (feed/-elem? (get (get ev :activity) :verb) verbs)))))
+
+; group key "verb|object" — deterministic, sortable
+(define
+  feed/-notify-key
+  (fn
+    (ev)
+    (let
+      ((a (get ev :activity)))
+      (string-append (get a :verb) "|" (get a :object)))))
+
+; digest: one entry per (verb, object) with the distinct actors and a count,
+; ordered by key for determinism.
+(define
+  feed/notify-digest
+  (fn
+    (inbox user)
+    (let
+      ((events (feed/items (feed/inbox-for inbox user))))
+      (let
+        ((groups (reduce (fn (g ev) (let ((a (get ev :activity)) (k (feed/-notify-key ev))) (let ((cur (get g k {:object (get a :object) :actors (list) :verb (get a :verb)}))) (assoc g k (assoc cur :actors (append (get cur :actors) (list (get a :actor)))))))) {} events)))
+        (map
+          (fn
+            (k)
+            (let
+              ((grp (get groups k)))
+              (assoc grp :count (len (get grp :actors)))))
+          (sort (keys groups)))))))

lib/feed/page.sx

@@ -0,0 +1,50 @@
+; feed/page — pagination. Offset/limit for indexed access, and cursor-based
+; (by :at) for recency feeds, which is stable under inserts: a cursor is the
+; :at of the last item seen, and the next page is the newest items older than it.
+;
+; Requires: lib/feed/stream.sx (feed/recent, feed/take, feed/filter).
+
+; --- offset / limit ---------------------------------------------------------
+
+(define
+  feed/page
+  (fn
+    (stream offset limit)
+    (feed/stream (take (drop (feed/items stream) offset) limit))))
+
+(define
+  feed/page-count
+  (fn (stream limit) (ceil (/ (feed/count stream) limit))))
+
+; --- cursor (recency feeds) -------------------------------------------------
+
+; activities strictly older than cursor (scroll down / load older)
+(define
+  feed/before
+  (fn
+    (stream cursor)
+    (feed/filter stream (fn (a) (< (get a :at) cursor)))))
+
+; activities strictly newer than cursor (load newer / "N new posts")
+(define
+  feed/after
+  (fn
+    (stream cursor)
+    (feed/filter stream (fn (a) (> (get a :at) cursor)))))
+
+; one page: the `limit` newest activities older than cursor, newest first
+(define
+  feed/page-before
+  (fn
+    (stream cursor limit)
+    (feed/take (feed/recent (feed/before stream cursor)) limit)))
+
+; cursor to fetch the next (older) page: :at of the last item of a page,
+; or nil when the page is empty (end of feed)
+(define
+  feed/next-cursor
+  (fn
+    (page)
+    (let
+      ((items (feed/items page)))
+      (if (= (len items) 0) nil (get (last items) :at)))))

lib/feed/rank.sx

@@ -0,0 +1,92 @@
+; feed/rank — scoring + ranking. Scorers are (activity -> number). Ranking is a
+; stable two-pass grade-down: first by :at descending (the tiebreak), then by
+; score descending — so ties resolve by recency, then by input order. Fully
+; deterministic on ties.
+;
+; Requires: lib/apl/runtime.sx, lib/feed/normalize.sx, lib/feed/stream.sx.
+
+; --- scorers ----------------------------------------------------------------
+
+; recency: half-life decay. score = 0.5 ^ (age / half-life). at==now -> 1.0.
+(define
+  feed/recency
+  (fn
+    (now half-life)
+    (fn (a) (expt 0.5 (/ (- now (get a :at)) half-life)))))
+
+; velocity: how many of this actor's activities fall in (at-window, at] —
+; a burst of recent activity scores higher.
+(define
+  feed/velocity
+  (fn
+    (stream window)
+    (fn
+      (a)
+      (len
+        (filter
+          (fn
+            (b)
+            (and
+              (equal? (get b :actor) (get a :actor))
+              (<= (get b :at) (get a :at))
+              (> (get b :at) (- (get a :at) window))))
+          (feed/items stream))))))
+
+; engagement: how many activities in the stream touch this activity's :object
+(define
+  feed/engagement
+  (fn
+    (stream)
+    (fn
+      (a)
+      (len
+        (filter
+          (fn (b) (equal? (get b :object) (get a :object)))
+          (feed/items stream))))))
+
+; composite: weighted sum. parts = (list (list weight scorer) ...)
+(define
+  feed/composite
+  (fn
+    (parts)
+    (fn
+      (a)
+      (reduce
+        (fn (acc p) (+ acc (* (first p) ((nth p 1) a))))
+        0
+        parts))))
+
+; --- ranking ----------------------------------------------------------------
+
+; stable reorder of items by key-fn, descending (grade-down is stable)
+(define
+  feed/-desc-by
+  (fn
+    (items key-fn)
+    (let
+      ((keys (make-array (list (len items)) (map key-fn items))))
+      (let
+        ((order (get (apl-grade-down keys) :ravel)))
+        (map (fn (i) (nth items (- i 1))) order)))))
+
+; rank by score descending; ties -> :at descending -> input order
+(define
+  feed/rank
+  (fn
+    (stream score-fn)
+    (let
+      ((by-at (feed/-desc-by (feed/items stream) feed/at)))
+      (feed/stream (feed/-desc-by by-at score-fn)))))
+
+; attach a :score to each activity (for inspection / debugging)
+(define
+  feed/with-scores
+  (fn
+    (stream score-fn)
+    (feed/stream
+      (map (fn (a) (assoc a :score (score-fn a))) (feed/items stream)))))
+
+; top-N ranked timeline
+(define
+  feed/top
+  (fn (stream score-fn n) (feed/take (feed/rank stream score-fn) n)))

lib/feed/scoreboard.json

@@ -0,0 +1,19 @@
+{
+  "suites": {
+    "basic": {"pass": 30, "fail": 0},
+    "fanout": {"pass": 29, "fail": 0},
+    "rank": {"pass": 24, "fail": 0},
+    "integration": {"pass": 22, "fail": 0},
+    "content": {"pass": 15, "fail": 0},
+    "notify": {"pass": 8, "fail": 0},
+    "home": {"pass": 6, "fail": 0},
+    "dedupe": {"pass": 9, "fail": 0},
+    "trending": {"pass": 11, "fail": 0},
+    "mute": {"pass": 9, "fail": 0},
+    "page": {"pass": 14, "fail": 0},
+    "thread": {"pass": 12, "fail": 0}
+  },
+  "total_pass": 189,
+  "total_fail": 0,
+  "total": 189
+}

lib/feed/scoreboard.md

@@ -0,0 +1,19 @@
+# feed Conformance Scoreboard
+
+_Generated by `lib/feed/conformance.sh`_
+
+| Suite | Pass | Fail | Total |
+|-------|-----:|-----:|------:|
+| basic | 30 | 0 | 30 |
+| fanout | 29 | 0 | 29 |
+| rank | 24 | 0 | 24 |
+| integration | 22 | 0 | 22 |
+| content | 15 | 0 | 15 |
+| notify | 8 | 0 | 8 |
+| home | 6 | 0 | 6 |
+| dedupe | 9 | 0 | 9 |
+| trending | 11 | 0 | 11 |
+| mute | 9 | 0 | 9 |
+| page | 14 | 0 | 14 |
+| thread | 12 | 0 | 12 |
+| **Total** | **189** | **0** | **189** |

lib/feed/stream.sx

@@ -0,0 +1,75 @@
+; feed/stream — a stream is an APL vector (rank-1 array) whose ravel holds
+; activity dicts. Operations lift APL primitives onto this shape: filter via
+; compress (/), sort via grade (⍋), take via ↑, reverse via ⌽.
+;
+; Requires: lib/apl/runtime.sx, lib/feed/normalize.sx (loaded by harness).
+
+(define feed/stream (fn (acts) (make-array (list (len acts)) acts)))
+
+(define feed/items (fn (s) (get s :ravel)))
+
+(define feed/count (fn (s) (len (get s :ravel))))
+
+(define feed/empty (feed/stream (list)))
+
+(define feed/empty? (fn (s) (= (feed/count s) 0)))
+
+; filter — bool mask ∘ compress. pred : activity -> truthy
+(define
+  feed/filter
+  (fn
+    (s pred)
+    (let
+      ((items (get s :ravel)))
+      (let
+        ((mask (make-array (list (len items)) (map (fn (a) (if (pred a) 1 0)) items))))
+        (apl-compress mask s)))))
+
+; sort-by — ascending, stable on ties (grade-up is stable). key-fn : activity -> number
+(define
+  feed/sort-by
+  (fn
+    (s key-fn)
+    (let
+      ((items (get s :ravel)))
+      (let
+        ((keys (make-array (list (len items)) (map key-fn items))))
+        (let
+          ((order (get (apl-grade-up keys) :ravel)))
+          (feed/stream (map (fn (i) (nth items (- i 1))) order)))))))
+
+(define feed/sort-by-at (fn (s) (feed/sort-by s feed/at)))
+
+; newest-first: ascending sort then reverse (⌽)
+(define feed/recent (fn (s) (apl-reverse (feed/sort-by-at s))))
+
+; take N (↑), clamped to stream length so it never over-takes/pads
+(define
+  feed/take
+  (fn
+    (s n)
+    (let
+      ((c (feed/count s)))
+      (if (>= n c) s (apl-take (apl-scalar n) s)))))
+
+(define feed/reverse (fn (s) (apl-reverse s)))
+
+; common predicates
+(define
+  feed/by-actor
+  (fn (s actor) (feed/filter s (fn (a) (equal? (get a :actor) actor)))))
+
+(define
+  feed/by-verb
+  (fn (s verb) (feed/filter s (fn (a) (equal? (get a :verb) verb)))))
+
+(define
+  feed/by-object
+  (fn
+    (s object)
+    (feed/filter s (fn (a) (equal? (get a :object) object)))))
+
+; activities at or after timestamp t
+(define
+  feed/since
+  (fn (s t) (feed/filter s (fn (a) (>= (get a :at) t)))))

lib/feed/tests/basic.sx

@@ -0,0 +1,118 @@
+; Phase 1 — normalize, stream ops, api. Uses the feed-test harness
+; (feed-test name got expected) provided by conformance.sh.
+
+; ---------- normalize ----------
+
+(feed-test
+  "normalize default actor"
+  (feed/actor (feed/normalize {}))
+  "")
+(feed-test
+  "normalize default verb"
+  (feed/verb (feed/normalize {}))
+  "post")
+(feed-test
+  "normalize default at"
+  (feed/at (feed/normalize {}))
+  0)
+(feed-test
+  "normalize default object"
+  (feed/object (feed/normalize {}))
+  nil)
+(feed-test
+  "normalize default tags"
+  (feed/tags (feed/normalize {}))
+  (list))
+(feed-test
+  "normalize keeps actor"
+  (feed/actor (feed/normalize {:actor "alice"}))
+  "alice")
+(feed-test
+  "normalize keeps verb"
+  (feed/verb (feed/normalize {:verb "like"}))
+  "like")
+(feed-test
+  "normalize scalar tag -> list"
+  (feed/tags (feed/normalize {:tags "x"}))
+  (list "x"))
+(feed-test
+  "normalize list tags kept"
+  (feed/tags (feed/normalize {:tags (list "a" "b")}))
+  (list "a" "b"))
+(feed-test
+  "activity constructor at"
+  (feed/at (feed/activity "a" "post" "o" 5 (list)))
+  5)
+(feed-test
+  "activity? on activity"
+  (feed/activity? (feed/normalize {:actor "a"}))
+  true)
+(feed-test "activity? on number" (feed/activity? 5) false)
+(feed-test "activity? on bare dict" (feed/activity? {:foo 1}) false)
+
+; ---------- stream ----------
+
+(define
+  S
+  (feed/stream
+    (list
+      (feed/activity "alice" "post" "p1" 30 (list))
+      (feed/activity "bob" "like" "p1" 10 (list))
+      (feed/activity "alice" "post" "p2" 20 (list)))))
+
+(feed-test "stream count" (feed/count S) 3)
+(feed-test "stream items len" (len (feed/items S)) 3)
+(feed-test
+  "sort-by-at actors asc"
+  (map feed/actor (feed/items (feed/sort-by-at S)))
+  (list "bob" "alice" "alice"))
+(feed-test
+  "recent newest first"
+  (map feed/at (feed/items (feed/recent S)))
+  (list 30 20 10))
+(feed-test
+  "take 2 of recent"
+  (feed/count (feed/take (feed/recent S) 2))
+  2)
+(feed-test
+  "take clamps past end"
+  (feed/count (feed/take S 10))
+  3)
+(feed-test
+  "by-actor alice count"
+  (feed/count (feed/by-actor S "alice"))
+  2)
+(feed-test
+  "by-verb like actor"
+  (map feed/actor (feed/items (feed/by-verb S "like")))
+  (list "bob"))
+(feed-test
+  "by-object p1 count"
+  (feed/count (feed/by-object S "p1"))
+  2)
+(feed-test
+  "since 20 count"
+  (feed/count (feed/since S 20))
+  2)
+(feed-test
+  "reverse ats"
+  (map feed/at (feed/items (feed/reverse S)))
+  (list 20 10 30))
+(feed-test "empty? on empty" (feed/empty? feed/empty) true)
+(feed-test
+  "empty? on filtered-out"
+  (feed/empty? (feed/by-actor S "zzz"))
+  true)
+
+; ---------- api ----------
+
+(feed/reset!)
+(feed/post {:actor "x" :at 1 :verb "post"})
+(feed/post {:actor "y" :at 2 :verb "like"})
+(feed-test "api size after posts" (feed/size) 2)
+(feed-test "api all count" (feed/count (feed/all)) 2)
+(feed-test
+  "post returns normalized verb"
+  (feed/verb (feed/post {:actor "z"}))
+  "post")
+(feed-test "api size after third post" (feed/size) 3)

lib/feed/tests/content.sx

@@ -0,0 +1,85 @@
+; Follow-up — TF-IDF content ranking over :tags. (feed-test name got expected)
+
+(define
+  corpus
+  (feed/stream
+    (list
+      (feed/normalize {:actor "u" :object "o1" :at 10 :tags (list "cats" "funny")})
+      (feed/normalize {:actor "u" :object "o2" :at 20 :tags (list "cats" "news")})
+      (feed/normalize {:actor "u" :object "o3" :at 30 :tags (list "politics" "news")})
+      (feed/normalize {:actor "u" :object "o4" :at 40 :tags (list "cats")}))))
+
+; ---------- document frequency ----------
+
+(feed-test "df cats" (get (feed/tag-df corpus) "cats") 3)
+(feed-test "df news" (get (feed/tag-df corpus) "news") 2)
+(feed-test "df funny" (get (feed/tag-df corpus) "funny") 1)
+(feed-test "df politics" (get (feed/tag-df corpus) "politics") 1)
+(feed-test "df full" (feed/tag-df corpus) {:news 2 :funny 1 :politics 1 :cats 3})
+
+; ---------- inverse document frequency ----------
+
+(feed-test
+  "idf news = log(4/2)"
+  (get (feed/tag-idf corpus) "news")
+  (log 2))
+(feed-test
+  "idf funny = log(4/1)"
+  (get (feed/tag-idf corpus) "funny")
+  (log 4))
+(feed-test
+  "rarer tag has higher idf"
+  (>
+    (get (feed/tag-idf corpus) "funny")
+    (get (feed/tag-idf corpus) "cats"))
+  true)
+
+; ---------- tf-idf scoring ----------
+
+(define idf (feed/tag-idf corpus))
+
+(feed-test
+  "score query funny on o1"
+  ((feed/tfidf-score idf (list "funny")) (feed/normalize {:actor "u" :object "x" :tags (list "cats" "funny")}))
+  (log 4))
+(feed-test
+  "score query funny on non-match"
+  ((feed/tfidf-score idf (list "funny")) (feed/normalize {:actor "u" :object "x" :tags (list "cats")}))
+  0)
+(feed-test
+  "unknown query tag scores 0"
+  ((feed/tfidf-score idf (list "zzz")) (feed/normalize {:actor "u" :object "x" :tags (list "cats")}))
+  0)
+
+; ---------- ranking by relevance ----------
+
+; query news: o2,o3 match (score log2), o1,o4 don't (0); ties break by :at desc
+(feed-test
+  "by-relevance news order"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/by-relevance corpus (list "news"))))
+  (list "o3" "o2" "o4" "o1"))
+
+; query funny: only o1 matches -> ranks first
+(feed-test
+  "by-relevance funny first"
+  (get
+    (nth (feed/items (feed/by-relevance corpus (list "funny"))) 0)
+    :object)
+  "o1")
+
+; query (cats news): o2 carries both tags -> highest combined tf-idf
+(feed-test
+  "by-relevance cats+news top"
+  (get
+    (nth
+      (feed/items (feed/by-relevance corpus (list "cats" "news")))
+      0)
+    :object)
+  "o2")
+
+(feed-test
+  "by-relevance preserves count"
+  (feed/count (feed/by-relevance corpus (list "cats")))
+  4)

lib/feed/tests/dedupe.sx

@@ -0,0 +1,56 @@
+; Follow-up — verb-aware (smart) dedupe. (feed-test name got expected)
+
+; reactions (like/follow) collapse cross-actor; posts stay distinct per actor
+(define
+  M
+  (feed/stream
+    (list
+      (feed/activity "alice" "like" "X" 1 (list))
+      (feed/activity "bob" "like" "X" 2 (list))
+      (feed/activity "alice" "post" "P" 3 (list))
+      (feed/activity "bob" "post" "P" 4 (list))
+      (feed/activity "alice" "follow" "C" 5 (list))
+      (feed/activity "bob" "follow" "C" 6 (list))))) ; collapses
+
+(feed-test
+  "smart dedupe total"
+  (feed/count (feed/dedupe-smart M))
+  4)
+(feed-test
+  "smart keeps both posts"
+  (feed/count (feed/by-verb (feed/dedupe-smart M) "post"))
+  2)
+(feed-test
+  "smart collapses likes to one"
+  (feed/count (feed/by-verb (feed/dedupe-smart M) "like"))
+  1)
+(feed-test
+  "smart collapses follows to one"
+  (feed/count (feed/by-verb (feed/dedupe-smart M) "follow"))
+  1)
+(feed-test
+  "collapsed like keeps first actor"
+  (map feed/actor (feed/items (feed/by-verb (feed/dedupe-smart M) "like")))
+  (list "alice"))
+
+; contrast: plain activity dedupe keeps cross-actor likes distinct
+(feed-test
+  "activity dedupe keeps both likes"
+  (feed/count (feed/by-verb (feed/dedupe-activities M) "like"))
+  2)
+
+; contrast: blanket collapse folds the two posts (same verb+object) too
+(feed-test
+  "collapse dedupe folds posts"
+  (feed/count (feed/by-verb (feed/dedupe-collapse M) "post"))
+  1)
+
+; smart-key dispatch
+(feed-test
+  "smart-key reaction -> (verb object)"
+  (feed/smart-key (feed/activity "alice" "like" "X" 0 (list)))
+  (list "like" "X"))
+(feed-test
+  "smart-key post -> (actor verb object)"
+  (feed/smart-key (feed/activity "alice" "post" "P" 0 (list)))
+  (list "alice" "post" "P"))

lib/feed/tests/fanout.sx

@@ -0,0 +1,187 @@
+; Phase 2 — fanout via outer product + dedupe. (feed-test name got expected)
+
+; ---------- graph ----------
+
+; edges: (follower followee). bob,carol follow alice; carol,dave follow bob.
+(define
+  G
+  (feed/follow-graph
+    (list
+      (list "bob" "alice")
+      (list "carol" "alice")
+      (list "carol" "bob")
+      (list "dave" "bob"))))
+
+(feed-test "followers alice" (feed/followers G "alice") (list "bob" "carol"))
+(feed-test "followers bob" (feed/followers G "bob") (list "carol" "dave"))
+(feed-test "followers unknown" (feed/followers G "zzz") (list))
+(feed-test "audience distinct" (feed/audience G) (list "bob" "carol" "dave"))
+
+; ---------- fanout ----------
+
+(define
+  S
+  (feed/stream
+    (list
+      (feed/activity "alice" "post" "p1" 10 (list))
+      (feed/activity "alice" "post" "p2" 20 (list))
+      (feed/activity "bob" "like" "p1" 30 (list)))))
+
+(define IB (feed/fanout S G))
+
+(feed-test "fanout total edges" (feed/count IB) 6)
+(feed-test
+  "inbox bob count"
+  (feed/count (feed/inbox-for IB "bob"))
+  2)
+(feed-test
+  "inbox carol count"
+  (feed/count (feed/inbox-for IB "carol"))
+  3)
+(feed-test
+  "inbox dave count"
+  (feed/count (feed/inbox-for IB "dave"))
+  1)
+(feed-test
+  "inbox alice (follows none)"
+  (feed/count (feed/inbox-for IB "alice"))
+  0)
+(feed-test
+  "recipients order"
+  (feed/recipients IB)
+  (list "bob" "carol" "dave"))
+(feed-test
+  "bob inbox objects"
+  (map (fn (a) (get a :object)) (feed/inbox-activities IB "bob"))
+  (list "p1" "p2"))
+(feed-test
+  "dave inbox objects"
+  (map (fn (a) (get a :object)) (feed/inbox-activities IB "dave"))
+  (list "p1"))
+(feed-test
+  "dave inbox verb"
+  (map (fn (a) (get a :verb)) (feed/inbox-activities IB "dave"))
+  (list "like"))
+
+; empty graph → no audience → no edges
+(feed-test
+  "empty graph fanout"
+  (feed/count (feed/fanout S {}))
+  0)
+
+; actor nobody follows produces no edges
+(define
+  Sghost
+  (feed/stream (list (feed/activity "ghost" "post" "g1" 5 (list)))))
+(feed-test
+  "unfollowed actor fanout"
+  (feed/count (feed/fanout Sghost G))
+  0)
+
+; ---------- high fanout (popular actor) ----------
+
+(define
+  Gstar
+  (feed/follow-graph
+    (list
+      (list "u1" "star")
+      (list "u2" "star")
+      (list "u3" "star")
+      (list "u4" "star")
+      (list "u5" "star"))))
+(define
+  Sstar
+  (feed/stream (list (feed/activity "star" "post" "s1" 1 (list)))))
+(feed-test
+  "star fanout count"
+  (feed/count (feed/fanout Sstar Gstar))
+  5)
+(feed-test "star audience size" (len (feed/audience Gstar)) 5)
+
+; ---------- mutual follow ----------
+
+(define Gmut (feed/follow-graph (list (list "a" "b") (list "b" "a"))))
+(define
+  Smut
+  (feed/stream
+    (list
+      (feed/activity "a" "post" "pa" 1 (list))
+      (feed/activity "b" "post" "pb" 2 (list)))))
+(define IBmut (feed/fanout Smut Gmut))
+(feed-test "mutual total" (feed/count IBmut) 2)
+(feed-test
+  "mutual a gets pb"
+  (map (fn (x) (get x :object)) (feed/inbox-activities IBmut "a"))
+  (list "pb"))
+(feed-test
+  "mutual b gets pa"
+  (map (fn (x) (get x :object)) (feed/inbox-activities IBmut "b"))
+  (list "pa"))
+
+; ---------- dedupe ----------
+
+(define
+  Sdup2
+  (feed/stream
+    (list
+      (feed/activity "alice" "post" "p1" 1 (list))
+      (feed/activity "alice" "post" "p1" 9 (list))
+      (feed/activity "alice" "post" "p2" 2 (list)))))
+(feed-test
+  "dedupe-activities collapses dup"
+  (feed/count (feed/dedupe-activities Sdup2))
+  2)
+(feed-test
+  "dedupe-activities keeps distinct"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/dedupe-activities Sdup2)))
+  (list "p1" "p2"))
+
+(define
+  Slikes
+  (feed/stream
+    (list
+      (feed/activity "alice" "like" "X" 1 (list))
+      (feed/activity "bob" "like" "X" 2 (list))
+      (feed/activity "carol" "like" "Y" 3 (list)))))
+(feed-test
+  "collapse cross-actor likes"
+  (feed/count (feed/dedupe-collapse Slikes))
+  2)
+(feed-test
+  "collapse keeps distinct objects"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/dedupe-collapse Slikes)))
+  (list "X" "Y"))
+
+(feed-test
+  "activity-key shape"
+  (feed/activity-key (feed/activity "a" "post" "o" 0 (list)))
+  (list "a" "post" "o"))
+(feed-test
+  "collapse-key shape"
+  (feed/collapse-key (feed/activity "a" "like" "o" 0 (list)))
+  (list "like" "o"))
+
+; cross-post: alice posts p1 twice → bob's inbox has it twice → dedupe-inbox → once
+(define
+  Scross
+  (feed/stream
+    (list
+      (feed/activity "alice" "post" "p1" 1 (list))
+      (feed/activity "alice" "post" "p1" 5 (list)))))
+(define IBcross (feed/fanout Scross G))
+(feed-test
+  "cross-post raw bob count"
+  (feed/count (feed/inbox-for IBcross "bob"))
+  2)
+(feed-test
+  "cross-post deduped bob count"
+  (feed/count (feed/inbox-for (feed/dedupe-inbox IBcross) "bob"))
+  1)
+(feed-test
+  "dedupe-inbox keeps distinct receivers"
+  (feed/count (feed/dedupe-inbox IBcross))
+  2)

lib/feed/tests/home.sx

@@ -0,0 +1,73 @@
+; Follow-up — feed/home capstone pipeline. (feed-test name got expected)
+
+; alice follows star and bob (edges: follower followee)
+(define
+  G
+  (feed/follow-graph (list (list "alice" "star") (list "alice" "bob"))))
+
+; star posts s1 then s2; bob posts b1; star re-posts s1 (cross-post dup);
+; zoe posts z1 (alice does NOT follow zoe)
+(define
+  S
+  (feed/stream
+    (list
+      (feed/activity "star" "post" "s1" 10 (list))
+      (feed/activity "star" "post" "s2" 20 (list))
+      (feed/activity "bob" "post" "b1" 15 (list))
+      (feed/activity "star" "post" "s1" 5 (list))
+      (feed/activity "zoe" "post" "z1" 30 (list)))))
+
+(define rec (feed/recency 100 10))
+
+(feed-test
+  "home count (deduped, followed only)"
+  (feed/count (feed/home S G "alice" feed/permit-public? rec 10))
+  3)
+
+(feed-test
+  "home order by recency"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/home S G "alice" feed/permit-public? rec 10)))
+  (list "s2" "b1" "s1"))
+
+(feed-test
+  "home excludes unfollowed zoe"
+  (feed/-elem?
+    "z1"
+    (map
+      (fn (a) (get a :object))
+      (feed/items (feed/home S G "alice" feed/permit-public? rec 10))))
+  false)
+
+(feed-test
+  "home top-2"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/home S G "alice" feed/permit-public? rec 2)))
+  (list "s2" "b1"))
+
+(feed-test
+  "home dedupes cross-post (one s1)"
+  (len
+    (filter
+      (fn (o) (equal? o "s1"))
+      (map
+        (fn (a) (get a :object))
+        (feed/items
+          (feed/home S G "alice" feed/permit-public? rec 10)))))
+  1)
+
+; ACL applied per-viewer in the home pipeline
+(define
+  Sacl
+  (feed/stream
+    (list (feed/normalize {:actor "star" :object "pub" :at 20}) (feed/normalize {:actor "star" :object "sec" :visible-to (list "carol") :at 25}))))
+(define Gacl (feed/follow-graph (list (list "alice" "star"))))
+
+(feed-test
+  "home hides activity alice not permitted"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/home Sacl Gacl "alice" feed/permit-acl? rec 10)))
+  (list "pub"))

lib/feed/tests/integration.sx

@@ -0,0 +1,155 @@
+; Phase 4 — visibility (ACL) + federation, and the end-to-end timeline.
+; (feed-test name got expected)
+
+; ---------- ACL visibility ----------
+; pub: public. sec: bob, allows carol. dm: frank, allows dave.
+
+(define
+  C
+  (feed/stream
+    (list
+      (feed/normalize {:actor "alice" :object "pub" :at 10})
+      (feed/normalize {:actor "bob" :object "sec" :visible-to (list "carol") :at 20})
+      (feed/normalize {:actor "frank" :object "dm" :visible-to (list "dave") :at 30}))))
+
+(feed-test
+  "public visible to anyone"
+  (feed/count (feed/visible C "zoe" feed/permit-acl?))
+  1)
+(feed-test
+  "carol sees allowlisted + public"
+  (feed/count (feed/visible C "carol" feed/permit-acl?))
+  2)
+(feed-test
+  "dave sees dm + public"
+  (feed/count (feed/visible C "dave" feed/permit-acl?))
+  2)
+(feed-test
+  "author always sees own private"
+  (feed/count (feed/visible C "frank" feed/permit-acl?))
+  2)
+(feed-test
+  "permit-public? lets all through"
+  (feed/count (feed/visible C "zoe" feed/permit-public?))
+  3)
+(feed-test
+  "visible objects for dave"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/visible C "dave" feed/permit-acl?)))
+  (list "pub" "dm"))
+
+; per-viewer: same stream, different timelines
+(feed-test
+  "zoe timeline differs from carol"
+  (not
+    (=
+      (feed/count (feed/visible C "zoe" feed/permit-acl?))
+      (feed/count (feed/visible C "carol" feed/permit-acl?))))
+  true)
+
+; ---------- federation: merge / ingest ----------
+
+(define
+  L
+  (feed/stream
+    (list
+      (feed/activity "alice" "post" "p1" 10 (list))
+      (feed/activity "alice" "post" "p2" 20 (list)))))
+(define
+  P
+  (feed/stream
+    (list
+      (feed/activity "alice" "post" "p2" 20 (list))
+      (feed/activity "peer" "post" "p9" 25 (list)))))
+
+(feed-test "merge concatenates" (feed/count (feed/merge L P)) 4)
+(feed-test
+  "ingest dedupes overlap"
+  (feed/count (feed/ingest L P))
+  3)
+
+(feed-test
+  "inbound normalizes + ingests"
+  (feed/count (feed/inbound L (list {:actor "peer" :object "p9" :at 25} {:actor "alice" :object "p1" :at 10})))
+  3)
+
+; backfill via injected fetch-fn
+(define peer-history (fn (peer-id) (list {:actor peer-id :object "h1" :at 1} {:actor peer-id :object "h2" :at 2})))
+(feed-test
+  "backfill merges peer history"
+  (feed/count (feed/backfill L peer-history "remote"))
+  4)
+(feed-test
+  "backfill objects present"
+  (map
+    (fn (a) (get a :object))
+    (feed/items
+      (feed/by-actor (feed/backfill L peer-history "remote") "remote")))
+  (list "h1" "h2"))
+
+; ---------- federation: outbound partition ----------
+
+; bob (local), alice@remote + carol@remote (remote) follow star
+(define
+  Gf
+  (feed/follow-graph
+    (list
+      (list "bob" "star")
+      (list "alice@remote" "star")
+      (list "carol@remote" "star"))))
+(define
+  Sf
+  (feed/stream (list (feed/activity "star" "post" "s1" 1 (list)))))
+(define
+  remote?
+  (fn (id) (feed/-elem? id (list "alice@remote" "carol@remote"))))
+(define parts (feed/federate Sf Gf remote?))
+
+(feed-test "local deliveries" (feed/count (get parts :local)) 1)
+(feed-test "remote deliveries" (feed/count (get parts :remote)) 2)
+(feed-test
+  "local recipient is bob"
+  (feed/recipients (get parts :local))
+  (list "bob"))
+
+; deliver: send-fn receives each remote event, local inbox returned
+(define sent (list))
+(define send-fn (fn (to act) (set! sent (append sent (list to)))))
+(define local-inbox (feed/deliver Sf Gf remote? send-fn))
+(feed-test "deliver returns local inbox" (feed/count local-inbox) 1)
+(feed-test "deliver sent to both remotes" (len sent) 2)
+(feed-test "deliver remote targets" sent (list "alice@remote" "carol@remote"))
+
+; ---------- end-to-end: federated, ACL-filtered, ranked timeline ----------
+
+(define
+  base
+  (feed/stream
+    (list
+      (feed/normalize {:actor "alice" :object "a1" :at 100})
+      (feed/normalize {:actor "bob" :object "b1" :visible-to (list "carol") :at 90})
+      (feed/normalize {:actor "eve" :object "e1" :visible-to (list "dave") :at 80}))))
+(define federated (feed/inbound base (list {:actor "peer" :object "x1" :at 110})))
+(define rec (feed/recency 120 10))
+(define
+  carol-tl
+  (feed/timeline federated "carol" feed/permit-acl? rec 3))
+
+; eve's :visible-to excludes carol -> filtered out; peer/alice public, bob allows carol
+(feed-test "carol federated timeline count" (feed/count carol-tl) 3)
+(feed-test
+  "carol timeline order (recency)"
+  (map (fn (a) (get a :object)) (feed/items carol-tl))
+  (list "x1" "a1" "b1"))
+(feed-test
+  "eve dm excluded from carol"
+  (feed/-elem? "e1" (map (fn (a) (get a :object)) (feed/items carol-tl)))
+  false)
+(feed-test
+  "dave sees eve dm not bob"
+  (map
+    (fn (a) (get a :object))
+    (feed/items
+      (feed/timeline federated "dave" feed/permit-acl? rec 5)))
+  (list "x1" "a1" "e1"))

