commerce: order ledger on persist + idempotent reconciliation (20 tests)

ledger.sx — each order is an append-only persist stream "order/<id>";
status/total/paid/recon are folds over events (ledger = source of truth).
order-pay / order-refund are idempotent via persist/append-once keyed on the
payment ref, so a replayed SumUp webhook records once. order-recon-of
classifies unpaid/ok/underpaid/overpaid on net vs total; ledger-mismatches
finds genuine paid != ordered across streams. minikanren+scheme/flow+persist
verified coexisting in one process. Total 132/132 across 8 suites.

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

lib/apl/conformance.conf

@@ -0,0 +1,63 @@
+# APL conformance config — sourced by lib/guest/conformance.sh.
+
+LANG_NAME=apl
+MODE=counters
+COUNTERS_PASS=apl-test-pass
+COUNTERS_FAIL=apl-test-fail
+TIMEOUT_PER_SUITE=300
+
+PRELOADS=(
+  spec/stdlib.sx
+  lib/r7rs.sx
+  lib/apl/runtime.sx
+  lib/apl/tokenizer.sx
+  lib/apl/parser.sx
+  lib/apl/transpile.sx
+  lib/apl/test-harness.sx
+)
+
+SUITES=(
+  "structural:lib/apl/tests/structural.sx"
+  "operators:lib/apl/tests/operators.sx"
+  "dfn:lib/apl/tests/dfn.sx"
+  "tradfn:lib/apl/tests/tradfn.sx"
+  "valence:lib/apl/tests/valence.sx"
+  "programs:lib/apl/tests/programs.sx"
+  "system:lib/apl/tests/system.sx"
+  "idioms:lib/apl/tests/idioms.sx"
+  "eval-ops:lib/apl/tests/eval-ops.sx"
+  "pipeline:lib/apl/tests/pipeline.sx"
+)
+
+emit_scoreboard_json() {
+  local n=${#GC_NAMES[@]} i sep
+  printf '{\n'
+  printf '  "suites": {\n'
+  for ((i=0; i<n; i++)); do
+    sep=","; [ $i -eq $((n-1)) ] && sep=""
+    printf '    "%s": {"pass": %d, "fail": %d}%s\n' \
+      "${GC_NAMES[$i]}" "${GC_PASS[$i]}" "${GC_FAIL[$i]}" "$sep"
+  done
+  printf '  },\n'
+  printf '  "total_pass": %d,\n' "$GC_TOTAL_PASS"
+  printf '  "total_fail": %d,\n' "$GC_TOTAL_FAIL"
+  printf '  "total": %d\n' "$GC_TOTAL"
+  printf '}\n'
+}
+
+emit_scoreboard_md() {
+  local n=${#GC_NAMES[@]} i
+  printf '# APL Conformance Scoreboard\n\n'
+  printf '_Generated by `lib/apl/conformance.sh`_\n\n'
+  printf '| Suite | Pass | Fail | Total |\n'
+  printf '|-------|-----:|-----:|------:|\n'
+  for ((i=0; i<n; i++)); do
+    printf '| %s | %d | %d | %d |\n' \
+      "${GC_NAMES[$i]}" "${GC_PASS[$i]}" "${GC_FAIL[$i]}" "${GC_TOTAL_S[$i]}"
+  done
+  printf '| **Total** | **%d** | **%d** | **%d** |\n' "$GC_TOTAL_PASS" "$GC_TOTAL_FAIL" "$GC_TOTAL"
+  printf '\n'
+  printf '## Notes\n\n'
+  printf '%s\n' '- Suites use the standard `apl-test name got expected` framework loaded against `lib/apl/runtime.sx` + `lib/apl/transpile.sx`.'
+  printf '%s\n' '- `lib/apl/tests/parse.sx` and `lib/apl/tests/scalar.sx` use their own self-contained frameworks and are excluded from this scoreboard.'
+}

lib/apl/conformance.sh

@@ -1,116 +1,5 @@
 #!/usr/bin/env bash
-# lib/apl/conformance.sh — run APL 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=(structural operators dfn tradfn valence programs system idioms eval-ops pipeline)
-
-OUT_JSON="lib/apl/scoreboard.json"
-OUT_MD="lib/apl/scoreboard.md"
-
-run_suite() {
-  local suite=$1
-  local file="lib/apl/tests/${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/apl/tokenizer.sx")
-(load "lib/apl/parser.sx")
-(load "lib/apl/transpile.sx")
-(epoch 2)
-(eval "(define apl-test-pass 0)")
-(eval "(define apl-test-fail 0)")
-(eval "(define apl-test (fn (name got expected) (if (= got expected) (set! apl-test-pass (+ apl-test-pass 1)) (set! apl-test-fail (+ apl-test-fail 1)))))")
-(epoch 3)
-(load "${file}")
-(epoch 4)
-(eval "(list apl-test-pass apl-test-fail)")
-EPOCHS
-
-  local OUTPUT
-  OUTPUT=$(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} ${F}"
-}
-
-declare -A SUITE_PASS
-declare -A SUITE_FAIL
-TOTAL_PASS=0
-TOTAL_FAIL=0
-
-echo "Running APL conformance suite..." >&2
-for s in "${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 '# APL Conformance Scoreboard\n\n'
-  printf '_Generated by `lib/apl/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))"
-  printf '\n'
-  printf '## Notes\n\n'
-  printf '%s\n' '- Suites use the standard `apl-test name got expected` framework loaded against `lib/apl/runtime.sx` + `lib/apl/transpile.sx`.'
-  printf '%s\n' '- `lib/apl/tests/parse.sx` and `lib/apl/tests/scalar.sx` use their own self-contained frameworks and are excluded from this scoreboard.'
-} > "$OUT_MD"
-
-echo "Wrote $OUT_JSON and $OUT_MD" >&2
-echo "Total: $TOTAL_PASS pass, $TOTAL_FAIL fail" >&2
-
-[ "$TOTAL_FAIL" -eq 0 ]
+# lib/apl/conformance.sh — APL conformance via the shared guest driver.
+# Config lives in lib/apl/conformance.conf (MODE=counters). Override the binary
+# with SX_SERVER=path/to/sx_server.exe bash lib/apl/conformance.sh
+exec bash "$(dirname "$0")/../guest/conformance.sh" "$(dirname "$0")/conformance.conf" "$@"

lib/apl/scoreboard.json

@@ -9,9 +9,9 @@
     "system": {"pass": 13, "fail": 0},
     "idioms": {"pass": 64, "fail": 0},
     "eval-ops": {"pass": 14, "fail": 0},
-    "pipeline": {"pass": 40, "fail": 0}
+    "pipeline": {"pass": 152, "fail": 0}
   },
-  "total_pass": 450,
+  "total_pass": 562,
   "total_fail": 0,
-  "total": 450
+  "total": 562
 }

lib/apl/scoreboard.md

@@ -13,8 +13,8 @@ _Generated by `lib/apl/conformance.sh`_
 | system | 13 | 0 | 13 |
 | idioms | 64 | 0 | 64 |
 | eval-ops | 14 | 0 | 14 |
-| pipeline | 40 | 0 | 40 |
-| **Total** | **450** | **0** | **450** |
+| pipeline | 152 | 0 | 152 |
+| **Total** | **562** | **0** | **562** |
 
 ## Notes
 

lib/apl/test-harness.sx

@@ -0,0 +1,15 @@
+; lib/apl/test-harness.sx — counters + assertion fn for the shared conformance
+; driver (lib/guest/conformance.sh, MODE=counters). Loaded as a PRELOAD so each
+; suite starts from a fresh 0/0; suites call (apl-test name got expected).
+
+(define apl-test-pass 0)
+(define apl-test-fail 0)
+
+(define
+  apl-test
+  (fn
+    (name got expected)
+    (if
+      (= got expected)
+      (set! apl-test-pass (+ apl-test-pass 1))
+      (set! apl-test-fail (+ apl-test-fail 1)))))

lib/commerce/api.sx

@@ -0,0 +1,56 @@
+;; lib/commerce/api.sx — public commerce surface.
+;;
+;; A session bundles a pricing context with a cart: {:ctx CTX :cart CART}.
+;; All operations are pure and return a new session. The total and the
+;; per-line breakdown are deterministic functions of (ctx, cart).
+;;
+;; commerce-checkout is a Phase-3 stub — the order lifecycle is a durable
+;; flow that suspends at the SumUp payment boundary.
+
+(define commerce-session (fn (ctx) {:cart empty-cart :ctx ctx}))
+
+(define commerce-ctx (fn (sess) (get sess :ctx)))
+(define commerce-cart (fn (sess) (get sess :cart)))
+(define commerce-lines (fn (sess) (cart-lines (get sess :cart))))
+(define commerce-count (fn (sess) (cart-count (get sess :cart))))
+
+(define
+  commerce-add
+  (fn
+    (sess sku variant qty)
+    (assoc sess :cart (cart-add (get sess :cart) sku variant qty))))
+
+(define
+  commerce-remove
+  (fn
+    (sess sku variant)
+    (assoc sess :cart (cart-remove (get sess :cart) sku variant))))
+
+(define
+  commerce-set-qty
+  (fn
+    (sess sku variant qty)
+    (assoc sess :cart (cart-set-qty (get sess :cart) sku variant qty))))
+
+;; True when the sku exists in the session's catalog snapshot.
+(define
+  commerce-can-add?
+  (fn (sess sku) (catalog-has? (ctx-catalog (get sess :ctx)) sku)))
+
+(define
+  commerce-total
+  (fn (sess) (cart-total (get sess :ctx) (get sess :cart))))
+
+;; Per-line audit breakdown — the "which line contributed what" view.
+(define
+  line-detail
+  (fn (ctx line) (let ((cat (ctx-catalog ctx))) {:sku (line-sku line) :unit (line-unit-price cat (line-sku line) (line-variant line)) :qty (line-qty line) :variant (line-variant line) :extended (line-extended cat line) :tax (line-tax ctx line)})))
+
+(define
+  commerce-explain
+  (fn
+    (sess)
+    (map (fn (l) (line-detail (get sess :ctx) l)) (get sess :cart))))
+
+;; Phase 3 — order lifecycle flow (reserve -> pay -> fulfil) lands here.
+(define commerce-checkout (fn (sess) {:note "order lifecycle flow lands in Phase 3" :phase 3 :status :not-implemented}))

lib/commerce/cart.sx

@@ -0,0 +1,86 @@
+;; lib/commerce/cart.sx — cart as an ordered list of line items.
+;;
+;; A cart is a native list of lines; a line is (list sku variant qty).
+;; All operations are pure: they return a new cart, never mutate. Line
+;; order is insertion order (stable) so totals are reproducible.
+;;
+;; cart-lineo is the relational view — because a line *is* a (sku variant qty)
+;; tuple, membero queries the cart directly, forward or backward.
+
+(define empty-cart (list))
+
+(define make-line (fn (sku variant qty) (list sku variant qty)))
+(define line-sku (fn (l) (nth l 0)))
+(define line-variant (fn (l) (nth l 1)))
+(define line-qty (fn (l) (nth l 2)))
+
+(define
+  same-line?
+  (fn
+    (l sku variant)
+    (and (= (line-sku l) sku) (= (line-variant l) variant))))
+
+(define
+  cart-qty
+  (fn
+    (cart sku variant)
+    (let
+      ((m (filter (fn (l) (same-line? l sku variant)) cart)))
+      (if (empty? m) 0 (line-qty (first m))))))
+
+(define
+  cart-remove
+  (fn
+    (cart sku variant)
+    (filter (fn (l) (not (same-line? l sku variant))) cart)))
+
+;; Add qty units; merges into an existing (sku,variant) line in place,
+;; otherwise appends a new line at the end.
+(define
+  cart-add
+  (fn
+    (cart sku variant qty)
+    (let
+      ((existing (cart-qty cart sku variant)))
+      (if
+        (= existing 0)
+        (append cart (list (make-line sku variant qty)))
+        (map
+          (fn
+            (l)
+            (if
+              (same-line? l sku variant)
+              (make-line sku variant (+ existing qty))
+              l))
+          cart)))))
+
+;; Set the absolute quantity; qty <= 0 removes the line.
+(define
+  cart-set-qty
+  (fn
+    (cart sku variant qty)
+    (if
+      (<= qty 0)
+      (cart-remove cart sku variant)
+      (if
+        (= (cart-qty cart sku variant) 0)
+        (append cart (list (make-line sku variant qty)))
+        (map
+          (fn
+            (l)
+            (if (same-line? l sku variant) (make-line sku variant qty) l))
+          cart)))))
+
+(define cart-empty? (fn (cart) (empty? cart)))
+(define cart-lines (fn (cart) cart))
+(define cart-skus (fn (cart) (map line-sku cart)))
+
+;; Total number of units across all lines.
+(define
+  cart-count
+  (fn (cart) (reduce (fn (acc l) (+ acc (line-qty l))) 0 cart)))
+
+;; Relational view of cart lines.
+(define
+  cart-lineo
+  (fn (cart sku variant qty) (membero (list sku variant qty) cart)))

lib/commerce/catalog.sx

@@ -0,0 +1,83 @@
+;; lib/commerce/catalog.sx — catalog snapshot + relational accessors.
+;;
+;; A catalog snapshot is an immutable dict:
+;;   {:products (list (list sku price class) ...)
+;;    :variants (list (list sku variant delta) ...)
+;;    :stock    (list (list sku variant qty) ...)}
+;;
+;; Money is integer minor units (pence/cents). class is a keyword product
+;; class consumed later by tax and promotion relations. delta is a signed
+;; price adjustment for a variant; qty is on-hand stock for (sku,variant).
+;;
+;; Accessor relations take the snapshot as the first argument and are fully
+;; multidirectional: (producto cat "widget" p c) binds p,c forward;
+;; (producto cat s 1000 c) enumerates every sku priced 1000 backward.
+
+(define empty-catalog {:products (list) :stock (list) :variants (list)})
+
+(define make-catalog (fn (products variants stock) {:products products :stock stock :variants variants}))
+
+(define cat-products (fn (cat) (get cat :products)))
+(define cat-variants (fn (cat) (get cat :variants)))
+(define cat-stock (fn (cat) (get cat :stock)))
+
+;; --- core fact relations ---
+
+(define
+  producto
+  (fn
+    (cat sku price class)
+    (membero (list sku price class) (get cat :products))))
+
+(define
+  varianto
+  (fn
+    (cat sku variant delta)
+    (membero (list sku variant delta) (get cat :variants))))
+
+(define
+  stocko
+  (fn
+    (cat sku variant qty)
+    (membero (list sku variant qty) (get cat :stock))))
+
+;; --- derived relations ---
+
+(define
+  priceo
+  (fn (cat sku price) (fresh (c) (producto cat sku price c))))
+
+(define
+  classo
+  (fn (cat sku class) (fresh (p) (producto cat sku p class))))
+
+;; Effective unit price of a (sku,variant): base + variant delta.
+(define
+  unit-priceo
+  (fn
+    (cat sku variant price)
+    (fresh
+      (base delta)
+      (priceo cat sku base)
+      (varianto cat sku variant delta)
+      (pluso-i base delta price))))
+
+;; --- deterministic lookups (first solution under fixed fact order) ---
+
+(define
+  catalog-price
+  (fn
+    (cat sku)
+    (let
+      ((rs (run 1 p (priceo cat sku p))))
+      (if (empty? rs) nil (first rs)))))
+
+(define
+  catalog-class
+  (fn
+    (cat sku)
+    (let
+      ((rs (run 1 c (classo cat sku c))))
+      (if (empty? rs) nil (first rs)))))
+
+(define catalog-has? (fn (cat sku) (not (nil? (catalog-price cat sku)))))

lib/commerce/conformance.sh

@@ -0,0 +1,133 @@
+#!/usr/bin/env bash
+# lib/commerce/conformance.sh — run commerce test suites in one sx_server
+# process per suite, emit scoreboard.json + scoreboard.md.
+#
+# commerce-on-sx builds pricing/promotion as miniKanren relations, so every
+# suite loads the miniKanren stack first, then the commerce modules.
+
+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=(catalog cart price api promo stack quote ledger)
+
+OUT_JSON="lib/commerce/scoreboard.json"
+OUT_MD="lib/commerce/scoreboard.md"
+
+run_suite() {
+  local suite=$1
+  local file="lib/commerce/tests/${suite}.sx"
+  local TMP
+  TMP=$(mktemp)
+  cat > "$TMP" << EPOCHS
+(epoch 1)
+(load "spec/stdlib.sx")
+(load "lib/r7rs.sx")
+(load "lib/guest/match.sx")
+(load "lib/minikanren/unify.sx")
+(load "lib/minikanren/stream.sx")
+(load "lib/minikanren/goals.sx")
+(load "lib/minikanren/fresh.sx")
+(load "lib/minikanren/conde.sx")
+(load "lib/minikanren/run.sx")
+(load "lib/minikanren/relations.sx")
+(load "lib/minikanren/project.sx")
+(load "lib/minikanren/intarith.sx")
+(load "lib/minikanren/matche.sx")
+(load "lib/minikanren/defrel.sx")
+(load "lib/persist/event.sx")
+(load "lib/persist/backend.sx")
+(load "lib/persist/log.sx")
+(load "lib/persist/kv.sx")
+(load "lib/persist/idempotency.sx")
+(load "lib/commerce/catalog.sx")
+(load "lib/commerce/cart.sx")
+(load "lib/commerce/price.sx")
+(load "lib/commerce/api.sx")
+(load "lib/commerce/promo.sx")
+(load "lib/commerce/stack.sx")
+(load "lib/commerce/quote.sx")
+(load "lib/commerce/ledger.sx")
+(epoch 2)
+(eval "(define ct-pass 0)")
+(eval "(define ct-fail 0)")
+(eval "(define ct-fails (list))")
+(eval "(define commerce-test (fn (name got expected) (if (= got expected) (set! ct-pass (+ ct-pass 1)) (begin (set! ct-fail (+ ct-fail 1)) (append! ct-fails name)))))")
+(epoch 3)
+(load "${file}")
+(epoch 4)
+(eval "(list ct-pass ct-fail)")
+(eval "ct-fails")
+EPOCHS
+
+  local OUTPUT
+  OUTPUT=$(timeout 300 "$SX_SERVER" < "$TMP" 2>/dev/null)
+  rm -f "$TMP"
+
+  # The (list ct-pass ct-fail) result follows its (ok-len 2 N) ack line.
+  local LINE
+  LINE=$(echo "$OUTPUT" | grep -oE '^\([0-9]+ [0-9]+\)$' | tail -1)
+  local P F
+  P=$(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} ${F}"
+}
+
+declare -A SUITE_PASS
+declare -A SUITE_FAIL
+TOTAL_PASS=0
+TOTAL_FAIL=0
+
+echo "Running commerce conformance suite..." >&2
+for s in "${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
+
+{
+  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"
+
+{
+  printf '# commerce Conformance Scoreboard\n\n'
+  printf '_Generated by `lib/commerce/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/commerce/ledger.sx

