self-review 2026-07-25: short-term inhibition-of-return + explicit embedding backfill

Working memory was winner-take-all: suppression_count never entered the
promotion score and was reset on promotion, so two high-salience nodes
pinned a saturated 24-slot WM for hours. Add Lebiere-Best (CogSci 2009)
short-term inhibition — raw_wm *= t_n/(t_n + 120s) from the most recent
recorded access — producing emergent round-robin over WM candidates.

embedded_count stalled at 93/12175 after restart: the lazy backfill only
runs inside engram_activate, which nothing calls on the authoritative
store in production, and in-RAM vectors were never snapshotted. Add
engram_embed_backfill(n) + GET/POST /api/embed-backfill route that
persists the canonical snapshot whenever it embeds anything; the soul
heartbeat pumps it at 32/min.

engram/src/server.el

@@ -246,6 +246,28 @@ fn route_health(method: String, path: String, body: String) -> String {
     "{\"status\":\"ok\",\"engine\":\"engram-runtime-native\"}"
 }
 
+// route_embed_backfill — GET/POST /api/embed-backfill?n=48
+//
+// (2026-07-25 self-review) The lazy embedding backfill runs only inside
+// engram_activate, and nothing in production calls /api/activate on this
+// store — the soul's curiosity loop activates its own in-process graph.
+// After a restart from a snapshot without vectors, embedded_count stalled
+// at 93/12175 and would never recover. This route lets the soul's
+// heartbeat pump the backfill explicitly (48/min clears a 12k backlog in
+// ~4h). Persists the canonical snapshot whenever new vectors were
+// generated — the 2026-07-25 regression happened precisely because 3747
+// in-RAM embeddings were never snapshotted before a restart. Self-
+// limiting: once coverage is full, embedded=0 and no save occurs.
+fn route_embed_backfill(method: String, path: String, body: String) -> String {
+    let n: Int = query_int(path, "n", 32)
+    let result: String = engram_embed_backfill(n)
+    let done: Float = json_get_float(result, "embedded")
+    if done > 0.0 {
+        let saved: Int = persist_canonical()
+    }
+    return result
+}
+
 // route_sync — return a snapshot of non-ISE/non-Working nodes for the soul daemon
 // to merge into its in-process graph via engram_load_merge.
 //
@@ -495,6 +517,11 @@ fn handle_request(method: String, path: String, body: String) -> String {
         return route_sync(method, path, body)
     }
 
+    // Embedding backfill — pumped by the soul heartbeat (2026-07-25)
+    if str_eq(clean, "/api/embed-backfill") {
+        return route_embed_backfill(method, path, body)
+    }
+
     "{\"error\":\"not found\",\"path\":\"" + clean + "\"}"
 }