lib/feed/tests/mute.sx

@@ -0,0 +1,68 @@
+; Follow-up — viewer mute/block filtering. (feed-test name got expected)
+
+(define
+  S
+  (feed/stream
+    (list
+      (feed/normalize {:actor "alice" :object "P1" :at 1 :tags (list "news")})
+      (feed/normalize {:actor "bob" :object "P2" :at 2 :tags (list "spam")})
+      (feed/normalize {:actor "alice" :object "P3" :at 3 :tags (list "cats")})
+      (feed/normalize {:actor "carol" :object "P4" :at 4 :tags (list "news" "spam")}))))
+
+; ---------- mute actors ----------
+
+(feed-test
+  "mute bob drops his post"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/mute-actors S (list "bob"))))
+  (list "P1" "P3" "P4"))
+(feed-test
+  "mute alice drops two"
+  (feed/count (feed/mute-actors S (list "alice")))
+  2)
+(feed-test
+  "mute nobody keeps all"
+  (feed/count (feed/mute-actors S (list)))
+  4)
+
+; ---------- mute tags ----------
+
+(feed-test
+  "mute spam tag drops two"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/mute-tags S (list "spam"))))
+  (list "P1" "P3"))
+(feed-test
+  "mute news+cats leaves spam-only"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/mute-tags S (list "news" "cats"))))
+  (list "P2"))
+
+; ---------- mute objects ----------
+
+(feed-test
+  "mute object P3 (thread mute)"
+  (feed/count (feed/mute-objects S (list "P3")))
+  3)
+
+; ---------- combined prefs ----------
+
+(feed-test
+  "apply-prefs actors + tags"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/apply-prefs S {:mute-actors (list "bob") :mute-tags (list "cats")})))
+  (list "P1" "P4"))
+(feed-test
+  "apply-prefs empty keeps all"
+  (feed/count (feed/apply-prefs S {}))
+  4)
+(feed-test
+  "apply-prefs all three filters"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/apply-prefs S {:mute-objects (list "P3") :mute-actors (list "carol") :mute-tags (list "spam")})))
+  (list "P1"))

lib/feed/tests/notify.sx

@@ -0,0 +1,69 @@
+; Follow-up — notification feed over an inbox. (feed-test name got expected)
+
+; an inbox is a stream of {:to receiver :activity act} events
+(define mk-ev (fn (to act) {:activity act :to to}))
+
+(define
+  IB
+  (feed/stream
+    (list
+      (mk-ev "alice" (feed/activity "bob" "like" "P" 10 (list)))
+      (mk-ev "alice" (feed/activity "carol" "like" "P" 20 (list)))
+      (mk-ev "alice" (feed/activity "dave" "reply" "Q" 30 (list)))
+      (mk-ev "bob" (feed/activity "eve" "like" "R" 40 (list))))))
+
+; ---------- raw notifications ----------
+
+(feed-test
+  "alice notification count"
+  (feed/count (feed/notifications IB "alice"))
+  3)
+(feed-test
+  "bob notification count"
+  (feed/count (feed/notifications IB "bob"))
+  1)
+(feed-test
+  "zoe no notifications"
+  (feed/count (feed/notifications IB "zoe"))
+  0)
+
+; ---------- verb filtering ----------
+
+(feed-test
+  "alice likes only"
+  (feed/count (feed/notify-verbs IB "alice" (list "like")))
+  2)
+(feed-test
+  "alice replies only"
+  (feed/count (feed/notify-verbs IB "alice" (list "reply")))
+  1)
+(feed-test
+  "alice like+reply"
+  (feed/count (feed/notify-verbs IB "alice" (list "like" "reply")))
+  3)
+(feed-test
+  "alice follow (none)"
+  (feed/count (feed/notify-verbs IB "alice" (list "follow")))
+  0)
+
+; ---------- digest ----------
+
+(define dig (feed/notify-digest IB "alice"))
+
+(feed-test "digest group count" (len dig) 2)
+(feed-test
+  "digest sorted by key (like|P before reply|Q)"
+  (map (fn (g) (get g :object)) dig)
+  (list "P" "Q"))
+(feed-test
+  "like group actors"
+  (get (nth dig 0) :actors)
+  (list "bob" "carol"))
+(feed-test "like group count" (get (nth dig 0) :count) 2)
+(feed-test "like group verb" (get (nth dig 0) :verb) "like")
+(feed-test "reply group count" (get (nth dig 1) :count) 1)
+(feed-test
+  "reply group actors"
+  (get (nth dig 1) :actors)
+  (list "dave"))
+(feed-test "empty digest for zoe" (feed/notify-digest IB "zoe") (list))

lib/feed/tests/page.sx

@@ -0,0 +1,86 @@
+; Follow-up — pagination (offset + cursor). (feed-test name got expected)
+
+; ---------- offset / limit ----------
+
+(define
+  O
+  (feed/stream
+    (list
+      (feed/activity "u" "post" "o1" 1 (list))
+      (feed/activity "u" "post" "o2" 2 (list))
+      (feed/activity "u" "post" "o3" 3 (list))
+      (feed/activity "u" "post" "o4" 4 (list))
+      (feed/activity "u" "post" "o5" 5 (list)))))
+
+(feed-test
+  "page 1"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/page O 0 2)))
+  (list "o1" "o2"))
+(feed-test
+  "page 2"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/page O 2 2)))
+  (list "o3" "o4"))
+(feed-test
+  "page 3 (partial)"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/page O 4 2)))
+  (list "o5"))
+(feed-test
+  "page past end empty"
+  (feed/count (feed/page O 10 2))
+  0)
+(feed-test "page-count 5/2 = 3" (feed/page-count O 2) 3)
+(feed-test "page-count 5/5 = 1" (feed/page-count O 5) 1)
+
+; ---------- cursor (recency) ----------
+
+(define
+  R
+  (feed/stream
+    (list
+      (feed/activity "u" "post" "a" 50 (list))
+      (feed/activity "u" "post" "b" 40 (list))
+      (feed/activity "u" "post" "c" 30 (list))
+      (feed/activity "u" "post" "d" 20 (list))
+      (feed/activity "u" "post" "e" 10 (list)))))
+
+(define p1 (feed/page-before R 100 2))
+(feed-test
+  "cursor page 1 newest first"
+  (map (fn (a) (get a :object)) (feed/items p1))
+  (list "a" "b"))
+(feed-test "next cursor after page 1" (feed/next-cursor p1) 40)
+
+(define p2 (feed/page-before R (feed/next-cursor p1) 2))
+(feed-test
+  "cursor page 2"
+  (map (fn (a) (get a :object)) (feed/items p2))
+  (list "c" "d"))
+(feed-test "next cursor after page 2" (feed/next-cursor p2) 20)
+
+(define p3 (feed/page-before R (feed/next-cursor p2) 2))
+(feed-test
+  "cursor page 3 (partial)"
+  (map (fn (a) (get a :object)) (feed/items p3))
+  (list "e"))
+
+(feed-test
+  "empty page nil cursor"
+  (feed/next-cursor (feed/page-before R 5 2))
+  nil)
+
+(feed-test
+  "after cursor loads newer"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/recent (feed/after R 30))))
+  (list "a" "b"))
+(feed-test
+  "before cursor count"
+  (feed/count (feed/before R 30))
+  2)

lib/feed/tests/rank.sx

@@ -0,0 +1,160 @@
+; Phase 3 — aggregation + ranking. (feed-test name got expected)
+
+; ---------- aggregation ----------
+
+(define
+  A
+  (feed/stream
+    (list
+      (feed/activity "alice" "post" "p1" 5 (list))
+      (feed/activity "alice" "post" "p2" 15 (list))
+      (feed/activity "bob" "post" "p3" 25 (list))
+      (feed/activity "alice" "like" "p1" 35 (list)))))
+
+(feed-test "actor-counts" (feed/actor-counts A) {:alice 3 :bob 1})
+(feed-test "object-counts" (feed/object-counts A) {:p2 1 :p3 1 :p1 2})
+(feed-test
+  "group-by actor alice len"
+  (len (get (feed/group-by A feed/actor) "alice"))
+  3)
+(feed-test
+  "group-count empty"
+  (feed/group-count feed/empty feed/actor)
+  {})
+
+; day bucketing
+(define
+  D
+  (feed/stream
+    (list
+      (feed/activity "alice" "post" "p1" 5 (list))
+      (feed/activity "alice" "post" "p2" 8 (list))
+      (feed/activity "alice" "post" "p3" 12 (list)))))
+
+(feed-test "feed/day floor" (feed/day 12 10) 1)
+(feed-test "feed/day same bucket" (feed/day 8 10) 0)
+(feed-test "by-actor-day" (feed/by-actor-day D 10) {:alice#0 2 :alice#1 1})
+
+; ---------- recency ----------
+
+(define rec (feed/recency 100 10))
+(feed-test
+  "recency at=now -> 1"
+  (rec (feed/activity "x" "post" "o" 100 (list)))
+  1)
+(feed-test
+  "recency age=hl -> .5"
+  (rec (feed/activity "x" "post" "o" 90 (list)))
+  0.5)
+(feed-test
+  "recency age=2hl -> .25"
+  (rec (feed/activity "x" "post" "o" 80 (list)))
+  0.25)
+
+; ---------- velocity ----------
+
+(define vel (feed/velocity D 10))
+(feed-test
+  "velocity burst (at=12)"
+  (vel (feed/activity "alice" "post" "z" 12 (list)))
+  3)
+(feed-test
+  "velocity mid (at=8)"
+  (vel (feed/activity "alice" "post" "z" 8 (list)))
+  2)
+(feed-test
+  "velocity first (at=5)"
+  (vel (feed/activity "alice" "post" "z" 5 (list)))
+  1)
+(feed-test
+  "velocity other actor"
+  (vel (feed/activity "bob" "post" "z" 12 (list)))
+  0)
+
+; ---------- engagement ----------
+
+(define eng (feed/engagement A))
+(feed-test
+  "engagement p1"
+  (eng (feed/activity "x" "post" "p1" 0 (list)))
+  2)
+(feed-test
+  "engagement p2"
+  (eng (feed/activity "x" "post" "p2" 0 (list)))
+  1)
+
+; ---------- composite ----------
+
+(define
+  cmp1
+  (feed/composite (list (list 2 (fn (a) (get a :at))))))
+(feed-test
+  "composite single part"
+  (cmp1 (feed/activity "x" "post" "o" 5 (list)))
+  10)
+(define
+  cmp2
+  (feed/composite
+    (list
+      (list 2 (fn (a) (get a :at)))
+      (list 3 (fn (a) 1)))))
+(feed-test
+  "composite two parts"
+  (cmp2 (feed/activity "x" "post" "o" 5 (list)))
+  13)
+
+; ---------- ranking ----------
+
+(define
+  R
+  (feed/stream
+    (list
+      (feed/activity "u" "post" "oC" 80 (list))
+      (feed/activity "u" "post" "oA" 100 (list))
+      (feed/activity "u" "post" "oB" 90 (list)))))
+
+(feed-test
+  "rank by recency objects"
+  (map (fn (a) (get a :object)) (feed/items (feed/rank R rec)))
+  (list "oA" "oB" "oC"))
+(feed-test
+  "top-2 by recency"
+  (map (fn (a) (get a :object)) (feed/items (feed/top R rec 2)))
+  (list "oA" "oB"))
+(feed-test "top-2 count" (feed/count (feed/top R rec 2)) 2)
+
+; constant score -> tiebreak by :at descending
+(define
+  T
+  (feed/stream
+    (list
+      (feed/activity "u" "post" "f" 10 (list))
+      (feed/activity "u" "post" "g" 30 (list))
+      (feed/activity "u" "post" "h" 20 (list)))))
+(feed-test
+  "tiebreak at-desc"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/rank T (fn (a) 0))))
+  (list "g" "h" "f"))
+
+; equal score AND equal :at -> stable input order
+(define
+  E
+  (feed/stream
+    (list
+      (feed/activity "u" "post" "first" 50 (list))
+      (feed/activity "u" "post" "second" 50 (list)))))
+(feed-test
+  "stable equal-key input order"
+  (map
+    (fn (a) (get a :object))
+    (feed/items (feed/rank E (fn (a) 0))))
+  (list "first" "second"))
+
+(feed-test
+  "with-scores attaches score"
+  (get (nth (feed/items (feed/with-scores R rec)) 1) :score)
+  1)
+
+(feed-test "rank preserves count" (feed/count (feed/rank A rec)) 4)

lib/feed/tests/thread.sx

@@ -0,0 +1,49 @@
+; Follow-up — conversation threading via :reply-to closure. (feed-test name got expected)
+
+(define
+  S
+  (feed/stream
+    (list
+      (feed/normalize {:actor "a" :object "root" :at 1})
+      (feed/normalize {:actor "b" :object "r1" :at 2 :verb "reply" :reply-to "root"})
+      (feed/normalize {:actor "c" :object "r2" :at 3 :verb "reply" :reply-to "root"})
+      (feed/normalize {:actor "d" :object "r3" :at 4 :verb "reply" :reply-to "r1"})
+      (feed/normalize {:actor "e" :object "x" :at 5}))))
+
+; ---------- direct replies ----------
+
+(feed-test "direct replies to root" (feed/reply-count S "root") 2)
+(feed-test "direct replies to r1" (feed/reply-count S "r1") 1)
+(feed-test "no replies to r3" (feed/reply-count S "r3") 0)
+(feed-test
+  "replies objects to root"
+  (map (fn (a) (get a :object)) (feed/items (feed/replies S "root")))
+  (list "r1" "r2"))
+
+; ---------- thread closure ----------
+
+(feed-test
+  "thread objects root (transitive)"
+  (feed/thread-objects S "root")
+  (list "root" "r1" "r2" "r3"))
+(feed-test
+  "thread root chronological"
+  (map (fn (a) (get a :object)) (feed/items (feed/thread S "root")))
+  (list "root" "r1" "r2" "r3"))
+(feed-test "thread size root" (feed/thread-size S "root") 4)
+(feed-test
+  "thread excludes unrelated x"
+  (feed/-elem?
+    "x"
+    (map (fn (a) (get a :object)) (feed/items (feed/thread S "root"))))
+  false)
+
+; ---------- sub-thread ----------
+
+(feed-test
+  "thread from r1 (sub-tree)"
+  (map (fn (a) (get a :object)) (feed/items (feed/thread S "r1")))
+  (list "r1" "r3"))
+(feed-test "thread size r1" (feed/thread-size S "r1") 2)
+(feed-test "leaf thread is itself" (feed/thread-size S "r3") 1)
+(feed-test "unrelated thread is itself" (feed/thread-size S "x") 1)

lib/feed/tests/trending.sx

@@ -0,0 +1,82 @@
+; Follow-up — trending objects/actors by recent activity. (feed-test name got expected)
+
+; window (50,100]: X@60,X@70 (a), Y@80 (b), Z@90 (c); W@40 is too old
+(define
+  S
+  (feed/stream
+    (list
+      (feed/activity "a" "post" "X" 60 (list))
+      (feed/activity "a" "post" "X" 70 (list))
+      (feed/activity "b" "post" "Y" 80 (list))
+      (feed/activity "c" "post" "Z" 90 (list))
+      (feed/activity "d" "post" "W" 40 (list)))))
+
+; ---------- trending objects ----------
+
+(feed-test
+  "trending count (3 in window)"
+  (len (feed/trending S 100 50 10))
+  3)
+(feed-test
+  "trending top object"
+  (get
+    (nth (feed/trending S 100 50 10) 0)
+    :object)
+  "X")
+(feed-test
+  "trending top count"
+  (get
+    (nth (feed/trending S 100 50 10) 0)
+    :count)
+  2)
+(feed-test
+  "trending order (count desc, key asc tiebreak)"
+  (map
+    (fn (e) (get e :object))
+    (feed/trending S 100 50 10))
+  (list "X" "Y" "Z"))
+(feed-test
+  "trending top-2"
+  (map
+    (fn (e) (get e :object))
+    (feed/trending S 100 50 2))
+  (list "X" "Y"))
+(feed-test
+  "old object W excluded"
+  (feed/-elem?
+    "W"
+    (map
+      (fn (e) (get e :object))
+      (feed/trending S 100 50 10)))
+  false)
+(feed-test
+  "narrow window keeps only newest"
+  (map
+    (fn (e) (get e :object))
+    (feed/trending S 100 15 10))
+  (list "Z"))
+(feed-test
+  "empty window -> nothing"
+  (feed/trending S 100 5 10)
+  (list))
+
+; ---------- trending actors ----------
+
+(feed-test
+  "trending actor top"
+  (get
+    (nth (feed/trending-actors S 100 50 10) 0)
+    :actor)
+  "a")
+(feed-test
+  "trending actor count"
+  (get
+    (nth (feed/trending-actors S 100 50 10) 0)
+    :count)
+  2)
+(feed-test
+  "trending actors order"
+  (map
+    (fn (e) (get e :actor))
+    (feed/trending-actors S 100 50 10))
+  (list "a" "b" "c"))

lib/feed/thread.sx

@@ -0,0 +1,59 @@
+; feed/thread — conversation threading. A reply carries :reply-to <parent-object>
+; (normalize preserves it). A thread is the transitive closure over :reply-to from
+; a root object: root + replies + replies-to-replies, gathered chronologically.
+;
+; Requires: lib/feed/normalize.sx, lib/feed/stream.sx, lib/feed/fanout.sx
+; (feed/-elem?, feed/-distinct).
+
+; direct replies to an object
+(define
+  feed/replies
+  (fn
+    (stream object)
+    (feed/filter stream (fn (a) (equal? (get a :reply-to) object)))))
+
+(define
+  feed/reply-count
+  (fn (stream object) (feed/count (feed/replies stream object))))
+
+; iterate f from x until the result stops growing (set-closure fixpoint)
+(define
+  feed/-fixpoint
+  (fn
+    (f x)
+    (let
+      ((nx (f x)))
+      (if (= (len nx) (len x)) x (feed/-fixpoint f nx)))))
+
+; the set of object-ids in the thread rooted at `root`
+(define
+  feed/thread-objects
+  (fn
+    (stream root)
+    (let
+      ((all (feed/items stream)))
+      (feed/-fixpoint
+        (fn
+          (acc)
+          (feed/-distinct
+            (append
+              acc
+              (map
+                (fn (a) (get a :object))
+                (filter (fn (a) (feed/-elem? (get a :reply-to) acc)) all)))))
+        (list root)))))
+
+; the full thread as a chronological stream (root + all descendants)
+(define
+  feed/thread
+  (fn
+    (stream root)
+    (let
+      ((objs (feed/thread-objects stream root)))
+      (feed/sort-by-at
+        (feed/filter stream (fn (a) (feed/-elem? (get a :object) objs)))))))
+
+; how many activities are in the thread (root counts as 1)
+(define
+  feed/thread-size
+  (fn (stream root) (feed/count (feed/thread stream root))))

lib/feed/trending.sx

@@ -0,0 +1,42 @@
+; feed/trending — what's hot right now: objects (or actors) ranked by activity
+; count within a recency window. Deterministic: count descending, ties broken by
+; key ascending (entries are pre-sorted by key, then stable grade-down by count).
+;
+; Requires: lib/feed/stream.sx, lib/feed/aggregate.sx (object/actor-counts),
+; lib/feed/rank.sx (feed/-desc-by).
+
+; activities within (now-window, now]
+(define
+  feed/-recent
+  (fn
+    (stream now window)
+    (feed/filter
+      stream
+      (fn (a) (and (<= (get a :at) now) (> (get a :at) (- now window)))))))
+
+; counts dict -> top-N entries {label key, :count n}, count desc, key asc
+(define
+  feed/-top-counts
+  (fn
+    (counts label n)
+    (let
+      ((entries (map (fn (k) (assoc {:count (get counts k)} label k)) (sort (keys counts)))))
+      (take (feed/-desc-by entries (fn (e) (get e :count))) n))))
+
+; top-N trending objects in the window
+(define
+  feed/trending
+  (fn
+    (stream now window n)
+    (feed/-top-counts
+      (feed/object-counts (feed/-recent stream now window))
+      :object n)))
+
+; top-N most active actors in the window
+(define
+  feed/trending-actors
+  (fn
+    (stream now window n)
+    (feed/-top-counts
+      (feed/actor-counts (feed/-recent stream now window))
+      :actor n)))

lib/flow/README.md

@@ -1,141 +0,0 @@
-# flow — durable DAG workflows on Scheme
-
-`flow` is a workflow engine for rose-ash: content pipelines (write → review →
-publish → federate), scheduled jobs, and multi-step user flows (signup, confirm,
-onboard) that **survive process restarts**. It is a thin Scheme prelude over the
-Scheme-on-SX guest (`lib/scheme/`); a flow runs *inside* the interpreter.
-
-Run the suite: `bash lib/flow/conformance.sh` → **151/151 across 10 suites**.
-
-## Model
-
-A **flow** is just a Scheme procedure of one argument — the upstream value:
-
-```
-node : input -> output
-```
-
-Combinators build composite nodes out of child nodes. A node that ignores its
-argument is effectively a thunk. There is no separate "graph" object: composition
-*is* function composition, so flows are values you can name, pass, and nest.
-
-```scheme
-(defflow publish
-  (sequence
-    (lambda (draft) (string-append draft "!"))
-    (branch (lambda (post) (>= (string-length post) 3))
-            (remote-node 'fed 'publish)
-            (flow-const 'rejected))))
-
-(flow/start publish "hello")   ; => federated, or a (flow-suspended id tag) state
-```
-
-## Building blocks (`spec.sx`)
-
-| Combinator | Meaning |
-|---|---|
-| `(flow-node f)` / `(flow-id x)` / `(flow-const v)` | leaf nodes |
-| `(sequence n ...)` | thread input left-to-right |
-| `(parallel n ...)` | fan input to every child, join results into a list (sequential eval) |
-| `(map-flow node)` | run `node` over each item of a list input, join results |
-| `(flow-while pred body max)` / `(flow-until ...)` | bounded iteration (cap `max` steps) |
-| `(defflow name body)` | bind + register a named flow (so it survives restart) |
-
-## Control flow + errors (`spec.sx`)
-
-| Combinator | Meaning |
-|---|---|
-| `(branch pred then else)` | `pred` on input selects `then`/`else` (`cond` is a Scheme special form) |
-| `(retry n node)` | re-run on a *raised exception*, up to `n` attempts |
-| `(timeout budget node)` | cooperative **step budget**: nodes call `(tick)`; the `(budget+1)`-th tick raises `flow-timeout` |
-| `(try-catch node handler)` | catch a raised exception → `(handler error)` |
-| `(fail reason)` / `(failed? x)` / `(fail-reason x)` | explicit failure *values* (flow downstream as data) |
-| `(recover node handler)` | the fail-VALUE counterpart of try-catch |
-| `(attempt n ...)` | railway sequence: stop at the first node returning a `(fail ...)` |
-| `(tap effect)` | run a side effect, return input unchanged |
-
-**Two error channels, on purpose.** Raised exceptions are for *bugs/transients*
-(caught by `retry`/`try-catch`). `(fail reason)` values are for *expected business
-outcomes* (validation rejected, declined) and compose via `attempt`/`recover`.
-
-## Suspend / resume — the durable core (`spec.sx`, `store.sx`)
-
-The guest Scheme's `call/cc` is **escape-only** — re-invoking a captured
-continuation after it returns *hangs* the runtime. So flow does **not** serialize
-continuations. Instead it uses **deterministic replay**:
-
-- `(suspend tag)` — if `tag` is already in the replay log, return its logged value;
-  otherwise escape to the driver as `(flow-suspended tag)`.
-- `resume` appends `(tag value)` to the log and **re-runs the flow from the start**.
-  Already-resolved suspends replay their values; the first unresolved one escapes
-  again (or the flow completes).
-
-The entire persisted state is the replay log — plain data. No live continuation is
-ever stored, so flows survive process restarts and even moves between instances.
-
-> **Author contract:** suspend `tag`s must be unique and deterministic across
-> replays, and **all** non-determinism / side effects must go through suspend
-> points (so their results are logged) — otherwise they re-run on every replay.
-
-### Lifecycle (`store.sx`)
-
-```scheme
-(flow/start flow input)   ; raw result if it completes, else (flow-suspended id tag)
-(flow/resume id value)    ; inject value at the waiting tag, continue
-(flow/cancel id)          ; terminate; a later resume is rejected
-```
-
-### Introspection & hygiene
-
-```scheme
-(flow/status id)   ; done | suspended | cancelled | unknown
-(flow/result id)   ; result if done, else (flow-error reason)
-(flow/list)        ; ((id status) ...)
-(flow/pending)     ; ((id waiting-tag) ...) — what each suspended flow awaits
-(flow/gc)          ; drop terminal records, keep live ones; returns count removed
-(flow/forget id)   ; drop one terminal record (refuses live flows)
-```
-
-### Crash recovery
-
-```scheme
-(flow-store-export)      ; the store as plain data (live procs nulled)
-(flow-store-import! d)   ; restore the store from exported data
-(flow-resumable-ids)     ; ids of suspended flows to wake on restart
-```
-
-On restart the flow definitions are reloaded (`defflow` re-registers names) and the
-exported store reimported; `resume` re-resolves each flow's procedure **by name**.
-
-## Distribution via fed-sx (`remote.sx`)
-
-```scheme
-(flow-peer-register! addr table)      ; mock a peer's exposed functions (fed-sx boundary)
-(remote-node addr fn)                 ; run a node on a peer
-(remote-failover addrs fn local)      ; try peers in order, fall through to a local node
-(flow-replicate-to addr)              ; copy this store to a peer's replica slot
-(flow-restore-from addr)              ; import a peer's replica (handoff)
-```
-
-**Handoff** is crash recovery across instances: replicate → local instance dies →
-peer restores the (plain-data) store and resumes. The replay log carries over, so
-all resolved suspends survive the move.
-
-## Files
-
-| File | Contents |
-|---|---|
-| `spec.sx` | combinators (flow-combinators-src / flow-control-src / flow-suspend-src) |
-| `store.sx` | durable store, lifecycle, crash recovery, introspection, hygiene |
-| `remote.sx` | fed-sx transport (mock peer registry), failover, replication |
-| `api.sx` | `flow-make-env` / `flow-run` SX helpers (one cached env, per-test reset) |
-| `tests/*.sx` | 10 suites, 151 cases |
-| `conformance.sh` | loads substrate + flow layer, runs every suite |
-
-## Notes on the substrate
-
-The guest Scheme (`lib/scheme/`, imported read-only) lacks dotted-rest params
-`(a . rest)` and named `let`; combinators use `(lambda args ...)` variadics + top-
-level recursion. `cons` is list-only (no dotted pairs), so log/assoc entries are
-2-element lists. Strings box as `{:scm-string "..."}`. Timeout is a step budget
-because there is no wall clock; `parallel` is sequential for the same reason.

lib/flow/api.sx

@@ -1,65 +0,0 @@
-;; lib/flow/api.sx — flow runtime entry points.
-;;
-;; Builds a Scheme env preloaded with the flow combinators (lib/flow/spec.sx),
-;; the durable store + lifecycle (lib/flow/store.sx), the fed-sx remote layer
-;; (lib/flow/remote.sx), and the host integration ABI (lib/flow/host.sx), and
-;; provides SX helpers to run flow programs.
-;;
-;; Scheme-level API (available inside flow programs):
-;;   (flow/start flow input) — run a flow; raw result if it completes, else
-;;                             (flow-suspended id tag). Defined in store.sx.
-;;   (flow/resume id value)  — resume a suspended flow (store.sx)
-;;   (flow/cancel id)        — cancel a flow (store.sx)
-;;   (suspend tag)           — suspension point (spec.sx)
-;;   (request kind payload)  — host request envelope over suspend (host.sx)
-;;   (remote-node addr fn)   — node executed on a federation peer (remote.sx)
-;;
-;; SX-level helpers (for hosts and tests):
-;;   (flow-make-env)        — fresh standard env + combinators + store + remote + host
-;;   (flow-run src)         — eval a Scheme program string in a reset shared env
-;;   (flow-run-in env src)  — eval a Scheme program string in a given env
-;;
-;; flow-run reuses ONE env (building the full standard env is expensive) and
-;; resets the mutable flow globals before each program, so tests stay isolated
-;; without paying for a fresh standard env each time. flow-registry persists (it
-;; models reloaded flow definitions surviving a restart).
-
-(define
-  flow-make-env
-  (fn
-    ()
-    (let
-      ((env (scheme-standard-env)))
-      (flow-load-combinators! env)
-      (flow-load-store! env)
-      (flow-load-remote! env)
-      (flow-load-host! env)
-      env)))
-
-(define
-  flow-run-in
-  (fn (env src) (scheme-eval-program (scheme-parse-all src) env)))
-
-(define
-  flow-reset-src
-  "(set! flow-store (list)) (set! flow-next-id 0) (set! flow-replay-log (list)) (set! flow-suspend-k #f) (set! flow-timeout-budget -1) (set! flow-peers (list)) (set! flow-replicas (list))")
-
-(define flow-env-cache false)
-
-(define
-  flow-shared-env
-  (fn
-    ()
-    (begin
-      (if flow-env-cache nil (set! flow-env-cache (flow-make-env)))
-      flow-env-cache)))
-
-(define
-  flow-run
-  (fn
-    (src)
-    (let
-      ((env (flow-shared-env)))
-      (begin
-        (scheme-eval-program (scheme-parse-all flow-reset-src) env)
-        (scheme-eval-program (scheme-parse-all src) env)))))

lib/flow/conformance.sh

@@ -1,103 +0,0 @@
-#!/usr/bin/env bash
-# flow-on-sx conformance runner — runs all flow test suites in one sx_server process.
-#
-# Usage:
-#   bash lib/flow/conformance.sh        # run all suites
-#   bash lib/flow/conformance.sh -v     # verbose (list each suite)
-
-set -uo pipefail
-cd "$(git rev-parse --show-toplevel)"
-
-SX_SERVER="${SX_SERVER:-hosts/ocaml/_build/default/bin/sx_server.exe}"
-if [ ! -x "$SX_SERVER" ]; then
-  SX_SERVER="/root/rose-ash/hosts/ocaml/_build/default/bin/sx_server.exe"
-fi
-if [ ! -x "$SX_SERVER" ]; then
-  echo "ERROR: sx_server.exe not found." >&2
-  exit 1
-fi
-
-VERBOSE="${1:-}"
-
-# Suites: NAME RUNNER-FN PATH
-SUITES=(
-  "basic       flow-basic-tests-run!     lib/flow/tests/basic.sx"
-  "control     flow-ctl-tests-run!       lib/flow/tests/control.sx"
-  "suspend     flow-sus-tests-run!       lib/flow/tests/suspend.sx"
-  "recovery    flow-rec-tests-run!       lib/flow/tests/recovery.sx"
-  "distributed flow-dist-tests-run!      lib/flow/tests/distributed.sx"
-  "api         flow-api-tests-run!       lib/flow/tests/api.sx"
-  "combinators flow-cmb-tests-run!       lib/flow/tests/combinators.sx"
-  "railway     flow-rail-tests-run!      lib/flow/tests/railway.sx"
-  "integration flow-int-tests-run!       lib/flow/tests/integration.sx"
-  "hygiene     flow-hyg-tests-run!       lib/flow/tests/hygiene.sx"
-  "host        flow-hst-tests-run!       lib/flow/tests/host.sx"
-)
-
-TMPFILE=$(mktemp); trap "rm -f $TMPFILE" EXIT
-EPOCH=1
-
-emit_load () { echo "(epoch $EPOCH)"; echo "(load \"$1\")"; EPOCH=$((EPOCH+1)); }
-emit_eval () { echo "(epoch $EPOCH)"; echo "(eval \"$1\")"; EPOCH=$((EPOCH+1)); }
-
-{
-  emit_load "lib/guest/lex.sx"
-  emit_load "lib/guest/reflective/env.sx"
-  emit_load "lib/guest/reflective/quoting.sx"
-  emit_load "lib/scheme/parser.sx"
-  emit_load "lib/scheme/eval.sx"
-  emit_load "lib/scheme/runtime.sx"
-  emit_load "lib/flow/spec.sx"
-  emit_load "lib/flow/store.sx"
-  emit_load "lib/flow/remote.sx"
-  emit_load "lib/flow/host.sx"
-  emit_load "lib/flow/api.sx"
-  for SUITE in "${SUITES[@]}"; do
-    read -r _NAME _RUNNER FILE <<< "$SUITE"
-    emit_load "$FILE"
-    emit_eval "($_RUNNER)"
-  done
-} > "$TMPFILE"
-
-OUTPUT=$(timeout 540 "$SX_SERVER" < "$TMPFILE" 2>&1 || true)
-
-TOTAL_PASS=0
-TOTAL_FAIL=0
-FAILED_SUITES=()
-
-LAST_DICT_LINES=$(echo "$OUTPUT" | grep -E '^\{:' || true)
-
-I=0
-while read -r LINE; do
-  [ -z "$LINE" ] && continue
-  P=$(echo "$LINE" | grep -oE ':passed [0-9]+' | awk '{print $2}')
-  F=$(echo "$LINE" | grep -oE ':failed [0-9]+' | awk '{print $2}')
-  [ -z "$P" ] && P=0
-  [ -z "$F" ] && F=0
-  SUITE_INFO="${SUITES[$I]}"
-  SUITE_NAME=$(echo "$SUITE_INFO" | awk '{print $1}')
-  TOTAL_PASS=$((TOTAL_PASS + P))
-  TOTAL_FAIL=$((TOTAL_FAIL + F))
-  if [ "$F" -gt 0 ]; then
-    FAILED_SUITES+=("$SUITE_NAME: $P/$((P+F))")
-    printf 'X %-12s %d/%d\n' "$SUITE_NAME" "$P" "$((P+F))"
-    echo "$LINE" | grep -oE ':name "[^"]*"' | sed 's/:name /    fail: /'
-  elif [ "$VERBOSE" = "-v" ]; then
-    printf 'ok %-12s %d passed\n' "$SUITE_NAME" "$P"
-  fi
-  I=$((I+1))
-done <<< "$LAST_DICT_LINES"
-
-TOTAL=$((TOTAL_PASS + TOTAL_FAIL))
-if [ "$TOTAL" -eq 0 ]; then
-  echo "ERROR: no suite results parsed. Raw output:" >&2
-  echo "$OUTPUT" >&2
-  exit 1
-fi
-if [ $TOTAL_FAIL -eq 0 ]; then
-  echo "ok $TOTAL_PASS/$TOTAL flow-on-sx tests passed (${#SUITES[@]} suites)"
-else
-  echo "FAIL $TOTAL_PASS/$TOTAL passed, $TOTAL_FAIL failed:"
-  for S in "${FAILED_SUITES[@]}"; do echo "  $S"; done
-  exit 1
-fi