@@ -0,0 +1,176 @@
+;; lib/commerce/ledger.sx — the order ledger as a persist event stream.
+;;
+;; Each order is an append-only stream "order/<id>" in a persist backend.
+;; Order state is never stored directly — it is a projection (fold) over the
+;; events, so the ledger is the single source of truth and replays identically.
+;;
+;; Lifecycle events:
+;;   :created   quote snapshot {:subtotal :discount :tax :total :codes ...}
+;;   :reserved  stock reserved
+;;   :paid      {:amount :ref}  — recorded idempotently on the payment ref
+;;   :fulfilled order shipped/delivered
+;;   :cancelled / :refunded
+;;
+;; Idempotency: the SumUp webhook can fire twice for one payment. order-pay
+;; uses persist/append-once keyed by the payment ref, so a replayed webhook
+;; yields the SAME :paid event without double-recording. Reconciliation then
+;; detects genuine mismatches (paid != ordered) across the whole ledger.
+
+(define order-stream (fn (order-id) (str "order/" order-id)))
+
+;; --- writes ---
+
+(define
+  order-create
+  (fn
+    (b order-id at quote)
+    (persist/append b (order-stream order-id) :created at quote)))
+
+(define
+  order-reserve
+  (fn
+    (b order-id at data)
+    (persist/append b (order-stream order-id) :reserved at data)))
+
+;; Idempotent on payment ref — a replayed webhook does not double-record.
+(define
+  order-pay
+  (fn
+    (b order-id ref at amount)
+    (persist/append-once b (order-stream order-id) ref :paid at {:amount amount :ref ref})))
+
+(define
+  order-fulfil
+  (fn
+    (b order-id at data)
+    (persist/append b (order-stream order-id) :fulfilled at data)))
+
+(define
+  order-cancel
+  (fn
+    (b order-id at reason)
+    (persist/append b (order-stream order-id) :cancelled at {:reason reason})))
+
+(define
+  order-refund
+  (fn
+    (b order-id ref at amount)
+    (persist/append-once
+      b
+      (order-stream order-id)
+      (str "refund/" ref)
+      :refunded at
+      {:amount amount :ref ref})))
+
+;; --- reads ---
+
+(define
+  order-events
+  (fn (b order-id) (persist/read b (order-stream order-id))))
+
+;; --- projections over an event list ---
+
+(define
+  order-status-of
+  (fn
+    (events)
+    (reduce
+      (fn
+        (st e)
+        (let
+          ((t (persist/event-type e)))
+          (cond
+            ((= t :created) :pending)
+            ((= t :reserved) :reserved)
+            ((= t :paid) :paid)
+            ((= t :fulfilled) :fulfilled)
+            ((= t :cancelled) :cancelled)
+            ((= t :refunded) :refunded)
+            (:else st))))
+      :new events)))
+
+(define
+  order-total-of
+  (fn
+    (events)
+    (let
+      ((created (filter (fn (e) (= (persist/event-type e) :created)) events)))
+      (if
+        (empty? created)
+        0
+        (get (persist/event-data (first created)) :total)))))
+
+(define
+  order-paid-amount-of
+  (fn
+    (events)
+    (reduce
+      (fn
+        (acc e)
+        (if
+          (= (persist/event-type e) :paid)
+          (+ acc (get (persist/event-data e) :amount))
+          acc))
+      0
+      events)))
+
+(define
+  order-refunded-amount-of
+  (fn
+    (events)
+    (reduce
+      (fn
+        (acc e)
+        (if
+          (= (persist/event-type e) :refunded)
+          (+ acc (get (persist/event-data e) :amount))
+          acc))
+      0
+      events)))
+
+;; Net settled = paid - refunded. Reconciliation compares this to the order
+;; total, but only once a payment exists.
+(define
+  order-recon-of
+  (fn
+    (events)
+    (let
+      ((net (- (order-paid-amount-of events) (order-refunded-amount-of events)))
+        (total (order-total-of events))
+        (has-paid (some (fn (e) (= (persist/event-type e) :paid)) events)))
+      (cond
+        ((not has-paid) :unpaid)
+        ((= net total) :ok)
+        ((< net total) :underpaid)
+        (:else :overpaid)))))
+
+;; --- backend-level helpers ---
+
+(define
+  order-status
+  (fn (b order-id) (order-status-of (order-events b order-id))))
+(define
+  order-total
+  (fn (b order-id) (order-total-of (order-events b order-id))))
+(define
+  order-paid
+  (fn (b order-id) (order-paid-amount-of (order-events b order-id))))
+(define
+  order-recon
+  (fn (b order-id) (order-recon-of (order-events b order-id))))
+
+(define order-ids (fn (b) (persist/backend-streams b)))
+
+;; Streams whose net payment does not match the order total (true mismatches,
+;; excluding orders that are simply not yet paid).
+(define
+  ledger-mismatches
+  (fn
+    (b)
+    (filter
+      (fn
+        (s)
+        (let
+          ((r (order-recon-of (persist/read b s))))
+          (or (= r :underpaid) (= r :overpaid))))
+      (persist/backend-streams b))))

lib/commerce/price.sx

@@ -0,0 +1,110 @@
+;; lib/commerce/price.sx — deterministic subtotal + jurisdiction-relational tax.
+;;
+;; A pricing context bundles the inputs that make a total reproducible:
+;;   {:catalog CAT :tax-rules RULES :jurisdiction J :customer C}
+;; Same context + same cart => identical total, every run.
+;;
+;; Tax is NOT a hardcoded VAT rate. Rules are facts indexed by
+;;   (jurisdiction, product-class, customer-class) -> rate-bps
+;; where rate-bps is an integer in basis points (2000 = 20%). taxo queries
+;; them multidirectionally. Money stays in integer minor units; rounding is
+;; half-up per line via integer arithmetic only — never floats.
+
+(define
+  make-pricing-context
+  (fn (catalog tax-rules jurisdiction customer) {:customer customer :jurisdiction jurisdiction :catalog catalog :tax-rules tax-rules}))
+
+(define ctx-catalog (fn (ctx) (get ctx :catalog)))
+
+;; --- unit + line pricing ---
+
+;; Variant delta, defaulting to 0 when the (sku,variant) has no variant fact.
+(define
+  variant-delta
+  (fn
+    (cat sku variant)
+    (let
+      ((rs (run 1 d (varianto cat sku variant d))))
+      (if (empty? rs) 0 (first rs)))))
+
+;; Effective unit price = base price + variant delta. nil if sku unknown.
+(define
+  line-unit-price
+  (fn
+    (cat sku variant)
+    (let
+      ((base (catalog-price cat sku)))
+      (if (nil? base) nil (+ base (variant-delta cat sku variant))))))
+
+;; Extended (line) price = unit price * quantity.
+(define
+  line-extended
+  (fn
+    (cat line)
+    (*
+      (line-unit-price cat (line-sku line) (line-variant line))
+      (line-qty line))))
+
+(define
+  cart-subtotal
+  (fn
+    (cat cart)
+    (reduce (fn (acc l) (+ acc (line-extended cat l))) 0 cart)))
+
+;; --- tax (jurisdiction-relational) ---
+
+;; rules: (list (list jurisdiction class customer bps) ...)
+(define
+  taxo
+  (fn
+    (rules juris class cust bps)
+    (membero (list juris class cust bps) rules)))
+
+;; Deterministic rate lookup; 0 when no rule matches.
+(define
+  rate-bps
+  (fn
+    (rules juris class cust)
+    (let
+      ((rs (run 1 b (taxo rules juris class cust b))))
+      (if (empty? rs) 0 (first rs)))))
+
+;; Apply a basis-point rate to an integer amount, rounding half up.
+(define
+  apply-bps
+  (fn (amount bps) (quotient (+ (* amount bps) 5000) 10000)))
+
+(define
+  line-tax
+  (fn
+    (ctx line)
+    (let
+      ((cat (ctx-catalog ctx)))
+      (let
+        ((class (catalog-class cat (line-sku line))))
+        (apply-bps
+          (line-extended cat line)
+          (rate-bps
+            (get ctx :tax-rules)
+            (get ctx :jurisdiction)
+            class
+            (get ctx :customer)))))))
+
+(define
+  cart-tax
+  (fn
+    (ctx cart)
+    (reduce (fn (acc l) (+ acc (line-tax ctx l))) 0 cart)))
+
+;; --- total ---
+
+;; Returns {:subtotal :discounts :tax :total}. discounts is 0 until Phase 2.
+(define
+  cart-total
+  (fn
+    (ctx cart)
+    (let
+      ((cat (ctx-catalog ctx)))
+      (let
+        ((sub (cart-subtotal cat cart)) (tax (cart-tax ctx cart)))
+        {:subtotal sub :discounts 0 :total (+ sub tax) :tax tax}))))

lib/commerce/promo.sx

@@ -0,0 +1,153 @@
+;; lib/commerce/promo.sx — promotions as relations over the cart + catalog.
+;;
+;; A promo is a tagged tuple; the second field is always its code:
+;;   (:percent code class pct-bps)   pct-bps off every line of product-class
+;;   (:fixed   code threshold amount) amount off when subtotal >= threshold
+;;   (:bundle  code sku n)            every nth unit of sku is free
+;;   (:member  code class pct-bps)    like :percent, members only
+;;
+;; A ruleset is a list of promo tuples. The discount a promo yields on a
+;; given cart is a pure integer computation (minor units); the *enumeration*
+;; of which promos apply is relational, so promo-applieso runs forward
+;; ("which codes apply and for how much?") and backward ("which code yields
+;; this discount?"). Stacking precedence is a separate layer (stack.sx).
+
+(define promo-kind (fn (p) (nth p 0)))
+(define promo-code (fn (p) (nth p 1)))
+
+;; Extended price of all lines whose sku is in product-class `class`.
+(define
+  class-extended
+  (fn
+    (ctx cart class)
+    (let
+      ((cat (ctx-catalog ctx)))
+      (reduce
+        (fn
+          (acc l)
+          (if
+            (= (catalog-class cat (line-sku l)) class)
+            (+ acc (line-extended cat l))
+            acc))
+        0
+        cart))))
+
+(define
+  sku-qty
+  (fn
+    (cart sku)
+    (reduce
+      (fn (acc l) (if (= (line-sku l) sku) (+ acc (line-qty l)) acc))
+      0
+      cart)))
+
+;; --- per-type discount amounts (pure, integer minor units) ---
+
+(define
+  percent-amount
+  (fn
+    (ctx cart p)
+    (apply-bps
+      (class-extended ctx cart (nth p 2))
+      (nth p 3))))
+
+(define
+  fixed-amount
+  (fn
+    (ctx cart p)
+    (let
+      ((sub (cart-subtotal (ctx-catalog ctx) cart)))
+      (if
+        (>= sub (nth p 2))
+        (min (nth p 3) sub)
+        0))))
+
+(define
+  bundle-amount
+  (fn
+    (ctx cart p)
+    (let
+      ((sku (nth p 2)) (n (nth p 3)))
+      (let
+        ((free (quotient (sku-qty cart sku) n)))
+        (* free (catalog-price (ctx-catalog ctx) sku))))))
+
+(define
+  member-amount
+  (fn
+    (ctx cart p)
+    (if
+      (= (get ctx :customer) :member)
+      (apply-bps
+        (class-extended ctx cart (nth p 2))
+        (nth p 3))
+      0)))
+
+;; Discount this promo yields on this cart (0 if it does not apply).
+(define
+  promo-amount
+  (fn
+    (ctx cart p)
+    (let
+      ((k (promo-kind p)))
+      (cond
+        ((= k :percent) (percent-amount ctx cart p))
+        ((= k :fixed) (fixed-amount ctx cart p))
+        ((= k :bundle) (bundle-amount ctx cart p))
+        ((= k :member) (member-amount ctx cart p))
+        (:else 0)))))
+
+;; --- relational enumeration ---
+
+;; (code, amount) for every promo in the ruleset (amount may be 0).
+(define
+  promo-discounto
+  (fn
+    (ctx cart ruleset code amount)
+    (fresh
+      (p)
+      (membero p ruleset)
+      (project
+        (p)
+        (== code (promo-code p))
+        (== amount (promo-amount ctx cart p))))))
+
+;; (code, amount) restricted to promos that actually apply (amount > 0).
+(define
+  promo-applieso
+  (fn
+    (ctx cart ruleset code amount)
+    (fresh
+      (p)
+      (membero p ruleset)
+      (project
+        (p)
+        (if
+          (> (promo-amount ctx cart p) 0)
+          (mk-conj
+            (== code (promo-code p))
+            (== amount (promo-amount ctx cart p)))
+          fail)))))
+
+;; --- deterministic helpers ---
+
+;; List of (list code amount) for applicable promos, in ruleset order.
+(define
+  applicable-promos
+  (fn
+    (ctx cart ruleset)
+    (run*
+      pair
+      (fresh
+        (code amount)
+        (promo-applieso ctx cart ruleset code amount)
+        (== pair (list code amount))))))
+
+;; Discount for one code (0 if absent / inapplicable).
+(define
+  promo-amount-for
+  (fn
+    (ctx cart ruleset code)
+    (let
+      ((rs (run 1 a (promo-applieso ctx cart ruleset code a))))
+      (if (empty? rs) 0 (first rs)))))

lib/commerce/quote.sx

@@ -0,0 +1,36 @@
+;; lib/commerce/quote.sx — the final priced quote: price + promo + stacking.
+;;
+;; A quote is the deterministic composition of the pricing pipeline for a
+;; (context, cart, ruleset, exclusions) tuple:
+;;   {:subtotal S :discount D :tax T :total (S - D + T) :codes (...)}
+;;
+;; Tax policy (explicit, for the determinism contract): tax is computed on the
+;; GROSS per-line amounts (pre-discount), via price.sx cart-tax. The best
+;; promo stacking reduces the payable total but not the tax base. Same inputs
+;; always yield the same quote — this is the value the order flow carries.
+
+(define
+  cart-quote
+  (fn
+    (ctx cart ruleset exclusions)
+    (let
+      ((cat (ctx-catalog ctx)))
+      (let
+        ((sub (cart-subtotal cat cart))
+          (disc (best-promo-discount ctx cart ruleset exclusions))
+          (tax (cart-tax ctx cart))
+          (codes (best-promo-codes ctx cart ruleset exclusions)))
+        {:codes codes :subtotal sub :discount disc :total (+ (- sub disc) tax) :tax tax}))))
+
+(define quote-subtotal (fn (q) (get q :subtotal)))
+(define quote-discount (fn (q) (get q :discount)))
+(define quote-tax (fn (q) (get q :tax)))
+(define quote-total (fn (q) (get q :total)))
+(define quote-codes (fn (q) (get q :codes)))
+
+;; Session-level convenience (a session is {:ctx :cart}).
+(define
+  session-quote
+  (fn
+    (sess ruleset exclusions)
+    (cart-quote (get sess :ctx) (get sess :cart) ruleset exclusions)))

