fed-sx-m1: Step 7b — gen_server-per-projection (start_link/3 + async_fold + query) + 11 tests

next/kernel/projection.erl

@@ -1,6 +1,9 @@
 -module(projection).
+-behaviour(gen_server).
 -export([new/2, new/3, fold_activity/2, replay/2,
          name/1, state/1, fold_fn/1]).
+-export([start_link/3, async_fold/2, query/1, stop/1]).
+-export([init/1, handle_call/3, handle_cast/2, handle_info/2]).
 
 %% Pure-functional projection driver per design §10.
 %%
@@ -52,3 +55,43 @@ field(_, []) -> erlang:error(badkey).
 set_field(K, V, [{K, _} | Rest]) -> [{K, V} | Rest];
 set_field(K, V, [P | Rest]) -> [P | set_field(K, V, Rest)];
 set_field(K, V, []) -> [{K, V}].
+
+%% ── Step 7b: gen_server wrapper ─────────────────────────────────
+%%
+%% Each projection runs in its own gen_server, registered under the
+%% projection's Name atom. `async_fold/2` casts an activity into the
+%% process; `query/1` synchronously fetches the current state.
+%%
+%% Port notes (mirroring Step 5b on the registry): `gen_server:start_link`
+%% returns the raw Pid; `?MODULE` macro is unsupported; spawned
+%% processes don't survive across separate `erlang-eval-ast` calls
+%% so tests must inline start_link with their operations.
+
+start_link(Name, InitialState, FoldFn) ->
+    Pid = gen_server:start_link(projection, [Name, InitialState, FoldFn]),
+    erlang:register(Name, Pid),
+    Pid.
+
+async_fold(Name, Activity) ->
+    gen_server:cast(Name, {fold, Activity}).
+
+query(Name) ->
+    gen_server:call(Name, get_state).
+
+stop(Name) ->
+    R = gen_server:call(Name, '$gen_stop'),
+    erlang:unregister(Name),
+    R.
+
+%% gen_server callbacks
+
+init([Name, InitialState, FoldFn]) ->
+    {ok, new(Name, InitialState, FoldFn)}.
+
+handle_call(get_state, _From, Proj) ->
+    {reply, state(Proj), Proj}.
+
+handle_cast({fold, Activity}, Proj) ->
+    {noreply, fold_activity(Proj, Activity)}.
+
+handle_info(_, Proj) -> {noreply, Proj}.