lib/flow/host.sx

@@ -1,42 +0,0 @@
-;; lib/flow/host.sx — the host integration ABI (Phase 8).
-;;
-;; `suspend` is flow's seam to the outside world, but a bare (suspend tag) is just a
-;; signal — every author would invent their own tag shape. This layer defines a
-;; stable request/response contract so a host (e.g. an art-dag driver, or a human
-;; review UI) can hook in WITHOUT reverse-engineering ad-hoc tags.
-;;
-;; A flow asks the host to do something and waits for the answer:
-;;   (request kind payload)  — suspend with a typed envelope (flow-request kind
-;;     payload); evaluates to the host's resume value.
-;;   (await-human prompt)    — request kind=human (a decision point)
-;;   (await-render recipe)   — request kind=render (e.g. an art-dag job)
-;;   (await-effect kind p)   — request of an arbitrary kind
-;;
-;; The host drives flows by polling its work queue and resuming:
-;;   (flow-host-requests)    — ((id kind payload) ...) for every SUSPENDED flow whose
-;;     waiting tag is a host request. The host dispatches by kind (render -> submit a
-;;     Celery job; human -> show UI), then calls (flow/resume id answer).
-;;   (request? tag) / (request-kind tag) / (request-payload tag) — parse one tag.
-;;
-;; Reference driver — the host only supplies `dispatch`, a (kind payload) -> answer:
-;;   (flow-drive-host dispatch)        — one tick: service every CURRENTLY pending
-;;     request (snapshot), resuming each with (dispatch kind payload); returns the
-;;     count serviced. Resumes may create new requests — serviced on the next tick.
-;;   (flow-run-host dispatch maxticks) — tick until quiescent (no pending requests)
-;;     or maxticks reached; returns total requests serviced. Bounded for determinism.
-;;
-;; Contract: the host owns IO and persistence. flow stays deterministic — a flow
-;; never performs IO itself, it only `request`s; the host performs the effect and
-;; feeds the result back via resume (which the replay log records, so the effect is
-;; not re-run on recovery). Persist with flow-store-export after each transition and
-;; flow-store-import! on boot.
-
-(define
-  flow-host-src
-  "(define (request kind payload) (suspend (list (quote flow-request) kind payload)))\n   (define (request? tag) (and (pair? tag) (eq? (car tag) (quote flow-request))))\n   (define (request-kind tag) (car (cdr tag)))\n   (define (request-payload tag) (car (cdr (cdr tag))))\n   (define (await-human prompt) (request (quote human) prompt))\n   (define (await-render recipe) (request (quote render) recipe))\n   (define (await-effect kind payload) (request kind payload))\n   (define (flow-host-req-step pend)\n     (if (null? pend)\n         (list)\n         (let ((id (car (car pend))) (tag (car (cdr (car pend)))))\n           (if (request? tag)\n               (cons (list id (request-kind tag) (request-payload tag))\n                     (flow-host-req-step (cdr pend)))\n               (flow-host-req-step (cdr pend))))))\n   (define (flow-host-requests) (flow-host-req-step (flow/pending)))\n   (define (flow-drive-host-step reqs dispatch)\n     (if (null? reqs)\n         0\n         (begin\n           (flow/resume (car (car reqs)) (dispatch (car (cdr (car reqs))) (car (cdr (cdr (car reqs))))))\n           (+ 1 (flow-drive-host-step (cdr reqs) dispatch)))))\n   (define (flow-drive-host dispatch) (flow-drive-host-step (flow-host-requests) dispatch))\n   (define (flow-run-host dispatch maxticks)\n     (if (<= maxticks 0)\n         0\n         (let ((n (flow-drive-host dispatch)))\n           (if (= n 0) 0 (+ n (flow-run-host dispatch (- maxticks 1)))))))")
-
-(define
-  flow-load-host!
-  (fn
-    (env)
-    (begin (scheme-eval-program (scheme-parse-all flow-host-src) env) env)))

lib/flow/remote.sx

@@ -1,34 +0,0 @@
-;; lib/flow/remote.sx — distributed nodes via fed-sx (Phase 4).
-;;
-;; A node can execute on a federation peer. The transport is the fed-sx boundary;
-;; it is MOCKED in tests by a peer registry mapping addr -> function table. In
-;; production flow-transport would issue a fed-sx call; here it dispatches locally.
-;;
-;;   (flow-peer-register! addr table) — register a mock peer. table is a list of
-;;     (fn-name proc) entries — the functions that peer exposes.
-;;   (flow-transport addr fn input)   — invoke fn on the peer with input. Raises
-;;     (flow-remote-unreachable) if the addr is unknown, (flow-remote-no-fn) if the
-;;     peer does not expose fn.
-;;   (remote-node addr fn)            — a node that runs fn on the peer at addr.
-;;   (remote-failover addrs fn local) — try fn on each peer in addrs in order; on a
-;;     raised error move to the next peer; if every peer fails, run the `local`
-;;     node as a fallback.
-;;
-;; Persistence across instances + handoff. Each instance runs the same flow
-;; definitions, so the only thing that needs to cross the wire is the (plain-data)
-;; store — exactly flow-store-export from store.sx. Replication pushes that export
-;; to a peer's replica slot; handoff = restore the replica on the peer and resume.
-;;
-;;   (flow-replicate-to addr) — copy this instance's store to peer addr's replica
-;;   (flow-restore-from addr) — import the replica from peer addr (#t / #f)
-;;   (flow-replica-get addr)  — the raw replicated store at addr (or #f)
-
-(define
-  flow-remote-src
-  "(define flow-peers (list))\n   (define (flow-assoc key alist)\n     (if (null? alist)\n         #f\n         (if (eq? (car (car alist)) key) (car (cdr (car alist))) (flow-assoc key (cdr alist)))))\n   (define (flow-peer-register! addr table) (set! flow-peers (cons (list addr table) flow-peers)))\n   (define (flow-transport addr fn input)\n     (let ((table (flow-assoc addr flow-peers)))\n       (if table\n           (let ((proc (flow-assoc fn table)))\n             (if proc (proc input) (raise (quote flow-remote-no-fn))))\n           (raise (quote flow-remote-unreachable)))))\n   (define (remote-node addr fn) (lambda (input) (flow-transport addr fn input)))\n   (define (flow-failover-step addrs fn input local)\n     (if (null? addrs)\n         (local input)\n         (guard (e (#t (flow-failover-step (cdr addrs) fn input local)))\n           (flow-transport (car addrs) fn input))))\n   (define (remote-failover addrs fn local)\n     (lambda (input) (flow-failover-step addrs fn input local)))\n\n   (define flow-replicas (list))\n   (define (flow-replicas-remove addr reps)\n     (if (null? reps)\n         (list)\n         (if (eq? (car (car reps)) addr)\n             (flow-replicas-remove addr (cdr reps))\n             (cons (car reps) (flow-replicas-remove addr (cdr reps))))))\n   (define (flow-replicate-to addr)\n     (set! flow-replicas (cons (list addr (flow-store-export)) (flow-replicas-remove addr flow-replicas))))\n   (define (flow-replica-get addr) (flow-assoc addr flow-replicas))\n   (define (flow-restore-from addr)\n     (let ((data (flow-replica-get addr)))\n       (if data (begin (flow-store-import! data) #t) #f)))")
-
-(define
-  flow-load-remote!
-  (fn
-    (env)
-    (begin (scheme-eval-program (scheme-parse-all flow-remote-src) env) env)))

lib/flow/scoreboard.json

@@ -1,19 +0,0 @@
-{
-  "total": 166,
-  "passed": 166,
-  "failed": 0,
-  "suites": {
-    "basic": { "passed": 18, "total": 18 },
-    "control": { "passed": 31, "total": 31 },
-    "suspend": { "passed": 17, "total": 17 },
-    "recovery": { "passed": 8, "total": 8 },
-    "distributed": { "passed": 19, "total": 19 },
-    "api": { "passed": 12, "total": 12 },
-    "combinators": { "passed": 17, "total": 17 },
-    "railway": { "passed": 10, "total": 10 },
-    "integration": { "passed": 10, "total": 10 },
-    "hygiene": { "passed": 9, "total": 9 },
-    "host": { "passed": 15, "total": 15 }
-  },
-  "phases": { "phase1": "done", "phase2": "done", "phase3": "done", "phase4": "done", "phase5": "done", "phase6": "done", "phase7": "done", "phase8": "done" }
-}

lib/flow/scoreboard.md

@@ -1,53 +0,0 @@
-# flow-on-sx Scoreboard
-
-**All tests pass: 166 / 166 across 11 suites. Phases 1-8 complete.**
-
-`bash lib/flow/conformance.sh`
-
-## Per-suite breakdown
-
-| Suite | Passing | Covers |
-|-------|--------:|--------|
-| basic |     18  | Phase 1: single nodes, linear sequence, data-flow threading, defflow, parallel fan/join, nested composition, publish-shaped flow |
-| control |  31  | Phase 2: `branch` (6); error model `fail`/`failed?`/`fail-reason` (6); `try-catch` (6); `retry n` (6); `timeout` cooperative step budget (7) |
-| suspend |  17  | Phase 3: suspend/resume/cancel via deterministic replay; multi-step, replay determinism, lifecycle guards, suspend-in-branch |
-| recovery |  8  | Phase 3: crash recovery — store export/import, resumable scan, restart-at-every-step, replay-log survival |
-| distributed | 19 | Phase 4: `remote-node` (7); `remote-failover` (6); replication + handoff across instances (6) |
-| api |  12  | Phase 5: introspection — `flow/status`, `flow/result`, `flow/list`, `flow/pending` |
-| combinators | 17 | Phase 5: `tap`, `recover` (fail-value), `map-flow` fan-over-list, `flow-while`/`flow-until` bounded iteration |
-| railway | 10 | Phase 6: `attempt` — fail-value short-circuiting sequence + recover rejoin |
-| integration | 10 | Phase 7: end-to-end order + onboarding flows composing every phase (suspend, branch, federation, crash recovery, handoff, introspection) |
-| hygiene | 9 | Phase 5: `flow/gc` (prune terminal flows), `flow/forget` (drop one terminal record) |
-| host | 15 | Phase 8: host ABI — `request`/`await-human`/`await-render`, `flow-host-requests` queue, `flow-run-host` reference driver; art-dag-shaped render→review→publish loop |
-
-## Architecture
-
-Flow combinators are a **Scheme prelude** (`lib/flow/spec.sx`) loaded onto
-`scheme-standard-env`. A flow is a Scheme procedure `input -> output`. The whole
-flow executes inside the Scheme interpreter, so Phase 3's `suspend` (call/cc) will
-capture the flow continuation directly.
-
-- `lib/flow/spec.sx` — combinators: `flow-node`, `flow-id`, `flow-const`,
-  `sequence`, `parallel`, `defflow`; `flow-load-combinators!`.
-- `lib/flow/api.sx` — `flow/start` (Scheme); `flow-make-env`, `flow-run`,
-  `flow-run-in` (SX helpers).
-- `lib/flow/tests/basic.sx` — 18 cases.
-- `lib/flow/conformance.sh` — loads substrate + flow layer, runs suites.
-
-## Semantics notes
-
-- **node** = 1-arg Scheme procedure; the upstream value is the argument. A node
-  ignoring its argument is effectively a thunk.
-- **sequence** threads left-to-right; empty sequence = identity.
-- **parallel** fans the same input to every branch and joins results into a list.
-  Evaluation is **sequential** for now; true concurrency arrives in Phase 3.
-
-## Phases
-
-- [x] Phase 1 — Declarative DAG + sequential execution (combinators + 18 tests, `flow/start`)
-- [x] Phase 2 — Control flow + error handling (branch, error model, try-catch, retry, timeout)
-- [x] Phase 3 — Suspend/resume (suspend/resume/cancel + crash recovery via deterministic replay)
-- [x] Phase 4 — Distributed nodes via fed-sx (remote-node, failover, replication + handoff)
-- [x] Phase 5 — Operational API + combinators (introspection, tap, recover, map-flow)
-- [ ] Phase 3 — Suspend / resume (the showcase)
-- [ ] Phase 4 — Distributed nodes via fed-sx

lib/flow/spec.sx

@@ -1,61 +0,0 @@
-;; lib/flow/spec.sx — flow combinators as a Scheme prelude.
-;;
-;; A flow is a Scheme procedure of one argument: the upstream value.
-;;   node : input -> output
-;; A leaf node ignoring its argument is effectively a thunk. Combinators
-;; build composite nodes out of child nodes. The whole flow runs INSIDE the
-;; Scheme interpreter.
-;;
-;; Phase 1 combinators (flow-combinators-src):
-;;   flow-node / flow-id / flow-const / sequence / parallel / defflow
-;;   defflow both binds the flow and registers it by name (flow-register!, in
-;;   store.sx) so it can be re-resolved after a process restart.
-;;   map-flow (Phase 5): run a node over each item of a list input, join results.
-;;   flow-while / flow-until (Phase 5): bounded iteration — re-run body, threading
-;;   the value, while/until pred holds, up to `max` steps (deterministic bound; no
-;;   unbounded loops in pure SX).
-;;
-;; Phase 2 combinators (flow-control-src):
-;;   branch / fail / failed? / fail-reason / try-catch / retry / timeout / tick
-;;   tap (Phase 5): side-effecting pass-through (returns input unchanged).
-;;   recover (Phase 5): the fail-VALUE counterpart of try-catch.
-;;   attempt (Phase 6): railway sequence — thread nodes left-to-right but stop at
-;;     the first node that returns a (fail ...) value, returning that failure.
-;;
-;; Phase 3 suspend core (flow-suspend-src):
-;;   The guest Scheme's call/cc is ESCAPE-ONLY (re-invoking a captured k after it
-;;   returns hangs the runtime), so suspend/resume CANNOT re-enter a continuation.
-;;   Instead, durability uses DETERMINISTIC REPLAY: a flow re-runs from the start
-;;   on each resume; suspend points that have already been resolved replay their
-;;   logged value, and the first unresolved suspend escapes back to the driver.
-;;   The entire persisted state is the replay log (plain (tag value) data), which
-;;   survives process restart — no live continuation is ever serialized.
-;;
-;;   (suspend tag)  — if tag is in the replay log, return its value; else escape
-;;     to the driver as (flow-suspended tag). tags must be unique & deterministic
-;;     across replays. ALL effects/non-determinism must go through suspend so their
-;;     results are logged (otherwise they re-run on every replay).
-;;   (flow-drive flow input log) — run flow with the given replay log; returns
-;;     (flow-done result) or (flow-suspended tag).
-
-(define
-  flow-combinators-src
-  "(define (flow-node f) f)\n   (define (flow-id input) input)\n   (define (flow-const v) (lambda (input) v))\n   (define (flow-seq-step ns v)\n     (if (null? ns) v (flow-seq-step (cdr ns) ((car ns) v))))\n   (define sequence (lambda ns (lambda (input) (flow-seq-step ns input))))\n   (define parallel (lambda ns (lambda (input) (map (lambda (n) (n input)) ns))))\n   (define (map-flow node) (lambda (items) (map node items)))\n   (define (flow-while-step pred body input n)\n     (if (<= n 0)\n         input\n         (if (pred input) (flow-while-step pred body (body input) (- n 1)) input)))\n   (define (flow-while pred body max) (lambda (input) (flow-while-step pred body input max)))\n   (define (flow-until-step pred body input n)\n     (if (<= n 0)\n         input\n         (if (pred input) input (flow-until-step pred body (body input) (- n 1)))))\n   (define (flow-until pred body max) (lambda (input) (flow-until-step pred body input max)))\n   (define-syntax defflow\n     (syntax-rules ()\n       ((defflow nm body)\n        (begin (define nm body) (flow-register! (quote nm) nm)))))")
-
-(define
-  flow-control-src
-  "(define (branch pred then else)\n     (lambda (input) (if (pred input) (then input) (else input))))\n   (define (fail reason) (list (quote flow-fail) reason))\n   (define (failed? x) (and (pair? x) (eq? (car x) (quote flow-fail))))\n   (define (fail-reason x) (car (cdr x)))\n   (define (recover node handler)\n     (lambda (input)\n       (let ((r (node input)))\n         (if (failed? r) (handler (fail-reason r)) r))))\n   (define (tap effect)\n     (lambda (input) (begin (effect input) input)))\n   (define (flow-attempt-step ns v)\n     (if (failed? v)\n         v\n         (if (null? ns) v (flow-attempt-step (cdr ns) ((car ns) v)))))\n   (define attempt (lambda ns (lambda (input) (flow-attempt-step ns input))))\n   (define (try-catch node handler)\n     (lambda (input) (guard (e (#t (handler e))) (node input))))\n   (define (flow-retry-step n node input)\n     (guard (e (#t (if (<= n 1) (raise e) (flow-retry-step (- n 1) node input))))\n       (node input)))\n   (define (retry n node) (lambda (input) (flow-retry-step n node input)))\n   (define flow-timeout-budget -1)\n   (define (tick)\n     (if (< flow-timeout-budget 0)\n         0\n         (begin\n           (set! flow-timeout-budget (- flow-timeout-budget 1))\n           (if (< flow-timeout-budget 0)\n               (raise (quote flow-timeout))\n               flow-timeout-budget))))\n   (define (timeout budget node)\n     (lambda (input)\n       (let ((saved flow-timeout-budget))\n         (set! flow-timeout-budget budget)\n         (guard (e (#t (begin (set! flow-timeout-budget saved) (raise e))))\n           (let ((result (node input)))\n             (set! flow-timeout-budget saved)\n             result)))))")
-
-(define
-  flow-suspend-src
-  "(define flow-replay-log (list))\n   (define flow-suspend-k #f)\n   (define (flow-log-lookup tag log)\n     (if (null? log)\n         (list #f #f)\n         (if (eq? (car (car log)) tag)\n             (list #t (car (cdr (car log))))\n             (flow-log-lookup tag (cdr log)))))\n   (define (suspend tag)\n     (let ((hit (flow-log-lookup tag flow-replay-log)))\n       (if (car hit)\n           (car (cdr hit))\n           (flow-suspend-k (list (quote flow-suspended) tag)))))\n   (define (flow-drive flow input log)\n     (set! flow-replay-log log)\n     (call/cc\n       (lambda (k)\n         (set! flow-suspend-k k)\n         (list (quote flow-done) (flow input)))))")
-
-(define
-  flow-load-combinators!
-  (fn
-    (env)
-    (begin
-      (scheme-eval-program (scheme-parse-all flow-combinators-src) env)
-      (scheme-eval-program (scheme-parse-all flow-control-src) env)
-      (scheme-eval-program (scheme-parse-all flow-suspend-src) env)
-      env)))

lib/flow/tests/api.sx

@@ -1,79 +0,0 @@
-;; lib/flow/tests/api.sx — Phase 5: operational introspection API.
-
-(define flow-api-pass 0)
-(define flow-api-fail 0)
-(define flow-api-fails (list))
-
-(define
-  flow-api-test
-  (fn
-    (name actual expected)
-    (if
-      (= actual expected)
-      (set! flow-api-pass (+ flow-api-pass 1))
-      (begin
-        (set! flow-api-fail (+ flow-api-fail 1))
-        (append! flow-api-fails {:name name :expected expected :actual actual})))))
-
-(define flow-a (fn (src) (flow-run src)))
-
-;; ── flow/status ─────────────────────────────────────────────────
-(flow-api-test "status: unknown id" (flow-a "(flow/status 999)") "unknown")
-(flow-api-test
-  "status: suspended flow"
-  (flow-a
-    "(defflow w (lambda (x) (suspend (quote q)))) (define id (car (cdr (flow/start w 0)))) (flow/status id)")
-  "suspended")
-(flow-api-test
-  "status: completed flow"
-  (flow-a
-    "(defflow w (sequence (lambda (x) (suspend (quote q))) (lambda (v) v))) (define id (car (cdr (flow/start w 0)))) (flow/resume id 5) (flow/status id)")
-  "done")
-(flow-api-test
-  "status: cancelled flow"
-  (flow-a
-    "(defflow w (lambda (x) (suspend (quote q)))) (define id (car (cdr (flow/start w 0)))) (flow/cancel id) (flow/status id)")
-  "cancelled")
-
-;; ── flow/result ─────────────────────────────────────────────────
-(flow-api-test
-  "result: returns the value of a completed flow"
-  (flow-a
-    "(defflow w (sequence (lambda (x) (suspend (quote q))) (lambda (v) (list (quote got) v)))) (define id (car (cdr (flow/start w 0)))) (flow/resume id 9) (flow/result id)")
-  (list "got" 9))
-(flow-api-test
-  "result: a still-suspended flow has no result"
-  (flow-a
-    "(defflow w (lambda (x) (suspend (quote q)))) (define id (car (cdr (flow/start w 0)))) (flow/result id)")
-  (list "flow-error" "not-done"))
-(flow-api-test
-  "result: unknown id errors"
-  (flow-a "(flow/result 999)")
-  (list "flow-error" "no-such-flow"))
-
-;; ── flow/list ───────────────────────────────────────────────────
-(flow-api-test "list: empty store" (flow-a "(flow/list)") (list))
-(flow-api-test
-  "list: reports id + status for each flow (newest first)"
-  (flow-a
-    "(defflow w (lambda (x) (suspend (quote q)))) (flow/start w 0) (flow/start (lambda (x) (* x 2)) 5) (flow/list)")
-  (list (list 2 "done") (list 1 "suspended")))
-
-;; ── flow/pending ────────────────────────────────────────────────
-(flow-api-test
-  "pending: lists suspended flows with their waiting tag"
-  (flow-a
-    "(defflow w (lambda (x) (suspend (quote review)))) (flow/start w 0) (flow/pending)")
-  (list (list 1 "review")))
-(flow-api-test
-  "pending: excludes completed and cancelled flows"
-  (flow-a
-    "(defflow w (lambda (x) (suspend (quote q)))) (defflow v (sequence (lambda (x) (suspend (quote r))) (lambda (y) y))) (define i1 (car (cdr (flow/start w 0)))) (define i2 (car (cdr (flow/start v 0)))) (define i3 (car (cdr (flow/start w 0)))) (flow/resume i2 1) (flow/cancel i3) (flow/pending)")
-  (list (list 1 "q")))
-(flow-api-test
-  "pending: operator can drain all pending flows"
-  (flow-a
-    "(defflow w (sequence (lambda (x) (suspend (quote q))) (lambda (v) (* v 10)))) (flow/start w 0) (flow/start w 0) (define ps (flow/pending)) (flow/resume (car (car ps)) 1) (flow/resume (car (car (cdr ps))) 2) (flow/list)")
-  (list (list 1 "done") (list 2 "done")))
-
-(define flow-api-tests-run! (fn () {:total (+ flow-api-pass flow-api-fail) :passed flow-api-pass :failed flow-api-fail :fails flow-api-fails}))

lib/flow/tests/basic.sx

@@ -1,121 +0,0 @@
-;; lib/flow/tests/basic.sx — Phase 1: declarative DAG + sequential execution.
-
-(define flow-basic-pass 0)
-(define flow-basic-fail 0)
-(define flow-basic-fails (list))
-
-(define
-  flow-basic-test
-  (fn
-    (name actual expected)
-    (if
-      (= actual expected)
-      (set! flow-basic-pass (+ flow-basic-pass 1))
-      (begin
-        (set! flow-basic-fail (+ flow-basic-fail 1))
-        (append! flow-basic-fails {:name name :expected expected :actual actual})))))
-
-;; Run a Scheme flow-program string and return its final value.
-(define flow-b (fn (src) (flow-run src)))
-
-;; Scheme strings are boxed as {:scm-string "..."}; unwrap to a host string.
-(define flow-bs (fn (src) (get (flow-run src) :scm-string)))
-
-;; ── single node ─────────────────────────────────────────────────
-(flow-basic-test
-  "node: identity passes input through"
-  (flow-b "(flow/start flow-id 7)")
-  7)
-(flow-basic-test
-  "node: const ignores input"
-  (flow-b "(flow/start (flow-const 99) 1)")
-  99)
-(flow-basic-test
-  "node: bare lambda is a node"
-  (flow-b "(flow/start (lambda (x) (* x x)) 6)")
-  36)
-
-;; ── linear sequence ─────────────────────────────────────────────
-(flow-basic-test
-  "sequence: empty is identity"
-  (flow-b "(flow/start (sequence) 42)")
-  42)
-(flow-basic-test
-  "sequence: single child"
-  (flow-b "(flow/start (sequence (lambda (x) (+ x 1))) 41)")
-  42)
-(flow-basic-test
-  "sequence: two children thread"
-  (flow-b
-    "(flow/start (sequence (lambda (x) (+ x 1)) (lambda (x) (* x 10))) 4)")
-  50)
-(flow-basic-test
-  "sequence: three children thread"
-  (flow-b
-    "(flow/start (sequence (lambda (x) (+ x 1)) (lambda (x) (* x 2)) (lambda (x) (- x 3))) 5)")
-  9)
-
-;; ── data flow between nodes ─────────────────────────────────────
-(flow-basic-test
-  "data flow: string accumulation"
-  (flow-bs
-    "(flow/start (sequence (lambda (s) (string-append s \"-a\")) (lambda (s) (string-append s \"-b\"))) \"x\")")
-  "x-a-b")
-(flow-basic-test
-  "data flow: list build"
-  (flow-b
-    "(flow/start (sequence (lambda (x) (cons x (list))) (lambda (xs) (cons 0 xs))) 7)")
-  (list 0 7))
-
-;; ── defflow ─────────────────────────────────────────────────────
-(flow-basic-test
-  "defflow: names a flow"
-  (flow-b
-    "(defflow inc2 (sequence (lambda (x) (+ x 1)) (lambda (x) (+ x 1)))) (flow/start inc2 40)")
-  42)
-(flow-basic-test
-  "defflow: reusable"
-  (flow-b
-    "(defflow dbl (lambda (x) (* x 2))) (+ (flow/start dbl 3) (flow/start dbl 10))")
-  26)
-
-;; ── parallel (sequential semantics, join into list) ─────────────
-(flow-basic-test
-  "parallel: fans input to all branches"
-  (flow-b
-    "(flow/start (parallel (lambda (x) (+ x 1)) (lambda (x) (* x 2)) (lambda (x) (- x 3))) 10)")
-  (list 11 20 7))
-(flow-basic-test
-  "parallel: empty joins to empty list"
-  (flow-b "(flow/start (parallel) 5)")
-  (list))
-(flow-basic-test
-  "parallel: single branch"
-  (flow-b "(flow/start (parallel (lambda (x) (* x x))) 9)")
-  (list 81))
-
-;; ── nested composition ──────────────────────────────────────────
-(flow-basic-test
-  "nested: sequence of sequences"
-  (flow-b
-    "(flow/start (sequence (sequence (lambda (x) (+ x 1)) (lambda (x) (+ x 1))) (sequence (lambda (x) (* x 3)))) 0)")
-  6)
-(flow-basic-test
-  "nested: parallel inside sequence, join then reduce"
-  (flow-b
-    "(flow/start (sequence (parallel (lambda (x) (+ x 1)) (lambda (x) (* x 2))) (lambda (xs) (apply + xs))) 10)")
-  31)
-(flow-basic-test
-  "nested: sequence inside parallel branch"
-  (flow-b
-    "(flow/start (parallel (sequence (lambda (x) (+ x 1)) (lambda (x) (* x 2))) (lambda (x) x)) 5)")
-  (list 12 5))
-
-;; ── publish-shaped flow (the architecture sketch) ───────────────
-(flow-basic-test
-  "publish: write -> (review | spell) -> join lengths"
-  (flow-b
-    "(defflow publish (sequence (lambda (draft) (string-append draft \"!\")) (parallel (lambda (c) (string-length c)) (lambda (c) (string-length (string-append c \"?\")))))) (flow/start publish \"hi\")")
-  (list 3 4))
-
-(define flow-basic-tests-run! (fn () {:total (+ flow-basic-pass flow-basic-fail) :passed flow-basic-pass :failed flow-basic-fail :fails flow-basic-fails}))

lib/flow/tests/combinators.sx

@@ -1,108 +0,0 @@
-;; lib/flow/tests/combinators.sx — Phase 5: combinator library (tap, recover, map-flow, iteration).
-
-(define flow-cmb-pass 0)
-(define flow-cmb-fail 0)
-(define flow-cmb-fails (list))
-
-(define
-  flow-cmb-test
-  (fn
-    (name actual expected)
-    (if
-      (= actual expected)
-      (set! flow-cmb-pass (+ flow-cmb-pass 1))
-      (begin
-        (set! flow-cmb-fail (+ flow-cmb-fail 1))
-        (append! flow-cmb-fails {:name name :expected expected :actual actual})))))
-
-(define flow-m (fn (src) (flow-run src)))
-
-;; ── tap (side-effecting pass-through) ───────────────────────────
-(flow-cmb-test
-  "tap: returns input unchanged"
-  (flow-m "(flow/start (tap (lambda (x) (* x 999))) 7)")
-  7)
-(flow-cmb-test
-  "tap: runs the side effect"
-  (flow-m
-    "(define seen 0) (flow/start (tap (lambda (x) (set! seen x))) 42) seen")
-  42)
-(flow-cmb-test
-  "tap: value flows on while the effect observes it"
-  (flow-m
-    "(define log 0) (flow/start (sequence (lambda (x) (+ x 1)) (tap (lambda (x) (set! log x))) (lambda (x) (* x 2))) 10) (list log (flow/result 1))")
-  (list 11 22))
-
-;; ── recover (fail-value counterpart of try-catch) ───────────────
-(flow-cmb-test
-  "recover: passes a non-fail value through"
-  (flow-m "(flow/start (recover (lambda (x) (* x 2)) (lambda (r) -1)) 5)")
-  10)
-(flow-cmb-test
-  "recover: handles a fail value via the reason"
-  (flow-m
-    "(flow/start (recover (lambda (x) (fail (quote too-small))) (lambda (r) (list (quote recovered) r))) 1)")
-  (list "recovered" "too-small"))
-(flow-cmb-test
-  "recover: handler can supply a default value"
-  (flow-m
-    "(flow/start (sequence (recover (lambda (x) (if (> x 0) x (fail (quote neg))) ) (flow-const 0)) (lambda (x) (* x 10))) -3)")
-  0)
-(flow-cmb-test
-  "recover: does not catch raised exceptions (those are try-catch's job)"
-  (flow-m
-    "(flow/start (try-catch (recover (lambda (x) (raise (quote boom))) (flow-const 0)) (lambda (e) e)) 1)")
-  "boom")
-
-;; ── map-flow (run a node over a list, join) ─────────────────────
-(flow-cmb-test
-  "map-flow: applies the node to each item"
-  (flow-m "(flow/start (map-flow (lambda (x) (* x x))) (list 1 2 3 4))")
-  (list 1 4 9 16))
-(flow-cmb-test
-  "map-flow: empty list joins to empty"
-  (flow-m "(flow/start (map-flow (lambda (x) (+ x 1))) (list))")
-  (list))
-(flow-cmb-test
-  "map-flow: each item runs an independent sub-flow"
-  (flow-m
-    "(flow/start (map-flow (sequence (lambda (x) (+ x 1)) (lambda (x) (* x 2)))) (list 0 4 9))")
-  (list 2 10 20))
-(flow-cmb-test
-  "map-flow: composes — fan over a list then reduce the join"
-  (flow-m
-    "(flow/start (sequence (map-flow (lambda (x) (* x 10))) (lambda (xs) (apply + xs))) (list 1 2 3))")
-  60)
-
-;; ── flow-while / flow-until (bounded iteration) ─────────────────
-(flow-cmb-test
-  "flow-while: iterates while the predicate holds"
-  (flow-m
-    "(flow/start (flow-while (lambda (x) (< x 10)) (lambda (x) (+ x 1)) 100) 0)")
-  10)
-(flow-cmb-test
-  "flow-while: a false predicate leaves input unchanged"
-  (flow-m
-    "(flow/start (flow-while (lambda (x) (< x 0)) (lambda (x) (+ x 1)) 100) 5)")
-  5)
-(flow-cmb-test
-  "flow-while: respects the max-iteration bound"
-  (flow-m "(flow/start (flow-while (lambda (x) #t) (lambda (x) (+ x 1)) 3) 0)")
-  3)
-(flow-cmb-test
-  "flow-while: doubles until past a threshold"
-  (flow-m
-    "(flow/start (flow-while (lambda (x) (< x 50)) (lambda (x) (* x 2)) 100) 3)")
-  96)
-(flow-cmb-test
-  "flow-until: iterates until the predicate becomes true"
-  (flow-m
-    "(flow/start (flow-until (lambda (x) (>= x 10)) (lambda (x) (+ x 3)) 100) 0)")
-  12)
-(flow-cmb-test
-  "flow-until: composes inside a sequence"
-  (flow-m
-    "(flow/start (sequence (flow-until (lambda (x) (> x 100)) (lambda (x) (* x 3)) 100) (lambda (x) (- x 100))) 5)")
-  35)
-
-(define flow-cmb-tests-run! (fn () {:total (+ flow-cmb-pass flow-cmb-fail) :passed flow-cmb-pass :failed flow-cmb-fail :fails flow-cmb-fails}))