lib/commerce/scoreboard.json

@@ -0,0 +1,15 @@
+{
+  "suites": {
+    "catalog": {"pass": 16, "fail": 0},
+    "cart": {"pass": 18, "fail": 0},
+    "price": {"pass": 20, "fail": 0},
+    "api": {"pass": 12, "fail": 0},
+    "promo": {"pass": 17, "fail": 0},
+    "stack": {"pass": 16, "fail": 0},
+    "quote": {"pass": 13, "fail": 0},
+    "ledger": {"pass": 20, "fail": 0}
+  },
+  "total_pass": 132,
+  "total_fail": 0,
+  "total": 132
+}

lib/commerce/scoreboard.md

@@ -0,0 +1,15 @@
+# commerce Conformance Scoreboard
+
+_Generated by `lib/commerce/conformance.sh`_
+
+| Suite | Pass | Fail | Total |
+|-------|-----:|-----:|------:|
+| catalog | 16 | 0 | 16 |
+| cart | 18 | 0 | 18 |
+| price | 20 | 0 | 20 |
+| api | 12 | 0 | 12 |
+| promo | 17 | 0 | 17 |
+| stack | 16 | 0 | 16 |
+| quote | 13 | 0 | 13 |
+| ledger | 20 | 0 | 20 |
+| **Total** | **132** | **0** | **132** |

lib/commerce/stack.sx

@@ -0,0 +1,121 @@
+;; lib/commerce/stack.sx — promotion stacking precedence + best price.
+;;
+;; Per the miniKanren design rule, precedence is NOT encoded inside the promo
+;; rules. promo.sx enumerates which promos apply; this layer enumerates which
+;; *combinations* are legal and selects the best one by an explicit cost
+;; function (max total discount = min price).
+;;
+;; Exclusivity is a list of unordered code pairs that may not both apply:
+;;   exclusions = (list (list code-a code-b) ...)
+;; A stacking is a subset of applicable (code amount) pairs containing no
+;; excluded pair. valid-stackings enumerates them; best-stacking is the
+;; deterministic selection layer; stacking-by-totalo is the backward query
+;; ("which legal stacking yields this total discount?").
+
+(define
+  excluded-pair?
+  (fn
+    (exclusions a b)
+    (some
+      (fn
+        (p)
+        (or
+          (and (= (first p) a) (= (nth p 1) b))
+          (and (= (first p) b) (= (nth p 1) a))))
+      exclusions)))
+
+;; True when no two distinct codes in the list are mutually excluded.
+(define
+  compatible?
+  (fn
+    (exclusions codes)
+    (every?
+      (fn
+        (a)
+        (every?
+          (fn (b) (or (= a b) (not (excluded-pair? exclusions a b))))
+          codes))
+      codes)))
+
+;; All subsets of xs, preserving element order. 2^n entries.
+(define
+  powerset
+  (fn
+    (xs)
+    (if
+      (empty? xs)
+      (list (list))
+      (let
+        ((r (powerset (cdr xs))))
+        (append r (map (fn (s) (cons (first xs) s)) r))))))
+
+(define stacking-codes (fn (st) (map first st)))
+
+(define
+  stacking-total
+  (fn
+    (st)
+    (reduce (fn (acc pair) (+ acc (nth pair 1))) 0 st)))
+
+;; Every legal stacking of the applicable (code amount) pairs.
+(define
+  valid-stackings
+  (fn
+    (exclusions applicable)
+    (filter
+      (fn (st) (compatible? exclusions (stacking-codes st)))
+      (powerset applicable))))
+
+;; Deterministic selection: the legal stacking with the greatest total
+;; discount; ties keep the earlier (stable) candidate, so the result is a
+;; reproducible function of (exclusions, applicable).
+(define
+  best-stacking
+  (fn
+    (exclusions applicable)
+    (reduce
+      (fn
+        (best st)
+        (if (> (stacking-total st) (stacking-total best)) st best))
+      (list)
+      (valid-stackings exclusions applicable))))
+
+(define
+  best-discount
+  (fn
+    (exclusions applicable)
+    (stacking-total (best-stacking exclusions applicable))))
+
+(define
+  best-codes
+  (fn
+    (exclusions applicable)
+    (stacking-codes (best-stacking exclusions applicable))))
+
+;; Backward query: legal stackings (as code lists) whose total discount = D.
+(define
+  stacking-by-totalo
+  (fn
+    (stackings codes total)
+    (fresh
+      (st)
+      (membero st stackings)
+      (project
+        (st)
+        (mk-conj
+          (== codes (stacking-codes st))
+          (== total (stacking-total st)))))))
+
+;; --- top-level entry: best discount for a cart under a ruleset ---
+
+(define
+  best-promo-discount
+  (fn
+    (ctx cart ruleset exclusions)
+    (best-discount exclusions (applicable-promos ctx cart ruleset))))
+
+(define
+  best-promo-codes
+  (fn
+    (ctx cart ruleset exclusions)
+    (best-codes exclusions (applicable-promos ctx cart ruleset))))

lib/commerce/tests/api.sx

@@ -0,0 +1,73 @@
+;; lib/commerce/tests/api.sx — public commerce session surface.
+;; Uses (commerce-test name got expected) provided by conformance.sh.
+
+(define
+  acat
+  (make-catalog
+    (list
+      (list "widget" 1000 :standard)
+      (list "book" 800 :zero-rated))
+    (list (list "widget" :small -200))
+    (list)))
+
+(define
+  arules
+  (list
+    (list :uk :standard :guest 2000)
+    (list :uk :zero-rated :guest 0)))
+
+(define actx (make-pricing-context acat arules :uk :guest))
+(define sess0 (commerce-session actx))
+
+;; --- empty session ---
+
+(commerce-test "new-session-empty" (commerce-cart sess0) empty-cart)
+(commerce-test "new-count" (commerce-count sess0) 0)
+(commerce-test "new-total" (commerce-total sess0) {:subtotal 0 :discounts 0 :total 0 :tax 0})
+
+;; --- add + total ---
+
+(define
+  sess1
+  (commerce-add
+    (commerce-add sess0 "widget" :small 2)
+    "book"
+    :none 1))
+
+(commerce-test "add-count" (commerce-count sess1) 3)
+(commerce-test
+  "add-lines"
+  (commerce-lines sess1)
+  (list (list "widget" :small 2) (list "book" :none 1)))
+(commerce-test "add-total" (commerce-total sess1) {:subtotal 2400 :discounts 0 :total 2720 :tax 320})
+
+;; --- mutate ---
+
+(commerce-test
+  "set-qty"
+  (commerce-lines (commerce-set-qty sess1 "widget" :small 1))
+  (list (list "widget" :small 1) (list "book" :none 1)))
+
+(commerce-test
+  "remove"
+  (commerce-lines (commerce-remove sess1 "book" :none))
+  (list (list "widget" :small 2)))
+
+;; --- validation ---
+
+(commerce-test "can-add-yes" (commerce-can-add? sess0 "widget") true)
+(commerce-test "can-add-no" (commerce-can-add? sess0 "ghost") false)
+
+;; --- audit breakdown ---
+
+(commerce-test
+  "explain"
+  (commerce-explain sess1)
+  (list {:sku "widget" :unit 800 :qty 2 :variant :small :extended 1600 :tax 320} {:sku "book" :unit 800 :qty 1 :variant :none :extended 800 :tax 0}))
+
+;; --- checkout stub ---
+
+(commerce-test
+  "checkout-stub"
+  (get (commerce-checkout sess1) :status)
+  :not-implemented)

lib/commerce/tests/cart.sx

@@ -0,0 +1,103 @@
+;; lib/commerce/tests/cart.sx — cart structure + line operations.
+;; Uses (commerce-test name got expected) provided by conformance.sh.
+
+;; --- add ---
+
+(commerce-test
+  "add-to-empty"
+  (cart-add empty-cart "widget" :small 2)
+  (list (list "widget" :small 2)))
+
+(commerce-test
+  "add-merges-same-line"
+  (cart-add
+    (cart-add empty-cart "widget" :small 2)
+    "widget"
+    :small 3)
+  (list (list "widget" :small 5)))
+
+(commerce-test
+  "add-different-variant-separate"
+  (cart-add
+    (cart-add empty-cart "widget" :small 2)
+    "widget"
+    :large 1)
+  (list (list "widget" :small 2) (list "widget" :large 1)))
+
+(commerce-test
+  "add-different-sku-separate"
+  (cart-add
+    (cart-add empty-cart "widget" :small 2)
+    "gadget"
+    :std 1)
+  (list (list "widget" :small 2) (list "gadget" :std 1)))
+
+(commerce-test
+  "add-preserves-order"
+  (cart-skus
+    (cart-add
+      (cart-add (cart-add empty-cart "a" :v 1) "b" :v 1)
+      "c"
+      :v 1))
+  (list "a" "b" "c"))
+
+;; --- qty queries ---
+
+(define
+  c2
+  (cart-add
+    (cart-add empty-cart "widget" :small 2)
+    "gadget"
+    :std 4))
+
+(commerce-test "cart-qty-found" (cart-qty c2 "widget" :small) 2)
+(commerce-test "cart-qty-missing" (cart-qty c2 "widget" :large) 0)
+(commerce-test "cart-count" (cart-count c2) 6)
+(commerce-test "cart-empty-yes" (cart-empty? empty-cart) true)
+(commerce-test "cart-empty-no" (cart-empty? c2) false)
+
+;; --- set-qty ---
+
+(commerce-test
+  "set-qty-existing"
+  (cart-set-qty c2 "widget" :small 10)
+  (list (list "widget" :small 10) (list "gadget" :std 4)))
+
+(commerce-test
+  "set-qty-new-line"
+  (cart-set-qty empty-cart "book" :std 3)
+  (list (list "book" :std 3)))
+
+(commerce-test
+  "set-qty-zero-removes"
+  (cart-set-qty c2 "widget" :small 0)
+  (list (list "gadget" :std 4)))
+
+;; --- remove ---
+
+(commerce-test
+  "remove-line"
+  (cart-remove c2 "gadget" :std)
+  (list (list "widget" :small 2)))
+
+(commerce-test
+  "remove-missing-noop"
+  (cart-remove c2 "nope" :std)
+  (list (list "widget" :small 2) (list "gadget" :std 4)))
+
+;; --- relational view ---
+
+(commerce-test
+  "cart-lineo-forward"
+  (run* q (cart-lineo c2 "gadget" :std q))
+  (list 4))
+
+(commerce-test
+  "cart-lineo-sku-by-qty-backward"
+  (run* sk (fresh (v) (cart-lineo c2 sk v 4)))
+  (list "gadget"))
+
+(commerce-test
+  "cart-lineo-all-skus"
+  (run* sk (fresh (v q) (cart-lineo c2 sk v q)))
+  (list "widget" "gadget"))

lib/commerce/tests/catalog.sx

@@ -0,0 +1,93 @@
+;; lib/commerce/tests/catalog.sx — catalog facts + relational accessors.
+;; Uses (commerce-test name got expected) provided by conformance.sh.
+;; Query vars avoid the name `s` (the run-n macro binds `s` internally).
+
+(define
+  cat
+  (make-catalog
+    (list
+      (list "widget" 1000 :standard)
+      (list "gadget" 2500 :standard)
+      (list "book" 800 :zero-rated)
+      (list "tea" 1000 :reduced))
+    (list
+      (list "widget" :small -200)
+      (list "widget" :large 500)
+      (list "gadget" :std 0))
+    (list
+      (list "widget" :small 5)
+      (list "widget" :large 0)
+      (list "gadget" :std 12))))
+
+;; --- forward lookups ---
+
+(commerce-test
+  "price-forward"
+  (run* p (priceo cat "widget" p))
+  (list 1000))
+(commerce-test
+  "class-forward"
+  (run* c (classo cat "book" c))
+  (list :zero-rated))
+(commerce-test
+  "product-forward"
+  (run* q (fresh (p c) (producto cat "gadget" p c) (== q (list p c))))
+  (list (list 2500 :standard)))
+
+;; --- backward lookups (the showcase) ---
+
+(commerce-test
+  "sku-by-price-backward"
+  (run* sk (priceo cat sk 1000))
+  (list "widget" "tea"))
+
+(commerce-test
+  "sku-by-class-backward"
+  (run* sk (classo cat sk :standard))
+  (list "widget" "gadget"))
+
+(commerce-test
+  "all-prices"
+  (run* p (fresh (sk) (priceo cat sk p)))
+  (list 1000 2500 800 1000))
+
+;; --- variants + effective unit price ---
+
+(commerce-test
+  "variant-delta-forward"
+  (run* d (varianto cat "widget" :small d))
+  (list -200))
+
+(commerce-test
+  "unit-price-small"
+  (run* p (unit-priceo cat "widget" :small p))
+  (list 800))
+
+(commerce-test
+  "unit-price-large"
+  (run* p (unit-priceo cat "widget" :large p))
+  (list 1500))
+
+(commerce-test
+  "variant-by-delta-backward"
+  (run* v (varianto cat "widget" v -200))
+  (list :small))
+
+;; --- stock ---
+
+(commerce-test
+  "stock-forward"
+  (run* q (stocko cat "widget" :small q))
+  (list 5))
+
+(commerce-test
+  "in-stock-skus-backward"
+  (run* sk (fresh (v q) (stocko cat sk v q) (lto-i 0 q)))
+  (list "widget" "gadget"))
+
+;; --- deterministic helpers ---
+
+(commerce-test "catalog-price-helper" (catalog-price cat "gadget") 2500)
+(commerce-test "catalog-class-helper" (catalog-class cat "tea") :reduced)
+(commerce-test "catalog-has-yes" (catalog-has? cat "book") true)
+(commerce-test "catalog-has-no" (catalog-has? cat "nonesuch") false)

lib/commerce/tests/ledger.sx

@@ -0,0 +1,80 @@
+;; lib/commerce/tests/ledger.sx — order ledger on persist + idempotent recon.
+;; Uses (commerce-test name got expected) provided by conformance.sh.
+
+(define q1 {:codes (list) :subtotal 1000 :discount 0 :total 1200 :tax 200})
+
+;; --- lifecycle status projection ---
+
+(define b1 (persist/mem-backend))
+(define _c1 (order-create b1 "A1" 100 q1))
+(commerce-test "status-pending" (order-status b1 "A1") :pending)
+(define _r1 (order-reserve b1 "A1" 101 {:lines 2}))
+(commerce-test "status-reserved" (order-status b1 "A1") :reserved)
+(define _p1 (order-pay b1 "A1" "ref-1" 102 1200))
+(commerce-test "status-paid" (order-status b1 "A1") :paid)
+(define _f1 (order-fulfil b1 "A1" 103 {:carrier "post"}))
+(commerce-test "status-fulfilled" (order-status b1 "A1") :fulfilled)
+
+(commerce-test "total-projection" (order-total b1 "A1") 1200)
+(commerce-test "paid-projection" (order-paid b1 "A1") 1200)
+(commerce-test "recon-ok" (order-recon b1 "A1") :ok)
+(commerce-test "event-count" (len (order-events b1 "A1")) 4)
+
+;; --- idempotency: replayed webhook does not double-record ---
+
+(define b2 (persist/mem-backend))
+(define _c2 (order-create b2 "B1" 200 q1))
+(define _p2a (order-pay b2 "B1" "sumup-9" 201 1200))
+(define _p2b (order-pay b2 "B1" "sumup-9" 201 1200))
+(define _p2c (order-pay b2 "B1" "sumup-9" 201 1200))
+
+(commerce-test "idem-single-event" (len (order-events b2 "B1")) 2)
+(commerce-test "idem-paid-once" (order-paid b2 "B1") 1200)
+(commerce-test "idem-recon-ok" (order-recon b2 "B1") :ok)
+(commerce-test "idem-same-event" (= _p2a _p2c) true)
+
+;; --- mismatch detection ---
+
+(define bun (persist/mem-backend))
+(define _cu (order-create bun "U1" 300 q1))
+(commerce-test "unpaid-recon" (order-recon bun "U1") :unpaid)
+
+(define bup (persist/mem-backend))
+(define _cp (order-create bup "U2" 300 q1))
+(define _pp1 (order-pay bup "U2" "r-a" 301 1200))
+(define _pp2 (order-pay bup "U2" "r-b" 302 1200))
+(commerce-test "double-charge-overpaid" (order-recon bup "U2") :overpaid)
+(commerce-test "double-charge-amount" (order-paid bup "U2") 2400)
+
+(define bsh (persist/mem-backend))
+(define _cs (order-create bsh "U3" 400 q1))
+(define _ps (order-pay bsh "U3" "r-short" 401 1000))
+(commerce-test "underpaid-recon" (order-recon bsh "U3") :underpaid)
+
+;; --- refund (idempotent) reduces net ---
+
+(define brf (persist/mem-backend))
+(define _crf (order-create brf "R1" 500 q1))
+(define _prf (order-pay brf "R1" "p-1" 501 1200))
+(define _rf1 (order-refund brf "R1" "rf-1" 502 200))
+(define _rf2 (order-refund brf "R1" "rf-1" 502 200))
+(commerce-test "refund-idem-net" (order-recon brf "R1") :underpaid)
+(commerce-test "refund-idem-events" (len (order-events brf "R1")) 3)
+
+;; --- cross-ledger reconciliation ---
+
+(define bL (persist/mem-backend))
+(define _l1 (order-create bL "OK1" 600 q1))
+(define _l1p (order-pay bL "OK1" "ok-ref" 601 1200))
+(define _l2 (order-create bL "OVER1" 600 q1))
+(define _l2a (order-pay bL "OVER1" "o-a" 602 1200))
+(define _l2b (order-pay bL "OVER1" "o-b" 603 1200))
+(define _l3 (order-create bL "UNDER1" 600 q1))
+(define _l3p (order-pay bL "UNDER1" "u-ref" 604 900))
+(define _l4 (order-create bL "PENDING1" 600 q1))
+
+(commerce-test "ledger-order-count" (len (order-ids bL)) 4)
+(commerce-test
+  "ledger-mismatches"
+  (sort (ledger-mismatches bL))
+  (sort (list (order-stream "OVER1") (order-stream "UNDER1"))))