next/tests/projection_server.sh

@@ -0,0 +1,117 @@
+#!/usr/bin/env bash
+# next/tests/projection_server.sh — Step 7b acceptance test.
+#
+# Exercises gen_server-per-projection: start_link/3, async_fold/2,
+# query/1. Each test inlines start_link with operations because
+# the Erlang-on-SX scheduler doesn't preserve processes across
+# separate erlang-eval-ast invocations. 10 cases.
+
+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="${1:-}"
+PASS=0; FAIL=0; ERRORS=""
+TMPFILE=$(mktemp); trap "rm -f $TMPFILE" EXIT
+
+cat > "$TMPFILE" <<'EPOCHS'
+(epoch 1)
+(load "lib/erlang/tokenizer.sx")
+(load "lib/erlang/parser.sx")
+(load "lib/erlang/parser-core.sx")
+(load "lib/erlang/parser-expr.sx")
+(load "lib/erlang/parser-module.sx")
+(load "lib/erlang/transpile.sx")
+(load "lib/erlang/runtime.sx")
+(load "lib/erlang/vm/dispatcher.sx")
+(epoch 2)
+(eval "(er-load-gen-server!)")
+(epoch 3)
+(eval "(get (erlang-load-module (file-read \"next/kernel/projection.erl\")) :name)")
+
+;; start_link returns a Pid registered under the given name
+(epoch 10)
+(eval "(get (erlang-eval-ast \"is_pid(projection:start_link(p1, 0, fun (_A, S) -> S + 1 end))\") :name)")
+
+;; query before any async_fold returns initial state
+(epoch 11)
+(eval "(erlang-eval-ast \"projection:start_link(p1, 0, fun (_A, S) -> S + 1 end), projection:query(p1)\")")
+
+;; Single async_fold + query returns new state
+(epoch 12)
+(eval "(erlang-eval-ast \"projection:start_link(p1, 0, fun (_A, S) -> S + 1 end), projection:async_fold(p1, a), projection:query(p1)\")")
+
+;; Five async_folds accumulate
+(epoch 13)
+(eval "(erlang-eval-ast \"projection:start_link(p1, 0, fun (_A, S) -> S + 1 end), projection:async_fold(p1, 1), projection:async_fold(p1, 2), projection:async_fold(p1, 3), projection:async_fold(p1, 4), projection:async_fold(p1, 5), projection:query(p1)\")")
+
+;; Custom initial state preserved
+(epoch 14)
+(eval "(erlang-eval-ast \"projection:start_link(p1, 42, fun (A, S) -> S + A end), projection:query(p1)\")")
+
+;; Fold can read the activity (sum activities)
+(epoch 15)
+(eval "(erlang-eval-ast \"projection:start_link(p1, 0, fun (A, S) -> S + A end), projection:async_fold(p1, 10), projection:async_fold(p1, 20), projection:async_fold(p1, 30), projection:query(p1)\")")
+
+;; List-append fold preserves insertion order (newest-first)
+(epoch 16)
+(eval "(get (erlang-eval-ast \"projection:start_link(p1, [], fun (A, S) -> [A | S] end), projection:async_fold(p1, a), projection:async_fold(p1, b), projection:async_fold(p1, c), projection:query(p1) =:= [c, b, a]\") :name)")
+
+;; Two named projections are independent
+(epoch 17)
+(eval "(get (erlang-eval-ast \"projection:start_link(p1, 0, fun (_A, S) -> S + 1 end), projection:start_link(p2, [], fun (A, S) -> [A | S] end), projection:async_fold(p1, x), projection:async_fold(p1, y), projection:async_fold(p2, x), {projection:query(p1), projection:query(p2)} =:= {2, [x]}\") :name)")
+
+;; Conditional fold (filter on activity tag)
+(epoch 18)
+(eval "(erlang-eval-ast \"projection:start_link(p1, 0, fun (A, S) -> case A of {keep, _} -> S + 1; _ -> S end end), projection:async_fold(p1, {keep, a}), projection:async_fold(p1, plain), projection:async_fold(p1, {keep, b}), projection:async_fold(p1, plain), projection:query(p1)\")")
+EPOCHS
+
+OUTPUT=$(timeout 180 "$SX_SERVER" < "$TMPFILE" 2>/dev/null)
+
+check() {
+  local epoch="$1" desc="$2" expected="$3"
+  local actual
+  actual=$(echo "$OUTPUT" | awk -v e="$epoch" '
+    $0 ~ "^\\(ok-len " e " " { getline; print; exit }
+    $0 ~ "^\\(ok " e " "     { print; exit }
+    $0 ~ "^\\(error " e " "  { print; exit }
+  ')
+  [ -z "$actual" ] && actual="<no output for epoch $epoch>"
+  if echo "$actual" | grep -qF -- "$expected"; then
+    PASS=$((PASS+1))
+    [ "$VERBOSE" = "-v" ] && echo "  ok $desc"
+  else
+    FAIL=$((FAIL+1))
+    ERRORS+="  FAIL [$desc] (epoch $epoch) expected: $expected | actual: $actual
+"
+  fi
+}
+
+check  2  "gen_server loaded"                "gen_server"
+check  3  "projection module loaded"         "projection"
+check 10  "start_link returns Pid"           "true"
+check 11  "initial state via query"          "0"
+check 12  "async_fold + query"               "1"
+check 13  "five async_folds accumulate"      "5"
+check 14  "custom initial state"             "42"
+check 15  "fold reads activity (sum)"        "60"
+check 16  "list-append fold order"           "true"
+check 17  "two named projections indep."     "true"
+check 18  "conditional fold (filter)"        "2"
+
+TOTAL=$((PASS+FAIL))
+if [ $FAIL -eq 0 ]; then
+  echo "ok $PASS/$TOTAL next/tests/projection_server.sh passed"
+else
+  echo "FAIL $PASS/$TOTAL passed, $FAIL failed:"
+  echo "$ERRORS"
+fi
+[ $FAIL -eq 0 ]