lib/flow/tests/control.sx

@@ -1,179 +0,0 @@
-;; lib/flow/tests/control.sx — Phase 2: control flow + error handling.
-
-(define flow-ctl-pass 0)
-(define flow-ctl-fail 0)
-(define flow-ctl-fails (list))
-
-(define
-  flow-ctl-test
-  (fn
-    (name actual expected)
-    (if
-      (= actual expected)
-      (set! flow-ctl-pass (+ flow-ctl-pass 1))
-      (begin
-        (set! flow-ctl-fail (+ flow-ctl-fail 1))
-        (append! flow-ctl-fails {:name name :expected expected :actual actual})))))
-
-(define flow-c (fn (src) (flow-run src)))
-(define flow-cs (fn (src) (get (flow-run src) :scm-string)))
-
-;; ── branch ──────────────────────────────────────────────────────
-(flow-ctl-test
-  "branch: true selects then"
-  (flow-c
-    "(flow/start (branch (lambda (x) (> x 0)) (lambda (x) (* x 100)) (lambda (x) (- 0 x))) 5)")
-  500)
-(flow-ctl-test
-  "branch: false selects else"
-  (flow-c
-    "(flow/start (branch (lambda (x) (> x 0)) (lambda (x) (* x 100)) (lambda (x) (- 0 x))) -3)")
-  3)
-(flow-ctl-test
-  "branch: predicate sees the threaded input"
-  (flow-c
-    "(flow/start (sequence (lambda (x) (+ x 1)) (branch (lambda (x) (> x 3)) (flow-const 100) (flow-const 0))) 3)")
-  100)
-(flow-ctl-test
-  "branch: branches are full nodes (sequence inside)"
-  (flow-c
-    "(flow/start (branch (lambda (x) (< x 10)) (sequence (lambda (x) (+ x 1)) (lambda (x) (* x 2))) (flow-const 0)) 4)")
-  10)
-(flow-ctl-test
-  "branch: nested branch (3-way sign)"
-  (flow-c
-    "(defflow sign (branch (lambda (x) (> x 0)) (flow-const 1) (branch (lambda (x) (< x 0)) (flow-const -1) (flow-const 0)))) (list (flow/start sign 7) (flow/start sign -7) (flow/start sign 0))")
-  (list 1 -1 0))
-(flow-ctl-test
-  "branch: publish-shaped approval gate"
-  (flow-cs
-    "(defflow publish (branch (lambda (post) (>= (string-length post) 3)) (lambda (post) (string-append post \" [published]\")) (lambda (post) (string-append post \" [rejected]\")))) (flow/start publish \"ok\")")
-  "ok [rejected]")
-
-;; ── error model — explicit (fail reason) values ─────────────────
-(flow-ctl-test
-  "fail: failed? is true for a failure value"
-  (flow-c "(failed? (fail 404))")
-  true)
-(flow-ctl-test
-  "fail: fail-reason extracts the reason"
-  (flow-c "(fail-reason (fail 404))")
-  404)
-(flow-ctl-test
-  "fail: failed? is false for a plain value"
-  (flow-c "(failed? 7)")
-  false)
-(flow-ctl-test
-  "fail: failed? is false for an ordinary list"
-  (flow-c "(failed? (list 1 2 3))")
-  false)
-(flow-ctl-test
-  "fail: a node may emit a failure as data"
-  (flow-c
-    "(defflow validate (lambda (s) (if (>= (string-length s) 3) s (fail (quote too-short))))) (failed? (flow/start validate \"hi\"))")
-  true)
-(flow-ctl-test
-  "fail: failure flows downstream, branch recovers"
-  (flow-c
-    "(defflow guarded (sequence (lambda (s) (if (>= (string-length s) 3) (string-length s) (fail (quote too-short)))) (branch failed? (lambda (f) (list (quote recovered) (fail-reason f))) (lambda (n) (list (quote ok) n))))) (flow/start guarded \"hi\")")
-  (list "recovered" "too-short"))
-
-;; ── try-catch — reify raised exceptions ─────────────────────────
-(flow-ctl-test
-  "try-catch: no exception returns node result"
-  (flow-c "(flow/start (try-catch (lambda (x) (* x 2)) (lambda (e) -1)) 5)")
-  10)
-(flow-ctl-test
-  "try-catch: handler runs on raise"
-  (flow-c
-    "(flow/start (try-catch (lambda (x) (raise (quote boom))) (flow-const 99)) 1)")
-  99)
-(flow-ctl-test
-  "try-catch: handler receives the reified error"
-  (flow-c "(flow/start (try-catch (lambda (x) (raise 42)) (lambda (e) e)) 0)")
-  42)
-(flow-ctl-test
-  "try-catch: catches exception from deep inside a sequence"
-  (flow-c
-    "(flow/start (try-catch (sequence (lambda (x) (+ x 1)) (lambda (x) (raise (quote deep)))) (flow-const -99)) 5)")
-  -99)
-(flow-ctl-test
-  "try-catch: handler may convert to a failure value"
-  (flow-c
-    "(failed? (flow/start (try-catch (lambda (x) (raise (quote bad))) (lambda (e) (fail e))) 0))")
-  true)
-(flow-ctl-test
-  "try-catch: composes — recover then continue"
-  (flow-c
-    "(flow/start (sequence (try-catch (lambda (x) (raise (quote x))) (flow-const 10)) (lambda (n) (* n 5))) 0)")
-  50)
-
-;; ── retry — re-run on raised exceptions ─────────────────────────
-(flow-ctl-test
-  "retry: succeeds after transient failures"
-  (flow-c
-    "(define ctr 0) (defflow flaky (lambda (x) (set! ctr (+ ctr 1)) (if (< ctr 3) (raise (quote nope)) (* x 10)))) (list (flow/start (retry 5 flaky) 7) ctr)")
-  (list 70 3))
-(flow-ctl-test
-  "retry: exhausted re-raises (caught by try-catch)"
-  (flow-c
-    "(flow/start (try-catch (retry 2 (lambda (x) (raise (quote always)))) (flow-const (quote gaveup))) 0)")
-  "gaveup")
-(flow-ctl-test
-  "retry: n=1 means a single attempt"
-  (flow-c
-    "(define ctr 0) (flow/start (try-catch (retry 1 (lambda (x) (set! ctr (+ ctr 1)) (raise (quote bad)))) (lambda (e) ctr)) 0)")
-  1)
-(flow-ctl-test
-  "retry: success on first attempt does not re-run"
-  (flow-c
-    "(define ctr 0) (flow/start (sequence (retry 5 (lambda (x) (set! ctr (+ ctr 1)) (* x 2))) (lambda (n) ctr)) 21)")
-  1)
-(flow-ctl-test
-  "retry: does not retry explicit failure values"
-  (flow-c
-    "(define ctr 0) (failed? (flow/start (retry 5 (lambda (x) (set! ctr (+ ctr 1)) (fail (quote bad)))) 0))")
-  true)
-(flow-ctl-test
-  "retry: failure-value path runs node exactly once"
-  (flow-c
-    "(define ctr 0) (flow/start (sequence (retry 5 (lambda (x) (set! ctr (+ ctr 1)) (fail (quote bad)))) (lambda (f) ctr)) 0)")
-  1)
-
-;; ── timeout — cooperative step budget ───────────────────────────
-(flow-ctl-test
-  "timeout: work within budget completes"
-  (flow-c
-    "(define (cd n) (if (<= n 0) 99 (begin (tick) (cd (- n 1))))) (flow/start (try-catch (timeout 10 (lambda (x) (cd x))) (flow-const (quote timed-out))) 5)")
-  99)
-(flow-ctl-test
-  "timeout: work exceeding budget raises flow-timeout"
-  (flow-c
-    "(define (cd n) (if (<= n 0) 99 (begin (tick) (cd (- n 1))))) (flow/start (try-catch (timeout 10 (lambda (x) (cd x))) (flow-const (quote timed-out))) 20)")
-  "timed-out")
-(flow-ctl-test
-  "timeout: exact budget boundary completes"
-  (flow-c
-    "(define (cd n) (if (<= n 0) 99 (begin (tick) (cd (- n 1))))) (flow/start (try-catch (timeout 5 (lambda (x) (cd x))) (flow-const (quote timed-out))) 5)")
-  99)
-(flow-ctl-test
-  "timeout: one tick over the budget raises"
-  (flow-c
-    "(define (cd n) (if (<= n 0) 99 (begin (tick) (cd (- n 1))))) (flow/start (try-catch (timeout 5 (lambda (x) (cd x))) (flow-const (quote timed-out))) 6)")
-  "timed-out")
-(flow-ctl-test
-  "timeout: the raised error is identifiable"
-  (flow-c
-    "(define (cd n) (if (<= n 0) 99 (begin (tick) (cd (- n 1))))) (flow/start (try-catch (timeout 2 (lambda (x) (cd x))) (lambda (e) e)) 9)")
-  "flow-timeout")
-(flow-ctl-test
-  "timeout: a node that never ticks is unbounded"
-  (flow-c "(flow/start (timeout 0 (lambda (x) (* x 2))) 5)")
-  10)
-(flow-ctl-test
-  "timeout: budget is restored across sequential timeouts"
-  (flow-c
-    "(define (cd n) (if (<= n 0) 1 (begin (tick) (cd (- n 1))))) (flow/start (sequence (timeout 4 (lambda (x) (cd x))) (timeout 4 (lambda (x) (cd 3))) (lambda (x) (begin (tick) (+ x 100)))) 3)")
-  101)
-
-(define flow-ctl-tests-run! (fn () {:total (+ flow-ctl-pass flow-ctl-fail) :passed flow-ctl-pass :failed flow-ctl-fail :fails flow-ctl-fails}))

lib/flow/tests/distributed.sx

@@ -1,120 +0,0 @@
-;; lib/flow/tests/distributed.sx — Phase 4: distributed nodes via fed-sx (mocked).
-
-(define flow-dist-pass 0)
-(define flow-dist-fail 0)
-(define flow-dist-fails (list))
-
-(define
-  flow-dist-test
-  (fn
-    (name actual expected)
-    (if
-      (= actual expected)
-      (set! flow-dist-pass (+ flow-dist-pass 1))
-      (begin
-        (set! flow-dist-fail (+ flow-dist-fail 1))
-        (append! flow-dist-fails {:name name :expected expected :actual actual})))))
-
-(define flow-d (fn (src) (flow-run src)))
-
-;; ── remote-node ─────────────────────────────────────────────────
-(flow-dist-test
-  "remote: a node executes on a peer"
-  (flow-d
-    "(flow-peer-register! (quote edge) (list (list (quote double) (lambda (x) (* x 2))))) (flow/start (remote-node (quote edge) (quote double)) 21)")
-  42)
-(flow-dist-test
-  "remote: remote nodes compose in a sequence"
-  (flow-d
-    "(flow-peer-register! (quote edge) (list (list (quote inc) (lambda (x) (+ x 1))) (list (quote double) (lambda (x) (* x 2))))) (flow/start (sequence (remote-node (quote edge) (quote inc)) (remote-node (quote edge) (quote double))) 4)")
-  10)
-(flow-dist-test
-  "remote: a remote node mixes with local nodes"
-  (flow-d
-    "(flow-peer-register! (quote edge) (list (list (quote double) (lambda (x) (* x 2))))) (flow/start (sequence (lambda (x) (+ x 5)) (remote-node (quote edge) (quote double)) (lambda (x) (- x 1))) 10)")
-  29)
-(flow-dist-test
-  "remote: unreachable peer raises flow-remote-unreachable"
-  (flow-d
-    "(flow/start (try-catch (remote-node (quote ghost) (quote double)) (lambda (e) e)) 1)")
-  "flow-remote-unreachable")
-(flow-dist-test
-  "remote: unknown function on a peer raises flow-remote-no-fn"
-  (flow-d
-    "(flow-peer-register! (quote edge) (list (list (quote double) (lambda (x) (* x 2))))) (flow/start (try-catch (remote-node (quote edge) (quote missing)) (lambda (e) e)) 1)")
-  "flow-remote-no-fn")
-(flow-dist-test
-  "remote: a remote node can suspend the flow (peer returns control)"
-  (flow-d
-    "(flow-peer-register! (quote edge) (list (list (quote review) (lambda (x) x)))) (flow/start (sequence (remote-node (quote edge) (quote review)) (lambda (x) (suspend (quote human))) (lambda (v) (list (quote published) v))) 7)")
-  (list "flow-suspended" 1 "human"))
-(flow-dist-test
-  "remote: a transient remote failure is recoverable with retry"
-  (flow-d
-    "(define hits 0) (flow-peer-register! (quote edge) (list (list (quote flaky) (lambda (x) (begin (set! hits (+ hits 1)) (if (< hits 2) (raise (quote down)) (* x 3))))))) (list (flow/start (retry 3 (remote-node (quote edge) (quote flaky))) 7) hits)")
-  (list 21 2))
-
-;; ── failover (retry on a different peer, fall through to local) ──
-(flow-dist-test
-  "failover: first reachable peer serves the request"
-  (flow-d
-    "(flow-peer-register! (quote p2) (list (list (quote f) (lambda (x) (+ x 100))))) (flow/start (remote-failover (list (quote p2) (quote down)) (quote f) (flow-const (quote local))) 5)")
-  105)
-(flow-dist-test
-  "failover: skips an unreachable peer to the next one"
-  (flow-d
-    "(flow-peer-register! (quote p2) (list (list (quote f) (lambda (x) (+ x 100))))) (flow/start (remote-failover (list (quote down) (quote p2)) (quote f) (flow-const (quote local))) 5)")
-  105)
-(flow-dist-test
-  "failover: skips a peer whose function raises"
-  (flow-d
-    "(flow-peer-register! (quote bad) (list (list (quote f) (lambda (x) (raise (quote boom)))))) (flow-peer-register! (quote good) (list (list (quote f) (lambda (x) (* x 10))))) (flow/start (remote-failover (list (quote bad) (quote good)) (quote f) (flow-const 0)) 4)")
-  40)
-(flow-dist-test
-  "failover: all peers fail, the local fallback runs"
-  (flow-d
-    "(flow/start (remote-failover (list (quote down1) (quote down2)) (quote f) (lambda (x) (* x -1))) 9)")
-  -9)
-(flow-dist-test
-  "failover: threads the input through to the chosen peer"
-  (flow-d
-    "(flow-peer-register! (quote p) (list (list (quote f) (lambda (x) (list (quote got) x))))) (flow/start (sequence (lambda (x) (+ x 1)) (remote-failover (list (quote p)) (quote f) (flow-const 0))) 41)")
-  (list "got" 42))
-(flow-dist-test
-  "failover: composes inside a larger sequence"
-  (flow-d
-    "(flow-peer-register! (quote p) (list (list (quote f) (lambda (x) (* x 2))))) (flow/start (sequence (remote-failover (list (quote down) (quote p)) (quote f) (flow-const 1)) (lambda (x) (+ x 3))) 5)")
-  13)
-
-;; ── replication + handoff ───────────────────────────────────────
-(flow-dist-test
-  "replicate: a peer holds the exported store"
-  (flow-d
-    "(defflow w (lambda (x) (suspend (quote q)))) (flow/start w 10) (flow-replicate-to (quote peerB)) (if (flow-replica-get (quote peerB)) (quote replicated) (quote missing))")
-  "replicated")
-(flow-dist-test
-  "handoff: a peer resumes a flow after the local instance dies"
-  (flow-d
-    "(defflow w (sequence (lambda (x) (suspend (quote q))) (lambda (v) (list (quote done) v)))) (define id (car (cdr (flow/start w 10)))) (flow-replicate-to (quote peerB)) (set! flow-store (list)) (flow-restore-from (quote peerB)) (flow/resume id 55)")
-  (list "done" 55))
-(flow-dist-test
-  "handoff: restored peer reports the flow as resumable"
-  (flow-d
-    "(defflow w (lambda (x) (suspend (quote q)))) (define id (car (cdr (flow/start w 10)))) (flow-replicate-to (quote peerB)) (set! flow-store (list)) (flow-restore-from (quote peerB)) (flow-resumable-ids)")
-  (list 1))
-(flow-dist-test
-  "handoff: without restore the dead instance has lost the flow"
-  (flow-d
-    "(defflow w (lambda (x) (suspend (quote q)))) (define id (car (cdr (flow/start w 10)))) (flow-replicate-to (quote peerB)) (set! flow-store (list)) (flow/resume id 1)")
-  (list "flow-error" "no-such-flow"))
-(flow-dist-test
-  "restore: from an unknown peer yields false"
-  (flow-d "(flow-restore-from (quote nowhere))")
-  false)
-(flow-dist-test
-  "handoff: replication preserves the replay log across the move"
-  (flow-d
-    "(defflow two (sequence (lambda (x) (suspend (quote a))) (lambda (x) (suspend (quote b))) (lambda (x) (list x)))) (define id (car (cdr (flow/start two 0)))) (flow/resume id 11) (flow-replicate-to (quote peerB)) (set! flow-store (list)) (flow-restore-from (quote peerB)) (flow/resume id 22)")
-  (list 22))
-
-(define flow-dist-tests-run! (fn () {:total (+ flow-dist-pass flow-dist-fail) :passed flow-dist-pass :failed flow-dist-fail :fails flow-dist-fails}))

lib/flow/tests/host.sx

@@ -1,106 +0,0 @@
-;; lib/flow/tests/host.sx — Phase 8: host integration ABI (request/await/host-queue/driver).
-
-(define flow-hst-pass 0)
-(define flow-hst-fail 0)
-(define flow-hst-fails (list))
-
-(define
-  flow-hst-test
-  (fn
-    (name actual expected)
-    (if
-      (= actual expected)
-      (set! flow-hst-pass (+ flow-hst-pass 1))
-      (begin
-        (set! flow-hst-fail (+ flow-hst-fail 1))
-        (append! flow-hst-fails {:name name :expected expected :actual actual})))))
-
-(define flow-hst (fn (src) (flow-run src)))
-
-;; ── request envelope ────────────────────────────────────────────
-(flow-hst-test
-  "request: suspends with a typed envelope"
-  (flow-hst
-    "(car (cdr (cdr (flow/start (lambda (x) (request (quote render) x)) 5))))")
-  (list "flow-request" "render" 5))
-(flow-hst-test
-  "request?: recognizes an envelope"
-  (flow-hst "(request? (list (quote flow-request) (quote human) 1))")
-  true)
-(flow-hst-test
-  "request?: a plain tag is not a request"
-  (flow-hst "(request? (list (quote review) 1))")
-  false)
-(flow-hst-test
-  "request-kind / request-payload: parse the envelope"
-  (flow-hst
-    "(define t (list (quote flow-request) (quote render) (list (quote recipe) 7))) (list (request-kind t) (request-payload t))")
-  (list "render" (list "recipe" 7)))
-
-;; ── named decision points ───────────────────────────────────────
-(flow-hst-test
-  "await-human: is a request of kind human"
-  (flow-hst
-    "(car (cdr (cdr (flow/start (lambda (x) (await-human x)) (quote approve?)))))")
-  (list "flow-request" "human" "approve?"))
-(flow-hst-test
-  "await-render: is a request of kind render"
-  (flow-hst
-    "(car (cdr (cdr (flow/start (lambda (x) (await-render x)) (quote recipe)))))")
-  (list "flow-request" "render" "recipe"))
-(flow-hst-test
-  "request: the host's resume value flows back into the flow"
-  (flow-hst
-    "(defflow f (sequence (lambda (x) (await-render x)) (lambda (art) (list (quote got) art)))) (define id (car (cdr (flow/start f 1)))) (flow/resume id (quote the-artifact))")
-  (list "got" "the-artifact"))
-
-;; ── host work queue ─────────────────────────────────────────────
-(flow-hst-test
-  "flow-host-requests: lists (id kind payload) for pending requests"
-  (flow-hst
-    "(flow/start (lambda (x) (await-render x)) 99) (flow-host-requests)")
-  (list (list 1 "render" 99)))
-(flow-hst-test
-  "flow-host-requests: excludes bare (non-request) suspends"
-  (flow-hst
-    "(defflow a (lambda (x) (await-render x))) (defflow b (lambda (x) (suspend (quote plain)))) (flow/start a 1) (flow/start b 2) (flow-host-requests)")
-  (list (list 1 "render" 1)))
-
-;; ── the art-dag-shaped host driver loop (manual resumes) ────────
-(flow-hst-test
-  "host driver: render then human-review then publish"
-  (flow-hst
-    "(defflow pipeline (sequence (lambda (recipe) (await-render recipe)) (lambda (art) (await-human (list (quote review) art))) (branch (lambda (d) (eq? d (quote approve))) (flow-const (quote published)) (flow-const (fail (quote rejected)))))) (define id (car (cdr (flow/start pipeline 99)))) (define r1 (flow-host-requests)) (flow/resume id (list (quote art) 99)) (define r2 (flow-host-requests)) (flow/resume id (quote approve)) (list r1 r2 (flow/status id) (flow/result id))")
-  (list
-    (list (list 1 "render" 99))
-    (list (list 1 "human" (list "review" (list "art" 99))))
-    "done"
-    "published"))
-(flow-hst-test
-  "host driver: rejection at the human gate yields a failure"
-  (flow-hst
-    "(defflow pipeline (sequence (lambda (recipe) (await-render recipe)) (lambda (art) (await-human (list (quote review) art))) (branch (lambda (d) (eq? d (quote approve))) (flow-const (quote published)) (flow-const (fail (quote rejected)))))) (define id (car (cdr (flow/start pipeline 1)))) (flow/resume id (quote artifact)) (failed? (flow/resume id (quote reject)))")
-  true)
-
-;; ── reference driver: host supplies only a dispatch fn ──────────
-(flow-hst-test
-  "flow-drive-host: one tick services every pending request"
-  (flow-hst
-    "(flow/start (lambda (x) (await-render x)) 5) (define n (flow-drive-host (lambda (k p) (list (quote done) p)))) (list n (flow/status 1) (flow/result 1))")
-  (list 1 "done" (list "done" 5)))
-(flow-hst-test
-  "flow-run-host: drives a render -> human pipeline to completion"
-  (flow-hst
-    "(defflow pipeline (sequence (lambda (recipe) (await-render recipe)) (lambda (art) (await-human (list (quote review) art))) (branch (lambda (d) (eq? d (quote approve))) (flow-const (quote published)) (flow-const (fail (quote rejected)))))) (define id (car (cdr (flow/start pipeline 99)))) (define serviced (flow-run-host (lambda (kind payload) (if (eq? kind (quote render)) (list (quote art) payload) (quote approve))) 10)) (list serviced (flow/status id) (flow/result id))")
-  (list 2 "done" "published"))
-(flow-hst-test
-  "flow-run-host: returns 0 when nothing is pending"
-  (flow-hst "(flow-run-host (lambda (k p) p) 5)")
-  0)
-(flow-hst-test
-  "flow-run-host: respects the maxticks bound"
-  (flow-hst
-    "(defflow pipe2 (sequence (lambda (r) (await-render r)) (lambda (a) (await-human a)) (lambda (d) d))) (define id (car (cdr (flow/start pipe2 1)))) (define serviced (flow-run-host (lambda (k p) p) 1)) (list serviced (flow/status id))")
-  (list 1 "suspended"))
-
-(define flow-hst-tests-run! (fn () {:total (+ flow-hst-pass flow-hst-fail) :passed flow-hst-pass :failed flow-hst-fail :fails flow-hst-fails}))

lib/flow/tests/hygiene.sx

@@ -1,67 +0,0 @@
-;; lib/flow/tests/hygiene.sx — Phase 5: store hygiene (flow/gc, flow/forget).
-
-(define flow-hyg-pass 0)
-(define flow-hyg-fail 0)
-(define flow-hyg-fails (list))
-
-(define
-  flow-hyg-test
-  (fn
-    (name actual expected)
-    (if
-      (= actual expected)
-      (set! flow-hyg-pass (+ flow-hyg-pass 1))
-      (begin
-        (set! flow-hyg-fail (+ flow-hyg-fail 1))
-        (append! flow-hyg-fails {:name name :expected expected :actual actual})))))
-
-(define flow-h (fn (src) (flow-run src)))
-
-;; ── flow/gc ─────────────────────────────────────────────────────
-(flow-hyg-test
-  "gc: empty store removes nothing"
-  (flow-h "(flow/gc)")
-  0)
-(flow-hyg-test
-  "gc: removes a done flow, keeps a suspended one"
-  (flow-h
-    "(defflow w (lambda (x) (suspend (quote q)))) (flow/start w 0) (flow/start (lambda (x) x) 5) (define removed (flow/gc)) (list removed (flow/list))")
-  (list 1 (list (list 1 "suspended"))))
-(flow-hyg-test
-  "gc: removes a cancelled flow"
-  (flow-h
-    "(defflow w (lambda (x) (suspend (quote q)))) (define id (car (cdr (flow/start w 0)))) (flow/cancel id) (flow/gc)")
-  1)
-(flow-hyg-test
-  "gc: a kept suspended flow is still resumable"
-  (flow-h
-    "(defflow w (sequence (lambda (x) (suspend (quote q))) (lambda (v) (* v 2)))) (define id (car (cdr (flow/start w 0)))) (flow/start (lambda (x) x) 1) (flow/gc) (flow/resume id 21)")
-  42)
-(flow-hyg-test
-  "gc: counts every terminal flow it drops"
-  (flow-h
-    "(flow/start (lambda (x) x) 1) (flow/start (lambda (x) x) 2) (defflow w (lambda (x) (suspend (quote q)))) (flow/start w 0) (flow/gc)")
-  2)
-
-;; ── flow/forget ─────────────────────────────────────────────────
-(flow-hyg-test
-  "forget: drops a completed flow"
-  (flow-h
-    "(defflow w (sequence (lambda (x) (suspend (quote q))) (lambda (v) v))) (define id (car (cdr (flow/start w 0)))) (flow/resume id 7) (list (flow/forget id) (flow/status id))")
-  (list true "unknown"))
-(flow-hyg-test
-  "forget: refuses to drop a live (suspended) flow"
-  (flow-h
-    "(defflow w (lambda (x) (suspend (quote q)))) (define id (car (cdr (flow/start w 0)))) (list (flow/forget id) (flow/status id))")
-  (list false "suspended"))
-(flow-hyg-test
-  "forget: drops a cancelled flow"
-  (flow-h
-    "(defflow w (lambda (x) (suspend (quote q)))) (define id (car (cdr (flow/start w 0)))) (flow/cancel id) (list (flow/forget id) (flow/status id))")
-  (list true "unknown"))
-(flow-hyg-test
-  "forget: unknown id yields false"
-  (flow-h "(flow/forget 999)")
-  false)
-
-(define flow-hyg-tests-run! (fn () {:total (+ flow-hyg-pass flow-hyg-fail) :passed flow-hyg-pass :failed flow-hyg-fail :fails flow-hyg-fails}))

lib/flow/tests/integration.sx

@@ -1,115 +0,0 @@
-;; lib/flow/tests/integration.sx — Phase 7: end-to-end flows composing every phase.
-
-(define flow-int-pass 0)
-(define flow-int-fail 0)
-(define flow-int-fails (list))
-
-(define
-  flow-int-test
-  (fn
-    (name actual expected)
-    (if
-      (= actual expected)
-      (set! flow-int-pass (+ flow-int-pass 1))
-      (begin
-        (set! flow-int-fail (+ flow-int-fail 1))
-        (append! flow-int-fails {:name name :expected expected :actual actual})))))
-
-(define flow-i (fn (src) (flow-run src)))
-
-;; The order-processing flow, defined once per program via this prelude string:
-;;   validate amount (attempt: fail if <= 0)
-;;   -> suspend for payment confirmation (resume value = confirmed amount)
-;;   -> branch: confirmed>0 ? record on the ledger peer : declined failure
-(define
-  order-prelude
-  "(flow-peer-register! (quote ledger) (list (list (quote record) (lambda (amt) (list (quote recorded) amt)))))\n   (defflow order\n     (attempt\n       (lambda (amt) (if (> amt 0) amt (fail (quote invalid-amount))))\n       (lambda (amt) (suspend (quote await-payment)))\n       (branch (lambda (amt) (> amt 0))\n               (remote-node (quote ledger) (quote record))\n               (flow-const (fail (quote declined))))))")
-
-;; ── happy path through every phase ──────────────────────────────
-(flow-int-test
-  "order: validate -> suspend -> resume -> branch -> federate"
-  (flow-i
-    (str
-      order-prelude
-      "(define id (car (cdr (flow/start order 100)))) (flow/resume id 250)"))
-  (list "recorded" 250))
-(flow-int-test
-  "order: starting suspends awaiting payment"
-  (flow-i
-    (str
-      order-prelude
-      "(define s (flow/start order 100)) (list (car s) (car (cdr (cdr s))))"))
-  (list "flow-suspended" "await-payment"))
-(flow-int-test
-  "order: invalid amount fails up front and never suspends"
-  (flow-i
-    (str
-      order-prelude
-      "(define r (flow/start order -5)) (list (failed? r) (fail-reason r))"))
-  (list true "invalid-amount"))
-(flow-int-test
-  "order: a declined payment yields a failure value"
-  (flow-i
-    (str
-      order-prelude
-      "(define id (car (cdr (flow/start order 100)))) (failed? (flow/resume id 0))"))
-  true)
-
-;; ── crash recovery mid-flow ─────────────────────────────────────
-(flow-int-test
-  "order: survives a simulated crash between suspend and resume"
-  (flow-i
-    (str
-      order-prelude
-      "(define id (car (cdr (flow/start order 100)))) (define saved (flow-store-export)) (set! flow-store (list)) (flow-store-import! saved) (flow/resume id 250)"))
-  (list "recorded" 250))
-
-;; ── handoff to a peer mid-flow ──────────────────────────────────
-(flow-int-test
-  "order: hands off to a peer that resumes and completes"
-  (flow-i
-    (str
-      order-prelude
-      "(define id (car (cdr (flow/start order 100)))) (flow-replicate-to (quote nodeB)) (set! flow-store (list)) (flow-restore-from (quote nodeB)) (flow/resume id 250)"))
-  (list "recorded" 250))
-
-;; ── introspection during the flow's life ────────────────────────
-(flow-int-test
-  "order: pending shows what the flow awaits, then result after resume"
-  (flow-i
-    (str
-      order-prelude
-      "(define id (car (cdr (flow/start order 100)))) (define p (flow/pending)) (flow/resume id 250) (list p (flow/status id) (flow/result id))"))
-  (list
-    (list (list 1 "await-payment"))
-    "done"
-    (list "recorded" 250)))
-
-;; ── onboarding: two human steps + cancellation ──────────────────
-(define
-  onboard-prelude
-  "(defflow onboard\n     (sequence\n       (lambda (user) (+ user 1))\n       (lambda (x) (suspend (quote confirm-email)))\n       (lambda (x) (suspend (quote complete-profile)))\n       (lambda (x) (list (quote onboarded) x))))")
-
-(flow-int-test
-  "onboard: two suspends resume in order to completion"
-  (flow-i
-    (str
-      onboard-prelude
-      "(define id (car (cdr (flow/start onboard 0)))) (flow/resume id 7) (flow/resume id 9)"))
-  (list "onboarded" 9))
-(flow-int-test
-  "onboard: the second pending tag appears after the first resume"
-  (flow-i
-    (str
-      onboard-prelude
-      "(define id (car (cdr (flow/start onboard 0)))) (flow/resume id 7) (car (cdr (car (flow/pending))))"))
-  "complete-profile")
-(flow-int-test
-  "onboard: cancelling abandons the flow"
-  (flow-i
-    (str
-      onboard-prelude
-      "(define id (car (cdr (flow/start onboard 0)))) (flow/cancel id) (list (flow/status id) (car (flow/resume id 7)))"))
-  (list "cancelled" "flow-error"))
-
-(define flow-int-tests-run! (fn () {:total (+ flow-int-pass flow-int-fail) :passed flow-int-pass :failed flow-int-fail :fails flow-int-fails}))