lib/commerce/tests/price.sx

@@ -0,0 +1,100 @@
+;; lib/commerce/tests/price.sx — subtotal + jurisdiction-relational tax.
+;; Uses (commerce-test name got expected) provided by conformance.sh.
+
+(define
+  pcat
+  (make-catalog
+    (list
+      (list "widget" 1000 :standard)
+      (list "book" 800 :zero-rated)
+      (list "tea" 1000 :reduced))
+    (list
+      (list "widget" :small -200)
+      (list "widget" :large 500))
+    (list)))
+
+(define
+  rules
+  (list
+    (list :uk :standard :guest 2000)
+    (list :uk :reduced :guest 500)
+    (list :uk :zero-rated :guest 0)
+    (list :uk :standard :member 1000)
+    (list :ie :standard :guest 2300)))
+
+(define gctx (make-pricing-context pcat rules :uk :guest))
+(define mctx (make-pricing-context pcat rules :uk :member))
+
+;; --- unit + line pricing ---
+
+(commerce-test
+  "unit-price-variant"
+  (line-unit-price pcat "widget" :small)
+  800)
+(commerce-test
+  "unit-price-no-variant"
+  (line-unit-price pcat "widget" :none)
+  1000)
+(commerce-test "unit-price-unknown" (line-unit-price pcat "ghost" :none) nil)
+(commerce-test
+  "line-extended"
+  (line-extended pcat (list "widget" :small 2))
+  1600)
+
+;; --- subtotal ---
+
+(define
+  cart1
+  (list (list "widget" :small 2) (list "book" :none 1)))
+
+(commerce-test "subtotal" (cart-subtotal pcat cart1) 2400)
+(commerce-test "subtotal-empty" (cart-subtotal pcat empty-cart) 0)
+
+;; --- tax rate lookup (relational, both directions) ---
+
+(commerce-test
+  "rate-forward"
+  (rate-bps rules :uk :standard :guest)
+  2000)
+(commerce-test
+  "rate-missing"
+  (rate-bps rules :fr :standard :guest)
+  0)
+(commerce-test
+  "rate-juris-by-bps-backward"
+  (run* j (fresh (cust) (taxo rules j :standard cust 2300)))
+  (list :ie))
+(commerce-test
+  "rate-customer-by-bps-backward"
+  (run* cust (taxo rules :uk :standard cust 1000))
+  (list :member))
+
+;; --- apply-bps rounding (half up, integer only) ---
+
+(commerce-test "bps-exact" (apply-bps 1600 2000) 320)
+(commerce-test "bps-round-up" (apply-bps 799 2000) 160)
+(commerce-test "bps-zero" (apply-bps 800 0) 0)
+
+;; --- line + cart tax ---
+
+(commerce-test
+  "line-tax-standard"
+  (line-tax gctx (list "widget" :small 2))
+  320)
+(commerce-test
+  "line-tax-zero-rated"
+  (line-tax gctx (list "book" :none 1))
+  0)
+(commerce-test
+  "line-tax-member"
+  (line-tax mctx (list "widget" :small 2))
+  160)
+(commerce-test "cart-tax-guest" (cart-tax gctx cart1) 320)
+
+;; --- total dict (deterministic) ---
+
+(commerce-test "total-guest" (cart-total gctx cart1) {:subtotal 2400 :discounts 0 :total 2720 :tax 320})
+
+(commerce-test "total-member" (cart-total mctx cart1) {:subtotal 2400 :discounts 0 :total 2560 :tax 160})
+
+(commerce-test "total-empty" (cart-total gctx empty-cart) {:subtotal 0 :discounts 0 :total 0 :tax 0})

lib/commerce/tests/promo.sx

@@ -0,0 +1,142 @@
+;; lib/commerce/tests/promo.sx — promo rules + relational enumeration.
+;; Uses (commerce-test name got expected) provided by conformance.sh.
+
+(define
+  pcat
+  (make-catalog
+    (list
+      (list "widget" 1000 :standard)
+      (list "book" 800 :zero-rated)
+      (list "tea" 1000 :reduced))
+    (list)
+    (list)))
+
+(define gctx (make-pricing-context pcat (list) :uk :guest))
+(define mctx (make-pricing-context pcat (list) :uk :member))
+
+(define
+  cart
+  (list
+    (list "widget" :none 3)
+    (list "book" :none 1)
+    (list "tea" :none 6)))
+
+(define
+  ruleset
+  (list
+    (list :percent "TEN" :standard 1000)
+    (list :fixed "FIVER" 5000 500)
+    (list :bundle "B3T" "tea" 3)
+    (list :member "MEM" :standard 1500)))
+
+;; --- per-type amounts ---
+
+(commerce-test
+  "percent-amount"
+  (promo-amount gctx cart (list :percent "TEN" :standard 1000))
+  300)
+
+(commerce-test
+  "fixed-amount-met"
+  (promo-amount gctx cart (list :fixed "FIVER" 5000 500))
+  500)
+
+(commerce-test
+  "fixed-amount-not-met"
+  (promo-amount
+    gctx
+    (list (list "widget" :none 1))
+    (list :fixed "FIVER" 5000 500))
+  0)
+
+(commerce-test
+  "fixed-amount-capped"
+  (promo-amount
+    gctx
+    (list (list "book" :none 1))
+    (list :fixed "BIG" 0 9999))
+  800)
+
+(commerce-test
+  "bundle-amount"
+  (promo-amount gctx cart (list :bundle "B3T" "tea" 3))
+  2000)
+
+(commerce-test
+  "member-amount-guest"
+  (promo-amount gctx cart (list :member "MEM" :standard 1500))
+  0)
+
+(commerce-test
+  "member-amount-member"
+  (promo-amount mctx cart (list :member "MEM" :standard 1500))
+  450)
+
+;; --- relational enumeration: forward ---
+
+(commerce-test
+  "discounto-all-guest"
+  (run*
+    pair
+    (fresh
+      (code amount)
+      (promo-discounto gctx cart ruleset code amount)
+      (== pair (list code amount))))
+  (list
+    (list "TEN" 300)
+    (list "FIVER" 500)
+    (list "B3T" 2000)
+    (list "MEM" 0)))
+
+(commerce-test
+  "applicable-guest"
+  (applicable-promos gctx cart ruleset)
+  (list
+    (list "TEN" 300)
+    (list "FIVER" 500)
+    (list "B3T" 2000)))
+
+(commerce-test
+  "applicable-member"
+  (applicable-promos mctx cart ruleset)
+  (list
+    (list "TEN" 300)
+    (list "FIVER" 500)
+    (list "B3T" 2000)
+    (list "MEM" 450)))
+
+;; --- relational enumeration: backward (the showcase) ---
+
+(commerce-test
+  "code-by-discount-2000"
+  (run* code (promo-applieso gctx cart ruleset code 2000))
+  (list "B3T"))
+
+(commerce-test
+  "code-by-discount-500"
+  (run* code (promo-applieso gctx cart ruleset code 500))
+  (list "FIVER"))
+
+(commerce-test
+  "code-by-discount-none"
+  (run* code (promo-applieso gctx cart ruleset code 9999))
+  (list))
+
+;; --- deterministic helpers ---
+
+(commerce-test
+  "amount-for-ten"
+  (promo-amount-for gctx cart ruleset "TEN")
+  300)
+(commerce-test
+  "amount-for-mem-guest"
+  (promo-amount-for gctx cart ruleset "MEM")
+  0)
+(commerce-test
+  "amount-for-mem-member"
+  (promo-amount-for mctx cart ruleset "MEM")
+  450)
+(commerce-test
+  "amount-for-absent"
+  (promo-amount-for gctx cart ruleset "NOPE")
+  0)

lib/commerce/tests/quote.sx

@@ -0,0 +1,108 @@
+;; lib/commerce/tests/quote.sx — composed priced quote (price+promo+stacking).
+;; Uses (commerce-test name got expected) provided by conformance.sh.
+
+(define
+  pcat
+  (make-catalog
+    (list
+      (list "widget" 1000 :standard)
+      (list "book" 800 :zero-rated)
+      (list "tea" 1000 :reduced))
+    (list)
+    (list)))
+
+(define
+  tax-rules
+  (list
+    (list :uk :standard :guest 2000)
+    (list :uk :reduced :guest 500)
+    (list :uk :zero-rated :guest 0)
+    (list :uk :standard :member 2000)
+    (list :uk :reduced :member 500)
+    (list :uk :zero-rated :member 0)))
+
+(define gctx (make-pricing-context pcat tax-rules :uk :guest))
+(define mctx (make-pricing-context pcat tax-rules :uk :member))
+
+(define
+  cart
+  (list
+    (list "widget" :none 3)
+    (list "book" :none 1)
+    (list "tea" :none 6)))
+
+(define
+  ruleset
+  (list
+    (list :percent "TEN" :standard 1000)
+    (list :percent "TWENTY" :standard 2000)
+    (list :fixed "FIVER" 5000 500)
+    (list :bundle "B3T" "tea" 3)
+    (list :member "MEM" :standard 2500)))
+
+(define
+  exclusions
+  (list (list "TEN" "TWENTY") (list "TEN" "MEM") (list "TWENTY" "MEM")))
+
+;; subtotal: 3000 + 800 + 6000 = 9800
+;; tax (gross): widget 600 + tea 300 + book 0 = 900
+;; guest discount: TWENTY 600 + FIVER 500 + B3T 2000 = 3100
+;; guest total: 9800 - 3100 + 900 = 7600
+
+(define gq (cart-quote gctx cart ruleset exclusions))
+
+(commerce-test "quote-subtotal" (quote-subtotal gq) 9800)
+(commerce-test "quote-tax" (quote-tax gq) 900)
+(commerce-test "quote-discount-guest" (quote-discount gq) 3100)
+(commerce-test "quote-total-guest" (quote-total gq) 7600)
+(commerce-test
+  "quote-codes-guest"
+  (quote-codes gq)
+  (list "TWENTY" "FIVER" "B3T"))
+
+(commerce-test "quote-full-guest" gq {:codes (list "TWENTY" "FIVER" "B3T") :subtotal 9800 :discount 3100 :total 7600 :tax 900})
+
+;; member discount: MEM 750 + FIVER 500 + B3T 2000 = 3250
+;; member total: 9800 - 3250 + 900 = 7450
+(define mq (cart-quote mctx cart ruleset exclusions))
+
+(commerce-test "quote-discount-member" (quote-discount mq) 3250)
+(commerce-test "quote-total-member" (quote-total mq) 7450)
+(commerce-test
+  "quote-codes-member"
+  (quote-codes mq)
+  (list "FIVER" "B3T" "MEM"))
+
+;; --- determinism: same inputs, identical quote ---
+
+(commerce-test
+  "quote-deterministic"
+  (=
+    (cart-quote gctx cart ruleset exclusions)
+    (cart-quote gctx cart ruleset exclusions))
+  true)
+
+;; --- no promos: discount 0, total = subtotal + tax ---
+
+(commerce-test
+  "quote-no-promos"
+  (cart-quote gctx cart (list) (list))
+  {:codes (list) :subtotal 9800 :discount 0 :total 10700 :tax 900})
+
+;; --- empty cart ---
+
+(commerce-test
+  "quote-empty"
+  (cart-quote gctx empty-cart ruleset exclusions)
+  {:codes (list) :subtotal 0 :discount 0 :total 0 :tax 0})
+
+;; --- session convenience ---
+
+(define
+  sess
+  (commerce-add (commerce-session gctx) "widget" :none 3))
+
+(commerce-test
+  "session-quote"
+  (quote-total (session-quote sess ruleset exclusions))
+  3000)

lib/commerce/tests/stack.sx

@@ -0,0 +1,127 @@
+;; lib/commerce/tests/stack.sx — stacking precedence, exclusivity, best price.
+;; Uses (commerce-test name got expected) provided by conformance.sh.
+
+(define
+  pcat
+  (make-catalog
+    (list
+      (list "widget" 1000 :standard)
+      (list "book" 800 :zero-rated)
+      (list "tea" 1000 :reduced))
+    (list)
+    (list)))
+
+(define gctx (make-pricing-context pcat (list) :uk :guest))
+(define mctx (make-pricing-context pcat (list) :uk :member))
+
+(define
+  cart
+  (list
+    (list "widget" :none 3)
+    (list "book" :none 1)
+    (list "tea" :none 6)))
+
+(define
+  ruleset
+  (list
+    (list :percent "TEN" :standard 1000)
+    (list :percent "TWENTY" :standard 2000)
+    (list :fixed "FIVER" 5000 500)
+    (list :bundle "B3T" "tea" 3)
+    (list :member "MEM" :standard 2500)))
+
+;; The three standard-class discounts are mutually exclusive.
+(define
+  exclusions
+  (list (list "TEN" "TWENTY") (list "TEN" "MEM") (list "TWENTY" "MEM")))
+
+;; --- exclusivity predicates ---
+
+(commerce-test
+  "excluded-pair-direct"
+  (excluded-pair? exclusions "TEN" "TWENTY")
+  true)
+(commerce-test
+  "excluded-pair-symmetric"
+  (excluded-pair? exclusions "TWENTY" "TEN")
+  true)
+(commerce-test
+  "excluded-pair-none"
+  (excluded-pair? exclusions "TEN" "FIVER")
+  false)
+(commerce-test
+  "compatible-yes"
+  (compatible? exclusions (list "FIVER" "B3T" "TWENTY"))
+  true)
+(commerce-test
+  "compatible-no"
+  (compatible? exclusions (list "TEN" "TWENTY" "B3T"))
+  false)
+
+;; --- powerset + valid stackings ---
+
+(commerce-test
+  "powerset-size"
+  (len (powerset (list 1 2 3 4)))
+  16)
+
+(define gappl (applicable-promos gctx cart ruleset))
+
+(commerce-test "applicable-guest-count" (len gappl) 4)
+
+;; 16 subsets minus the 4 containing both TEN and TWENTY = 12 legal.
+(commerce-test
+  "valid-stackings-count"
+  (len (valid-stackings exclusions gappl))
+  12)
+
+(commerce-test
+  "stacking-total"
+  (stacking-total (list (list "TWENTY" 600) (list "B3T" 2000)))
+  2600)
+
+;; --- best price (deterministic selection) ---
+
+(commerce-test
+  "best-discount-guest"
+  (best-promo-discount gctx cart ruleset exclusions)
+  3100)
+(commerce-test
+  "best-codes-guest"
+  (best-promo-codes gctx cart ruleset exclusions)
+  (list "TWENTY" "FIVER" "B3T"))
+
+;; exclusivity holds: the cheaper conflicting code is dropped.
+(commerce-test
+  "best-excludes-ten"
+  (some
+    (fn (c) (= c "TEN"))
+    (best-promo-codes gctx cart ruleset exclusions))
+  false)
+
+;; --- member vs guest ---
+
+(commerce-test
+  "best-discount-member"
+  (best-promo-discount mctx cart ruleset exclusions)
+  3250)
+(commerce-test
+  "best-codes-member"
+  (best-promo-codes mctx cart ruleset exclusions)
+  (list "FIVER" "B3T" "MEM"))
+
+;; --- best price backward query (the showcase) ---
+
+(commerce-test
+  "stacking-by-total-backward"
+  (run*
+    codes
+    (stacking-by-totalo (valid-stackings exclusions gappl) codes 3100))
+  (list (list "TWENTY" "FIVER" "B3T")))
+
+;; --- edge: no applicable promos ---
+
+(commerce-test
+  "best-empty"
+  (best-promo-discount gctx empty-cart ruleset exclusions)
+  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