plans/fed-sx-milestone-1.md

@@ -457,7 +457,7 @@ publish(ActorId, ActivityRequest) ->
 
 **Sub-deliverables:**
 - [x] **7a** — Pure-functional `next/kernel/projection.erl`: `new/2,3`, `fold_activity/2`, `replay/2`, `name/1`, `state/1`, `fold_fn/1`. Projection record is `[{name, _}, {state, _}, {fold, fun}]`; fold body is an Erlang fun in v1 (SX-source eval bridge deferred). `next/tests/projection_pure.sh` (12 cases).
-- [ ] **7b** — gen_server wrapper: `start_link/1`, named-per-projection, `async_fold/2`, `query/1`, `snapshot/1`.
+- [x] **7b** — gen_server-per-projection: `start_link/3(Name, InitialState, FoldFn)` + `async_fold/2(Name, Activity)` (cast) + `query/1(Name)` (call) + `stop/1`. Each projection registered under its own Name atom. `next/tests/projection_server.sh` (11 cases). Snapshot persistence deferred (needs SX-source eval + on-disk state).
 - [ ] **7c** — Broadcast hook from `outbox:publish` — feed `Signed` to every projection process.
 - [ ] **7d** — `sandbox:eval_pure/2` (Erlang sandbox-mode caller — gas budget + IO denial) once an SX-source eval bridge exists.
 
@@ -977,6 +977,7 @@ A few things still under-specified; resolve as work begins.
 Newest first. One line per sub-deliverable commit. Erlang conformance gate
 (`bash lib/erlang/conformance.sh`) must remain 729/729 on every entry.
 
+- **2026-05-28** — Step 7b: `projection.erl` extended with gen_server callbacks + per-projection named-process API. `start_link/3(Name, InitialState, FoldFn)` spawns and registers under the supplied atom; `async_fold/2(Name, Activity)` casts a fold message; `query/1(Name)` synchronously returns the current state. Same port quirks as registry gen_server (Step 5b): raw Pid return, no `?MODULE` macro, processes don't survive between separate `erlang-eval-ast` calls — tests inline start_link with operations. Two named projections are independent. Snapshot persistence deferred to a later sub-step (needs SX-source eval + on-disk state). `next/tests/projection_server.sh` 11/11. Erlang conformance 729/729.
 - **2026-05-28** — Step 7a: `next/kernel/projection.erl` — pure-functional projection driver. Record shape `[{name, _}, {state, _}, {fold, fun}]`; `fold_activity/2` advances state by one activity; `replay/2` folds a whole list (mirrors `log:entries/1` semantics); `new/2` defaults to the identity fold and `new/3` accepts a custom Erlang fun. Multiple projections share no state — independent record values. Step 7 split into 7a (done) + 7b (gen_server-per-projection) + 7c (broadcast hook from outbox) + 7d (sandbox eval, needs SX-source bridge). `next/tests/projection_pure.sh` 12/12. Erlang conformance 729/729.
 - **2026-05-28** — Step 6d-publish: `outbox:publish/2(Request, Context)` orchestrates construct + sign + `pipeline:run_stages` + `log:append`. Stage list is `[stage_envelope, stage_signature(AS), stage_replay(LogState)]` — so a duplicate publish (same Request, same Published) halts at the replay stage and returns `{error, replay, LogState}` with the log unchanged; bad key material halts at `bad_signature`. Happy path returns `{ok, [{cid, Cid}, {activity, Signed}], NewLog}`. Projection-scheduler dispatch deferred to Step 7. `next/tests/outbox_publish.sh` 13/13 covers happy path, replay halt, sig halt, multi-publish progression, CID stability across fresh logs. Erlang conformance 729/729.
 - **2026-05-28** — Step 6d-cs: `next/kernel/outbox.erl` — envelope construction + signing. `construct/4` takes `(Type, ActorId, Published, Object)`, builds the canonical key-sorted property list, and derives the activity `:id` from `cid:to_string({activity_envelope, Skeleton})`. `sign/2` extracts key_id/algorithm/key-material from a KeySpec proplist, computes the v1 HMAC over canonical bytes, and appends the `:signature` pair. `cid_of/1` is a convenience accessor. Round-trip end-to-end through `envelope:verify_signature/2` verified (correct key passes, wrong key returns bad_signature). Step 6d split into 6d-cs (done) + 6d-publish (orchestration). `next/tests/outbox_construct.sh` 13/13. Erlang conformance 729/729.