lib/flow/tests/railway.sx

@@ -1,73 +0,0 @@
-;; lib/flow/tests/railway.sx — Phase 6: railway-oriented composition (attempt).
-
-(define flow-rail-pass 0)
-(define flow-rail-fail 0)
-(define flow-rail-fails (list))
-
-(define
-  flow-rail-test
-  (fn
-    (name actual expected)
-    (if
-      (= actual expected)
-      (set! flow-rail-pass (+ flow-rail-pass 1))
-      (begin
-        (set! flow-rail-fail (+ flow-rail-fail 1))
-        (append! flow-rail-fails {:name name :expected expected :actual actual})))))
-
-(define flow-r (fn (src) (flow-run src)))
-
-;; ── attempt — short-circuit on the first (fail ...) ─────────────
-(flow-rail-test
-  "attempt: threads like sequence when nothing fails"
-  (flow-r
-    "(flow/start (attempt (lambda (x) (+ x 1)) (lambda (x) (* x 10))) 4)")
-  50)
-(flow-rail-test
-  "attempt: empty is identity"
-  (flow-r "(flow/start (attempt) 7)")
-  7)
-(flow-rail-test
-  "attempt: returns the first failure"
-  (flow-r
-    "(failed? (flow/start (attempt (lambda (x) (fail (quote bad))) (lambda (x) (* x 10))) 4))")
-  true)
-(flow-rail-test
-  "attempt: the failure carries its reason"
-  (flow-r
-    "(fail-reason (flow/start (attempt (lambda (x) x) (lambda (x) (fail (quote rejected)))) 4))")
-  "rejected")
-(flow-rail-test
-  "attempt: nodes after a failure do not run"
-  (flow-r
-    "(define ran 0) (flow/start (attempt (lambda (x) (fail (quote stop))) (lambda (x) (begin (set! ran (+ ran 1)) x))) 0) ran")
-  0)
-(flow-rail-test
-  "attempt: a failed input short-circuits immediately"
-  (flow-r
-    "(define ran 0) (fail-reason (flow/start (attempt (lambda (x) (begin (set! ran (+ ran 1)) x))) (fail (quote pre))))")
-  "pre")
-(flow-rail-test
-  "attempt: middle failure halts the chain"
-  (flow-r
-    "(define ran 0) (flow/start (attempt (lambda (x) (+ x 1)) (lambda (x) (fail (quote mid))) (lambda (x) (begin (set! ran (+ ran 1)) x))) 5) ran")
-  0)
-
-;; ── attempt + recover (rejoin the happy track) ──────────────────
-(flow-rail-test
-  "attempt + recover: recover turns a failure into a value"
-  (flow-r
-    "(flow/start (recover (attempt (lambda (x) (if (> x 0) x (fail (quote non-positive)))) (lambda (x) (* x 2))) (flow-const 0)) -5)")
-  0)
-(flow-rail-test
-  "attempt + recover: happy path passes recover through"
-  (flow-r
-    "(flow/start (recover (attempt (lambda (x) (if (> x 0) x (fail (quote non-positive)))) (lambda (x) (* x 2))) (flow-const 0)) 5)")
-  10)
-(flow-rail-test
-  "attempt: validation pipeline reports the failing stage"
-  (flow-r
-    "(defflow validate (attempt (lambda (s) (if (>= (string-length s) 3) s (fail (quote too-short)))) (lambda (s) (if (<= (string-length s) 8) s (fail (quote too-long)))) (lambda (s) (list (quote ok) (string-length s))))) (list (fail-reason (flow/start validate \"hi\")) (flow/start validate \"hello\"))")
-  (list "too-short" (list "ok" 5)))
-
-(define flow-rail-tests-run! (fn () {:total (+ flow-rail-pass flow-rail-fail) :passed flow-rail-pass :failed flow-rail-fail :fails flow-rail-fails}))

lib/flow/tests/recovery.sx

@@ -1,71 +0,0 @@
-;; lib/flow/tests/recovery.sx — Phase 3: crash recovery (store export/import + restart).
-;;
-;; "restart" is simulated within one program: (set! flow-store (list)) wipes the
-;; in-memory store (process death), while flow-registry persists as it would after
-;; reloading flow definitions. Recovery = import the exported (plain-data) store and
-;; resume; the flow proc is re-resolved by name.
-
-(define flow-rec-pass 0)
-(define flow-rec-fail 0)
-(define flow-rec-fails (list))
-
-(define
-  flow-rec-test
-  (fn
-    (name actual expected)
-    (if
-      (= actual expected)
-      (set! flow-rec-pass (+ flow-rec-pass 1))
-      (begin
-        (set! flow-rec-fail (+ flow-rec-fail 1))
-        (append! flow-rec-fails {:name name :expected expected :actual actual})))))
-
-(define flow-r (fn (src) (flow-run src)))
-
-;; ── export / wipe / import ──────────────────────────────────────
-(flow-rec-test
-  "export nulls the live procedure"
-  (flow-r
-    "(defflow w (lambda (x) (suspend (quote await)))) (flow/start w 10) (car (cdr (car (cdr (car (flow-store-export))))))")
-  false)
-(flow-rec-test
-  "a wiped store loses the flow (process death)"
-  (flow-r
-    "(defflow w (lambda (x) (suspend (quote await)))) (define id (car (cdr (flow/start w 10)))) (set! flow-store (list)) (flow/resume id 1)")
-  (list "flow-error" "no-such-flow"))
-(flow-rec-test
-  "import restores a wiped store and resume completes"
-  (flow-r
-    "(defflow w (sequence (lambda (x) (suspend (quote await))) (lambda (c) (list (quote done) c)))) (define id (car (cdr (flow/start w 10)))) (define saved (flow-store-export)) (set! flow-store (list)) (flow-store-import! saved) (flow/resume id 777)")
-  (list "done" 777))
-
-;; ── resumable scan ──────────────────────────────────────────────
-(flow-rec-test
-  "resumable-ids lists the suspended flow after import"
-  (flow-r
-    "(defflow w (lambda (x) (suspend (quote await)))) (define id (car (cdr (flow/start w 10)))) (define saved (flow-store-export)) (set! flow-store (list)) (flow-store-import! saved) (flow-resumable-ids)")
-  (list 1))
-(flow-rec-test
-  "resumable-ids excludes completed flows"
-  (flow-r
-    "(defflow w (sequence (lambda (x) (suspend (quote await))) (lambda (c) c))) (define id (car (cdr (flow/start w 10)))) (flow/resume id 5) (flow-resumable-ids)")
-  (list))
-(flow-rec-test
-  "resumable-ids excludes cancelled flows after import"
-  (flow-r
-    "(defflow w (lambda (x) (suspend (quote await)))) (define id (car (cdr (flow/start w 10)))) (flow/cancel id) (define saved (flow-store-export)) (set! flow-store (list)) (flow-store-import! saved) (flow-resumable-ids)")
-  (list))
-
-;; ── restart at every step ───────────────────────────────────────
-(flow-rec-test
-  "two suspends survive a restart between each step"
-  (flow-r
-    "(defflow two (sequence (lambda (x) (suspend (quote a))) (lambda (x) (suspend (quote b))) (lambda (x) (list (quote end) x)))) (define id (car (cdr (flow/start two 0)))) (define s1 (flow-store-export)) (set! flow-store (list)) (flow-store-import! s1) (flow/resume id 100) (define s2 (flow-store-export)) (set! flow-store (list)) (flow-store-import! s2) (flow/resume id 200)")
-  (list "end" 200))
-(flow-rec-test
-  "import preserves the replay log (earlier value survives restart)"
-  (flow-r
-    "(defflow two (sequence (lambda (x) (suspend (quote a))) (lambda (x) (suspend (quote b))) (lambda (x) (list x)))) (define id (car (cdr (flow/start two 0)))) (flow/resume id 11) (define saved (flow-store-export)) (set! flow-store (list)) (flow-store-import! saved) (flow/resume id 22)")
-  (list 22))
-
-(define flow-rec-tests-run! (fn () {:total (+ flow-rec-pass flow-rec-fail) :passed flow-rec-pass :failed flow-rec-fail :fails flow-rec-fails}))

lib/flow/tests/suspend.sx

@@ -1,114 +0,0 @@
-;; lib/flow/tests/suspend.sx — Phase 3: suspend / resume / cancel (deterministic replay).
-
-(define flow-sus-pass 0)
-(define flow-sus-fail 0)
-(define flow-sus-fails (list))
-
-(define
-  flow-sus-test
-  (fn
-    (name actual expected)
-    (if
-      (= actual expected)
-      (set! flow-sus-pass (+ flow-sus-pass 1))
-      (begin
-        (set! flow-sus-fail (+ flow-sus-fail 1))
-        (append! flow-sus-fails {:name name :expected expected :actual actual})))))
-
-(define flow-s (fn (src) (flow-run src)))
-
-;; ── flow/start ──────────────────────────────────────────────────
-(flow-sus-test
-  "start: non-suspending flow returns the raw result"
-  (flow-s "(flow/start (lambda (x) (* x 2)) 5)")
-  10)
-(flow-sus-test
-  "start: a suspending flow returns a flow-suspended state"
-  (flow-s
-    "(defflow w (sequence (lambda (x) (+ x 1)) (lambda (g) (suspend (quote await))) (lambda (c) c))) (car (flow/start w 10))")
-  "flow-suspended")
-(flow-sus-test
-  "start: suspended state carries a numeric id"
-  (flow-s
-    "(defflow w (lambda (x) (suspend (quote await)))) (car (cdr (flow/start w 10)))")
-  1)
-(flow-sus-test
-  "start: suspended state carries the suspend tag"
-  (flow-s
-    "(defflow w (lambda (x) (suspend (quote await)))) (car (cdr (cdr (flow/start w 10))))")
-  "await")
-
-;; ── flow/resume ─────────────────────────────────────────────────
-(flow-sus-test
-  "resume: injects the value and completes"
-  (flow-s
-    "(defflow w (sequence (lambda (x) (+ x 1)) (lambda (g) (suspend (quote await))) (lambda (c) (list (quote done) c)))) (define s (flow/start w 10)) (flow/resume (car (cdr s)) 777)")
-  (list "done" 777))
-(flow-sus-test
-  "resume: injected value threads into the next node"
-  (flow-s
-    "(defflow w (sequence (lambda (x) (suspend (quote v))) (lambda (n) (* n 3)))) (define s (flow/start w 0)) (flow/resume (car (cdr s)) 14)")
-  42)
-(flow-sus-test
-  "resume: replays earlier suspends (recompute is deterministic)"
-  (flow-s
-    "(define runs 0) (defflow w (sequence (lambda (x) (begin (set! runs (+ runs 1)) (+ x 1))) (lambda (g) (suspend (quote await))) (lambda (c) c))) (define s (flow/start w 10)) (flow/resume (car (cdr s)) 99) runs")
-  2)
-
-;; ── multi-step suspension ───────────────────────────────────────
-(flow-sus-test
-  "multi: first resume suspends at the next tag"
-  (flow-s
-    "(defflow two (sequence (lambda (x) (suspend (quote a))) (lambda (x) (suspend (quote b))) (lambda (x) (list (quote end) x)))) (define s (flow/start two 0)) (define s2 (flow/resume (car (cdr s)) 100)) (car (cdr (cdr s2)))")
-  "b")
-(flow-sus-test
-  "multi: second resume completes with the latest value"
-  (flow-s
-    "(defflow two (sequence (lambda (x) (suspend (quote a))) (lambda (x) (suspend (quote b))) (lambda (x) (list (quote end) x)))) (define id (car (cdr (flow/start two 0)))) (flow/resume id 100) (flow/resume id 200)")
-  (list "end" 200))
-
-;; ── error / lifecycle guards ────────────────────────────────────
-(flow-sus-test
-  "resume: completed flow cannot be resumed again"
-  (flow-s
-    "(defflow w (lambda (x) (suspend (quote q)))) (define id (car (cdr (flow/start w 0)))) (flow/resume id 1) (flow/resume id 2)")
-  (list "flow-error" "not-suspended"))
-(flow-sus-test
-  "resume: unknown id errors"
-  (flow-s "(flow/resume 999 1)")
-  (list "flow-error" "no-such-flow"))
-
-;; ── flow/cancel ─────────────────────────────────────────────────
-(flow-sus-test
-  "cancel: returns a flow-cancelled state"
-  (flow-s
-    "(defflow w (lambda (x) (suspend (quote q)))) (define id (car (cdr (flow/start w 0)))) (flow/cancel id)")
-  (list "flow-cancelled" 1))
-(flow-sus-test
-  "cancel: a cancelled flow cannot be resumed (stale resume rejected)"
-  (flow-s
-    "(defflow w (lambda (x) (suspend (quote q)))) (define id (car (cdr (flow/start w 0)))) (flow/cancel id) (flow/resume id 5)")
-  (list "flow-error" "not-suspended"))
-(flow-sus-test
-  "cancel: unknown id errors"
-  (flow-s "(flow/cancel 999)")
-  (list "flow-error" "no-such-flow"))
-
-;; ── composition ─────────────────────────────────────────────────
-(flow-sus-test
-  "suspend inside a branch arm"
-  (flow-s
-    "(defflow gate (branch (lambda (x) (> x 0)) (lambda (x) (suspend (quote approve))) (flow-const (quote rejected)))) (define s (flow/start gate 5)) (flow/resume (car (cdr s)) (quote approved))")
-  "approved")
-(flow-sus-test
-  "two independent runs get independent ids"
-  (flow-s
-    "(defflow w (lambda (x) (suspend (quote q)))) (list (car (cdr (flow/start w 0))) (car (cdr (flow/start w 0))))")
-  (list 1 2))
-(flow-sus-test
-  "suspend reason may be a structured value"
-  (flow-s
-    "(defflow w (lambda (x) (suspend (list (quote needs) (quote approval))))) (car (cdr (cdr (flow/start w 0))))")
-  (list "needs" "approval"))
-
-(define flow-sus-tests-run! (fn () {:total (+ flow-sus-pass flow-sus-fail) :passed flow-sus-pass :failed flow-sus-fail :fails flow-sus-fails}))

lib/persist/api.sx

@@ -0,0 +1,10 @@
+; persist/api — the public entry point. persist/open returns a backend (the
+; in-memory one by default; pass a custom backend to inject file/pg/ipfs-ref).
+; All facet functions take this backend as their first argument.
+; Requires: lib/persist/backend.sx, lib/persist/log.sx, lib/persist/kv.sx.
+
+(define
+  persist/open
+  (fn
+    (&rest args)
+    (if (= (len args) 0) (persist/mem-backend) (first args))))

lib/persist/backend.sx

@@ -0,0 +1,34 @@
+; persist/backend — the injected storage protocol. Every facet (log, kv,
+; snapshot) goes through a backend dict, never touching storage directly, so
+; file/pg/ipfs-ref backends swap in unchanged. A backend is a dict of fns:
+;   {:append :read :last-seq :truncate-through :streams
+;    :kv-get :kv-put :kv-delete :kv-has? :kv-keys}
+; The in-memory backend is the test default. State is three dicts held in a
+; closure and mutated with set!: logs (stream -> event list), seqs (stream ->
+; last assigned seq — a monotonic high-water mark that survives compaction so
+; truncating the log prefix never lets a future append reuse a seq), kv. The
+; stream catalog comes from seqs, so a fully-compacted stream still lists.
+
+(define
+  persist/mem-backend
+  (fn
+    ()
+    (let ((logs {}) (seqs {}) (kv {})) {:truncate-through (fn (stream n) (let ((cur (get logs stream))) (set! logs (assoc logs stream (filter (fn (e) (> (persist/event-seq e) n)) (if cur cur (list))))))) :kv-keys (fn () (keys kv)) :read (fn (stream) (let ((cur (get logs stream))) (if cur cur (list)))) :kv-has? (fn (key) (has-key? kv key)) :last-seq (fn (stream) (let ((s (get seqs stream))) (if s s 0))) :streams (fn () (keys seqs)) :append (fn (stream event) (begin (let ((cur (get logs stream))) (set! logs (assoc logs stream (append (if cur cur (list)) event)))) (set! seqs (assoc seqs stream (persist/event-seq event))))) :kv-delete (fn (key) (set! kv (dissoc kv key))) :kv-put (fn (key val) (set! kv (assoc kv key val))) :kv-get (fn (key) (get kv key))})))
+
+; protocol accessors — call a backend op by keyword
+(define
+  persist/backend-append
+  (fn (b stream event) ((get b :append) stream event)))
+(define persist/backend-read (fn (b stream) ((get b :read) stream)))
+(define
+  persist/backend-last-seq
+  (fn (b stream) ((get b :last-seq) stream)))
+(define persist/backend-streams (fn (b) ((get b :streams))))
+(define
+  persist/backend-truncate
+  (fn (b stream n) ((get b :truncate-through) stream n)))
+(define persist/backend-kv-get (fn (b key) ((get b :kv-get) key)))
+(define persist/backend-kv-put (fn (b key val) ((get b :kv-put) key val)))
+(define persist/backend-kv-delete (fn (b key) ((get b :kv-delete) key)))
+(define persist/backend-kv-has? (fn (b key) ((get b :kv-has?) key)))
+(define persist/backend-kv-keys (fn (b) ((get b :kv-keys))))

lib/persist/batch.sx

@@ -0,0 +1,40 @@
+; persist/batch — commit several events to a stream as one contiguous block.
+; Each spec is (type at data). Plain append-batch always appends; the -expect
+; form is the transactional commit: it checks the stream is still at `expected`
+; before writing ANY event, so a batch is all-or-nothing under a concurrent
+; writer (conflict is a value, not a partial write). For an order + its line
+; items, an audit entry + its reason, etc. Requires: lib/persist/log.sx.
+
+; append a list of (type at data) specs as one block; returns the stored events
+; (a real cons-list, in order, with contiguous seqs)
+(define
+  persist/append-batch
+  (fn
+    (b stream specs)
+    (reverse
+      (reduce
+        (fn
+          (acc spec)
+          (cons
+            (persist/append
+              b
+              stream
+              (first spec)
+              (nth spec 1)
+              (nth spec 2))
+            acc))
+        (list)
+        specs))))
+
+; transactional batch: commit all specs only if the stream is still at expected,
+; else return a conflict and write nothing
+(define
+  persist/append-batch-expect
+  (fn
+    (b stream expected specs)
+    (let
+      ((actual (persist/last-seq b stream)))
+      (if
+        (= actual expected)
+        (persist/append-batch b stream specs)
+        {:actual actual :expected expected :conflict true}))))

lib/persist/blob.sx

@@ -0,0 +1,66 @@
+; persist/blob — large objects (images, media) are NOT persist's to hold. They
+; live in a content-addressed store (artdag/IPFS); persist stores only a
+; reference: {:cid :size :mime}. The blob store is a SEPARATE injected
+; dependency with its own transport (perform in production, a mock content store
+; in tests), distinct from the event/kv backend. The invariant: a blob ref that
+; lands in the log or kv carries the CID + metadata and never the bytes.
+; Requires: lib/persist/backend.sx.
+
+(define persist/blob-ref (fn (cid size mime) {:mime mime :size size :cid cid}))
+(define persist/blob-ref? (fn (r) (has-key? r :cid)))
+(define persist/blob-cid (fn (r) (get r :cid)))
+(define persist/blob-size (fn (r) (get r :size)))
+(define persist/blob-mime (fn (r) (get r :mime)))
+
+; blob store protocol over an injectable transport
+(define persist/blob-io (fn (transport) {:put (fn (bytes mime) (transport {:op "blob/put" :args (list bytes mime)})) :get (fn (cid) (transport {:op "blob/get" :args (list cid)})) :has? (fn (cid) (transport {:op "blob/has?" :args (list cid)}))}))
+
+; production blob store — transport is the kernel's perform
+(define
+  persist/blob-store-backend
+  (fn () (persist/blob-io (fn (req) (perform req)))))
+
+; store bytes via the blob backend; return ONLY the ref (cid + metadata) — this
+; is what the caller persists in the log/kv. The bytes never enter persist.
+(define
+  persist/blob-store
+  (fn
+    (blob bytes mime)
+    (let
+      ((cid ((get blob :put) bytes mime)))
+      (persist/blob-ref cid (len bytes) mime))))
+
+(define
+  persist/blob-fetch
+  (fn (blob ref) ((get blob :get) (persist/blob-cid ref))))
+(define
+  persist/blob-exists?
+  (fn (blob ref) ((get blob :has?) (persist/blob-cid ref))))
+
+; mock content-addressed store (stands in for artdag/IPFS). CID is a
+; deterministic content address: identical bytes dedupe to one CID. A real
+; store computes a SHA3/IPFS CID host-side; the prefix keeps the mock readable.
+(define persist/blob-cid-of (fn (bytes) (str "cid:" bytes)))
+
+(define
+  persist/blob-serve
+  (fn
+    (store req)
+    (let
+      ((op (get req :op)) (args (get req :args)))
+      (cond
+        ((equal? op "blob/put")
+          (let
+            ((cid (persist/blob-cid-of (first args))))
+            (begin (persist/backend-kv-put store cid (first args)) cid)))
+        ((equal? op "blob/get") (persist/backend-kv-get store (first args)))
+        ((equal? op "blob/has?")
+          (persist/backend-kv-has? store (first args)))
+        (else (error (str "persist/blob-serve: unknown op " op)))))))
+
+(define
+  persist/blob-mock-transport
+  (fn (store) (fn (req) (persist/blob-serve store req))))
+(define
+  persist/mock-blob
+  (fn (store) (persist/blob-io (persist/blob-mock-transport store))))

lib/persist/catalog.sx

@@ -0,0 +1,35 @@
+; persist/catalog — enumerate the streams a backend holds. The catalog is the
+; set of streams ever appended to (from the seq high-water marks), so a stream
+; whose log has been fully compacted still appears. $-prefixed streams are
+; reserved for internal indexes (e.g. the $global commit index) and are hidden
+; from the public catalog; use streams-all to see them. For admin, global ops,
+; and cross-stream tooling. Requires: lib/persist/backend.sx, lib/persist/log.sx.
+
+(define persist/reserved-stream? (fn (s) (starts-with? s "$")))
+
+; every stream including reserved internal indexes
+(define persist/streams-all (fn (b) (persist/backend-streams b)))
+
+; public streams (reserved internal indexes hidden)
+(define
+  persist/streams
+  (fn
+    (b)
+    (filter
+      (fn (s) (not (persist/reserved-stream? s)))
+      (persist/streams-all b))))
+
+(define persist/stream-count (fn (b) (len (persist/streams b))))
+(define
+  persist/stream-exists?
+  (fn (b stream) (contains? (persist/streams b) stream)))
+
+; total logical events across all public streams (sum of high-water marks)
+(define
+  persist/total-events
+  (fn
+    (b)
+    (reduce
+      (fn (acc s) (+ acc (persist/last-seq b s)))
+      0
+      (persist/streams b))))

lib/persist/compaction.sx

@@ -0,0 +1,43 @@
+; persist/compaction — once a snapshot subsumes a log prefix, those events are
+; dead weight: replay starts from the snapshot, so events with seq <= the
+; snapshot's seq are never folded again. Compaction checkpoints then truncates
+; that prefix. The seq counter is monotonic (backend high-water mark) so future
+; appends keep climbing — the surviving tail keeps its original seqs and replay
+; from the snapshot still equals a full replay of the pre-compaction log.
+; Policy is explicit: compact when the uncompacted tail reaches `every` events.
+; Requires: lib/persist/snapshot.sx, lib/persist/log.sx.
+
+; events accumulated since the last snapshot for name
+(define
+  persist/uncompacted
+  (fn
+    (b stream name seed)
+    (-
+      (persist/last-seq b stream)
+      (persist/project-seq (persist/snapshot-load b name seed)))))
+
+; policy: should we compact yet? tail since snapshot >= every
+(define
+  persist/should-compact?
+  (fn
+    (b stream name every seed)
+    (>= (persist/uncompacted b stream name seed) every)))
+
+; checkpoint then drop the snapshotted prefix; returns the new snapshot state
+(define
+  persist/compact
+  (fn
+    (b stream name step seed)
+    (let
+      ((state (persist/checkpoint b stream name step seed)))
+      (begin (persist/truncate b stream (persist/project-seq state)) state))))
+
+; compact only if the policy fires; always returns the current snapshot state
+(define
+  persist/maybe-compact
+  (fn
+    (b stream name step seed every)
+    (if
+      (persist/should-compact? b stream name every seed)
+      (persist/compact b stream name step seed)
+      (persist/snapshot-load b name seed))))

lib/persist/concurrency.sx

@@ -0,0 +1,24 @@
+; persist/concurrency — optimistic concurrency for the log facet. The caller
+; passes the seq it believes is current (the last-seq it last observed). If the
+; stream has advanced since, the append is refused and a conflict VALUE is
+; returned — never a crash, never a silent overwrite. The caller re-reads the
+; tail and retries. This is the substrate-level answer to "two writers, one
+; stream": the loser gets a result it can act on.
+; Requires: lib/persist/log.sx.
+
+(define
+  persist/append-expect
+  (fn
+    (b stream expected type at data)
+    (let
+      ((actual (persist/last-seq b stream)))
+      (if
+        (= actual expected)
+        (persist/append b stream type at data)
+        {:actual actual :expected expected :conflict true}))))
+
+(define
+  persist/conflict?
+  (fn (r) (if (has-key? r :conflict) (get r :conflict) false)))
+(define persist/conflict-expected (fn (r) (get r :expected)))
+(define persist/conflict-actual (fn (r) (get r :actual)))

lib/persist/conformance.sh

@@ -0,0 +1,128 @@
+#!/usr/bin/env bash
+# lib/persist/conformance.sh — run persist test suites, emit scoreboard.json + scoreboard.md.
+
+set -uo pipefail
+cd "$(git rev-parse --show-toplevel)"
+
+SX_SERVER="${SX_SERVER:-/root/rose-ash/hosts/ocaml/_build/default/bin/sx_server.exe}"
+if [ ! -x "$SX_SERVER" ]; then
+  SX_SERVER="hosts/ocaml/_build/default/bin/sx_server.exe"
+fi
+if [ ! -x "$SX_SERVER" ]; then
+  echo "ERROR: sx_server.exe not found." >&2
+  exit 1
+fi
+
+SUITES=(event log kv project subscribe concurrency snapshot compaction durable blob view cas catalog query batch upcast idempotency global example-acl recovery)
+
+OUT_JSON="lib/persist/scoreboard.json"
+OUT_MD="lib/persist/scoreboard.md"
+
+run_suite() {
+  local suite=$1
+  local file="lib/persist/tests/${suite}.sx"
+  local TMP
+  TMP=$(mktemp)
+  cat > "$TMP" << EPOCHS
+(epoch 1)
+(load "spec/stdlib.sx")
+(load "lib/r7rs.sx")
+(load "lib/persist/event.sx")
+(load "lib/persist/backend.sx")
+(load "lib/persist/log.sx")
+(load "lib/persist/kv.sx")
+(load "lib/persist/project.sx")
+(load "lib/persist/concurrency.sx")
+(load "lib/persist/snapshot.sx")
+(load "lib/persist/compaction.sx")
+(load "lib/persist/durable.sx")
+(load "lib/persist/blob.sx")
+(load "lib/persist/view.sx")
+(load "lib/persist/catalog.sx")
+(load "lib/persist/query.sx")
+(load "lib/persist/batch.sx")
+(load "lib/persist/upcast.sx")
+(load "lib/persist/idempotency.sx")
+(load "lib/persist/global.sx")
+(load "lib/persist/examples/acl.sx")
+(load "lib/persist/subscribe.sx")
+(load "lib/persist/api.sx")
+(epoch 2)
+(eval "(define persist-test-pass 0)")
+(eval "(define persist-test-fail 0)")
+(eval "(define persist-test (fn (name got expected) (if (equal? got expected) (set! persist-test-pass (+ persist-test-pass 1)) (set! persist-test-fail (+ persist-test-fail 1)))))")
+(epoch 3)
+(load "${file}")
+(epoch 4)
+(eval "(list persist-test-pass persist-test-fail)")
+EPOCHS
+
+  local OUTPUT
+  OUTPUT=$(timeout 300 "$SX_SERVER" < "$TMP" 2>/dev/null)
+  rm -f "$TMP"
+
+  local LINE
+  LINE=$(echo "$OUTPUT" | awk '/^\(ok-len 4 / {getline; print; exit}')
+  if [ -z "$LINE" ]; then
+    LINE=$(echo "$OUTPUT" | grep -E '^\(ok 4 \([0-9]+ [0-9]+\)\)' | tail -1 \
+            | sed -E 's/^\(ok 4 //; s/\)$//')
+  fi
+
+  local P F
+  P=$(echo "$LINE" | sed -E 's/^\(([0-9]+) ([0-9]+)\).*/\1/')
+  F=$(echo "$LINE" | sed -E 's/^\(([0-9]+) ([0-9]+)\).*/\2/')
+  P=${P:-0}
+  F=${F:-0}
+  echo "${P} ${F}"
+}
+
+declare -A SUITE_PASS
+declare -A SUITE_FAIL
+TOTAL_PASS=0
+TOTAL_FAIL=0
+
+echo "Running persist conformance suite..." >&2
+for s in "${SUITES[@]}"; do
+  read -r p f < <(run_suite "$s")
+  SUITE_PASS[$s]=$p
+  SUITE_FAIL[$s]=$f
+  TOTAL_PASS=$((TOTAL_PASS + p))
+  TOTAL_FAIL=$((TOTAL_FAIL + f))
+  printf "  %-12s %d/%d\n" "$s" "$p" "$((p+f))" >&2
+done
+
+# scoreboard.json
+{
+  printf '{\n'
+  printf '  "suites": {\n'
+  first=1
+  for s in "${SUITES[@]}"; do
+    if [ $first -eq 0 ]; then printf ',\n'; fi
+    printf '    "%s": {"pass": %d, "fail": %d}' "$s" "${SUITE_PASS[$s]}" "${SUITE_FAIL[$s]}"
+    first=0
+  done
+  printf '\n  },\n'
+  printf '  "total_pass": %d,\n' "$TOTAL_PASS"
+  printf '  "total_fail": %d,\n' "$TOTAL_FAIL"
+  printf '  "total": %d\n' "$((TOTAL_PASS + TOTAL_FAIL))"
+  printf '}\n'
+} > "$OUT_JSON"
+
+# scoreboard.md
+{
+  printf '# persist Conformance Scoreboard\n\n'
+  printf '_Generated by `lib/persist/conformance.sh`_\n\n'
+  printf '| Suite | Pass | Fail | Total |\n'
+  printf '|-------|-----:|-----:|------:|\n'
+  for s in "${SUITES[@]}"; do
+    p=${SUITE_PASS[$s]}
+    f=${SUITE_FAIL[$s]}
+    printf '| %s | %d | %d | %d |\n' "$s" "$p" "$f" "$((p+f))"
+  done
+  printf '| **Total** | **%d** | **%d** | **%d** |\n' "$TOTAL_PASS" "$TOTAL_FAIL" "$((TOTAL_PASS + TOTAL_FAIL))"
+} > "$OUT_MD"
+
+echo "Wrote $OUT_JSON and $OUT_MD" >&2
+echo "Total: $TOTAL_PASS pass, $TOTAL_FAIL fail" >&2
+
+[ "$TOTAL_FAIL" -eq 0 ]

lib/persist/durable.sx

@@ -0,0 +1,71 @@
+; persist/durable — a backend whose every op crosses the kernel's IO-suspension
+; boundary. Each op performs an IO request {:op "persist/..." :args (...)};
+; under the real kernel `perform` suspends the CEK machine and the host (file,
+; pg, ipfs-ref) services the request and resumes with the result — so the facet
+; code above (log/kv/project/snapshot/compaction) never changes. The TRANSPORT
+; is injectable: production passes the kernel's perform; tests pass a mock
+; servicer over an in-memory disk. Same request shapes either way, so the whole
+; existing facet stack runs unchanged on the mock-durable backend.
+; Requires: lib/persist/backend.sx.
+
+; request encoders — the exact payloads the durable backend performs
+(define persist/req-append (fn (stream event) {:op "persist/append" :args (list stream event)}))
+(define persist/req-read (fn (stream) {:op "persist/read" :args (list stream)}))
+(define persist/req-last-seq (fn (stream) {:op "persist/last-seq" :args (list stream)}))
+(define persist/req-streams (fn () {:op "persist/streams" :args (list)}))
+(define persist/req-truncate (fn (stream n) {:op "persist/truncate" :args (list stream n)}))
+(define persist/req-kv-get (fn (key) {:op "persist/kv-get" :args (list key)}))
+(define persist/req-kv-put (fn (key val) {:op "persist/kv-put" :args (list key val)}))
+(define persist/req-kv-delete (fn (key) {:op "persist/kv-delete" :args (list key)}))
+(define persist/req-kv-has? (fn (key) {:op "persist/kv-has?" :args (list key)}))
+(define persist/req-kv-keys (fn () {:op "persist/kv-keys" :args (list)}))
+
+; a backend parameterized over a transport (req -> response)
+(define persist/io-backend (fn (transport) {:truncate-through (fn (stream n) (transport (persist/req-truncate stream n))) :kv-keys (fn () (transport (persist/req-kv-keys))) :read (fn (stream) (transport (persist/req-read stream))) :kv-has? (fn (key) (transport (persist/req-kv-has? key))) :last-seq (fn (stream) (transport (persist/req-last-seq stream))) :streams (fn () (transport (persist/req-streams))) :append (fn (stream event) (transport (persist/req-append stream event))) :kv-delete (fn (key) (transport (persist/req-kv-delete key))) :kv-put (fn (key val) (transport (persist/req-kv-put key val))) :kv-get (fn (key) (transport (persist/req-kv-get key)))}))
+
+; production backend — transport is the kernel's perform (suspends; host resumes)
+(define
+  persist/durable-backend
+  (fn () (persist/io-backend (fn (req) (perform req)))))
+
+; reference host: service one request against a disk (any backend protocol impl).
+; This is what a real host plugs into the kernel's IO resolver, and the mock-IO
+; harness for tests: it never touches a real disk, just an in-memory backend.
+(define
+  persist/serve
+  (fn
+    (disk req)
+    (let
+      ((op (get req :op)) (args (get req :args)))
+      (cond
+        ((equal? op "persist/append")
+          (persist/backend-append disk (first args) (nth args 1)))
+        ((equal? op "persist/read")
+          (persist/backend-read disk (first args)))
+        ((equal? op "persist/last-seq")
+          (persist/backend-last-seq disk (first args)))
+        ((equal? op "persist/streams") (persist/backend-streams disk))
+        ((equal? op "persist/truncate")
+          (persist/backend-truncate disk (first args) (nth args 1)))
+        ((equal? op "persist/kv-get")
+          (persist/backend-kv-get disk (first args)))
+        ((equal? op "persist/kv-put")
+          (persist/backend-kv-put disk (first args) (nth args 1)))
+        ((equal? op "persist/kv-delete")
+          (persist/backend-kv-delete disk (first args)))
+        ((equal? op "persist/kv-has?")
+          (persist/backend-kv-has? disk (first args)))
+        ((equal? op "persist/kv-keys") (persist/backend-kv-keys disk))
+        (else (error (str "persist/serve: unknown op " op)))))))
+
+; mock transport: a perform-replacement that services against a disk in-process
+(define
+  persist/mock-transport
+  (fn (disk) (fn (req) (persist/serve disk req))))
+
+; a durable backend wired to a mock disk — exercises the full io-backend path
+; (request-encode -> serve -> disk) with no suspension, so the existing facet
+; suite runs against it unchanged.
+(define
+  persist/mock-durable
+  (fn (disk) (persist/io-backend (persist/mock-transport disk))))