@@ -0,0 +1,141 @@
+# 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

@@ -0,0 +1,65 @@
+;; 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

@@ -0,0 +1,103 @@
+#!/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

@@ -0,0 +1,42 @@
+;; 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

@@ -0,0 +1,34 @@
+;; 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

@@ -0,0 +1,19 @@
+{
+  "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

@@ -0,0 +1,53 @@
+# 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

@@ -0,0 +1,61 @@
+;; 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

@@ -0,0 +1,79 @@
+;; 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

@@ -0,0 +1,121 @@
+;; 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

@@ -0,0 +1,108 @@
+;; 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

@@ -0,0 +1,179 @@
+;; 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

@@ -0,0 +1,120 @@
+;; 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

@@ -0,0 +1,106 @@
+;; 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

@@ -0,0 +1,67 @@
+;; 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

@@ -0,0 +1,115 @@
+;; 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

@@ -0,0 +1,73 @@
+;; 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

@@ -0,0 +1,71 @@
+;; 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

@@ -0,0 +1,114 @@
+;; 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/mod/activity.sx

@@ -0,0 +1,40 @@
+;; lib/mod/activity.sx — export decisions as ActivityPub-shaped events.
+;;
+;; The rose-ash platform propagates cross-domain effects as ActivityPub-shaped
+;; activities. A moderation decision maps to a moderation verb so the rest of the
+;; platform (and federated peers) can act on it: remove→Delete, ban→Block,
+;; hide/escalate→Flag, keep→no activity. The precise mod action is preserved in
+;; :action so a consumer can disambiguate (e.g. hide vs escalate, both Flag).
+
+(define
+  mod/action->verb
+  (fn
+    (action)
+    (cond
+      ((= action "remove") "Delete")
+      ((= action "ban") "Block")
+      ((= action "hide") "Flag")
+      ((= action "escalate") "Flag")
+      (true nil))))
+
+(define
+  mod/decision->activity
+  (fn
+    (d actor)
+    (let
+      ((verb (mod/action->verb (get d :action))))
+      (if (nil? verb) nil {:type verb :action (get d :action) :actor actor :summary (str "moderation/" (get d :action) " via " (get d :rule)) :object (get d :report-id) :rule (get d :rule)}))))
+
+;; map a batch of decisions to activities, dropping the no-op keeps
+(define
+  mod/decisions->activities
+  (fn
+    (decisions actor)
+    (reduce
+      (fn
+        (acc d)
+        (let
+          ((a (mod/decision->activity d actor)))
+          (if (nil? a) acc (append acc (list a)))))
+      (list)
+      decisions)))

lib/mod/api.sx

@@ -0,0 +1,163 @@
+;; lib/mod/api.sx — report registry + lifecycle façade + public entry points.
+;;
+;; mod/report files a report (assigning a sequential id) and opens a lifecycle
+;; case for it; mod/add-evidence accumulates evidence; mod/decide runs the engine
+;; and commits to the audit log. The lifecycle façade (mod/triage, mod/resolve,
+;; mod/review, mod/appeal, mod/finalize) drives the per-report case through its
+;; states, logging each committed decision to the audit trail.
+
+(define mod/*reports* (list))
+(define mod/*cases* (list))
+(define mod/*counter* 0)
+(define mod/*rules* mod/default-rules)
+
+(define
+  mod/reset!
+  (fn
+    ()
+    (begin
+      (set! mod/*reports* (list))
+      (set! mod/*cases* (list))
+      (set! mod/*counter* 0)
+      (mod/audit-reset!))))
+
+(define
+  mod/report
+  (fn
+    (by about reason)
+    (begin
+      (set! mod/*counter* (+ mod/*counter* 1))
+      (let
+        ((id (str "r" mod/*counter*)))
+        (let
+          ((r (mod/mk-report id by about reason)))
+          (begin
+            (append! mod/*reports* r)
+            (append! mod/*cases* {:id id :case (mod/mk-case r)})
+            r))))))
+
+(define
+  mod/get-report
+  (fn
+    (id)
+    (reduce
+      (fn (acc r) (if (= (mod/report-id r) id) r acc))
+      nil
+      mod/*reports*)))
+
+(define
+  mod/add-evidence
+  (fn
+    (id kind val)
+    (let
+      ((r (mod/get-report id)))
+      (if
+        (nil? r)
+        nil
+        (let
+          ((updated (mod/attach-evidence r (mod/mk-evidence kind val))))
+          (begin
+            (set!
+              mod/*reports*
+              (map
+                (fn (x) (if (= (mod/report-id x) id) updated x))
+                mod/*reports*))
+            updated))))))
+
+(define
+  mod/decide
+  (fn
+    (id)
+    (let
+      ((r (mod/get-report id)))
+      (if
+        (nil? r)
+        nil
+        (let
+          ((d (mod/decide-report r mod/*reports* mod/*rules*)))
+          (begin (mod/log-decision! d (mod/report-evidence r)) d))))))
+
+;; ── lifecycle façade over the case registry ──
+
+(define
+  mod/case-of
+  (fn
+    (id)
+    (reduce
+      (fn (acc rec) (if (= (get rec :id) id) (get rec :case) acc))
+      nil
+      mod/*cases*)))
+
+(define
+  mod/case-store!
+  (fn
+    (id c)
+    (set!
+      mod/*cases*
+      (map
+        (fn (rec) (if (= (get rec :id) id) {:id id :case c} rec))
+        mod/*cases*))))
+
+;; apply a lifecycle op to the stored case, persist it, and (when a decision was
+;; committed cleanly) append it to the audit log; returns the updated case
+(define
+  mod/case-apply!
+  (fn
+    (id op log?)
+    (let
+      ((c (mod/case-of id)))
+      (if
+        (nil? c)
+        nil
+        (let
+          ((c2 (op c)))
+          (begin
+            (mod/case-store! id c2)
+            (when
+              log?
+              (when
+                (nil? (mod/case-error c2))
+                (let
+                  ((d (mod/case-decision c2)))
+                  (if
+                    (nil? d)
+                    nil
+                    (mod/log-decision!
+                      d
+                      (mod/report-evidence (mod/case-report c2)))))))
+            c2))))))
+
+(define
+  mod/triage
+  (fn
+    (id)
+    (mod/case-apply!
+      id
+      (fn (c) (mod/case-triage c mod/*reports* mod/*rules*))
+      false)))
+
+(define
+  mod/resolve
+  (fn (id) (mod/case-apply! id (fn (c) (mod/case-resolve c)) true)))
+
+(define
+  mod/review
+  (fn
+    (id kind val)
+    (mod/case-apply!
+      id
+      (fn (c) (mod/case-review c kind val mod/*reports* mod/*rules*))
+      true)))
+
+(define
+  mod/appeal
+  (fn
+    (id kind val)
+    (mod/case-apply!
+      id
+      (fn (c) (mod/case-appeal c kind val mod/*reports* mod/*rules*))
+      true)))
+
+(define
+  mod/finalize
+  (fn (id) (mod/case-apply! id (fn (c) (mod/case-finalize c)) false)))

lib/mod/audit.sx

@@ -0,0 +1,54 @@
+;; lib/mod/audit.sx — append-only decision log.
+;;
+;; Every decision the api commits is recorded as an immutable audit entry holding
+;; the decision (action + matching rule), the proof tree (the derivation that
+;; justified it), and a snapshot of the evidence in force at decision time. The
+;; log is append-only: entries are never mutated or removed, only appended, each
+;; with a monotonic sequence number. Retrieval is by report id (full history) or
+;; by sequence.
+
+(define mod/*audit-log* (list))
+(define mod/*audit-seq* 0)
+
+(define
+  mod/audit-reset!
+  (fn
+    ()
+    (begin (set! mod/*audit-log* (list)) (set! mod/*audit-seq* 0))))
+
+(define mod/mk-audit-entry (fn (seq decision evidence-snapshot) {:action (get decision :action) :evidence evidence-snapshot :proof (get decision :proof) :rule (get decision :rule) :report-id (get decision :report-id) :seq seq}))
+
+(define
+  mod/log-decision!
+  (fn
+    (decision evidence-snapshot)
+    (begin
+      (set! mod/*audit-seq* (+ mod/*audit-seq* 1))
+      (let
+        ((entry (mod/mk-audit-entry mod/*audit-seq* decision evidence-snapshot)))
+        (begin (append! mod/*audit-log* entry) entry)))))
+
+;; entries for one report, in chronological (sequence) order
+(define
+  mod/audit
+  (fn
+    (id)
+    (reduce
+      (fn
+        (acc e)
+        (if (= (get e :report-id) id) (append acc (list e)) acc))
+      (list)
+      mod/*audit-log*)))
+
+(define mod/audit-all (fn () mod/*audit-log*))
+(define mod/audit-count (fn () (len mod/*audit-log*)))
+
+;; most recent decision logged for a report (nil if none)
+(define
+  mod/audit-latest
+  (fn
+    (id)
+    (reduce
+      (fn (acc e) (if (= (get e :report-id) id) e acc))
+      nil
+      mod/*audit-log*)))

lib/mod/batch.sx

@@ -0,0 +1,55 @@
+;; lib/mod/batch.sx — batch triage + corpus analytics.
+;;
+;; Operational layer: decide a whole queue of reports at once, summarize the
+;; outcomes by action, and measure which rules actually fire across a corpus.
+;; mod/never-fired is the empirical complement to lint's static unreachable check
+;; (Ext 5): lint finds rules that CAN'T fire by structure; never-fired finds rules
+;; that DIDN'T fire on real data.
+
+(define
+  mod/decide-batch
+  (fn
+    (reports rules)
+    (map (fn (r) (mod/decide-report r reports rules)) reports)))
+
+(define
+  mod/count-action
+  (fn
+    (decisions action)
+    (reduce
+      (fn (acc d) (if (= (get d :action) action) (+ acc 1) acc))
+      0
+      decisions)))
+
+(define mod/action-histogram (fn (decisions) {:keep (mod/count-action decisions "keep") :remove (mod/count-action decisions "remove") :escalate (mod/count-action decisions "escalate") :hide (mod/count-action decisions "hide") :ban (mod/count-action decisions "ban")}))
+
+(define
+  mod/rule-fire-count
+  (fn
+    (decisions rule-name)
+    (reduce
+      (fn (acc d) (if (= (get d :rule) rule-name) (+ acc 1) acc))
+      0
+      decisions)))
+
+(define
+  mod/rule-coverage
+  (fn
+    (reports rules)
+    (let
+      ((decisions (mod/decide-batch reports rules)))
+      (map (fn (rule) {:rule (mod/rule-name rule) :fired (mod/rule-fire-count decisions (mod/rule-name rule))}) rules))))
+
+(define
+  mod/never-fired
+  (fn
+    (reports rules)
+    (reduce
+      (fn
+        (acc c)
+        (if
+          (= (get c :fired) 0)
+          (append acc (list (get c :rule)))
+          acc))
+      (list)
+      (mod/rule-coverage reports rules))))

lib/mod/conformance.conf

@@ -0,0 +1,60 @@
+# Mod conformance config — sourced by lib/guest/conformance.sh.
+
+LANG_NAME=mod
+MODE=dict
+
+PRELOADS=(
+  lib/guest/pratt.sx
+  lib/prolog/tokenizer.sx
+  lib/prolog/parser.sx
+  lib/prolog/runtime.sx
+  lib/prolog/query.sx
+  lib/prolog/compiler.sx
+  lib/mod/schema.sx
+  lib/mod/policy.sx
+  lib/mod/defrule.sx
+  lib/mod/engine.sx
+  lib/mod/explain.sx
+  lib/mod/severity.sx
+  lib/mod/offenders.sx
+  lib/mod/quorum.sx
+  lib/mod/trace.sx
+  lib/mod/whatif.sx
+  lib/mod/batch.sx
+  lib/mod/temporal.sx
+  lib/mod/sla.sx
+  lib/mod/wire.sx
+  lib/mod/activity.sx
+  lib/mod/policies.sx
+  lib/mod/pipeline.sx
+  lib/mod/lifecycle.sx
+  lib/mod/audit.sx
+  lib/mod/api.sx
+  lib/mod/fed.sx
+  lib/mod/link.sx
+  lib/mod/lint.sx
+)
+
+SUITES=(
+  "decide:lib/mod/tests/decide.sx:(mod-decide-tests-run!)"
+  "audit:lib/mod/tests/audit.sx:(mod-audit-tests-run!)"
+  "escalation:lib/mod/tests/escalation.sx:(mod-escalation-tests-run!)"
+  "fed:lib/mod/tests/fed.sx:(mod-fed-tests-run!)"
+  "extensions:lib/mod/tests/extensions.sx:(mod-extensions-tests-run!)"
+  "link:lib/mod/tests/link.sx:(mod-link-tests-run!)"
+  "lint:lib/mod/tests/lint.sx:(mod-lint-tests-run!)"
+  "severity:lib/mod/tests/severity.sx:(mod-severity-tests-run!)"
+  "offenders:lib/mod/tests/offenders.sx:(mod-offenders-tests-run!)"
+  "quorum:lib/mod/tests/quorum.sx:(mod-quorum-tests-run!)"
+  "trace:lib/mod/tests/trace.sx:(mod-trace-tests-run!)"
+  "whatif:lib/mod/tests/whatif.sx:(mod-whatif-tests-run!)"
+  "batch:lib/mod/tests/batch.sx:(mod-batch-tests-run!)"
+  "temporal:lib/mod/tests/temporal.sx:(mod-temporal-tests-run!)"
+  "sla:lib/mod/tests/sla.sx:(mod-sla-tests-run!)"
+  "wire:lib/mod/tests/wire.sx:(mod-wire-tests-run!)"
+  "disjunction:lib/mod/tests/disjunction.sx:(mod-disjunction-tests-run!)"
+  "activity:lib/mod/tests/activity.sx:(mod-activity-tests-run!)"
+  "policies:lib/mod/tests/policies.sx:(mod-policies-tests-run!)"
+  "defrule:lib/mod/tests/defrule.sx:(mod-defrule-tests-run!)"
+  "pipeline:lib/mod/tests/pipeline.sx:(mod-pipeline-tests-run!)"
+)

lib/mod/conformance.sh

@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+# Thin wrapper — see lib/guest/conformance.sh and lib/mod/conformance.conf.
+exec bash "$(dirname "$0")/../guest/conformance.sh" "$(dirname "$0")/conformance.conf" "$@"

lib/mod/defrule.sx

@@ -0,0 +1,16 @@
+;; lib/mod/defrule.sx — ergonomic rule / ruleset construction.
+;;
+;; The roadmap sketched a (defrule action :when conditions) surface. Conditions
+;; already evaluate to plain data, so this needs no macro — variadic functions
+;; suffice: mod/defrule collects its trailing condition forms via &rest (dropping
+;; the explicit outer (list ...)), and mod/ruleset assembles rules the same way.
+;;
+;;   (mod/ruleset
+;;     (mod/defrule "spam-hide" :hide (list :classification "spam"))
+;;     (mod/defrule "default-keep" :keep))
+
+(define
+  mod/defrule
+  (fn (name action &rest conds) (mod/mk-rule name action conds)))
+
+(define mod/ruleset (fn (&rest rules) rules))

