self-review 2026-07-24: wire embedding cosine similarity into activation (bl-b2d1c944)

Semantic activation was spec-only since 2026-06-30 — the seed loop used
istr_contains and nothing else. Per the 07-21 integration brief:

- EngramNode gains a lazily-backfilled nomic-embed-text vector (8/call
  inside engram_activate, newest-first; no create-path latency, no bulk
  Ollama hammering during sync seeds)
- query embedding (cached) drives a top-K cosine seed supplement
  (HippoRAG use-similarity-twice) plus an additive WM term with
  shift-and-floor at 0.45 — raw cosine is a constant bias in anisotropic
  spaces (unrelated pairs read 0.4-0.7), floor-and-ramp makes it a signal
- 4s embed timeout (http_do_t) + 3-strike circuit breaker: activation
  never wedges on a dead embedder; everything degrades to lexical
- embeddings persist as %.4g comma lists in snapshots, parsed by both
  loaders; embedded_count in /api/stats tracks coverage
- engram_cosine_sim + http_delete_json exposed (DELETE now carries a
  body — the server's _auth scheme requires it)
- route_create_node honored only content/node_type/salience; label,
  importance, tier, tags were silently dropped (label defaulted to
  content). Now honored via engram_node_full.

Verified live: embedded_count 0->96 across activations, semantic-only
promotion observed (zero token overlap), snapshot round-trip intact.

lang/releases/v1.0.0-20260501/el_runtime.h

@@ -117,6 +117,15 @@ el_val_t  el_min(el_val_t a, el_val_t b);
 void      el_retain(el_val_t v);
 void      el_release(el_val_t v);
 
+/* ── Arena scoping ────────────────────────────────────────────────────────────
+ * el_arena_push() activates the string arena (if not already active) and
+ * returns a mark; el_arena_pop(mark) frees all strings allocated since that
+ * mark. Used by codegen for per-function/statement scoping and by long-running
+ * EL loops (e.g. the soul daemon's awareness tick) to reclaim per-iteration
+ * allocations. */
+el_val_t  el_arena_push(void);
+el_val_t  el_arena_pop(el_val_t mark);
+
 /* ── List ────────────────────────────────────────────────────────────────── */
 
 el_val_t  el_list_new(el_val_t count, ...);
@@ -142,6 +151,7 @@ el_val_t  http_get_with_headers(el_val_t url, el_val_t headers_map);
 el_val_t  http_post_with_headers(el_val_t url, el_val_t body, el_val_t headers_map);
 el_val_t  http_post_form_auth(el_val_t url, el_val_t form_body, el_val_t auth_header);
 el_val_t  http_delete(el_val_t url);
+el_val_t  http_delete_json(el_val_t url, el_val_t json_body);
 void      http_serve(el_val_t port, el_val_t handler);
 void      http_set_handler(el_val_t name);
 
@@ -167,6 +177,11 @@ void      http_set_handler(el_val_t name);
 void      http_serve_v2(el_val_t port, el_val_t handler);
 void      http_set_handler_v2(el_val_t name);
 
+/* Non-blocking variant of http_serve: runs the accept loop in a background
+ * pthread and returns immediately so the caller can continue (used by the
+ * soul daemon to run awareness_run() after starting its HTTP API). */
+void      http_serve_async(el_val_t port, el_val_t handler);
+
 /* Build an HTTP response envelope. `headers_json` should be a JSON object
  * literal like `{"WWW-Authenticate":"Basic"}` (or "" / "{}" for none). The
  * returned string carries the discriminator `{"el_http_response":1,...}`
@@ -576,6 +591,7 @@ el_val_t  engram_list_layers(void);
 el_val_t  engram_get_node(el_val_t id);
 void      engram_strengthen(el_val_t node_id);
 void      engram_forget(el_val_t node_id);
+el_val_t  engram_prune_telemetry(el_val_t older_than_ms);
 el_val_t  engram_node_count(void);
 el_val_t  engram_search(el_val_t query, el_val_t limit);
 el_val_t  engram_scan_nodes(el_val_t limit, el_val_t offset);
@@ -594,12 +610,14 @@ el_val_t  engram_load(el_val_t path);
  * can pass results straight through without round-tripping ElList/ElMap
  * through json_stringify. */
 el_val_t  engram_get_node_json(el_val_t id);
+el_val_t  engram_get_node_by_label(el_val_t label);
 el_val_t  engram_search_json(el_val_t query, el_val_t limit);
 el_val_t  engram_scan_nodes_json(el_val_t limit, el_val_t offset);
 el_val_t  engram_scan_nodes_by_type_json(el_val_t node_type, el_val_t limit, el_val_t offset);
 el_val_t  engram_neighbors_json(el_val_t node_id, el_val_t max_depth, el_val_t direction);
 el_val_t  engram_activate_json(el_val_t query, el_val_t depth);
 el_val_t  engram_stats_json(void);
+el_val_t  engram_cosine_sim(el_val_t id_a, el_val_t id_b);
 el_val_t  engram_list_layers_json(void);
 /* Working memory introspection — count, mean weight, and top-N snapshot.
  * Ported from el-compiler/runtime on 2026-06-30 self-review. */