lib/persist/event.sx

@@ -0,0 +1,13 @@
+; persist/event — an event is the unit of the log facet:
+;   {:stream :seq :type :at :data}
+; stream = which append-only stream, seq = 1-based position within it,
+; type = event kind, at = caller-supplied timestamp (never a clock here:
+; replay must stay pure), data = payload dict.
+
+(define persist/event (fn (stream seq type at data) {:data data :type type :at at :stream stream :seq seq}))
+
+(define persist/event-stream (fn (e) (get e :stream)))
+(define persist/event-seq (fn (e) (get e :seq)))
+(define persist/event-type (fn (e) (get e :type)))
+(define persist/event-at (fn (e) (get e :at)))
+(define persist/event-data (fn (e) (get e :data)))

lib/persist/examples/acl.sx

@@ -0,0 +1,79 @@
+; persist/examples/acl — a WORKED MIGRATION REFERENCE. A subsystem (acl grants:
+; who may access what) currently hand-rolls an in-memory mutable map that loses
+; every grant on restart and keeps no audit trail. This shows the same subsystem
+; rebuilt on persist. It is the template other subsystem loops copy; it does NOT
+; touch the real lib/acl (out of this loop's scope).
+;
+; BEFORE — hand-rolled, ephemeral, no history, no concurrency safety:
+;   (define acl-grants {})                      ; resource -> principal list (mutable)
+;   (define acl-grant!  (fn (r p) (set! acl-grants (assoc acl-grants r (cons p (get acl-grants r))))))
+;   (define acl-revoke! (fn (r p) (set! acl-grants (assoc acl-grants r (remove p ...)))))
+;   (define acl-can?    (fn (r p) (contains? (get acl-grants r) p)))
+;   ;; vanishes on restart; "when/why was X granted?" is unanswerable.
+;
+; AFTER — on persist. Grants/revokes are EVENTS (history matters), the current
+; grant set is a PROJECTION, checks read a materialized VIEW, and the audit trail
+; is a time-windowed query. Every fn takes a backend `b`, so the same code runs
+; on the in-memory backend today and the durable backend unchanged.
+; Requires: lib/persist/log.sx, lib/persist/project.sx, lib/persist/view.sx,
+;           lib/persist/query.sx.
+
+(define acl/stream (fn (resource) (str "acl/" resource)))
+
+; write side — grant/revoke append events (the history is the source of truth)
+(define
+  acl/grant
+  (fn
+    (b resource principal at)
+    (persist/append b (acl/stream resource) "granted" at {:principal principal})))
+(define
+  acl/revoke
+  (fn
+    (b resource principal at)
+    (persist/append b (acl/stream resource) "revoked" at {:principal principal})))
+
+; fold step: grant adds a principal (once), revoke removes it
+(define
+  acl/step
+  (fn
+    (set e)
+    (let
+      ((p (get (persist/event-data e) :principal)))
+      (if
+        (equal? (persist/event-type e) "granted")
+        (if (contains? set p) set (append set p))
+        (filter (fn (x) (not (equal? x p))) set)))))
+
+; read side — current grant set + membership check (replays the log)
+(define
+  acl/grants
+  (fn
+    (b resource)
+    (persist/project-fold b (acl/stream resource) acl/step (list))))
+(define
+  acl/can?
+  (fn (b resource principal) (contains? (acl/grants b resource) principal)))
+
+; materialized view — attach to a hub for O(1) checks that stay current on write
+(define
+  acl/view
+  (fn
+    (resource)
+    (persist/view
+      (str "acl-current/" resource)
+      (acl/stream resource)
+      acl/step
+      (list))))
+(define
+  acl/can-fast?
+  (fn
+    (b resource principal)
+    (contains? (persist/view-peek b (acl/view resource)) principal)))
+
+; audit — grants/revokes for a resource in a time window (the new capability the
+; hand-rolled version could never answer)
+(define
+  acl/audit-window
+  (fn
+    (b resource from to)
+    (persist/read-window b (acl/stream resource) from to)))

lib/persist/global.sx

@@ -0,0 +1,55 @@
+; persist/global — a global commit ordering across streams. Per-stream seqs only
+; order within a stream; a unified timeline (e.g. feed's home feed, a global
+; audit trail) needs a single order across streams. `persist/gappend` appends to
+; the target stream and then records a pointer in a reserved $global index whose
+; own seq IS the global commit position. Reading the index in order and
+; resolving each pointer yields every event in commit order. This is opt-in:
+; streams that don't need global ordering use plain persist/append and never
+; touch $global. Determinism: the order is the $global append order, replayed
+; identically. Requires: lib/persist/log.sx, lib/persist/catalog.sx.
+
+(define persist/global-stream "$global")
+
+; append with a global commit position. Returns the stored stream event; the
+; event's global position is the seq of its pointer in $global.
+(define
+  persist/gappend
+  (fn
+    (b stream type at data)
+    (let
+      ((ev (persist/append b stream type at data)))
+      (begin (persist/append b persist/global-stream "ref" at {:stream stream :seq (persist/event-seq ev)}) ev))))
+
+; the global index: pointer events in commit order (each pointer's seq = gpos)
+(define persist/global-log (fn (b) (persist/read b persist/global-stream)))
+
+; the current global commit position (count of globally-ordered appends)
+(define
+  persist/global-pos
+  (fn (b) (persist/last-seq b persist/global-stream)))
+
+; resolve a pointer event to the actual stream event it references
+(define
+  persist/resolve-ref
+  (fn
+    (b ptr)
+    (let
+      ((d (persist/event-data ptr)))
+      (first (persist/read-from b (get d :stream) (get d :seq))))))
+
+; every globally-ordered event, in commit order
+(define
+  persist/read-global
+  (fn
+    (b)
+    (map (fn (ptr) (persist/resolve-ref b ptr)) (persist/global-log b))))
+
+; pointer events at or after a global position (incremental global consumers)
+(define
+  persist/global-from
+  (fn (b gpos) (persist/read-from b persist/global-stream gpos)))
+
+; fold over all events in global commit order
+(define
+  persist/project-global
+  (fn (b step seed) (reduce step seed (persist/read-global b))))

lib/persist/idempotency.sx

@@ -0,0 +1,28 @@
+; persist/idempotency — exactly-once append under retries. A command retried
+; after a network blip must not append its event twice. The caller supplies an
+; idempotency key; the first append for that (stream, key) stores the event and
+; remembers the key in the kv facet; a repeat returns the SAME event without
+; appending. Because the marker lives in kv, idempotency holds across a restart
+; too. Keyed per stream. Requires: lib/persist/log.sx, lib/persist/kv.sx.
+
+(define persist/idem-key (fn (stream key) (str "idem/" stream "/" key)))
+
+; true if an append-once has already been recorded for (stream, key)
+(define
+  persist/seen?
+  (fn (b stream key) (persist/kv-has? b (persist/idem-key stream key))))
+
+; append at most once per (stream, key). Returns the stored event either way —
+; freshly appended on first use, the remembered one on a repeat.
+(define
+  persist/append-once
+  (fn
+    (b stream key type at data)
+    (let
+      ((k (persist/idem-key stream key)))
+      (if
+        (persist/kv-has? b k)
+        (persist/kv-get b k)
+        (let
+          ((ev (persist/append b stream type at data)))
+          (begin (persist/kv-put b k ev) ev))))))

lib/persist/kv.sx

@@ -0,0 +1,44 @@
+; persist/kv — the kv facet: current-state values, no history. For things
+; whose history does NOT matter (stock counts, config, profiles, session
+; blobs) and where projections materialize their read models.
+; Requires: lib/persist/backend.sx.
+
+(define persist/kv-get (fn (b key) (persist/backend-kv-get b key)))
+(define
+  persist/kv-put
+  (fn (b key val) (begin (persist/backend-kv-put b key val) val)))
+(define persist/kv-delete (fn (b key) (persist/backend-kv-delete b key)))
+(define persist/kv-has? (fn (b key) (persist/backend-kv-has? b key)))
+(define persist/kv-keys (fn (b) (persist/backend-kv-keys b)))
+
+; get with a default when the key is absent
+(define
+  persist/kv-get-or
+  (fn
+    (b key dflt)
+    (if (persist/kv-has? b key) (persist/kv-get b key) dflt)))
+
+; read-modify-write: apply f to the current value (or dflt if absent), store result
+(define
+  persist/kv-update
+  (fn
+    (b key dflt f)
+    (persist/kv-put b key (f (persist/kv-get-or b key dflt)))))
+
+; compare-and-swap: set key to new ONLY if its current value equals expected.
+; Returns new on success, or a conflict value {:conflict true :expected :actual}
+; the caller can re-read and retry on. The kv analogue of log append-expect.
+(define
+  persist/kv-cas
+  (fn
+    (b key expected new)
+    (let
+      ((actual (persist/kv-get b key)))
+      (if (equal? actual expected) (persist/kv-put b key new) {:actual actual :expected expected :conflict true}))))
+
+; create-only: put a value only if the key is absent; conflict if it exists
+(define
+  persist/kv-put-new
+  (fn
+    (b key val)
+    (if (persist/kv-has? b key) {:actual (persist/kv-get b key) :conflict true :reason "exists"} (persist/kv-put b key val))))

lib/persist/log.sx

@@ -0,0 +1,43 @@
+; persist/log — the log facet: append-only event streams. seq is assigned from
+; a monotonic per-stream high-water mark (1-based) held by the backend, so it
+; keeps climbing even after the log prefix is compacted away. Reads return the
+; events currently stored, oldest-first.
+; Requires: lib/persist/event.sx, lib/persist/backend.sx.
+
+; logical last seq assigned in a stream (0 if none) — survives compaction
+(define
+  persist/last-seq
+  (fn (b stream) (persist/backend-last-seq b stream)))
+
+; number of events physically stored in a stream (shrinks on compaction)
+(define
+  persist/count
+  (fn (b stream) (len (persist/backend-read b stream))))
+
+; append an event, auto-assigning the next seq. Returns the stored event.
+(define
+  persist/append
+  (fn
+    (b stream type at data)
+    (let
+      ((seq (+ 1 (persist/last-seq b stream))))
+      (let
+        ((ev (persist/event stream seq type at data)))
+        (begin (persist/backend-append b stream ev) ev)))))
+
+; read all events currently stored in a stream, oldest-first
+(define persist/read (fn (b stream) (persist/backend-read b stream)))
+
+; read events with seq >= from
+(define
+  persist/read-from
+  (fn
+    (b stream from)
+    (filter
+      (fn (e) (>= (persist/event-seq e) from))
+      (persist/read b stream))))
+
+; drop events with seq <= n (compaction); the seq counter is untouched
+(define
+  persist/truncate
+  (fn (b stream n) (persist/backend-truncate b stream n)))

lib/persist/project.sx

@@ -0,0 +1,30 @@
+; persist/project — a projection folds a stream's events into a read model.
+; A projection state is {:value v :seq s} where s is the last seq folded in,
+; so a projection can resume incrementally from where it left off (replay only
+; the tail). step : (value event) -> value. Determinism: step must be pure —
+; time lives on the event (event-at), never a clock here.
+; Requires: lib/persist/event.sx, lib/persist/log.sx.
+
+; fold the tail (events with seq > prior's seq) onto a prior projection state
+(define
+  persist/project-resume
+  (fn
+    (b stream step prior)
+    (let
+      ((tail (persist/read-from b stream (+ 1 (get prior :seq)))))
+      (reduce (fn (acc e) {:value (step (get acc :value) e) :seq (persist/event-seq e)}) prior tail))))
+
+; project the whole stream from seed
+(define
+  persist/project
+  (fn (b stream step seed) (persist/project-resume b stream step {:value seed :seq 0})))
+
+(define persist/project-value (fn (p) (get p :value)))
+(define persist/project-seq (fn (p) (get p :seq)))
+
+; convenience: project and return just the value
+(define
+  persist/project-fold
+  (fn
+    (b stream step seed)
+    (persist/project-value (persist/project b stream step seed))))

lib/persist/query.sx

@@ -0,0 +1,54 @@
+; persist/query — read-side helpers over a stream: slice by seq range, filter by
+; timestamp / type / predicate. Pure reads composed from persist/read, no
+; backend changes. The log is bad at ad-hoc relational queries (project into a
+; kv read model for those) but these cover the common log scans: an audit window
+; by time, a type filter, a since-cursor for incremental consumers.
+; Requires: lib/persist/log.sx.
+
+; events with seq in [from, to] inclusive
+(define
+  persist/read-between
+  (fn
+    (b stream from to)
+    (filter
+      (fn
+        (e)
+        (and (>= (persist/event-seq e) from) (<= (persist/event-seq e) to)))
+      (persist/read b stream))))
+
+; events at or after a timestamp (events carry :at; never a clock here)
+(define
+  persist/read-since
+  (fn
+    (b stream at)
+    (filter (fn (e) (>= (persist/event-at e) at)) (persist/read b stream))))
+
+; events whose :at is in [from, to] inclusive — an audit window
+(define
+  persist/read-window
+  (fn
+    (b stream from to)
+    (filter
+      (fn
+        (e)
+        (and (>= (persist/event-at e) from) (<= (persist/event-at e) to)))
+      (persist/read b stream))))
+
+; events matching a predicate (e -> truthy)
+(define
+  persist/read-where
+  (fn (b stream pred) (filter pred (persist/read b stream))))
+
+; events of a given type
+(define
+  persist/read-by-type
+  (fn
+    (b stream type)
+    (filter
+      (fn (e) (equal? (persist/event-type e) type))
+      (persist/read b stream))))
+
+; count events matching a predicate
+(define
+  persist/count-where
+  (fn (b stream pred) (len (persist/read-where b stream pred))))

lib/persist/scoreboard.json

@@ -0,0 +1,27 @@
+{
+  "suites": {
+    "event": {"pass": 6, "fail": 0},
+    "log": {"pass": 9, "fail": 0},
+    "kv": {"pass": 13, "fail": 0},
+    "project": {"pass": 9, "fail": 0},
+    "subscribe": {"pass": 9, "fail": 0},
+    "concurrency": {"pass": 8, "fail": 0},
+    "snapshot": {"pass": 11, "fail": 0},
+    "compaction": {"pass": 11, "fail": 0},
+    "durable": {"pass": 15, "fail": 0},
+    "blob": {"pass": 14, "fail": 0},
+    "view": {"pass": 11, "fail": 0},
+    "cas": {"pass": 11, "fail": 0},
+    "catalog": {"pass": 10, "fail": 0},
+    "query": {"pass": 9, "fail": 0},
+    "batch": {"pass": 10, "fail": 0},
+    "upcast": {"pass": 9, "fail": 0},
+    "idempotency": {"pass": 9, "fail": 0},
+    "global": {"pass": 11, "fail": 0},
+    "example-acl": {"pass": 10, "fail": 0},
+    "recovery": {"pass": 6, "fail": 0}
+  },
+  "total_pass": 201,
+  "total_fail": 0,
+  "total": 201
+}

lib/persist/scoreboard.md

@@ -0,0 +1,27 @@
+# persist Conformance Scoreboard
+
+_Generated by `lib/persist/conformance.sh`_
+
+| Suite | Pass | Fail | Total |
+|-------|-----:|-----:|------:|
+| event | 6 | 0 | 6 |
+| log | 9 | 0 | 9 |
+| kv | 13 | 0 | 13 |
+| project | 9 | 0 | 9 |
+| subscribe | 9 | 0 | 9 |
+| concurrency | 8 | 0 | 8 |
+| snapshot | 11 | 0 | 11 |
+| compaction | 11 | 0 | 11 |
+| durable | 15 | 0 | 15 |
+| blob | 14 | 0 | 14 |
+| view | 11 | 0 | 11 |
+| cas | 11 | 0 | 11 |
+| catalog | 10 | 0 | 10 |
+| query | 9 | 0 | 9 |
+| batch | 10 | 0 | 10 |
+| upcast | 9 | 0 | 9 |
+| idempotency | 9 | 0 | 9 |
+| global | 11 | 0 | 11 |
+| example-acl | 10 | 0 | 10 |
+| recovery | 6 | 0 | 6 |
+| **Total** | **201** | **0** | **201** |

lib/persist/snapshot.sx

@@ -0,0 +1,40 @@
+; persist/snapshot — checkpoint a projection so a read model rebuilds as
+; snapshot + tail instead of a full replay. A snapshot is just a projection
+; state {:value :seq} stored in the kv facet under a namespaced key. The
+; headline property (tested both ways): snapshot + tail == full replay. Replay
+; is pure — it depends only on the stored snapshot and the log tail, never a
+; clock. Requires: lib/persist/project.sx, lib/persist/kv.sx.
+
+(define persist/snapshot-key (fn (name) (str "snapshot/" name)))
+
+; load the stored snapshot for name, or a fresh {:value seed :seq 0} if none
+(define
+  persist/snapshot-load
+  (fn
+    (b name seed)
+    (persist/kv-get-or b (persist/snapshot-key name) {:value seed :seq 0})))
+
+; store a projection state as the snapshot for name; returns the state
+(define
+  persist/snapshot-save
+  (fn (b name state) (persist/kv-put b (persist/snapshot-key name) state)))
+
+(define
+  persist/snapshot-exists?
+  (fn (b name) (persist/kv-has? b (persist/snapshot-key name))))
+
+; replay = snapshot + tail: load the snapshot then fold events after it
+(define
+  persist/replay
+  (fn
+    (b stream name step seed)
+    (persist/project-resume b stream step (persist/snapshot-load b name seed))))
+
+; replay then persist the new snapshot; returns the updated state
+(define
+  persist/checkpoint
+  (fn
+    (b stream name step seed)
+    (let
+      ((state (persist/replay b stream name step seed)))
+      (begin (persist/snapshot-save b name state) state))))

lib/persist/subscribe.sx

@@ -0,0 +1,21 @@
+; persist/subscribe — a subscription hub wraps a backend with per-stream
+; callbacks fired after each append. The canonical use: a callback re-runs a
+; projection (or bumps a kv counter) so read models update incrementally on
+; write instead of being recomputed on read.
+;   callback signature: (backend stream event) -> ignored
+; Publish goes through the hub; direct persist/append on the backend bypasses
+; subscribers by design (bulk loads, replay).
+; Requires: lib/persist/log.sx.
+
+(define persist/hub (fn (b) (let ((subs {})) {:subscriber-count (fn (stream) (let ((cs (get subs stream))) (if cs (len cs) 0))) :publish (fn (stream type at data) (let ((ev (persist/append b stream type at data))) (begin (for-each (fn (cb) (cb b stream ev)) (let ((cs (get subs stream))) (if cs cs (list)))) ev))) :subscribe (fn (stream cb) (let ((cur (get subs stream))) (set! subs (assoc subs stream (append (if cur cur (list)) cb))))) :backend b})))
+
+(define persist/hub-backend (fn (h) (get h :backend)))
+(define
+  persist/subscribe
+  (fn (h stream cb) ((get h :subscribe) stream cb)))
+(define
+  persist/publish
+  (fn (h stream type at data) ((get h :publish) stream type at data)))
+(define
+  persist/subscriber-count
+  (fn (h stream) ((get h :subscriber-count) stream)))

lib/persist/tests/batch.sx

@@ -0,0 +1,122 @@
+; Extension — atomic batch append: contiguous seqs, transactional all-or-nothing.
+
+(persist-test
+  "batch assigns contiguous seqs"
+  (let
+    ((b (persist/open)))
+    (let
+      ((evs (persist/append-batch b "s" (list (list "a" 0 {}) (list "b" 0 {}) (list "c" 0 {})))))
+      (list
+        (persist/event-seq (first evs))
+        (persist/event-seq (nth evs 2)))))
+  (list 1 3))
+(persist-test
+  "batch returns events in order"
+  (let
+    ((b (persist/open)))
+    (let
+      ((evs (persist/append-batch b "s" (list (list "a" 0 {}) (list "b" 0 {})))))
+      (list
+        (persist/event-type (first evs))
+        (persist/event-type (nth evs 1)))))
+  (list "a" "b"))
+(persist-test
+  "batch grows the stream by its size"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append-batch
+        b
+        "s"
+        (list
+          (list "a" 0 {})
+          (list "b" 0 {})
+          (list "c" 0 {})))
+      (persist/count b "s")))
+  3)
+(persist-test
+  "batch continues an existing stream"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (let
+        ((evs (persist/append-batch b "s" (list (list "a" 0 {}) (list "b" 0 {})))))
+        (persist/event-seq (first evs)))))
+  2)
+(persist-test
+  "empty batch is a no-op"
+  (let
+    ((b (persist/open)))
+    (begin (persist/append-batch b "s" (list)) (persist/count b "s")))
+  0)
+(persist-test
+  "batch-expect with correct seq commits all"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append-batch-expect
+        b
+        "s"
+        0
+        (list
+          (list "a" 0 {})
+          (list "b" 0 {})))
+      (persist/count b "s")))
+  2)
+(persist-test
+  "batch-expect with stale seq writes nothing"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append-batch-expect
+        b
+        "s"
+        0
+        (list
+          (list "a" 0 {})
+          (list "b" 0 {})))
+      (persist/count b "s")))
+  1)
+(persist-test
+  "batch-expect stale returns a conflict"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/conflict?
+        (persist/append-batch-expect
+          b
+          "s"
+          0
+          (list (list "a" 0 {}))))))
+  true)
+(persist-test
+  "batch data is preserved"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append-batch
+        b
+        "order"
+        (list
+          (list "placed" 0 {:id 1})
+          (list "line" 0 {:sku "x"})))
+      (get
+        (persist/event-data (nth (persist/read b "order") 1))
+        :sku)))
+  "x")
+(persist-test
+  "batch works on the durable backend"
+  (let
+    ((db (persist/mock-durable (persist/mem-backend))))
+    (begin
+      (persist/append-batch
+        db
+        "s"
+        (list
+          (list "a" 0 {})
+          (list "b" 0 {})))
+      (persist/last-seq db "s")))
+  2)

lib/persist/tests/blob.sx

@@ -0,0 +1,112 @@
+; Phase 4 — blob backend: store the ref, never the bytes. Bytes live in a
+; separate content-addressed store (mock here).
+
+(persist-test
+  "blob-ref carries cid"
+  (persist/blob-cid (persist/blob-ref "c1" 10 "image/png"))
+  "c1")
+(persist-test
+  "blob-ref carries size"
+  (persist/blob-size (persist/blob-ref "c1" 10 "image/png"))
+  10)
+(persist-test
+  "blob-ref carries mime"
+  (persist/blob-mime (persist/blob-ref "c1" 10 "image/png"))
+  "image/png")
+(persist-test
+  "blob-ref? true for a ref"
+  (persist/blob-ref? (persist/blob-ref "c1" 1 "x"))
+  true)
+(persist-test
+  "blob-ref? false for a plain dict"
+  (persist/blob-ref? {:n 1})
+  false)
+
+(persist-test
+  "store returns a ref, not the bytes"
+  (let
+    ((blob (persist/mock-blob (persist/mem-backend))))
+    (persist/blob-ref? (persist/blob-store blob "PNGDATA" "image/png")))
+  true)
+(persist-test
+  "store records the byte length as size"
+  (let
+    ((blob (persist/mock-blob (persist/mem-backend))))
+    (persist/blob-size (persist/blob-store blob "12345" "text/plain")))
+  5)
+(persist-test
+  "fetch round-trips the bytes via the ref"
+  (let
+    ((blob (persist/mock-blob (persist/mem-backend))))
+    (let
+      ((ref (persist/blob-store blob "PAYLOAD" "text/plain")))
+      (persist/blob-fetch blob ref)))
+  "PAYLOAD")
+(persist-test
+  "exists? true after store"
+  (let
+    ((blob (persist/mock-blob (persist/mem-backend))))
+    (let
+      ((ref (persist/blob-store blob "X" "text/plain")))
+      (persist/blob-exists? blob ref)))
+  true)
+(persist-test
+  "content addressing: same bytes dedupe to same cid"
+  (let
+    ((blob (persist/mock-blob (persist/mem-backend))))
+    (equal?
+      (persist/blob-cid (persist/blob-store blob "SAME" "text/plain"))
+      (persist/blob-cid (persist/blob-store blob "SAME" "text/plain"))))
+  true)
+(persist-test
+  "different bytes get different cids"
+  (let
+    ((blob (persist/mock-blob (persist/mem-backend))))
+    (equal?
+      (persist/blob-cid (persist/blob-store blob "A" "text/plain"))
+      (persist/blob-cid (persist/blob-store blob "B" "text/plain"))))
+  false)
+
+; ---------- the invariant: persist holds the ref, never the bytes ----------
+(persist-test
+  "a blob ref stored in kv is a ref"
+  (let
+    ((db (persist/mock-durable (persist/mem-backend)))
+      (blob (persist/mock-blob (persist/mem-backend))))
+    (begin
+      (persist/kv-put
+        db
+        "avatar"
+        (persist/blob-store blob "BIGIMAGE" "image/png"))
+      (persist/blob-ref? (persist/kv-get db "avatar"))))
+  true)
+(persist-test
+  "the kv value does not contain the bytes"
+  (let
+    ((db (persist/mock-durable (persist/mem-backend)))
+      (blob (persist/mock-blob (persist/mem-backend))))
+    (begin
+      (persist/kv-put
+        db
+        "avatar"
+        (persist/blob-store blob "BIGIMAGE" "image/png"))
+      (has-key? (persist/kv-get db "avatar") :bytes)))
+  false)
+(persist-test
+  "a blob ref stored in the log is a ref, bytes fetched separately"
+  (let
+    ((db (persist/mock-durable (persist/mem-backend)))
+      (store (persist/mem-backend)))
+    (let
+      ((blob (persist/mock-blob store)))
+      (begin
+        (persist/append
+          db
+          "uploads"
+          "added"
+          0
+          (persist/blob-store blob "FILEBYTES" "application/pdf"))
+        (let
+          ((ref (persist/event-data (first (persist/read db "uploads")))))
+          (list (persist/blob-ref? ref) (persist/blob-fetch blob ref))))))
+  (list true "FILEBYTES"))

lib/persist/tests/cas.sx

@@ -0,0 +1,96 @@
+; Extension — kv compare-and-swap: atomic current-state updates. Uses
+; persist/conflict? from concurrency.sx.
+
+(persist-test
+  "cas on absent key with nil expected succeeds"
+  (let ((b (persist/open))) (persist/kv-cas b "k" nil 1))
+  1)
+(persist-test
+  "cas with matching expected succeeds"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/kv-put b "k" 5)
+      (persist/kv-cas b "k" 5 6)
+      (persist/kv-get b "k")))
+  6)
+(persist-test
+  "cas with stale expected returns a conflict"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/kv-put b "k" 5)
+      (persist/conflict? (persist/kv-cas b "k" 4 6))))
+  true)
+(persist-test
+  "a conflicting cas does not write"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/kv-put b "k" 5)
+      (persist/kv-cas b "k" 4 6)
+      (persist/kv-get b "k")))
+  5)
+(persist-test
+  "cas conflict carries expected and actual"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/kv-put b "k" 5)
+      (let
+        ((r (persist/kv-cas b "k" 4 6)))
+        (list (persist/conflict-expected r) (persist/conflict-actual r)))))
+  (list 4 5))
+(persist-test
+  "two cas racers: first wins, second conflicts"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/kv-put b "stock" 10)
+      (persist/kv-cas b "stock" 10 9)
+      (persist/conflict? (persist/kv-cas b "stock" 10 9))))
+  true)
+(persist-test
+  "retry after cas conflict succeeds"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/kv-put b "stock" 10)
+      (persist/kv-cas b "stock" 10 9)
+      (let
+        ((r (persist/kv-cas b "stock" 10 9)))
+        (if
+          (persist/conflict? r)
+          (persist/kv-cas b "stock" (persist/conflict-actual r) 8)
+          r))))
+  8)
+(persist-test
+  "put-new on absent key succeeds"
+  (let ((b (persist/open))) (persist/kv-put-new b "k" 1))
+  1)
+(persist-test
+  "put-new on existing key conflicts"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/kv-put b "k" 1)
+      (persist/conflict? (persist/kv-put-new b "k" 2))))
+  true)
+(persist-test
+  "put-new does not overwrite"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/kv-put b "k" 1)
+      (persist/kv-put-new b "k" 2)
+      (persist/kv-get b "k")))
+  1)
+(persist-test
+  "cas works on the durable backend"
+  (let
+    ((db (persist/mock-durable (persist/mem-backend))))
+    (begin
+      (persist/kv-put db "k" 1)
+      (persist/kv-cas db "k" 1 2)
+      (persist/kv-get db "k")))
+  2)

lib/persist/tests/catalog.sx

@@ -0,0 +1,86 @@
+; Extension — stream catalog: enumerate streams, count, existence, totals.
+
+(persist-test
+  "empty backend has no streams"
+  (persist/stream-count (persist/open))
+  0)
+(persist-test
+  "stream-exists? false when absent"
+  (persist/stream-exists? (persist/open) "orders")
+  false)
+(persist-test
+  "append registers a stream"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "orders" "x" 0 {})
+      (persist/stream-exists? b "orders")))
+  true)
+(persist-test
+  "stream-count counts distinct streams"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "a" "x" 0 {})
+      (persist/append b "b" "x" 0 {})
+      (persist/append b "a" "x" 0 {})
+      (persist/stream-count b)))
+  2)
+(persist-test
+  "compacted-away stream still lists"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "a" "x" 0 {})
+      (persist/checkpoint b "a" "snap" (fn (acc e) acc) 0)
+      (persist/truncate b "a" 1)
+      (list (persist/count b "a") (persist/stream-exists? b "a"))))
+  (list 0 true))
+(persist-test
+  "kv-only backend lists no streams"
+  (let
+    ((b (persist/open)))
+    (begin (persist/kv-put b "k" 1) (persist/stream-count b)))
+  0)
+(persist-test
+  "total-events sums high-water marks"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "a" "x" 0 {})
+      (persist/append b "a" "x" 0 {})
+      (persist/append b "b" "x" 0 {})
+      (persist/total-events b)))
+  3)
+(persist-test
+  "total-events counts compacted events too"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "a" "x" 0 {})
+      (persist/append b "a" "x" 0 {})
+      (persist/checkpoint b "a" "snap" (fn (acc e) acc) 0)
+      (persist/truncate b "a" 2)
+      (persist/total-events b)))
+  2)
+(persist-test
+  "catalog works on the durable backend"
+  (let
+    ((db (persist/mock-durable (persist/mem-backend))))
+    (begin
+      (persist/append db "a" "x" 0 {})
+      (persist/append db "b" "x" 0 {})
+      (persist/stream-count db)))
+  2)
+(persist-test
+  "catalog survives restart"
+  (let
+    ((disk (persist/mem-backend)))
+    (begin
+      (let
+        ((db (persist/mock-durable disk)))
+        (begin
+          (persist/append db "a" "x" 0 {})
+          (persist/append db "b" "x" 0 {})))
+      (persist/stream-count (persist/mock-durable disk))))
+  2)