lib/mod/engine.sx

@@ -0,0 +1,64 @@
+;; lib/mod/engine.sx — decide a report by querying the policy program.
+;;
+;; build-program assembles the report's facts plus the compiled policy clauses;
+;; decide-report runs the Prolog query and returns a decision. A decision is a
+;; proof, not a bare keyword: it carries the matching rule, the conditions it
+;; required, the evidence that satisfied them, and a derivation — the proof tree.
+;;
+;; The proof tree is built constructively: for the matching rule, each body goal
+;; is re-queried against the same DB with the report id bound, recording the goal
+;; text, whether it was solved, and the bindings that satisfied it. That is a
+;; genuine derivation drawn from the Prolog database, ready for the audit trail.
+
+(define
+  mod/find-rule
+  (fn
+    (rules name)
+    (reduce
+      (fn
+        (acc r)
+        (if (nil? acc) (if (= (mod/rule-name r) name) r acc) acc))
+      nil
+      rules)))
+
+(define
+  mod/build-program
+  (fn
+    (r count rules)
+    (str (mod/report-facts r count) "\n" (mod/rules->program rules))))
+
+(define
+  mod/proof-goals
+  (fn
+    (db id conds)
+    (if
+      (empty? conds)
+      (list {:solved true :goal "true" :bindings {}})
+      (map
+        (fn
+          (c)
+          (let
+            ((g (mod/cond->goal c id)))
+            (let ((sols (pl-query-all db g))) {:solved (if (empty? sols) false true) :goal g :bindings (if (empty? sols) {} (first sols))})))
+        conds))))
+
+(define
+  mod/decide-report
+  (fn
+    (r reports rules)
+    (let
+      ((count (mod/report-count (mod/report-about r) reports))
+        (kinds (mod/classify-keywords r))
+        (id (mod/report-id r)))
+      (let
+        ((program (mod/build-program r count rules)))
+        (let
+          ((db (pl-load program)))
+          (let
+            ((sol (pl-query-one db (str "policy_action(" id ", Action, Rule)"))))
+            (if
+              (nil? sol)
+              {:action "keep" :proof {:goals (list) :evidence kinds :conditions (list) :rule "none" :count count} :report-id id :rule "none"}
+              (let
+                ((rname (dict-get sol "Rule")))
+                (let ((rule (mod/find-rule rules rname))) {:action (mod/rule-action rule) :proof {:goals (mod/proof-goals db id (mod/rule-when rule)) :evidence kinds :conditions (mod/rule-when rule) :rule rname :count count} :report-id id :rule rname})))))))))

lib/mod/explain.sx

@@ -0,0 +1,55 @@
+;; lib/mod/explain.sx — human-readable proof explanation.
+;;
+;; Turns a decision (from mod/decide-report, or any audit entry) into a readable
+;; multi-line "why": the action, the rule that fired, the evidence in play, and
+;; the derivation goal-by-goal with [proved]/[unproved] marks and the unification
+;; bindings that satisfied each goal. Pure SX over the Phase-2 proof tree.
+
+(define
+  mod/explain-binds
+  (fn
+    (binds)
+    (mod/join-with
+      ", "
+      (map (fn (k) (str k "=" (dict-get binds k))) (keys binds)))))
+
+(define
+  mod/explain-goal
+  (fn
+    (g)
+    (let
+      ((mark (if (get g :solved) "  [proved] " "  [unproved] "))
+        (binds (get g :bindings)))
+      (if
+        (empty? (keys binds))
+        (str mark (get g :goal))
+        (str mark (get g :goal) "  {" (mod/explain-binds binds) "}")))))
+
+(define
+  mod/explain-evidence
+  (fn
+    (evidence)
+    (if
+      (empty? evidence)
+      "Evidence: (none)"
+      (str "Evidence: " (mod/join-with ", " evidence)))))
+
+(define
+  mod/explain
+  (fn
+    (decision)
+    (let
+      ((id (get decision :report-id))
+        (action (get decision :action))
+        (rule (get decision :rule))
+        (proof (get decision :proof)))
+      (let
+        ((goals (get proof :goals)) (evidence (get proof :evidence)))
+        (mod/join-with
+          "\n"
+          (append
+            (list
+              (str "Report " id ": " action " (rule: " rule ")")
+              (mod/explain-evidence evidence)
+              "Because:")
+            (map mod/explain-goal goals)))))))

lib/mod/fed.sx

@@ -0,0 +1,145 @@
+;; lib/mod/fed.sx — federation: cross-instance reports, decision sharing, trust,
+;; revocation. fed-sx itself is mocked here (an in-memory outbox); the real wire
+;; transport would replace mod/fed-send!.
+;;
+;; Trust is advisory by default (the hard rule): a peer's decision only binds
+;; locally when (mod/trusted? peer :mod) holds. An untrusted peer's decision is
+;; recorded as a suggestion in the advisory log and is NOT applied. Local
+;; decisions propagate outward via the outbox. Revocation undoes a locally
+;; applied action when its proof is invalidated, notifying the origin peer.
+
+(define mod/*fed-trust* (list))     ;; {:peer :scope}
+(define mod/*fed-outbox* (list))    ;; {:to :type :payload}
+(define mod/*fed-advisory* (list))  ;; {:peer :decision} — received, not applied
+(define mod/*fed-applied* (list))   ;; {:report-id :action :origin :revoked}
+(define mod/*fed-origins* (list))   ;; {:id :origin}
+
+(define
+  mod/fed-reset!
+  (fn
+    ()
+    (begin
+      (set! mod/*fed-trust* (list))
+      (set! mod/*fed-outbox* (list))
+      (set! mod/*fed-advisory* (list))
+      (set! mod/*fed-applied* (list))
+      (set! mod/*fed-origins* (list)))))
+
+;; ── trust model ──
+
+(define
+  mod/trust-match?
+  (fn
+    (t peer scope)
+    (if (= (get t :peer) peer) (= (get t :scope) scope) false)))
+
+(define
+  mod/grant-trust
+  (fn (peer scope) (begin (append! mod/*fed-trust* {:scope scope :peer peer}) true)))
+
+(define
+  mod/revoke-trust
+  (fn
+    (peer scope)
+    (set!
+      mod/*fed-trust*
+      (reduce
+        (fn
+          (acc t)
+          (if (mod/trust-match? t peer scope) acc (append acc (list t))))
+        (list)
+        mod/*fed-trust*))))
+
+(define
+  mod/trusted?
+  (fn
+    (peer scope)
+    (mod/any? (fn (t) (mod/trust-match? t peer scope)) mod/*fed-trust*)))
+
+;; ── cross-instance reports ──
+
+(define
+  mod/fed-receive-report
+  (fn
+    (peer by about reason)
+    (let
+      ((r (mod/report by about reason)))
+      (begin (append! mod/*fed-origins* {:id (mod/report-id r) :origin peer}) r))))
+
+(define
+  mod/report-origin
+  (fn
+    (id)
+    (reduce
+      (fn (acc o) (if (= (get o :id) id) (get o :origin) acc))
+      "local"
+      mod/*fed-origins*)))
+
+;; ── decision sharing (mock fed-sx send) ──
+
+(define
+  mod/fed-send!
+  (fn (to type payload) (begin (append! mod/*fed-outbox* {:type type :to to :payload payload}) true)))
+
+(define mod/fed-outbox (fn () mod/*fed-outbox*))
+
+(define
+  mod/fed-share-decision
+  (fn
+    (decision peers)
+    (reduce
+      (fn
+        (acc p)
+        (begin (mod/fed-send! p "decision" decision) (append acc (list p))))
+      (list)
+      peers)))
+
+;; ── receiving a peer's decision (advisory unless trusted) ──
+
+(define
+  mod/fed-applied-action
+  (fn
+    (report-id)
+    (reduce
+      (fn (acc a) (if (= (get a :report-id) report-id) a acc))
+      nil
+      mod/*fed-applied*)))
+
+(define
+  mod/fed-receive-decision
+  (fn
+    (peer decision)
+    (if
+      (mod/trusted? peer :mod)
+      (begin (append! mod/*fed-applied* {:revoked false :action (get decision :action) :report-id (get decision :report-id) :origin peer}) {:advisory false :peer peer :applied true :decision decision})
+      (begin (append! mod/*fed-advisory* {:peer peer :decision decision}) {:advisory true :peer peer :applied false :decision decision}))))
+
+;; ── revocation ──
+
+(define
+  mod/fed-revoke!
+  (fn
+    (report-id reason)
+    (begin
+      (set!
+        mod/*fed-applied*
+        (map
+          (fn (a) (if (= (get a :report-id) report-id) {:revoked true :action (get a :action) :report-id (get a :report-id) :origin (get a :origin)} a))
+          mod/*fed-applied*))
+      (mod/fed-send! (mod/report-origin report-id) "revocation" {:report-id report-id :reason reason})
+      report-id)))
+
+;; re-run the engine; if the action no longer holds, the prior decision's proof
+;; is invalidated — revoke the applied moderation.
+(define
+  mod/fed-revoke-if-invalidated
+  (fn
+    (report decision reports rules)
+    (let
+      ((d2 (mod/decide-report report reports rules)))
+      (if
+        (= (get d2 :action) (get decision :action))
+        {:revoked false :decision d2}
+        (begin
+          (mod/fed-revoke! (get decision :report-id) "proof invalidated")
+          {:revoked true :decision d2})))))

lib/mod/lifecycle.sx

@@ -0,0 +1,160 @@
+;; lib/mod/lifecycle.sx — report lifecycle state machine (pure SX over the engine).
+;;
+;; Lifecycle state is deliberately separate from policy: the Prolog rules answer
+;; "what action?", this module answers "where in the process is this report?".
+;;
+;;   :open ──triage──▶ :triaged ──resolve/review──▶ :decided ──appeal──▶ :appealed
+;;                                                      │                    │
+;;                                                      └────finalize───▶ :final ◀┘
+;;
+;; A case is an immutable value {:report :state :decision :tier :error :history}.
+;; Every transition returns a NEW case; illegal transitions return the case
+;; unchanged with :error set. Tiers: triage runs the engine (auto-tier); a
+;; terminal action (hide/remove/keep) resolves immediately, an :escalate action
+;; flags the case for human review (human-tier) before it can be resolved.
+
+(define mod/case* (fn (report state decision tier err history) {:history history :state state :report report :error err :tier tier :decision decision}))
+
+(define
+  mod/mk-case
+  (fn (report) (mod/case* report "open" nil nil nil (list))))
+
+(define mod/case-report (fn (c) (get c :report)))
+(define mod/case-state (fn (c) (get c :state)))
+(define mod/case-decision (fn (c) (get c :decision)))
+(define mod/case-tier (fn (c) (get c :tier)))
+(define mod/case-error (fn (c) (get c :error)))
+(define mod/case-history (fn (c) (get c :history)))
+
+;; ── transition table ──
+
+(define mod/lc-transitions {:final (list) :appealed (list "final") :decided (list "appealed" "final") :open (list "triaged") :triaged (list "decided")})
+
+(define mod/member? (fn (x lst) (mod/any? (fn (y) (= y x)) lst)))
+
+(define
+  mod/lc-can-transition?
+  (fn
+    (from to)
+    (let
+      ((outs (get mod/lc-transitions from)))
+      (if (nil? outs) false (mod/member? to outs)))))
+
+;; ── core transition: validate, record history, or flag :error ──
+
+(define
+  mod/case-goto
+  (fn
+    (c to note report decision tier)
+    (let
+      ((from (mod/case-state c)))
+      (if
+        (mod/lc-can-transition? from to)
+        (mod/case*
+          report
+          to
+          decision
+          tier
+          nil
+          (append (mod/case-history c) (list {:note note :to to :from from})))
+        (mod/case*
+          (mod/case-report c)
+          from
+          (mod/case-decision c)
+          (mod/case-tier c)
+          (str "illegal transition: " from " -> " to)
+          (mod/case-history c))))))
+
+(define
+  mod/case-error-set
+  (fn
+    (c msg)
+    (mod/case*
+      (mod/case-report c)
+      (mod/case-state c)
+      (mod/case-decision c)
+      (mod/case-tier c)
+      msg
+      (mod/case-history c))))
+
+;; ── lifecycle operations ──
+
+;; :open → :triaged — run the auto-tier first pass.
+(define
+  mod/case-triage
+  (fn
+    (c reports rules)
+    (let
+      ((d (mod/decide-report (mod/case-report c) reports rules)))
+      (let
+        ((tier (if (= (get d :action) "escalate") "human" "auto")))
+        (mod/case-goto
+          c
+          "triaged"
+          "auto-tier first pass"
+          (mod/case-report c)
+          d
+          tier)))))
+
+;; :triaged → :decided — auto-tier resolves; human-tier is blocked until review.
+(define
+  mod/case-resolve
+  (fn
+    (c)
+    (if
+      (= (mod/case-tier c) "human")
+      (mod/case-error-set c "awaiting human review (escalated)")
+      (mod/case-goto
+        c
+        "decided"
+        "auto-tier resolved"
+        (mod/case-report c)
+        (mod/case-decision c)
+        (mod/case-tier c)))))
+
+;; :triaged → :decided — human review: attach evidence, re-decide, resolve.
+(define
+  mod/case-review
+  (fn
+    (c kind val reports rules)
+    (let
+      ((nr (mod/attach-evidence (mod/case-report c) (mod/mk-evidence kind val))))
+      (let
+        ((d (mod/decide-report nr reports rules)))
+        (mod/case-goto c "decided" (str "human review: " kind) nr d "human")))))
+
+;; :decided → :appealed — appeal: attach evidence, re-decide (may override).
+(define
+  mod/case-appeal
+  (fn
+    (c kind val reports rules)
+    (let
+      ((nr (mod/attach-evidence (mod/case-report c) (mod/mk-evidence kind val))))
+      (let
+        ((d (mod/decide-report nr reports rules)))
+        (mod/case-goto
+          c
+          "appealed"
+          (str "appeal: " kind)
+          nr
+          d
+          (mod/case-tier c))))))
+
+;; :decided | :appealed → :final
+(define
+  mod/case-finalize
+  (fn
+    (c)
+    (mod/case-goto
+      c
+      "final"
+      "finalized"
+      (mod/case-report c)
+      (mod/case-decision c)
+      (mod/case-tier c))))
+
+(define
+  mod/case-action
+  (fn
+    (c)
+    (let ((d (mod/case-decision c))) (if (nil? d) nil (get d :action)))))

lib/mod/link.sx

@@ -0,0 +1,92 @@
+;; lib/mod/link.sx — report linking + deduplication.
+;;
+;; Reports about the same subject form a cluster; identical reports (same
+;; reporter + subject + reason) are duplicates. Linking is Prolog-backed: all
+;; report facts are loaded and related ids are found by unification — the same
+;; relational substrate the policy engine uses, here for retrieval rather than
+;; decision. Dedup is pure SX over a normalized link key.
+
+(define
+  mod/link-key
+  (fn
+    (r)
+    (str
+      (mod/report-by r)
+      "|"
+      (mod/report-about r)
+      "|"
+      (downcase (mod/report-reason r)))))
+
+(define
+  mod/dedup-reports
+  (fn
+    (reports)
+    (reduce
+      (fn
+        (acc r)
+        (if
+          (mod/any? (fn (x) (= (mod/link-key x) (mod/link-key r))) acc)
+          acc
+          (append acc (list r))))
+      (list)
+      reports)))
+
+(define
+  mod/duplicate-count
+  (fn (reports) (- (len reports) (len (mod/dedup-reports reports)))))
+
+;; ── Prolog-backed relational retrieval ──
+
+(define
+  mod/report-rel-facts
+  (fn
+    (reports)
+    (mod/join-with
+      "\n"
+      (map
+        (fn
+          (r)
+          (str
+            "report("
+            (mod/report-id r)
+            ", "
+            (mod/pl-quote (mod/report-by r))
+            ", "
+            (mod/pl-quote (mod/report-about r))
+            ")."))
+        reports))))
+
+(define
+  mod/related-ids
+  (fn
+    (subject reports)
+    (let
+      ((db (pl-load (mod/report-rel-facts reports))))
+      (map
+        (fn (sol) (dict-get sol "Id"))
+        (pl-query-all db (str "report(Id, _, " (mod/pl-quote subject) ")"))))))
+
+(define
+  mod/reporters-of
+  (fn
+    (subject reports)
+    (let
+      ((db (pl-load (mod/report-rel-facts reports))))
+      (map
+        (fn (sol) (dict-get sol "By"))
+        (pl-query-all db (str "report(_, By, " (mod/pl-quote subject) ")"))))))
+
+(define
+  mod/distinct
+  (fn
+    (items)
+    (reduce
+      (fn
+        (acc x)
+        (if (mod/any? (fn (y) (= y x)) acc) acc (append acc (list x))))
+      (list)
+      items)))
+
+(define
+  mod/distinct-reporters-of
+  (fn (subject reports) (mod/distinct (mod/reporters-of subject reports))))

lib/mod/lint.sx

@@ -0,0 +1,69 @@
+;; lib/mod/lint.sx — static analysis of a policy rule set.
+;;
+;; Because precedence is "first matching clause wins" (pl-query-one), the rule
+;; order has correctness consequences a moderator can get wrong: a rule placed
+;; after an unconditional (empty :when) rule can never fire, and a rule set with
+;; no unconditional rule may leave some reports undecided. lint-rules surfaces
+;; these without running the engine.
+
+(define mod/rule-unconditional? (fn (r) (empty? (mod/rule-when r))))
+
+;; names of rules that follow the first unconditional rule — structurally dead,
+;; since the unconditional rule always matches first
+(define
+  mod/unreachable-rules
+  (fn
+    (rules)
+    (get
+      (reduce
+        (fn
+          (acc r)
+          (if
+            (get acc :hit)
+            {:dead (append (get acc :dead) (list (mod/rule-name r))) :hit true}
+            (if (mod/rule-unconditional? r) {:dead (get acc :dead) :hit true} acc)))
+        {:dead (list) :hit false}
+        rules)
+      :dead)))
+
+(define
+  mod/has-catchall?
+  (fn (rules) (mod/any? mod/rule-unconditional? rules)))
+
+(define
+  mod/count-eq
+  (fn
+    (x lst)
+    (reduce (fn (a y) (if (= y x) (+ a 1) a)) 0 lst)))
+
+(define
+  mod/duplicate-rule-names
+  (fn
+    (rules)
+    (let
+      ((names (map mod/rule-name rules)))
+      (mod/distinct
+        (reduce
+          (fn
+            (acc n)
+            (if
+              (< 1 (mod/count-eq n names))
+              (append acc (list n))
+              acc))
+          (list)
+          names)))))
+
+(define mod/lint-rules (fn (rules) {:duplicate-names (mod/duplicate-rule-names rules) :has-catchall (mod/has-catchall? rules) :unreachable (mod/unreachable-rules rules)}))
+
+;; a rule set is well-formed when nothing is dead, it has a catch-all, and rule
+;; names are unique
+(define
+  mod/rules-ok?
+  (fn
+    (rules)
+    (let
+      ((l (mod/lint-rules rules)))
+      (if
+        (empty? (get l :unreachable))
+        (if (get l :has-catchall) (empty? (get l :duplicate-names)) false)
+        false))))

lib/mod/offenders.sx

@@ -0,0 +1,59 @@
+;; lib/mod/offenders.sx — repeat-offender escalation (audit log as evidence).
+;;
+;; The append-only audit trail is itself a source of evidence: a subject already
+;; sanctioned several times is a repeat offender. mod/decide-escalating decides a
+;; report normally, then — if the action is a sanction and the subject has at
+;; least k PRIOR sanctions in the audit log — upgrades it to :ban. This is the one
+;; place a decision depends on history beyond the single report, and it reads that
+;; history from the audit log rather than re-deriving it.
+
+(define
+  mod/sanction?
+  (fn
+    (action)
+    (mod/any? (fn (a) (= a action)) (list "hide" "remove" "ban"))))
+
+;; count of prior sanctioning decisions in the audit log about a subject
+(define
+  mod/subject-sanctions
+  (fn
+    (subject)
+    (reduce
+      (fn
+        (acc e)
+        (let
+          ((r (mod/get-report (get e :report-id))))
+          (if
+            (nil? r)
+            acc
+            (if
+              (if
+                (= (mod/report-about r) subject)
+                (mod/sanction? (get e :action))
+                false)
+              (+ acc 1)
+              acc))))
+      0
+      (mod/audit-all))))
+
+(define
+  mod/repeat-offender?
+  (fn (subject k) (<= k (mod/subject-sanctions subject))))
+
+(define
+  mod/decide-escalating
+  (fn
+    (id k)
+    (let
+      ((r (mod/get-report id)))
+      (if
+        (nil? r)
+        nil
+        (let
+          ((priors (mod/subject-sanctions (mod/report-about r))))
+          (let
+            ((d (mod/decide id)))
+            (if
+              (if (mod/sanction? (get d :action)) (<= k priors) false)
+              {:action "ban" :proof {:goals (get (get d :proof) :goals) :prior-sanctions priors :evidence (get (get d :proof) :evidence) :conditions (list) :rule "repeat-offender-ban" :count (get (get d :proof) :count)} :report-id id :rule "repeat-offender-ban" :strategy "escalating"}
+              d)))))))

lib/mod/pipeline.sx

@@ -0,0 +1,18 @@
+;; lib/mod/pipeline.sx — end-to-end triage orchestration.
+;;
+;; A single entry point that runs a report through the subsystem and returns the
+;; full artifact bundle: the decision (under the report's domain policy), a
+;; human-readable explanation, an ActivityPub-shaped event for the bus, and the
+;; wire line for federated peers. Composes policies (Ext 17), explain (Ext 3),
+;; activity (Ext 16) and wire (Ext 14) — the modules are independent, this is just
+;; the convenience that wires them together for the common "process a report" path.
+
+(define
+  mod/triage-pipeline
+  (fn
+    (domain r reports actor)
+    (let ((d (mod/decide-in domain r reports))) {:activity (mod/decision->activity d actor) :action (get d :action) :wire (mod/decision->wire d) :rule (get d :rule) :decision d :explanation (mod/explain d)})))
+
+(define mod/pipeline-action (fn (p) (get p :action)))
+(define mod/pipeline-activity (fn (p) (get p :activity)))
+(define mod/pipeline-wire (fn (p) (get p :wire)))

lib/mod/policies.sx

@@ -0,0 +1,40 @@
+;; lib/mod/policies.sx — per-domain policy registry.
+;;
+;; rose-ash spans domains (blog, market, events, federation, …) that want
+;; different moderation — a marketplace listing and a blog comment are not held to
+;; the same bar. This registry maps a domain to a rule set; mod/decide-in resolves
+;; the right policy and decides. Unregistered domains fall back to the default
+;; rules, so adding a domain never leaves it unmoderated.
+
+(define mod/*policies* (list))
+
+(define mod/policies-reset! (fn () (set! mod/*policies* (list))))
+
+(define
+  mod/register-policy!
+  (fn (domain rules) (begin (append! mod/*policies* {:domain domain :rules rules}) true)))
+
+(define
+  mod/policy-registered?
+  (fn
+    (domain)
+    (mod/any? (fn (p) (= (get p :domain) domain)) mod/*policies*)))
+
+(define
+  mod/policy-for
+  (fn
+    (domain)
+    (reduce
+      (fn (acc p) (if (= (get p :domain) domain) (get p :rules) acc))
+      mod/default-rules
+      mod/*policies*)))
+
+(define
+  mod/decide-in
+  (fn
+    (domain r reports)
+    (mod/decide-report r reports (mod/policy-for domain))))
+
+(define
+  mod/registered-domains
+  (fn () (map (fn (p) (get p :domain)) mod/*policies*)))

lib/mod/policy.sx

@@ -0,0 +1,137 @@
+;; lib/mod/policy.sx — moderation rules → Prolog clauses.
+;;
+;; A rule is {:name :action :when}. :when is a list of condition forms; each
+;; compiles to a Prolog goal. The conditions in a :when list are ANDed (joined by
+;; ", "); :not negates and :any (a list of sub-conditions) disjoins — so the
+;; condition language is a small boolean algebra over the leaf predicates.
+;; Rule order is precedence: the engine queries with pl-query-one, so the first
+;; clause that proves wins. The final default rule has an empty body (true) so
+;; every report yields at least :keep — "no rule matched" is a real result, not a
+;; query failure.
+;;
+;; cond->goal takes an id-term so the same condition can be compiled with the
+;; head variable "Id" (for clause bodies) or a concrete report id (for proof-tree
+;; goal-by-goal re-querying in the engine).
+;;
+;; Precedence (top wins): exoneration evidence (appeal override) > confirmed-abuse
+;; evidence (human review) > spam/abuse classification > repeated-report count >
+;; default keep.
+
+(define mod/mk-rule (fn (name action conds) {:when conds :name name :action action}))
+
+(define mod/rule-name (fn (r) (get r :name)))
+(define mod/rule-action (fn (r) (get r :action)))
+(define mod/rule-when (fn (r) (get r :when)))
+
+(define
+  mod/default-rules
+  (list
+    (mod/mk-rule
+      "exonerated-keep"
+      :keep (list (list :evidence "exonerated")))
+    (mod/mk-rule
+      "reviewer-remove"
+      :remove (list (list :evidence "confirmed-abuse")))
+    (mod/mk-rule "spam-hide" :hide (list (list :classification "spam")))
+    (mod/mk-rule
+      "abuse-remove"
+      :remove (list (list :classification "abuse")))
+    (mod/mk-rule
+      "repeated-escalate"
+      :escalate (list (list :count-at-least 3)))
+    (mod/mk-rule "default-keep" :keep (list))))
+
+;; ── condition → Prolog goal ──
+;;
+;; (:classification "spam")  → classification(Id, spam)
+;; (:evidence "kind")        → evidence(Id, 'kind', _)
+;; (:attr "verified")        → attr(Id, verified)
+;; (:not <cond>)             → not(<cond>)                        (negation)
+;; (:any (list c1 c2 ...))   → (g1 ; g2 ; ...)                    (disjunction)
+;; (:count-at-least 3)       → report(Id, B, S), report_count(S, N), N >= 3
+;; (:score-at-least 5)       → aggregate_all(sum(W), signal(Id, _, W), T), T >= 5
+;; (:reporters-at-least 2)   → report(Id, _, Sr), setof(Br, report(_, Br, Sr), Bsr),
+;;                             length(Bsr, Nr), Nr >= 2   (quorum engine)
+;; (:burst-at-least 3)       → report(Id, _, Sb), burst_count(Sb, Nb), Nb >= 3
+;;                             (temporal engine)
+
+(define
+  mod/cond->goal
+  (fn
+    (c idterm)
+    (let
+      ((tag (first c)))
+      (cond
+        ((= tag :classification)
+          (str "classification(" idterm ", " (nth c 1) ")"))
+        ((= tag :evidence)
+          (str
+            "evidence("
+            idterm
+            ", "
+            (mod/pl-quote (nth c 1))
+            ", _)"))
+        ((= tag :attr) (str "attr(" idterm ", " (nth c 1) ")"))
+        ((= tag :not)
+          (str "not(" (mod/cond->goal (nth c 1) idterm) ")"))
+        ((= tag :any)
+          (str
+            "("
+            (mod/join-with
+              " ; "
+              (map
+                (fn (sub) (mod/cond->goal sub idterm))
+                (nth c 1)))
+            ")"))
+        ((= tag :count-at-least)
+          (str
+            "report("
+            idterm
+            ", B, S), report_count(S, N), N >= "
+            (nth c 1)))
+        ((= tag :score-at-least)
+          (str
+            "aggregate_all(sum(W), signal("
+            idterm
+            ", _, W), T), T >= "
+            (nth c 1)))
+        ((= tag :reporters-at-least)
+          (str
+            "report("
+            idterm
+            ", _, Sr), setof(Br, report(_, Br, Sr), Bsr), "
+            "length(Bsr, Nr), Nr >= "
+            (nth c 1)))
+        ((= tag :burst-at-least)
+          (str
+            "report("
+            idterm
+            ", _, Sb), burst_count(Sb, Nb), Nb >= "
+            (nth c 1)))
+        (true "true")))))
+
+(define
+  mod/conds->body
+  (fn
+    (conds idterm)
+    (if
+      (empty? conds)
+      "true"
+      (mod/join-with ", " (map (fn (c) (mod/cond->goal c idterm)) conds)))))
+
+(define
+  mod/rule->clause
+  (fn
+    (r)
+    (str
+      "policy_action(Id, "
+      (mod/rule-action r)
+      ", '"
+      (mod/rule-name r)
+      "') :- "
+      (mod/conds->body (mod/rule-when r) "Id")
+      ".")))
+
+(define
+  mod/rules->program
+  (fn (rules) (mod/join-with "\n" (map mod/rule->clause rules))))

lib/mod/quorum.sx

@@ -0,0 +1,40 @@
+;; lib/mod/quorum.sx — quorum decisions over distinct reporters (anti-brigade).
+;;
+;; The base engine asserts only the decided report's report/3 fact, so it can't
+;; reason about WHO reported a subject. The quorum engine additionally asserts
+;; every report's report/3 fact (via link's rel-facts), letting a rule require N
+;; *distinct* reporters with `setof`/`length` — so one user filing many reports
+;; does not manufacture consensus. Same decision shape as the base engine, plus
+;; :strategy "quorum".
+
+(define
+  mod/build-quorum-program
+  (fn
+    (r count reports rules)
+    (str
+      (mod/report-rel-facts reports)
+      "\n"
+      (mod/report-facts r count)
+      "\n"
+      (mod/rules->program rules))))
+
+(define
+  mod/decide-quorum
+  (fn
+    (r reports rules)
+    (let
+      ((count (mod/report-count (mod/report-about r) reports))
+        (kinds (mod/classify-keywords r))
+        (id (mod/report-id r)))
+      (let
+        ((program (mod/build-quorum-program r count reports rules)))
+        (let
+          ((db (pl-load program)))
+          (let
+            ((sol (pl-query-one db (str "policy_action(" id ", Action, Rule)"))))
+            (if
+              (nil? sol)
+              {:action "keep" :proof {:goals (list) :evidence kinds :conditions (list) :rule "none" :count count} :report-id id :rule "none" :strategy "quorum"}
+              (let
+                ((rule (mod/find-rule rules (dict-get sol "Rule"))))
+                {:action (mod/rule-action rule) :proof {:goals (mod/proof-goals db id (mod/rule-when rule)) :evidence kinds :conditions (mod/rule-when rule) :rule (mod/rule-name rule) :count count} :report-id id :rule (mod/rule-name rule) :strategy "quorum"}))))))))

lib/mod/schema.sx

@@ -0,0 +1,259 @@
+;; lib/mod/schema.sx — report representation + Prolog fact generation.
+;;
+;; A report is a dict {:id :by :about :reason :evidence :attrs :signals :at}.
+;;   :evidence — accumulated {:kind :val} entries (human review, scanners)
+;;   :attrs    — attribute names ("verified") for negation-as-failure conditions
+;;   :signals  — weighted {:kind :weight} entries for aggregate scoring rules
+;;   :at       — integer timestamp/tick (deterministic; supplied, not clock-read)
+;; The engine derives keyword classifications from the reason text and projects
+;; the report, its classifications, evidence, attributes, and signals into Prolog
+;; facts that policy clauses match against.
+
+(define mod/mk-report (fn (id by about reason) {:attrs (list) :id id :signals (list) :by by :evidence (list) :about about :at 0 :reason reason}))
+
+(define mod/report-id (fn (r) (get r :id)))
+(define mod/report-by (fn (r) (get r :by)))
+(define mod/report-about (fn (r) (get r :about)))
+(define mod/report-reason (fn (r) (get r :reason)))
+
+(define
+  mod/report-evidence
+  (fn (r) (let ((e (get r :evidence))) (if (nil? e) (list) e))))
+
+(define
+  mod/report-attrs
+  (fn (r) (let ((a (get r :attrs))) (if (nil? a) (list) a))))
+
+(define
+  mod/report-signals
+  (fn (r) (let ((s (get r :signals))) (if (nil? s) (list) s))))
+
+(define
+  mod/report-at
+  (fn (r) (let ((t (get r :at))) (if (nil? t) 0 t))))
+
+(define mod/mk-evidence (fn (kind val) {:val val :kind kind}))
+(define mod/evidence-kind (fn (e) (get e :kind)))
+(define mod/evidence-val (fn (e) (get e :val)))
+
+(define mod/mk-signal (fn (kind weight) {:kind kind :weight weight}))
+(define mod/signal-kind (fn (s) (get s :kind)))
+(define mod/signal-weight (fn (s) (get s :weight)))
+
+(define mod/report* (fn (r evs attrs sigs at) {:attrs attrs :id (mod/report-id r) :signals sigs :by (mod/report-by r) :evidence evs :about (mod/report-about r) :at at :reason (mod/report-reason r)}))
+
+(define
+  mod/with-evidence
+  (fn
+    (r evs)
+    (mod/report*
+      r
+      evs
+      (mod/report-attrs r)
+      (mod/report-signals r)
+      (mod/report-at r))))
+
+(define
+  mod/with-attrs
+  (fn
+    (r attrs)
+    (mod/report*
+      r
+      (mod/report-evidence r)
+      attrs
+      (mod/report-signals r)
+      (mod/report-at r))))
+
+(define
+  mod/with-signals
+  (fn
+    (r sigs)
+    (mod/report*
+      r
+      (mod/report-evidence r)
+      (mod/report-attrs r)
+      sigs
+      (mod/report-at r))))
+
+(define
+  mod/with-at
+  (fn
+    (r at)
+    (mod/report*
+      r
+      (mod/report-evidence r)
+      (mod/report-attrs r)
+      (mod/report-signals r)
+      at)))
+
+(define
+  mod/attach-evidence
+  (fn
+    (r e)
+    (mod/with-evidence r (append (mod/report-evidence r) (list e)))))
+
+(define
+  mod/attach-attr
+  (fn (r a) (mod/with-attrs r (append (mod/report-attrs r) (list a)))))
+
+(define
+  mod/attach-signal
+  (fn (r s) (mod/with-signals r (append (mod/report-signals r) (list s)))))
+
+;; ── substring search (the prolog-loaded env lacks includes?; slice/len do work) ──
+
+(define
+  mod/contains-at?
+  (fn
+    (hay needle hl nl pos)
+    (if
+      (< hl (+ pos nl))
+      false
+      (if
+        (= (slice hay pos (+ pos nl)) needle)
+        true
+        (mod/contains-at? hay needle hl nl (+ pos 1))))))
+
+(define
+  mod/str-contains?
+  (fn
+    (hay needle)
+    (let
+      ((hl (len hay)) (nl (len needle)))
+      (if
+        (= nl 0)
+        true
+        (mod/contains-at? hay needle hl nl 0)))))
+
+;; ── evidence derivation (keyword classification) ──
+
+(define
+  mod/spam-keywords
+  (list "spam" "buy now" "click here" "free money" "viagra" "limited offer"))
+
+(define
+  mod/abuse-keywords
+  (list "abuse" "harassment" "threat" "slur" "hate speech"))
+
+(define
+  mod/any?
+  (fn (pred coll) (reduce (fn (acc x) (if acc acc (pred x))) false coll)))
+
+(define
+  mod/reason-matches?
+  (fn
+    (reason kws)
+    (let
+      ((low (downcase reason)))
+      (mod/any? (fn (k) (mod/str-contains? low k)) kws))))
+
+(define
+  mod/classify-keywords
+  (fn
+    (r)
+    (let
+      ((reason (mod/report-reason r)) (kinds (list)))
+      (begin
+        (when
+          (mod/reason-matches? reason mod/spam-keywords)
+          (append! kinds "spam"))
+        (when
+          (mod/reason-matches? reason mod/abuse-keywords)
+          (append! kinds "abuse"))
+        kinds))))
+
+(define
+  mod/report-count
+  (fn
+    (about reports)
+    (reduce
+      (fn
+        (acc r)
+        (if (= (mod/report-about r) about) (+ acc 1) acc))
+      0
+      reports)))
+
+;; ── Prolog fact projection ──
+
+(define
+  mod/join-with
+  (fn
+    (sep items)
+    (reduce (fn (acc x) (if (= acc "") x (str acc sep x))) "" items)))
+
+(define mod/pl-quote (fn (s) (str "'" s "'")))
+
+(define
+  mod/classification-facts
+  (fn
+    (id kinds)
+    (mod/join-with
+      "\n"
+      (map (fn (k) (str "classification(" id ", " k ").")) kinds))))
+
+(define
+  mod/evidence-facts
+  (fn
+    (id evs)
+    (mod/join-with
+      "\n"
+      (map
+        (fn
+          (e)
+          (str
+            "evidence("
+            id
+            ", "
+            (mod/pl-quote (mod/evidence-kind e))
+            ", "
+            (mod/pl-quote (str (mod/evidence-val e)))
+            ")."))
+        evs))))
+
+(define
+  mod/attr-facts
+  (fn
+    (id attrs)
+    (mod/join-with "\n" (map (fn (a) (str "attr(" id ", " a ").")) attrs))))
+
+(define
+  mod/signal-facts
+  (fn
+    (id sigs)
+    (mod/join-with
+      "\n"
+      (map
+        (fn
+          (s)
+          (str
+            "signal("
+            id
+            ", "
+            (mod/pl-quote (mod/signal-kind s))
+            ", "
+            (mod/signal-weight s)
+            ")."))
+        sigs))))
+
+(define
+  mod/report-facts
+  (fn
+    (r count)
+    (let
+      ((id (mod/report-id r))
+        (by (mod/pl-quote (mod/report-by r)))
+        (about (mod/pl-quote (mod/report-about r))))
+      (let
+        ((cls (mod/classification-facts id (mod/classify-keywords r)))
+          (evs (mod/evidence-facts id (mod/report-evidence r)))
+          (ats (mod/attr-facts id (mod/report-attrs r)))
+          (sgs (mod/signal-facts id (mod/report-signals r))))
+        (mod/join-with
+          "\n"
+          (list
+            (str "report(" id ", " by ", " about ").")
+            (str "report_count(" about ", " count ").")
+            cls
+            evs
+            ats
+            sgs))))))