lib/persist/tests/compaction.sx

@@ -0,0 +1,124 @@
+; Phase 3 — compaction: drop the snapshotted prefix; replay determinism holds.
+
+(define comp-count (fn (acc e) (+ acc 1)))
+
+(persist-test
+  "uncompacted counts events since snapshot"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/uncompacted b "s" "snap" 0)))
+  2)
+(persist-test
+  "should-compact? false below threshold"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/should-compact? b "s" "snap" 3 0)))
+  false)
+(persist-test
+  "should-compact? true at threshold"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/should-compact? b "s" "snap" 3 0)))
+  true)
+(persist-test
+  "compact truncates the snapshotted prefix"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/compact b "s" "snap" comp-count 0)
+      (persist/count b "s")))
+  0)
+(persist-test
+  "compact preserves logical last-seq"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/compact b "s" "snap" comp-count 0)
+      (persist/last-seq b "s")))
+  2)
+(persist-test
+  "append after compaction continues the seq"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/compact b "s" "snap" comp-count 0)
+      (persist/event-seq (persist/append b "s" "x" 0 {}))))
+  3)
+(persist-test
+  "replay after compaction == full count before compaction"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/compact b "s" "snap" comp-count 0)
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/project-value
+        (persist/replay b "s" "snap" comp-count 0))))
+  5)
+(persist-test
+  "determinism: post-compaction replay value equals uncompacted full replay"
+  (let
+    ((b (persist/open)) (c (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/append c "s" "x" 0 {})
+      (persist/append c "s" "x" 0 {})
+      (persist/append c "s" "x" 0 {})
+      (persist/compact b "s" "snap" comp-count 0)
+      (persist/append b "s" "x" 0 {})
+      (persist/append c "s" "x" 0 {})
+      (equal?
+        (persist/project-value
+          (persist/replay b "s" "snap" comp-count 0))
+        (persist/project-fold c "s" comp-count 0))))
+  true)
+(persist-test
+  "maybe-compact below threshold does not truncate"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/maybe-compact b "s" "snap" comp-count 0 5)
+      (persist/count b "s")))
+  1)
+(persist-test
+  "maybe-compact at threshold truncates"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/maybe-compact b "s" "snap" comp-count 0 2)
+      (persist/count b "s")))
+  0)
+(persist-test
+  "compact is idempotent on an empty tail"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/compact b "s" "snap" comp-count 0)
+      (persist/project-value
+        (persist/compact b "s" "snap" comp-count 0))))
+  1)

lib/persist/tests/concurrency.sx

@@ -0,0 +1,96 @@
+; Phase 2 — optimistic concurrency: conflict is a real result, not a crash.
+
+(persist-test
+  "append-expect 0 on empty stream succeeds"
+  (persist/event-seq
+    (persist/append-expect
+      (persist/open)
+      "s"
+      0
+      "x"
+      0
+      {}))
+  1)
+(persist-test
+  "append-expect with correct seq succeeds"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/event-seq
+        (persist/append-expect b "s" 1 "x" 0 {}))))
+  2)
+(persist-test
+  "append-expect with stale seq returns a conflict"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/conflict?
+        (persist/append-expect b "s" 1 "x" 0 {}))))
+  true)
+(persist-test
+  "a successful append is not a conflict"
+  (persist/conflict?
+    (persist/append-expect
+      (persist/open)
+      "s"
+      0
+      "x"
+      0
+      {}))
+  false)
+(persist-test
+  "conflict carries expected and actual"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (let
+        ((r (persist/append-expect b "s" 0 "x" 0 {})))
+        (list (persist/conflict-expected r) (persist/conflict-actual r)))))
+  (list 0 2))
+(persist-test
+  "a conflicting append does not write"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append-expect b "s" 0 "x" 0 {})
+      (persist/count b "s")))
+  1)
+(persist-test
+  "two writers: first wins, second conflicts"
+  (let
+    ((b (persist/open)))
+    (let
+      ((seen (persist/last-seq b "s")))
+      (begin
+        (persist/append-expect b "s" seen "x" 0 {:who "A"})
+        (persist/conflict?
+          (persist/append-expect b "s" seen "x" 0 {:who "B"})))))
+  true)
+(persist-test
+  "retry after conflict succeeds"
+  (let
+    ((b (persist/open)))
+    (let
+      ((seen (persist/last-seq b "s")))
+      (begin
+        (persist/append-expect b "s" seen "x" 0 {:who "A"})
+        (let
+          ((r (persist/append-expect b "s" seen "x" 0 {:who "B"})))
+          (if
+            (persist/conflict? r)
+            (persist/event-seq
+              (persist/append-expect
+                b
+                "s"
+                (persist/conflict-actual r)
+                "x"
+                0
+                {:who "B"}))
+            (persist/event-seq r))))))
+  2)

lib/persist/tests/durable.sx

@@ -0,0 +1,163 @@
+; Phase 4 — durable backend over the IO-suspension boundary, tested with a mock
+; transport (the mock-IO harness for the durable protocol). The whole facet
+; stack must run unchanged on mock-durable, and a "crash/restart" (drop the
+; backend, keep the disk) must recover state by replay.
+
+(define dur-count (fn (acc e) (+ acc 1)))
+
+; ---------- request encoders ----------
+(persist-test
+  "req-append encodes op + args"
+  (persist/req-append "s" {:k 1})
+  {:op "persist/append" :args (list "s" {:k 1})})
+(persist-test
+  "req-kv-put encodes op + args"
+  (persist/req-kv-put "k" 7)
+  {:op "persist/kv-put" :args (list "k" 7)})
+
+; ---------- serve round-trips against a disk ----------
+(persist-test
+  "serve append then serve read"
+  (let
+    ((disk (persist/mem-backend)))
+    (begin
+      (persist/serve
+        disk
+        (persist/req-append
+          "s"
+          (persist/event "s" 1 "x" 0 {:n 1})))
+      (get
+        (persist/event-data
+          (first (persist/serve disk (persist/req-read "s"))))
+        :n)))
+  1)
+(persist-test
+  "serve kv-put then kv-get"
+  (let
+    ((disk (persist/mem-backend)))
+    (begin
+      (persist/serve disk (persist/req-kv-put "k" 42))
+      (persist/serve disk (persist/req-kv-get "k"))))
+  42)
+(persist-test
+  "serve unknown op is a clear error"
+  (let
+    ((disk (persist/mem-backend)))
+    (guard (e (true "errored")) (persist/serve disk {:op "persist/bogus" :args (list)})))
+  "errored")
+
+; ---------- full facet stack on mock-durable ----------
+(persist-test
+  "log facet works on mock-durable"
+  (let
+    ((db (persist/mock-durable (persist/mem-backend))))
+    (begin
+      (persist/append db "s" "x" 0 {})
+      (persist/append db "s" "x" 0 {})
+      (persist/count db "s")))
+  2)
+(persist-test
+  "seq assignment works on mock-durable"
+  (let
+    ((db (persist/mock-durable (persist/mem-backend))))
+    (begin
+      (persist/append db "s" "x" 0 {})
+      (persist/event-seq (persist/append db "s" "x" 0 {}))))
+  2)
+(persist-test
+  "kv facet works on mock-durable"
+  (let
+    ((db (persist/mock-durable (persist/mem-backend))))
+    (begin (persist/kv-put db "k" 5) (persist/kv-get db "k")))
+  5)
+(persist-test
+  "projection works on mock-durable"
+  (let
+    ((db (persist/mock-durable (persist/mem-backend))))
+    (begin
+      (persist/append db "s" "x" 0 {})
+      (persist/append db "s" "x" 0 {})
+      (persist/append db "s" "x" 0 {})
+      (persist/project-fold db "s" dur-count 0)))
+  3)
+(persist-test
+  "snapshot + replay work on mock-durable"
+  (let
+    ((db (persist/mock-durable (persist/mem-backend))))
+    (begin
+      (persist/append db "s" "x" 0 {})
+      (persist/append db "s" "x" 0 {})
+      (persist/checkpoint db "s" "snap" dur-count 0)
+      (persist/append db "s" "x" 0 {})
+      (persist/project-value
+        (persist/replay db "s" "snap" dur-count 0))))
+  3)
+(persist-test
+  "compaction works on mock-durable"
+  (let
+    ((db (persist/mock-durable (persist/mem-backend))))
+    (begin
+      (persist/append db "s" "x" 0 {})
+      (persist/append db "s" "x" 0 {})
+      (persist/compact db "s" "snap" dur-count 0)
+      (list (persist/count db "s") (persist/last-seq db "s"))))
+  (list 0 2))
+
+; ---------- crash / restart replay ----------
+(persist-test
+  "restart recovers log state from the disk"
+  (let
+    ((disk (persist/mem-backend)))
+    (begin
+      (let
+        ((db (persist/mock-durable disk)))
+        (begin
+          (persist/append db "s" "x" 0 {})
+          (persist/append db "s" "x" 0 {})))
+      (let
+        ((db2 (persist/mock-durable disk)))
+        (persist/project-fold db2 "s" dur-count 0))))
+  2)
+(persist-test
+  "restart continues the seq counter"
+  (let
+    ((disk (persist/mem-backend)))
+    (begin
+      (let
+        ((db (persist/mock-durable disk)))
+        (begin
+          (persist/append db "s" "x" 0 {})
+          (persist/append db "s" "x" 0 {})))
+      (let
+        ((db2 (persist/mock-durable disk)))
+        (persist/event-seq (persist/append db2 "s" "x" 0 {})))))
+  3)
+(persist-test
+  "restart recovers a kv value"
+  (let
+    ((disk (persist/mem-backend)))
+    (begin
+      (let
+        ((db (persist/mock-durable disk)))
+        (persist/kv-put db "cfg" "on"))
+      (let ((db2 (persist/mock-durable disk))) (persist/kv-get db2 "cfg"))))
+  "on")
+(persist-test
+  "restart from snapshot equals full replay"
+  (let
+    ((disk (persist/mem-backend)))
+    (begin
+      (let
+        ((db (persist/mock-durable disk)))
+        (begin
+          (persist/append db "s" "x" 0 {})
+          (persist/append db "s" "x" 0 {})
+          (persist/checkpoint db "s" "snap" dur-count 0)
+          (persist/append db "s" "x" 0 {})))
+      (let
+        ((db2 (persist/mock-durable disk)))
+        (equal?
+          (persist/project-value
+            (persist/replay db2 "s" "snap" dur-count 0))
+          (persist/project-fold db2 "s" dur-count 0)))))
+  true)

lib/persist/tests/event.sx

@@ -0,0 +1,30 @@
+; Phase 1 — event record accessors. Uses the persist-test harness
+; (persist-test name got expected) provided by conformance.sh.
+
+(persist-test
+  "event-stream"
+  (persist/event-stream
+    (persist/event "s" 1 "t" 0 {}))
+  "s")
+(persist-test
+  "event-seq"
+  (persist/event-seq (persist/event "s" 3 "t" 0 {}))
+  3)
+(persist-test
+  "event-type"
+  (persist/event-type
+    (persist/event "s" 1 "create" 0 {}))
+  "create")
+(persist-test
+  "event-at"
+  (persist/event-at (persist/event "s" 1 "t" 42 {}))
+  42)
+(persist-test
+  "event-data"
+  (persist/event-data
+    (persist/event "s" 1 "t" 0 {:x 9}))
+  {:x 9})
+(persist-test
+  "event is a dict with all fields"
+  (len (keys (persist/event "s" 1 "t" 0 {})))
+  5)

lib/persist/tests/example-acl.sx

@@ -0,0 +1,104 @@
+; Reference migration — acl grants on persist. Proves the AFTER behaviour,
+; including the capabilities the hand-rolled BEFORE version could not provide
+; (durability across restart + an audit trail).
+
+(persist-test
+  "grant then can?"
+  (let
+    ((b (persist/open)))
+    (begin
+      (acl/grant b "doc-1" "alice" 0)
+      (acl/can? b "doc-1" "alice")))
+  true)
+(persist-test
+  "no grant means no access"
+  (acl/can? (persist/open) "doc-1" "alice")
+  false)
+(persist-test
+  "revoke removes access"
+  (let
+    ((b (persist/open)))
+    (begin
+      (acl/grant b "doc-1" "alice" 0)
+      (acl/revoke b "doc-1" "alice" 1)
+      (acl/can? b "doc-1" "alice")))
+  false)
+(persist-test
+  "multiple principals tracked independently"
+  (let
+    ((b (persist/open)))
+    (begin
+      (acl/grant b "doc-1" "alice" 0)
+      (acl/grant b "doc-1" "bob" 1)
+      (acl/revoke b "doc-1" "alice" 2)
+      (list (acl/can? b "doc-1" "alice") (acl/can? b "doc-1" "bob"))))
+  (list false true))
+(persist-test
+  "granting twice is idempotent in the set"
+  (let
+    ((b (persist/open)))
+    (begin
+      (acl/grant b "doc-1" "alice" 0)
+      (acl/grant b "doc-1" "alice" 1)
+      (len (acl/grants b "doc-1"))))
+  1)
+(persist-test
+  "grants on different resources are isolated"
+  (let
+    ((b (persist/open)))
+    (begin
+      (acl/grant b "doc-1" "alice" 0)
+      (acl/grant b "doc-2" "bob" 0)
+      (list (acl/can? b "doc-1" "bob") (acl/can? b "doc-2" "bob"))))
+  (list false true))
+(persist-test
+  "audit window answers when-was-it-granted (new capability)"
+  (let
+    ((b (persist/open)))
+    (begin
+      (acl/grant b "doc-1" "alice" 100)
+      (acl/revoke b "doc-1" "alice" 200)
+      (acl/grant b "doc-1" "bob" 300)
+      (len (acl/audit-window b "doc-1" 150 300))))
+  2)
+(persist-test
+  "materialized view stays current on publish"
+  (let
+    ((b (persist/open)))
+    (let
+      ((h (persist/view-attach (persist/hub b) (acl/view "doc-1"))))
+      (begin
+        (persist/publish
+          h
+          (acl/stream "doc-1")
+          "granted"
+          0
+          {:principal "alice"})
+        (acl/can-fast? b "doc-1" "alice"))))
+  true)
+(persist-test
+  "grants survive restart on the durable backend (the headline win)"
+  (let
+    ((disk (persist/mem-backend)))
+    (begin
+      (let
+        ((db (persist/mock-durable disk)))
+        (begin
+          (acl/grant db "doc-1" "alice" 0)
+          (acl/grant db "doc-1" "bob" 1)))
+      (let
+        ((db2 (persist/mock-durable disk)))
+        (list (acl/can? db2 "doc-1" "alice") (acl/can? db2 "doc-1" "bob")))))
+  (list true true))
+(persist-test
+  "revoke before restart is still revoked after"
+  (let
+    ((disk (persist/mem-backend)))
+    (begin
+      (let
+        ((db (persist/mock-durable disk)))
+        (begin
+          (acl/grant db "doc-1" "alice" 0)
+          (acl/revoke db "doc-1" "alice" 1)))
+      (acl/can? (persist/mock-durable disk) "doc-1" "alice")))
+  false)

lib/persist/tests/global.sx

@@ -0,0 +1,123 @@
+; Extension — global commit ordering across streams.
+
+(persist-test
+  "gappend returns the stream event with its local seq"
+  (let
+    ((b (persist/open)))
+    (persist/event-seq
+      (persist/gappend b "orders" "placed" 0 {})))
+  1)
+(persist-test
+  "global-pos advances per gappend regardless of stream"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/gappend b "orders" "placed" 0 {})
+      (persist/gappend b "users" "joined" 0 {})
+      (persist/gappend b "orders" "placed" 0 {})
+      (persist/global-pos b)))
+  3)
+(persist-test
+  "read-global returns events in commit order across streams"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/gappend b "orders" "placed" 0 {:n 1})
+      (persist/gappend b "users" "joined" 0 {:n 2})
+      (persist/gappend b "orders" "placed" 0 {:n 3})
+      (let
+        ((g (persist/read-global b)))
+        (list
+          (get (persist/event-data (nth g 0)) :n)
+          (get (persist/event-data (nth g 1)) :n)
+          (get (persist/event-data (nth g 2)) :n)))))
+  (list 1 2 3))
+(persist-test
+  "read-global resolves to the right streams"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/gappend b "orders" "placed" 0 {})
+      (persist/gappend b "users" "joined" 0 {})
+      (let
+        ((g (persist/read-global b)))
+        (list
+          (persist/event-stream (nth g 0))
+          (persist/event-stream (nth g 1))))))
+  (list "orders" "users"))
+(persist-test
+  "project-global folds across all streams in order"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/gappend b "a" "x" 0 {:v 10})
+      (persist/gappend b "b" "x" 0 {:v 20})
+      (persist/gappend b "a" "x" 0 {:v 30})
+      (persist/project-global
+        b
+        (fn (acc e) (+ acc (get (persist/event-data e) :v)))
+        0)))
+  60)
+(persist-test
+  "global index is hidden from the public catalog"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/gappend b "orders" "placed" 0 {})
+      (persist/gappend b "users" "joined" 0 {})
+      (list (persist/stream-count b) (persist/stream-exists? b "$global"))))
+  (list 2 false))
+(persist-test
+  "streams-all reveals the reserved index"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/gappend b "orders" "placed" 0 {})
+      (contains? (persist/streams-all b) "$global")))
+  true)
+(persist-test
+  "global-from gives pointers at or after a position"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/gappend b "a" "x" 0 {})
+      (persist/gappend b "a" "x" 0 {})
+      (persist/gappend b "a" "x" 0 {})
+      (len (persist/global-from b 2))))
+  2)
+(persist-test
+  "plain append does not touch the global index"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "orders" "placed" 0 {})
+      (persist/gappend b "orders" "placed" 0 {})
+      (persist/global-pos b)))
+  1)
+(persist-test
+  "global ordering works on the durable backend"
+  (let
+    ((db (persist/mock-durable (persist/mem-backend))))
+    (begin
+      (persist/gappend db "a" "x" 0 {:v 1})
+      (persist/gappend db "b" "x" 0 {:v 2})
+      (persist/project-global
+        db
+        (fn (acc e) (+ acc (get (persist/event-data e) :v)))
+        0)))
+  3)
+(persist-test
+  "global order survives restart (determinism)"
+  (let
+    ((disk (persist/mem-backend)))
+    (begin
+      (let
+        ((db (persist/mock-durable disk)))
+        (begin
+          (persist/gappend db "a" "x" 0 {:v 1})
+          (persist/gappend db "b" "x" 0 {:v 2})))
+      (persist/project-global
+        (persist/mock-durable disk)
+        (fn (acc e) (+ acc (get (persist/event-data e) :v)))
+        0)))
+  3)

lib/persist/tests/idempotency.sx

@@ -0,0 +1,92 @@
+; Extension — exactly-once append under retries.
+
+(persist-test
+  "seen? false before first append"
+  (persist/seen? (persist/open) "orders" "cmd-1")
+  false)
+(persist-test
+  "append-once appends on first use"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append-once b "orders" "cmd-1" "placed" 0 {})
+      (persist/count b "orders")))
+  1)
+(persist-test
+  "seen? true after first append"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append-once b "orders" "cmd-1" "placed" 0 {})
+      (persist/seen? b "orders" "cmd-1")))
+  true)
+(persist-test
+  "repeat with same key does not append again"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append-once b "orders" "cmd-1" "placed" 0 {})
+      (persist/append-once b "orders" "cmd-1" "placed" 0 {})
+      (persist/append-once b "orders" "cmd-1" "placed" 0 {})
+      (persist/count b "orders")))
+  1)
+(persist-test
+  "repeat returns the same event (same seq)"
+  (let
+    ((b (persist/open)))
+    (let
+      ((e1 (persist/append-once b "orders" "cmd-1" "placed" 0 {})))
+      (persist/event-seq
+        (persist/append-once b "orders" "cmd-1" "placed" 0 {}))))
+  1)
+(persist-test
+  "different keys append separately"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append-once b "orders" "cmd-1" "placed" 0 {})
+      (persist/append-once b "orders" "cmd-2" "placed" 0 {})
+      (persist/count b "orders")))
+  2)
+(persist-test
+  "idempotency is per-stream"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append-once b "a" "cmd-1" "x" 0 {})
+      (persist/append-once b "b" "cmd-1" "x" 0 {})
+      (list (persist/count b "a") (persist/count b "b"))))
+  (list 1 1))
+(persist-test
+  "stored data is preserved on first append"
+  (let
+    ((b (persist/open)))
+    (get
+      (persist/event-data
+        (persist/append-once b "s" "k" "x" 0 {:n 9}))
+      :n))
+  9)
+(persist-test
+  "idempotency survives restart on the durable backend"
+  (let
+    ((disk (persist/mem-backend)))
+    (begin
+      (persist/append-once
+        (persist/mock-durable disk)
+        "orders"
+        "cmd-1"
+        "placed"
+        0
+        {})
+      (let
+        ((db2 (persist/mock-durable disk)))
+        (begin
+          (persist/append-once
+            db2
+            "orders"
+            "cmd-1"
+            "placed"
+            0
+            {})
+          (persist/count db2 "orders")))))
+  1)

lib/persist/tests/kv.sx

@@ -0,0 +1,86 @@
+; Phase 1 — kv facet: get/put/delete/has?/keys, get-or, update.
+
+(persist-test "absent key reads nil" (persist/kv-get (persist/open) "x") nil)
+(persist-test
+  "has? false when absent"
+  (persist/kv-has? (persist/open) "x")
+  false)
+(persist-test
+  "put then get"
+  (let
+    ((b (persist/open)))
+    (begin (persist/kv-put b "x" 7) (persist/kv-get b "x")))
+  7)
+(persist-test
+  "put returns value"
+  (let ((b (persist/open))) (persist/kv-put b "x" 9))
+  9)
+(persist-test
+  "has? true after put"
+  (let
+    ((b (persist/open)))
+    (begin (persist/kv-put b "x" 1) (persist/kv-has? b "x")))
+  true)
+(persist-test
+  "put overwrites"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/kv-put b "x" 1)
+      (persist/kv-put b "x" 2)
+      (persist/kv-get b "x")))
+  2)
+(persist-test
+  "delete removes key"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/kv-put b "x" 1)
+      (persist/kv-delete b "x")
+      (persist/kv-has? b "x")))
+  false)
+(persist-test
+  "delete then get is nil"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/kv-put b "x" 1)
+      (persist/kv-delete b "x")
+      (persist/kv-get b "x")))
+  nil)
+(persist-test
+  "keys lists stored keys"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/kv-put b "a" 1)
+      (persist/kv-put b "b" 2)
+      (len (persist/kv-keys b))))
+  2)
+(persist-test
+  "get-or returns default when absent"
+  (persist/kv-get-or (persist/open) "x" 99)
+  99)
+(persist-test
+  "get-or returns value when present"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/kv-put b "x" 5)
+      (persist/kv-get-or b "x" 99)))
+  5)
+(persist-test
+  "kv-update applies fn over default"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/kv-update b "n" 0 (fn (v) (+ v 1)))
+      (persist/kv-update b "n" 0 (fn (v) (+ v 1)))
+      (persist/kv-get b "n")))
+  2)
+(persist-test
+  "kv facet does not touch log"
+  (let
+    ((b (persist/open)))
+    (begin (persist/kv-put b "x" 1) (persist/count b "x")))
+  0)

lib/persist/tests/log.sx

@@ -0,0 +1,81 @@
+; Phase 1 — log facet: append/read/read-from, sequential seq, stream isolation.
+; Note: map returns an array-backed list not equal? to a (list ...) literal,
+; so assertions build their compared list with list/nth, not map.
+
+(persist-test
+  "empty stream reads empty"
+  (len (persist/read (persist/open) "orders"))
+  0)
+(persist-test
+  "last-seq empty is 0"
+  (persist/last-seq (persist/open) "orders")
+  0)
+(persist-test
+  "append returns event with seq 1"
+  (persist/event-seq
+    (persist/append (persist/open) "orders" "placed" 0 {:id 1}))
+  1)
+(persist-test
+  "append assigns sequential seqs"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "orders" "placed" 0 {})
+      (persist/append b "orders" "placed" 1 {})
+      (persist/event-seq
+        (persist/append b "orders" "placed" 2 {}))))
+  3)
+(persist-test
+  "read returns events oldest-first"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "a" 0 {:n 1})
+      (persist/append b "s" "b" 0 {:n 2})
+      (let
+        ((es (persist/read b "s")))
+        (list
+          (get (persist/event-data (nth es 0)) :n)
+          (get (persist/event-data (nth es 1)) :n)))))
+  (list 1 2))
+(persist-test
+  "count tracks appends"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "a" 0 {})
+      (persist/append b "s" "a" 0 {})
+      (persist/count b "s")))
+  2)
+(persist-test
+  "streams are isolated"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s1" "a" 0 {})
+      (persist/append b "s2" "a" 0 {})
+      (persist/append b "s2" "a" 0 {})
+      (list (persist/count b "s1") (persist/count b "s2"))))
+  (list 1 2))
+(persist-test
+  "read-from filters by seq"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "a" 0 {})
+      (persist/append b "s" "a" 0 {})
+      (persist/append b "s" "a" 0 {})
+      (let
+        ((es (persist/read-from b "s" 2)))
+        (list
+          (persist/event-seq (nth es 0))
+          (persist/event-seq (nth es 1))))))
+  (list 2 3))
+(persist-test
+  "read-from past end is empty"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "a" 0 {})
+      (len (persist/read-from b "s" 5))))
+  0)

lib/persist/tests/project.sx

@@ -0,0 +1,115 @@
+; Phase 2 — projections: fold a stream into a read model, resume incrementally.
+
+(persist-test
+  "project empty stream returns seed value"
+  (persist/project-fold
+    (persist/open)
+    "s"
+    (fn (acc e) (+ acc 1))
+    0)
+  0)
+(persist-test
+  "project empty stream seq is 0"
+  (persist/project-seq
+    (persist/project (persist/open) "s" (fn (a e) a) 0))
+  0)
+(persist-test
+  "project counts events"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/project-fold
+        b
+        "s"
+        (fn (acc e) (+ acc 1))
+        0)))
+  3)
+(persist-test
+  "project sums event data"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "ledger" "credit" 0 {:amt 10})
+      (persist/append b "ledger" "credit" 1 {:amt 5})
+      (persist/append b "ledger" "debit" 2 {:amt 3})
+      (persist/project-fold
+        b
+        "ledger"
+        (fn
+          (bal e)
+          (if
+            (equal? (persist/event-type e) "credit")
+            (+ bal (get (persist/event-data e) :amt))
+            (- bal (get (persist/event-data e) :amt))))
+        0)))
+  12)
+(persist-test
+  "project tracks last seq"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/project-seq (persist/project b "s" (fn (a e) a) 0))))
+  2)
+(persist-test
+  "resume folds only the tail"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (let
+        ((p1 (persist/project b "s" (fn (acc e) (+ acc 1)) 0)))
+        (begin
+          (persist/append b "s" "x" 0 {})
+          (persist/project-value
+            (persist/project-resume
+              b
+              "s"
+              (fn (acc e) (+ acc 1))
+              p1))))))
+  3)
+(persist-test
+  "resume with no new events is a no-op"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (let
+        ((p1 (persist/project b "s" (fn (acc e) (+ acc 1)) 0)))
+        (persist/project-value
+          (persist/project-resume b "s" (fn (acc e) (+ acc 1)) p1)))))
+  1)
+(persist-test
+  "resume advances seq"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (let
+        ((p1 (persist/project b "s" (fn (a e) a) 0)))
+        (begin
+          (persist/append b "s" "x" 0 {})
+          (persist/append b "s" "x" 0 {})
+          (persist/project-seq
+            (persist/project-resume b "s" (fn (a e) a) p1))))))
+  3)
+(persist-test
+  "full project equals seed-resume from zero"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (equal?
+        (persist/project b "s" (fn (acc e) (+ acc 1)) 0)
+        (persist/project-resume
+          b
+          "s"
+          (fn (acc e) (+ acc 1))
+          {:value 0 :seq 0}))))
+  true)

lib/persist/tests/query.sx

@@ -0,0 +1,101 @@
+; Extension — read-side query helpers. Assertions count / index, not map vs list.
+
+(define q-seqs (fn (es) (map persist/event-seq es)))
+
+(persist-test
+  "read-between slices a seq range"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (let
+        ((es (persist/read-between b "s" 2 3)))
+        (list
+          (len es)
+          (persist/event-seq (first es))
+          (persist/event-seq (nth es 1))))))
+  (list 2 2 3))
+(persist-test
+  "read-between is inclusive of endpoints"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (len (persist/read-between b "s" 1 3))))
+  3)
+(persist-test
+  "read-since filters by timestamp"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 100 {})
+      (persist/append b "s" "x" 200 {})
+      (persist/append b "s" "x" 300 {})
+      (len (persist/read-since b "s" 200))))
+  2)
+(persist-test
+  "read-window is an inclusive time range"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 100 {})
+      (persist/append b "s" "x" 200 {})
+      (persist/append b "s" "x" 300 {})
+      (persist/append b "s" "x" 400 {})
+      (len (persist/read-window b "s" 200 300))))
+  2)
+(persist-test
+  "read-by-type filters by event type"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "created" 0 {})
+      (persist/append b "s" "updated" 0 {})
+      (persist/append b "s" "created" 0 {})
+      (len (persist/read-by-type b "s" "created"))))
+  2)
+(persist-test
+  "read-where filters by predicate over data"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {:amt 5})
+      (persist/append b "s" "x" 0 {:amt 15})
+      (persist/append b "s" "x" 0 {:amt 25})
+      (len
+        (persist/read-where
+          b
+          "s"
+          (fn (e) (> (get (persist/event-data e) :amt) 10))))))
+  2)
+(persist-test
+  "count-where counts matches"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "a" 0 {})
+      (persist/append b "s" "b" 0 {})
+      (persist/append b "s" "a" 0 {})
+      (persist/count-where
+        b
+        "s"
+        (fn (e) (equal? (persist/event-type e) "a")))))
+  2)
+(persist-test
+  "queries return empty on empty stream"
+  (len (persist/read-since (persist/open) "s" 0))
+  0)
+(persist-test
+  "queries work on the durable backend"
+  (let
+    ((db (persist/mock-durable (persist/mem-backend))))
+    (begin
+      (persist/append db "s" "x" 100 {})
+      (persist/append db "s" "x" 200 {})
+      (len (persist/read-since db "s" 150))))
+  1)

lib/persist/tests/recovery.sx

@@ -0,0 +1,126 @@
+; Phase 4 — crash/restart integration. A whole subsystem (an order ledger:
+; event log + a kv read model kept by a subscription + a periodic snapshot + an
+; invoice blob ref) on the durable backend must survive a restart. "Crash" =
+; drop every in-process object (backend, hub, projections); "restart" = rebuild
+; them over the SAME disk + blob store. Nothing but the disk and content store
+; carries across, exactly as a real process restart.
+
+(define rec-count (fn (acc e) (+ acc 1)))
+
+(persist-test
+  "log survives restart and seq continues"
+  (let
+    ((disk (persist/mem-backend)))
+    (begin
+      (let
+        ((db (persist/mock-durable disk)))
+        (begin
+          (persist/append db "orders" "placed" 0 {:id "a"})
+          (persist/append db "orders" "placed" 1 {:id "b"})))
+      (let
+        ((db2 (persist/mock-durable disk)))
+        (list
+          (persist/project-fold db2 "orders" rec-count 0)
+          (persist/event-seq
+            (persist/append db2 "orders" "placed" 2 {:id "c"}))))))
+  (list 2 3))
+(persist-test
+  "subscription-driven kv read model survives restart"
+  (let
+    ((disk (persist/mem-backend)))
+    (begin
+      (let
+        ((h (persist/hub (persist/mock-durable disk))))
+        (begin
+          (persist/subscribe
+            h
+            "orders"
+            (fn
+              (bk s e)
+              (persist/kv-update
+                bk
+                "order-count"
+                0
+                (fn (n) (+ n 1)))))
+          (persist/publish h "orders" "placed" 0 {})
+          (persist/publish h "orders" "placed" 1 {})))
+      (let
+        ((db2 (persist/mock-durable disk)))
+        (persist/kv-get db2 "order-count"))))
+  2)
+(persist-test
+  "snapshot taken before crash drives replay after restart"
+  (let
+    ((disk (persist/mem-backend)))
+    (begin
+      (let
+        ((db (persist/mock-durable disk)))
+        (begin
+          (persist/append db "orders" "placed" 0 {})
+          (persist/append db "orders" "placed" 1 {})
+          (persist/checkpoint db "orders" "count" rec-count 0)
+          (persist/append db "orders" "placed" 2 {})))
+      (let
+        ((db2 (persist/mock-durable disk)))
+        (equal?
+          (persist/project-value
+            (persist/replay db2 "orders" "count" rec-count 0))
+          (persist/project-fold db2 "orders" rec-count 0)))))
+  true)
+(persist-test
+  "compacted log still replays correctly after restart"
+  (let
+    ((disk (persist/mem-backend)))
+    (begin
+      (let
+        ((db (persist/mock-durable disk)))
+        (begin
+          (persist/append db "orders" "placed" 0 {})
+          (persist/append db "orders" "placed" 1 {})
+          (persist/append db "orders" "placed" 2 {})
+          (persist/compact db "orders" "count" rec-count 0)
+          (persist/append db "orders" "placed" 3 {})))
+      (let
+        ((db2 (persist/mock-durable disk)))
+        (persist/project-value
+          (persist/replay db2 "orders" "count" rec-count 0)))))
+  4)
+(persist-test
+  "invoice blob ref survives restart, bytes fetched from content store"
+  (let
+    ((disk (persist/mem-backend)) (store (persist/mem-backend)))
+    (begin
+      (let
+        ((db (persist/mock-durable disk)) (blob (persist/mock-blob store)))
+        (persist/kv-put
+          db
+          "invoice"
+          (persist/blob-store blob "INVOICEPDF" "application/pdf")))
+      (let
+        ((db2 (persist/mock-durable disk))
+          (blob2 (persist/mock-blob store)))
+        (persist/blob-fetch blob2 (persist/kv-get db2 "invoice")))))
+  "INVOICEPDF")
+(persist-test
+  "two independent restarts converge to the same state (determinism)"
+  (let
+    ((disk (persist/mem-backend)))
+    (begin
+      (let
+        ((db (persist/mock-durable disk)))
+        (begin
+          (persist/append db "orders" "placed" 0 {})
+          (persist/append db "orders" "placed" 1 {})
+          (persist/append db "orders" "placed" 2 {})))
+      (equal?
+        (persist/project-fold
+          (persist/mock-durable disk)
+          "orders"
+          rec-count
+          0)
+        (persist/project-fold
+          (persist/mock-durable disk)
+          "orders"
+          rec-count
+          0))))
+  true)