lib/mod/scoreboard.json

@@ -0,0 +1,30 @@
+{
+  "lang": "mod",
+  "total_passed": 390,
+  "total_failed": 0,
+  "total": 390,
+  "suites": [
+    {"name":"decide","passed":31,"failed":0,"total":31},
+    {"name":"audit","passed":29,"failed":0,"total":29},
+    {"name":"escalation","passed":46,"failed":0,"total":46},
+    {"name":"fed","passed":26,"failed":0,"total":26},
+    {"name":"extensions","passed":32,"failed":0,"total":32},
+    {"name":"link","passed":12,"failed":0,"total":12},
+    {"name":"lint","passed":14,"failed":0,"total":14},
+    {"name":"severity","passed":14,"failed":0,"total":14},
+    {"name":"offenders","passed":19,"failed":0,"total":19},
+    {"name":"quorum","passed":9,"failed":0,"total":9},
+    {"name":"trace","passed":15,"failed":0,"total":15},
+    {"name":"whatif","passed":13,"failed":0,"total":13},
+    {"name":"batch","passed":17,"failed":0,"total":17},
+    {"name":"temporal","passed":15,"failed":0,"total":15},
+    {"name":"sla","passed":15,"failed":0,"total":15},
+    {"name":"wire","passed":16,"failed":0,"total":16},
+    {"name":"disjunction","passed":10,"failed":0,"total":10},
+    {"name":"activity","passed":17,"failed":0,"total":17},
+    {"name":"policies","passed":14,"failed":0,"total":14},
+    {"name":"defrule","passed":11,"failed":0,"total":11},
+    {"name":"pipeline","passed":15,"failed":0,"total":15}
+  ],
+  "generated": "2026-06-06T19:40:03+00:00"
+}

lib/mod/scoreboard.md

@@ -0,0 +1,27 @@
+# mod scoreboard
+
+**390 / 390 passing** (0 failure(s)).
+
+| Suite | Passed | Total | Status |
+|-------|--------|-------|--------|
+| decide | 31 | 31 | ok |
+| audit | 29 | 29 | ok |
+| escalation | 46 | 46 | ok |
+| fed | 26 | 26 | ok |
+| extensions | 32 | 32 | ok |
+| link | 12 | 12 | ok |
+| lint | 14 | 14 | ok |
+| severity | 14 | 14 | ok |
+| offenders | 19 | 19 | ok |
+| quorum | 9 | 9 | ok |
+| trace | 15 | 15 | ok |
+| whatif | 13 | 13 | ok |
+| batch | 17 | 17 | ok |
+| temporal | 15 | 15 | ok |
+| sla | 15 | 15 | ok |
+| wire | 16 | 16 | ok |
+| disjunction | 10 | 10 | ok |
+| activity | 17 | 17 | ok |
+| policies | 14 | 14 | ok |
+| defrule | 11 | 11 | ok |
+| pipeline | 15 | 15 | ok |

lib/mod/severity.sx

@@ -0,0 +1,60 @@
+;; lib/mod/severity.sx — "strictest-wins" decision strategy.
+;;
+;; The default engine resolves precedence by rule ORDER (first proven clause wins,
+;; via pl-query-one). Some policies instead want the HARSHEST applicable sanction
+;; regardless of order. mod/decide-strictest collects every rule that proves
+;; (pl-query-all) and picks the highest-severity action. Same decision shape as
+;; the engine, plus :strategy. Built over the engine's helpers; engine untouched.
+
+(define
+  mod/action-severity
+  (fn
+    (action)
+    (cond
+      ((= action "ban") 4)
+      ((= action "remove") 3)
+      ((= action "hide") 2)
+      ((= action "escalate") 1)
+      (true 0))))
+
+(define
+  mod/strictest-sol
+  (fn
+    (sols)
+    (reduce
+      (fn
+        (acc s)
+        (if
+          (nil? acc)
+          s
+          (if
+            (<
+              (mod/action-severity (dict-get acc "Action"))
+              (mod/action-severity (dict-get s "Action")))
+            s
+            acc)))
+      nil
+      sols)))
+
+(define
+  mod/decide-strictest
+  (fn
+    (r reports rules)
+    (let
+      ((count (mod/report-count (mod/report-about r) reports))
+        (kinds (mod/classify-keywords r))
+        (id (mod/report-id r)))
+      (let
+        ((program (mod/build-program r count rules)))
+        (let
+          ((db (pl-load program)))
+          (let
+            ((sols (pl-query-all db (str "policy_action(" id ", Action, Rule)"))))
+            (let
+              ((best (mod/strictest-sol sols)))
+              (if
+                (nil? best)
+                {:action "keep" :proof {:goals (list) :evidence kinds :conditions (list) :rule "none" :count count} :report-id id :rule "none" :strategy "strictest"}
+                (let
+                  ((rule (mod/find-rule rules (dict-get best "Rule"))))
+                  {:action (mod/rule-action rule) :proof {:goals (mod/proof-goals db id (mod/rule-when rule)) :evidence kinds :conditions (mod/rule-when rule) :rule (mod/rule-name rule) :count count} :report-id id :rule (mod/rule-name rule) :strategy "strictest"})))))))))

lib/mod/sla.sx

@@ -0,0 +1,47 @@
+;; lib/mod/sla.sx — service-level sweep over pending lifecycle cases.
+;;
+;; Composes the Phase-3 lifecycle with the Ext-12 time dimension: a case left in a
+;; pending state (open / triaged / appealed) past a deadline has breached SLA and
+;; should resurface. A timed-case pairs a case with the tick it entered its
+;; current state (the caller stamps this — the lifecycle stays timeless and pure).
+;; Terminal states (decided / final) never breach.
+
+(define mod/pending-states (list "open" "triaged" "appealed"))
+(define mod/pending-state? (fn (s) (mod/member? s mod/pending-states)))
+
+(define mod/mk-timed-case (fn (c entered-at) {:entered-at entered-at :case c}))
+(define mod/tc-case (fn (tc) (get tc :case)))
+(define mod/tc-entered-at (fn (tc) (get tc :entered-at)))
+
+(define
+  mod/overdue?
+  (fn
+    (tc now deadline)
+    (if
+      (mod/pending-state? (mod/case-state (mod/tc-case tc)))
+      (< deadline (- now (mod/tc-entered-at tc)))
+      false)))
+
+(define
+  mod/sla-sweep
+  (fn
+    (timed-cases now deadline)
+    (reduce
+      (fn
+        (acc tc)
+        (if
+          (mod/overdue? tc now deadline)
+          (append
+            acc
+            (list (mod/report-id (mod/case-report (mod/tc-case tc)))))
+          acc))
+      (list)
+      timed-cases)))
+
+(define
+  mod/overdue-count
+  (fn
+    (timed-cases now deadline)
+    (len (mod/sla-sweep timed-cases now deadline))))
+
+(define mod/age (fn (tc now) (- now (mod/tc-entered-at tc))))

lib/mod/temporal.sx

@@ -0,0 +1,62 @@
+;; lib/mod/temporal.sx — burst detection over a time window.
+;;
+;; A plain report count can't tell a burst (N reports in minutes) from slow
+;; accumulation (N reports over months). mod/decide-temporal takes a `now` tick
+;; and a `window`, counts reports about the subject with :at within [now-window,
+;; now], asserts it as burst_count/2, and lets a `(:burst-at-least K)` rule fire
+;; only on a genuine burst. Time is supplied (deterministic), never clock-read.
+
+(define
+  mod/window-count
+  (fn
+    (subject reports now window)
+    (reduce
+      (fn
+        (acc r)
+        (if
+          (if
+            (= (mod/report-about r) subject)
+            (<= (- now window) (mod/report-at r))
+            false)
+          (+ acc 1)
+          acc))
+      0
+      reports)))
+
+(define
+  mod/build-temporal-program
+  (fn
+    (r count bcount rules)
+    (str
+      (mod/report-facts r count)
+      "\n"
+      "burst_count("
+      (mod/pl-quote (mod/report-about r))
+      ", "
+      bcount
+      ").\n"
+      (mod/rules->program rules))))
+
+(define
+  mod/decide-temporal
+  (fn
+    (r reports rules now window)
+    (let
+      ((about (mod/report-about r))
+        (id (mod/report-id r))
+        (kinds (mod/classify-keywords r)))
+      (let
+        ((count (mod/report-count about reports))
+          (bcount (mod/window-count about reports now window)))
+        (let
+          ((program (mod/build-temporal-program r count bcount rules)))
+          (let
+            ((db (pl-load program)))
+            (let
+              ((sol (pl-query-one db (str "policy_action(" id ", Action, Rule)"))))
+              (if
+                (nil? sol)
+                {:action "keep" :proof {:burst bcount :goals (list) :evidence kinds :conditions (list) :rule "none" :count count} :report-id id :rule "none" :strategy "temporal"}
+                (let
+                  ((rule (mod/find-rule rules (dict-get sol "Rule"))))
+                  {:action (mod/rule-action rule) :proof {:burst bcount :goals (mod/proof-goals db id (mod/rule-when rule)) :evidence kinds :conditions (mod/rule-when rule) :rule (mod/rule-name rule) :count count} :report-id id :rule (mod/rule-name rule) :strategy "temporal"})))))))))

lib/mod/tests/activity.sx

@@ -0,0 +1,95 @@
+;; lib/mod/tests/activity.sx — Ext 16: ActivityPub-shaped decision export.
+
+(define mod-ap-count 0)
+(define mod-ap-pass 0)
+(define mod-ap-fail 0)
+(define mod-ap-failures (list))
+
+(define
+  mod-ap-test!
+  (fn
+    (name got expected)
+    (begin
+      (set! mod-ap-count (+ mod-ap-count 1))
+      (if
+        (= got expected)
+        (set! mod-ap-pass (+ mod-ap-pass 1))
+        (begin
+          (set! mod-ap-fail (+ mod-ap-fail 1))
+          (append!
+            mod-ap-failures
+            (str name "\n    expected: " expected "\n    got:      " got)))))))
+
+;; ── action → AP verb ──
+
+(mod-ap-test! "remove → Delete" (mod/action->verb "remove") "Delete")
+(mod-ap-test! "ban → Block" (mod/action->verb "ban") "Block")
+(mod-ap-test! "hide → Flag" (mod/action->verb "hide") "Flag")
+(mod-ap-test! "escalate → Flag" (mod/action->verb "escalate") "Flag")
+(mod-ap-test! "keep → nil (no activity)" (mod/action->verb "keep") nil)
+
+;; ── single decision → activity ──
+
+(define mod-ap-spam (mod/mk-report "r1" "a" "bob" "this is spam"))
+(define
+  mod-ap-dec
+  (mod/decide-report mod-ap-spam (list mod-ap-spam) mod/default-rules))
+(define mod-ap-act (mod/decision->activity mod-ap-dec "instance.example"))
+
+(mod-ap-test! "activity type is Flag (hide)" (get mod-ap-act :type) "Flag")
+(mod-ap-test! "activity object is report id" (get mod-ap-act :object) "r1")
+(mod-ap-test!
+  "activity actor preserved"
+  (get mod-ap-act :actor)
+  "instance.example")
+(mod-ap-test!
+  "activity preserves precise action"
+  (get mod-ap-act :action)
+  "hide")
+(mod-ap-test! "activity carries rule" (get mod-ap-act :rule) "spam-hide")
+(mod-ap-test!
+  "activity summary"
+  (get mod-ap-act :summary)
+  "moderation/hide via spam-hide")
+
+;; ── keep produces no activity ──
+
+(define mod-ap-clean (mod/mk-report "r2" "a" "b" "a fine post"))
+(define
+  mod-ap-keep
+  (mod/decide-report mod-ap-clean (list mod-ap-clean) mod/default-rules))
+(mod-ap-test!
+  "keep decision → nil activity"
+  (mod/decision->activity mod-ap-keep "x")
+  nil)
+
+;; ── abuse → Delete ──
+
+(define mod-ap-abuse (mod/mk-report "r3" "a" "b" "harassment here"))
+(define
+  mod-ap-abuse-dec
+  (mod/decide-report mod-ap-abuse (list mod-ap-abuse) mod/default-rules))
+(mod-ap-test!
+  "abuse decision → Delete activity"
+  (get (mod/decision->activity mod-ap-abuse-dec "x") :type)
+  "Delete")
+
+;; ── batch export drops keeps ──
+
+(define mod-ap-decisions (list mod-ap-dec mod-ap-keep mod-ap-abuse-dec))
+(define mod-ap-acts (mod/decisions->activities mod-ap-decisions "inst"))
+(mod-ap-test! "batch export drops the keep" (len mod-ap-acts) 2)
+(mod-ap-test!
+  "batch export first is the Flag"
+  (get (first mod-ap-acts) :type)
+  "Flag")
+(mod-ap-test!
+  "batch export second is the Delete"
+  (get (nth mod-ap-acts 1) :type)
+  "Delete")
+(mod-ap-test!
+  "empty decisions → no activities"
+  (mod/decisions->activities (list) "inst")
+  (list))
+
+(define mod-activity-tests-run! (fn () {:failures mod-ap-failures :total mod-ap-count :passed mod-ap-pass :failed mod-ap-fail}))