lib/persist/tests/snapshot.sx

@@ -0,0 +1,114 @@
+; Phase 3 — snapshots + replay. Headline: snapshot + tail == full replay.
+
+(define snap-count (fn (acc e) (+ acc 1)))
+
+(persist-test
+  "no snapshot loads fresh seed state"
+  (persist/snapshot-load (persist/open) "feed" 0)
+  {:value 0 :seq 0})
+(persist-test
+  "snapshot-exists? false initially"
+  (persist/snapshot-exists? (persist/open) "feed")
+  false)
+(persist-test
+  "checkpoint stores a snapshot"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/checkpoint b "s" "snap" snap-count 0)
+      (persist/snapshot-exists? b "snap")))
+  true)
+(persist-test
+  "checkpoint value equals full projection"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/project-value
+        (persist/checkpoint b "s" "snap" snap-count 0))))
+  3)
+(persist-test
+  "checkpoint records the last seq"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/project-seq
+        (persist/checkpoint b "s" "snap" snap-count 0))))
+  2)
+(persist-test
+  "replay after checkpoint only folds the tail"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/checkpoint b "s" "snap" snap-count 0)
+      (persist/append b "s" "x" 0 {})
+      (persist/project-value
+        (persist/replay b "s" "snap" snap-count 0))))
+  3)
+(persist-test
+  "snapshot + tail == full replay (value)"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (persist/checkpoint b "s" "snap" snap-count 0)
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (equal?
+        (persist/project-value
+          (persist/replay b "s" "snap" snap-count 0))
+        (persist/project-fold b "s" snap-count 0))))
+  true)
+(persist-test
+  "snapshot + tail == full replay (whole state)"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/checkpoint b "s" "snap" snap-count 0)
+      (persist/append b "s" "x" 0 {})
+      (persist/append b "s" "x" 0 {})
+      (equal?
+        (persist/replay b "s" "snap" snap-count 0)
+        (persist/project b "s" snap-count 0))))
+  true)
+(persist-test
+  "replay determinism: two replays from same snapshot agree"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/checkpoint b "s" "snap" snap-count 0)
+      (persist/append b "s" "x" 0 {})
+      (equal?
+        (persist/replay b "s" "snap" snap-count 0)
+        (persist/replay b "s" "snap" snap-count 0))))
+  true)
+(persist-test
+  "re-checkpoint advances the snapshot"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/checkpoint b "s" "snap" snap-count 0)
+      (persist/append b "s" "x" 0 {})
+      (persist/checkpoint b "s" "snap" snap-count 0)
+      (persist/project-seq (persist/snapshot-load b "snap" 0))))
+  2)
+(persist-test
+  "snapshots are keyed independently"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "s" "x" 0 {})
+      (persist/checkpoint b "s" "a" snap-count 0)
+      (persist/snapshot-exists? b "b")))
+  false)

lib/persist/tests/subscribe.sx

@@ -0,0 +1,130 @@
+; Phase 2 — subscription hub: callbacks fire on publish, drive read models.
+
+(persist-test
+  "no subscribers initially"
+  (persist/subscriber-count (persist/hub (persist/open)) "s")
+  0)
+(persist-test
+  "subscribe registers a callback"
+  (let
+    ((h (persist/hub (persist/open))))
+    (begin
+      (persist/subscribe h "s" (fn (b s e) nil))
+      (persist/subscriber-count h "s")))
+  1)
+(persist-test
+  "publish appends to the log"
+  (let
+    ((b (persist/open)))
+    (let
+      ((h (persist/hub b)))
+      (begin
+        (persist/publish h "s" "x" 0 {})
+        (persist/publish h "s" "x" 0 {})
+        (persist/count b "s"))))
+  2)
+(persist-test
+  "publish returns the stored event"
+  (let
+    ((h (persist/hub (persist/open))))
+    (persist/event-seq (persist/publish h "s" "x" 0 {:id 1})))
+  1)
+(persist-test
+  "callback fires on publish — drives a kv read model"
+  (let
+    ((b (persist/open)))
+    (let
+      ((h (persist/hub b)))
+      (begin
+        (persist/subscribe
+          h
+          "s"
+          (fn
+            (bk s e)
+            (persist/kv-update
+              bk
+              "count"
+              0
+              (fn (n) (+ n 1)))))
+        (persist/publish h "s" "x" 0 {})
+        (persist/publish h "s" "x" 0 {})
+        (persist/publish h "s" "x" 0 {})
+        (persist/kv-get b "count"))))
+  3)
+(persist-test
+  "callback receives the event"
+  (let
+    ((b (persist/open)))
+    (let
+      ((h (persist/hub b)))
+      (begin
+        (persist/subscribe
+          h
+          "s"
+          (fn (bk s e) (persist/kv-put bk "last" (persist/event-type e))))
+        (persist/publish h "s" "created" 0 {})
+        (persist/kv-get b "last"))))
+  "created")
+(persist-test
+  "subscriptions are per-stream"
+  (let
+    ((b (persist/open)))
+    (let
+      ((h (persist/hub b)))
+      (begin
+        (persist/subscribe
+          h
+          "s1"
+          (fn
+            (bk s e)
+            (persist/kv-update bk "n" 0 (fn (n) (+ n 1)))))
+        (persist/publish h "s2" "x" 0 {})
+        (persist/kv-get-or b "n" 0))))
+  0)
+(persist-test
+  "multiple subscribers all fire"
+  (let
+    ((b (persist/open)))
+    (let
+      ((h (persist/hub b)))
+      (begin
+        (persist/subscribe
+          h
+          "s"
+          (fn
+            (bk s e)
+            (persist/kv-update bk "a" 0 (fn (n) (+ n 1)))))
+        (persist/subscribe
+          h
+          "s"
+          (fn
+            (bk s e)
+            (persist/kv-update bk "b" 0 (fn (n) (+ n 10)))))
+        (persist/publish h "s" "x" 0 {})
+        (list (persist/kv-get b "a") (persist/kv-get b "b")))))
+  (list 1 10))
+(persist-test
+  "incremental read model via resume in callback"
+  (let
+    ((b (persist/open)))
+    (let
+      ((h (persist/hub b)))
+      (begin
+        (persist/kv-put b "proj" {:value 0 :seq 0})
+        (persist/subscribe
+          h
+          "s"
+          (fn
+            (bk s e)
+            (persist/kv-put
+              bk
+              "proj"
+              (persist/project-resume
+                bk
+                s
+                (fn (acc ev) (+ acc 1))
+                (persist/kv-get bk "proj")))))
+        (persist/publish h "s" "x" 0 {})
+        (persist/publish h "s" "x" 0 {})
+        (persist/project-value (persist/kv-get b "proj")))))
+  2)

lib/persist/tests/upcast.sx

@@ -0,0 +1,115 @@
+; Extension — event schema evolution via upcasters.
+
+; v1 "placed" events had {:total N}; v2 wants {:amount N :currency "GBP"}.
+(define up-placed (fn (e) (persist/upcast-data e {:amount (get (persist/event-data e) :total) :currency "GBP"})))
+
+(persist-test
+  "unregistered type passes through unchanged"
+  (let
+    ((reg (persist/upcasters)))
+    (persist/event-data
+      (persist/upcast
+        reg
+        (persist/event "s" 1 "other" 0 {:x 1}))))
+  {:x 1})
+(persist-test
+  "registered upcaster lifts an old event"
+  (let
+    ((reg (persist/register-upcaster (persist/upcasters) "placed" up-placed)))
+    (get
+      (persist/event-data
+        (persist/upcast
+          reg
+          (persist/event "s" 1 "placed" 0 {:total 50})))
+      :amount))
+  50)
+(persist-test
+  "upcaster adds the new field"
+  (let
+    ((reg (persist/register-upcaster (persist/upcasters) "placed" up-placed)))
+    (get
+      (persist/event-data
+        (persist/upcast
+          reg
+          (persist/event "s" 1 "placed" 0 {:total 50})))
+      :currency))
+  "GBP")
+(persist-test
+  "upcast preserves stream/seq/type/at"
+  (let
+    ((reg (persist/register-upcaster (persist/upcasters) "placed" up-placed)))
+    (let
+      ((e (persist/upcast reg (persist/event "orders" 7 "placed" 99 {:total 1}))))
+      (list
+        (persist/event-seq e)
+        (persist/event-at e)
+        (persist/event-type e))))
+  (list 7 99 "placed"))
+(persist-test
+  "registry is immutable — register returns a new dict"
+  (let
+    ((r0 (persist/upcasters)))
+    (begin
+      (persist/register-upcaster r0 "placed" up-placed)
+      (has-key? r0 "placed")))
+  false)
+(persist-test
+  "read-upcast lifts every event in a stream"
+  (let
+    ((b (persist/open))
+      (reg
+        (persist/register-upcaster (persist/upcasters) "placed" up-placed)))
+    (begin
+      (persist/append b "orders" "placed" 0 {:total 10})
+      (persist/append b "orders" "placed" 0 {:total 20})
+      (let
+        ((es (persist/read-upcast b "orders" reg)))
+        (list
+          (get (persist/event-data (nth es 0)) :amount)
+          (get (persist/event-data (nth es 1)) :amount)))))
+  (list 10 20))
+(persist-test
+  "project-upcast folds over the current shape"
+  (let
+    ((b (persist/open))
+      (reg
+        (persist/register-upcaster (persist/upcasters) "placed" up-placed)))
+    (begin
+      (persist/append b "orders" "placed" 0 {:total 10})
+      (persist/append b "orders" "placed" 0 {:total 20})
+      (persist/project-upcast
+        b
+        "orders"
+        reg
+        (fn (acc e) (+ acc (get (persist/event-data e) :amount)))
+        0)))
+  30)
+(persist-test
+  "mixed old and new events fold uniformly"
+  (let
+    ((b (persist/open))
+      (reg
+        (persist/register-upcaster (persist/upcasters) "placed" up-placed)))
+    (begin
+      (persist/append b "orders" "placed" 0 {:total 5})
+      (persist/append b "orders" "placed" 0 {:total 7 :amount 7})
+      (persist/project-upcast
+        b
+        "orders"
+        reg
+        (fn (acc e) (+ acc (get (persist/event-data e) :amount)))
+        0)))
+  12)
+(persist-test
+  "upcast works on the durable backend"
+  (let
+    ((db (persist/mock-durable (persist/mem-backend)))
+      (reg
+        (persist/register-upcaster (persist/upcasters) "placed" up-placed)))
+    (begin
+      (persist/append db "orders" "placed" 0 {:total 42})
+      (get
+        (persist/event-data
+          (nth (persist/read-upcast db "orders" reg) 0))
+        :amount)))
+  42)

lib/persist/tests/view.sx

@@ -0,0 +1,105 @@
+; Extension — materialized views: stay current on write, read O(1) via peek.
+
+(define vw-count (fn (acc e) (+ acc 1)))
+(define vw (persist/view "order-count" "orders" vw-count 0))
+
+(persist-test "view-name" (persist/view-name vw) "order-count")
+(persist-test "view-stream" (persist/view-stream vw) "orders")
+(persist-test
+  "view-value folds the stream"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "orders" "x" 0 {})
+      (persist/append b "orders" "x" 0 {})
+      (persist/view-value b vw)))
+  2)
+(persist-test
+  "view-refresh persists a snapshot that peek then reads"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "orders" "x" 0 {})
+      (persist/view-refresh b vw)
+      (persist/view-peek b vw)))
+  1)
+(persist-test
+  "peek lags an un-refreshed tail"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "orders" "x" 0 {})
+      (persist/view-refresh b vw)
+      (persist/append b "orders" "x" 0 {})
+      (persist/view-peek b vw)))
+  1)
+(persist-test
+  "view-value sees the whole stream even after a stale snapshot"
+  (let
+    ((b (persist/open)))
+    (begin
+      (persist/append b "orders" "x" 0 {})
+      (persist/view-refresh b vw)
+      (persist/append b "orders" "x" 0 {})
+      (persist/view-value b vw)))
+  2)
+(persist-test
+  "attached view stays current on publish — peek needs no manual refresh"
+  (let
+    ((b (persist/open)))
+    (let
+      ((h (persist/view-attach (persist/hub b) vw)))
+      (begin
+        (persist/publish h "orders" "x" 0 {})
+        (persist/publish h "orders" "x" 0 {})
+        (persist/publish h "orders" "x" 0 {})
+        (persist/view-peek b vw))))
+  3)
+(persist-test
+  "attached view advances the snapshot seq incrementally"
+  (let
+    ((b (persist/open)))
+    (let
+      ((h (persist/view-attach (persist/hub b) vw)))
+      (begin
+        (persist/publish h "orders" "x" 0 {})
+        (persist/publish h "orders" "x" 0 {})
+        (persist/project-seq
+          (persist/snapshot-load b "order-count" 0)))))
+  2)
+(persist-test
+  "attach only reacts to its own stream"
+  (let
+    ((b (persist/open)))
+    (let
+      ((h (persist/view-attach (persist/hub b) vw)))
+      (begin
+        (persist/publish h "other" "x" 0 {})
+        (persist/view-peek b vw))))
+  0)
+(persist-test
+  "materialized view works on the durable backend"
+  (let
+    ((db (persist/mock-durable (persist/mem-backend))))
+    (let
+      ((h (persist/view-attach (persist/hub db) vw)))
+      (begin
+        (persist/publish h "orders" "x" 0 {})
+        (persist/publish h "orders" "x" 0 {})
+        (persist/view-peek db vw))))
+  2)
+(persist-test
+  "view sum over event data"
+  (let
+    ((b (persist/open))
+      (sumv
+        (persist/view
+          "rev"
+          "sales"
+          (fn (acc e) (+ acc (get (persist/event-data e) :amt)))
+          0)))
+    (begin
+      (persist/append b "sales" "sale" 0 {:amt 10})
+      (persist/append b "sales" "sale" 1 {:amt 25})
+      (persist/view-value b sumv)))
+  35)

lib/persist/upcast.sx

@@ -0,0 +1,44 @@
+; persist/upcast — event schema evolution. An append-only log keeps events
+; forever, so old events have old shapes. Rather than migrate stored data (you
+; can't rewrite history) or branch every projection on version, register an
+; upcaster per event type: a pure (event -> event) that lifts an old event to
+; the current shape. Reads pass through the registry so projections see ONE
+; shape. The registry is an immutable dict the consumer threads (no global
+; mutable state). Requires: lib/persist/event.sx, lib/persist/log.sx.
+
+(define persist/upcasters (fn () {}))
+(define persist/register-upcaster (fn (reg type fn) (assoc reg type fn)))
+
+; apply the registered upcaster for an event's type, or pass it through unchanged
+(define
+  persist/upcast
+  (fn
+    (reg e)
+    (let ((f (get reg (persist/event-type e)))) (if f (f e) e))))
+
+; read a stream with every event lifted to current shape
+(define
+  persist/read-upcast
+  (fn
+    (b stream reg)
+    (map (fn (e) (persist/upcast reg e)) (persist/read b stream))))
+
+; project over upcasted events — projections never see a legacy shape
+(define
+  persist/project-upcast
+  (fn
+    (b stream reg step seed)
+    (reduce step seed (persist/read-upcast b stream reg))))
+
+; helper: upcast an event's :data by merging in/overriding fields, keeping the
+; record's stream/seq/type/at. Common upcaster body.
+(define
+  persist/upcast-data
+  (fn
+    (e new-data)
+    (persist/event
+      (persist/event-stream e)
+      (persist/event-seq e)
+      (persist/event-type e)
+      (persist/event-at e)
+      (merge (persist/event-data e) new-data))))

lib/persist/view.sx

@@ -0,0 +1,49 @@
+; persist/view — a materialized view: the consumer-facing read model. It bundles
+; a stream, a fold (step + seed) and a snapshot name. Attached to a hub it
+; refreshes incrementally on every publish, so the materialized value stays
+; current on write and reads are O(1) snapshot loads (persist/view-peek) instead
+; of a full fold. This is what feed indices, mod audit rollups, search counters,
+; etc. sit on. Requires: lib/persist/snapshot.sx, lib/persist/subscribe.sx.
+
+(define persist/view (fn (name stream step seed) {:name name :step step :stream stream :seed seed}))
+(define persist/view-name (fn (v) (get v :name)))
+(define persist/view-stream (fn (v) (get v :stream)))
+
+; bring the view's snapshot up to date with the log tail; returns the state
+(define
+  persist/view-refresh
+  (fn
+    (b v)
+    (persist/checkpoint
+      b
+      (get v :stream)
+      (get v :name)
+      (get v :step)
+      (get v :seed))))
+
+; current materialized value — refreshes first, so never stale
+(define
+  persist/view-value
+  (fn (b v) (persist/project-value (persist/view-refresh b v))))
+
+; O(1) read of the last persisted snapshot value WITHOUT folding the tail. Equal
+; to view-value when the view is attached (kept current on every publish);
+; otherwise may lag the log by the un-refreshed tail.
+(define
+  persist/view-peek
+  (fn
+    (b v)
+    (persist/project-value
+      (persist/snapshot-load b (get v :name) (get v :seed)))))
+
+; attach to a hub: refresh the view on every publish to its stream
+(define
+  persist/view-attach
+  (fn
+    (h v)
+    (begin
+      (persist/subscribe
+        h
+        (persist/view-stream v)
+        (fn (bk s e) (persist/view-refresh bk v)))
+      h)))

plans/agent-briefings/host-persist-loop.md

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+# host-persist loop agent (single agent, builds the durable storage host)
+
+Role: make `lib/persist`'s durable backend **actually durable**. The persist
+substrate (`lib/persist/**`, 201/201 tests) performs `{:op "persist/..." :args}`
+IO requests for every storage op; under `sx_server.exe` today nothing services
+them, so writes silently vanish. You build the **host-side adapter** that answers
+those ops against real on-disk storage — the one piece standing between persist
+and "all subsystems share a durable substrate."
+
+```
+worktree:    /root/rose-ash-loops/host-persist
+branch:      loops/host-persist   (push origin/loops/host-persist; NEVER main/architecture)
+```
+
+## The authoritative contract — read this first, every restart
+
+`plans/persist-on-sx.md` → **Blockers → "OPEN — host durable-storage adapter"**.
+That entry is the spec: the silent-data-loss repro, the full op contract table,
+the hard invariants (monotonic `last-seq`, etc.), the blob adapter shape, where
+to register in `sx_server.ml`, and the acceptance test. Do not restate it here —
+read it there and implement it. The reference implementation to mirror is
+`persist/serve` in `lib/persist/durable.sx` (same op names, same shapes).
+
+## Restart baseline — check before iterating
+
+1. Read the Blocker spec (above) + this briefing.
+2. `git log --oneline -8` on `loops/host-persist` to see what's done.
+3. Is there a worktree-local build? `ls hosts/ocaml/_build/default/bin/sx_server.exe`.
+   Fresh worktrees have none — the first build is the first task.
+4. If an acceptance suite exists (e.g. `hosts/ocaml/test/persist_durable_*` or a
+   `lib/persist/tests/durable-real.sx`), run it against the **worktree-built**
+   binary. Green before new work.
+
+## The queue (phases)
+
+- **Phase 0 — reproduce.** Confirm the silent-data-loss repro from the spec under
+  this worktree. Builds your mental model; costs one short run.
+- **Phase 1 — storage module.** A new OCaml module under `hosts/ocaml/` that
+  implements the op contract over **real persistent storage**. Start simple and
+  correct: a filesystem-backed store (one append-only file per stream + a kv
+  file + a per-stream seq high-water file), or SQLite if the toolchain has it.
+  Honour every invariant in the spec — especially: `last-seq` is a monotonic
+  counter stored separately from rows so it survives `truncate`; values
+  round-trip structurally.
+- **Phase 2 — register.** Wire a `"persist/..."` arm into the kernel's IO
+  resolver (`Sx_types._cek_io_resolver`, ~line 3864 of `hosts/ocaml/bin/sx_server.ml`)
+  and/or the `cek_run_with_io` bridge path (~528–576), dispatching to the storage
+  module. Op names are the contract — do not rename.
+- **Phase 3 — acceptance.** New tests that use `persist/durable-backend` (REAL
+  `perform`, not the mock) run under the freshly-built worktree binary: the
+  `durable` + `recovery` semantics must pass, and a **real process restart**
+  (start the built server, write, stop it, start again, replay) must recover
+  state from disk. Put host-owned tests under a host path (e.g.
+  `hosts/ocaml/test/`) — do not churn persist's existing suites.
+- **Phase 4 — blob adapter.** Same pattern for `blob/put|get|has?` backed by a
+  content-addressed directory; persist stores only the ref.
+
+Every iteration: implement → build → test → commit (short factual message) →
+push → update `plans/persist-on-sx.md` (tick the Blocker toward CLOSED, append a
+dated Progress-log line, newest first) → next.
+
+## Ground rules (hard)
+
+- **Build is your job** (unlike the persist loop). But build **only in this
+  worktree's `_build`** via `dune` from `/root/rose-ash-loops/host-persist`.
+  **NEVER overwrite the shared binary** at
+  `/root/rose-ash/hosts/ocaml/_build/default/bin/sx_server.exe` — every sibling
+  loop uses it; clobbering it breaks them all. Point acceptance tests at the
+  worktree binary (`hosts/ocaml/_build/default/bin/sx_server.exe` *inside this
+  worktree*).
+- **First build is slow** (full OCaml). The `sx_build` MCP tool has a ~600s
+  watchdog that may kill it — prefer `dune build bin/sx_server.exe` (or `@all`)
+  run via Bash with `run_in_background: true` and a long timeout, then poll.
+- **NEVER `pkill sx_server`** — siblings share the process/binary. Start your own
+  server on a throwaway path/port for restart tests and stop only that PID; bound
+  every run with `timeout`.
+- **Scope:** `hosts/**`, host-owned test files, and the Blocker entry +
+  Progress log in `plans/persist-on-sx.md`. Do **not** modify `lib/persist/**`
+  source (the persist loop owns it; its API is your contract, not your code) —
+  if you need an upstream change, leave a note in the Blocker entry.
+- **Determinism:** replay from disk must equal the in-memory semantics; same log
+  → same state.
+- **Commits:** one feature per commit; push to `origin/loops/host-persist`.
+- **SX files:** `sx-tree` MCP tools ONLY, `file:` not `path:`, `sx_validate`
+  after edits. (Most of your work is OCaml — edit those with normal tools.)
+
+## Definition of done
+
+The Blocker entry flips to **CLOSED**: `persist/durable-backend` writes land on
+disk, survive a real server restart, and the durable + recovery acceptance suites
+are green against the worktree-built binary. At that point a subsystem migrated
+per `lib/persist/examples/acl.sx` is genuinely durable.
+
+Go. Read the Blocker spec; reproduce the gap; build the storage module.

plans/agent-briefings/persist-loop.md

@@ -0,0 +1,115 @@
+# persist-on-sx loop agent (single agent, queue-driven)
+
+Role: iterates `plans/persist-on-sx.md` forever. **Durable state on the SX kernel**
+— the foundation substrate every other subsystem currently fakes with an in-memory
+mutable list. Event log (append-only streams) + kv (current-state) over one
+injectable backend; pure projections; snapshots; durable IO at the kernel's
+`perform` boundary. This is **substrate-level**, not a guest language.
+
+```
+description: persist-on-sx queue loop
+subagent_type: general-purpose
+run_in_background: true
+isolation: worktree
+```
+
+## Prompt
+
+You are the sole background agent working `plans/persist-on-sx.md`. Isolated
+worktree `/root/rose-ash-loops/persist` on branch `loops/persist`, forever, one
+commit per feature. Push to `origin/loops/persist` after every commit. Never touch
+`main` or `architecture`.
+
+## Restart baseline — check before iterating
+
+1. Read `plans/persist-on-sx.md` — roadmap + Progress log. Note the scope table:
+   persist owns the **log** + **kv** facets; blobs are delegated (store the CID,
+   not the bytes); cache is out of scope. Do not event-source everything.
+2. `ls lib/persist/` — pick up from the most advanced file.
+3. If `lib/persist/tests/*.sx` exist, run them via `bash lib/persist/conformance.sh`.
+   Green before new work.
+4. If `lib/persist/scoreboard.md` exists, that's your baseline.
+5. **Learn the substrate before writing durable code.** persist sits on the kernel's
+   IO-suspension surface — the third CEK phase: `perform`, `cek-step-loop`,
+   `cek-resume`, `make-cek-suspended`. Study how IO is requested and resumed, and
+   how `spec/harness.sx` mocks an IO platform for tests (assert-io-*). Phases 1–3
+   need NO real IO — the in-memory backend is pure SX. Real durable IO (Phase 4)
+   goes through `perform` and is tested against the mock-IO harness, not a real disk.
+   Verify the actual exported names with sx_find_all / grep before relying on them.
+
+## The queue
+
+Phase order per `plans/persist-on-sx.md`:
+
+- **Phase 1** — log + kv + in-memory backend (event record, injectable backend
+  protocol, append/read, kv get/put/delete, api).
+- **Phase 2** — projections (`fold step seed`) + subscriptions; concurrency
+  conflict as a real result.
+- **Phase 3** — snapshots + replay (checkpoint, replay = snapshot + tail,
+  determinism).
+- **Phase 4** — durable backend via kernel IO (`perform`), blob-ref interface,
+  crash/restart replay against the mock-IO harness.
+
+Within a phase, pick the checkbox that unlocks the most tests per effort.
+
+Every iteration: implement → test → commit → tick `[ ]` → Progress log → next.
+
+## Ground rules (hard)
+
+- **Scope:** only `lib/persist/**` and `plans/persist-on-sx.md`. Do **not** edit
+  `spec/`, `hosts/`, `shared/`, or any `lib/<lang>/`. You may **import** the
+  kernel's IO-suspension + platform-IO surface only. **Do NOT add host primitives.**
+  If a durable IO op you need doesn't exist, it belongs in `hosts/` (out of scope) →
+  Blockers entry with a minimal repro, and stop on that item.
+- **NEVER call `sx_build`.** 600s watchdog. If the sx_server binary is broken →
+  Blockers entry, stop. Run tests by invoking the sx_server binary directly from a
+  conformance.sh (model it on an existing one, e.g. `lib/apl/conformance.sh`),
+  pointing `SX_SERVER` at `/root/rose-ash/hosts/ocaml/_build/default/bin/sx_server.exe`
+  — fresh worktrees have no `_build/`.
+- **Determinism:** replay must be pure — same log → same state. No clocks/randomness
+  inside projections; timestamps live on the event, passed in.
+- **Shared-file issues** → plan's Blockers with minimal repro; don't fix here.
+- **SX files:** `sx-tree` MCP tools ONLY. **They take `file:` not `path:`** — a
+  wrong key yields `Yojson Type_error("Expected string, got null")`, which looks
+  like a broken binary but is just a param mismatch. `sx_validate` after edits.
+  Path-based edits (`sx_replace_node`) count comment headers in their indices and
+  can clobber the wrong node — re-read after, or prefer `sx_write_file` for small
+  files.
+- **Unicode in `.sx`:** raw UTF-8 only, never `\uXXXX` escapes.
+- **Commit granularity:** one feature per commit. Short factual messages
+  (`persist: kv facet get/put/delete + 6 tests`). Push to `origin/loops/persist`.
+- **Plan file:** update Progress log (newest first) + tick boxes every commit.
+
+## persist-specific gotchas
+
+- **Two facets, not one.** Don't force current-state values (a stock count, a
+  config value, a session blob) through the event log — that's the kv facet. Event
+  log is for things whose *history* matters.
+- **Backend is injected.** The in-memory backend is the test default; never hardwire
+  it. Every op goes through the backend protocol so file/pg/ipfs swap in unchanged.
+- **Optimistic concurrency is a real result.** A conflicting append returns a
+  conflict value the caller can retry on — not a crash, not a silent overwrite.
+- **Blobs by reference only.** persist stores a content-address/CID + metadata. The
+  bytes live in a content-addressed store (artdag/IPFS). Never put large payloads in
+  the log.
+- **Replay determinism is the headline property.** Snapshot + tail must equal full
+  replay. Test it explicitly, both directions.
+
+## General gotchas (all loops)
+
+- SX `do` = R7RS iteration. Use `begin` for multi-expr sequences.
+- `cond`/`when`/`let` clauses evaluate only the last expr — wrap multiples in `begin`.
+- `let` is parallel, not sequential — nest `let`s when a binding references an earlier one.
+- `env-bind!` creates a binding; `env-set!` mutates an existing one (walks scope chain).
+- `sx_validate` after every structural edit.
+- Namespace-prefix all helpers (`persist/...`) — short/host-colliding names get
+  silently shadowed or hang the runtime.
+
+## Style
+
+- No comments in `.sx` unless non-obvious.
+- No new planning docs — update `plans/persist-on-sx.md` inline.
+- Short, factual commit messages.
+- One feature per iteration. Commit. Log. Push. Next.
+
+Go. Start by reading the plan; find the first unchecked `[ ]`; implement it.

plans/commerce-on-sx.md

@@ -0,0 +1,82 @@
+# commerce-on-sx: Catalog, cart, pricing & orders on miniKanren
+
+> **DRAFT outline.** The revenue vertical. Depends on `persist-on-sx` (durable
+> orders) and `flow-on-sx` (checkout as a durable flow). Don't start before
+> persist-on-sx Phase 1 is green.
+
+rose-ash's revenue engine — market (catalog), cart (checkout), orders (SumUp
+payment, reconciliation) — has no SX subsystem. The hard part of commerce isn't
+CRUD; it's **pricing**: discounts, bundles, tax, membership rates, promotions that
+stack (or don't). These are relations, and a relational engine can run them in
+multiple directions — forward ("what's the total?") and backward ("what promo code
+yields this total?", "which line item triggered the discount?").
+
+That's a miniKanren fit. Pricing/promotion rules are relational; cart and order
+*lifecycle* (reserve → pay → fulfil → reconcile) is a durable `flow`; the order
+ledger is a `persist` stream. Commerce is the first real **composition** subsystem.
+
+End-state: a catalog model, a relational pricing/promotion engine, a cart with
+deterministic totals, and an order lifecycle flow with payment-webhook
+reconciliation — all auditable via the event log.
+
+## Status (rolling)
+
+`bash lib/commerce/conformance.sh` → **0/0** (not yet started)
+
+## Ground rules
+
+- **Scope:** only `lib/commerce/**` and `plans/commerce-on-sx.md`. May **import**
+  from `lib/minikanren/`, and (once they exist) `lib/persist/` + `lib/flow/`. Do not
+  edit substrates.
+- **Architecture:** prices/promotions are miniKanren relations over catalog facts;
+  a cart total is a *deterministic* query result (first solution under a fixed rule
+  order). Order lifecycle is a `flow` that suspends at the payment IO boundary.
+  Money is integer minor units — never floats.
+- **Determinism:** promotion stacking must have explicit, tested precedence;
+  totals must be reproducible from the cart + catalog snapshot.
+- **Commits:** one feature per commit. Progress log + tick boxes.
+
+## Architecture sketch
+
+```
+Catalog + cart                          Total / order
+  product(id,price,tags)                  {:subtotal :discounts :tax :total}
+        │                                       ▲
+        ▼                                       │
+lib/commerce/catalog.sx                 lib/commerce/price.sx
+  — product / variant / stock facts       — miniKanren pricing relations
+        │                                  — promo stacking, membership rates
+        ▼                                       ▲
+lib/commerce/cart.sx                    lib/commerce/order.sx  (flow + store)
+  — line items, quantities                — reserve→pay→fulfil→reconcile
+        │                                  — SumUp webhook = flow resume
+        ▼                                       │
+lib/commerce/api.sx ── (commerce/add) (commerce/total) (commerce/checkout) ──┘
+```
+
+## Phase 1 — Catalog + cart + deterministic totals
+- [ ] `catalog.sx` — product/variant/stock as facts
+- [ ] `cart.sx` — line items, add/remove/qty
+- [ ] `price.sx` — base pricing relation, subtotal; tax
+- [ ] `api.sx` + tests + scoreboard + conformance.sh
+
+## Phase 2 — Promotions (relational)
+- [ ] promo rules: percentage, fixed, bundle, member rate
+- [ ] explicit stacking precedence; "best price" backward query
+- [ ] tests: stacking order, mutually-exclusive promos, member vs guest
+
+## Phase 3 — Order lifecycle (flow + store)
+- [ ] order flow: reserve stock → await payment → fulfil
+- [ ] payment webhook resumes the suspended flow
+- [ ] order ledger as a `persist` stream; idempotent reconciliation
+
+## Phase 4 — Reconciliation + federation
+- [ ] mismatch detection (paid≠ordered) as queries over the ledger
+- [ ] cross-instance catalog (federated marketplace) — out-of-scope stub
+- [ ] tests: webhook replay, partial refund, double-charge guard
+
+## Progress log
+(loop fills this in)
+
+## Blockers
+(loop fills this in)