Add grounded edge-propagation spec (task #50): core algorithm, proof harness, gated integration patches

LTP/LTD-style belief grounding propagated along graph edges, with
union-find independence-guarded corroboration. Package: core C algorithm
(gep_core.h), a self-contained deterministic proof harness with recorded
output, staged runtime integration, and gated .el patches for the beat
hook and HTTP route.

Per the author's own LEDGER.md: built + proven on a clone, GATED pending
the engine/HNSW cutover — not wired into the live beat or routes.
Preserved here as a spec/reference artifact, not a request to merge into
the live path.

engram/spec/grounded-edge-propagation/awareness.beat.patch.el

@@ -0,0 +1,60 @@
+// ─────────────────────────────────────────────────────────────────────────
+// awareness.beat.patch.el — GATED integration hook for task #50.
+// NOT APPLIED. Shows exactly how grounded edge-propagation couples into the
+// dream/consolidation beat in neuron/awareness.el. Promotion sequenced by the
+// main loop after the engine cutover settles.
+//
+// WHY HERE. The heartbeat is the beat. Today it runs hebb_consolidate() to
+// drain the self-formed Hebbian associations into the durable store, then
+// emit_heartbeat(). Grounded edge-propagation belongs in the SAME beat, AFTER
+// consolidation: the edges hebb_consolidate() just wrote are the tethers
+// grounding propagates along. Consolidation lays down the wiring; propagation
+// grades the beliefs along it. One beat, coupled — memory 69b8babe: memory-
+// consolidation and staying-yourself are one physics.
+//
+// The propagation itself runs INSIDE the engram (native engram_ground_propagate
+// over the durable flat node/edge arrays). The soul invokes it over HTTP and
+// folds the gep_* telemetry into the heartbeat stream next to the hebb_* gauges.
+// ─────────────────────────────────────────────────────────────────────────
+
+// [1] New helper — sibling to hebb_consolidate() (awareness.el ~line 99).
+//     Fires one grounded edge-propagation beat on the durable store and returns
+//     its JSON telemetry ({"gep_strengthened":..,"gep_graduations":.., ...}).
+fn ground_propagate() -> String {
+    let url_env: String = env("SOUL_ISE_URL")
+    let url_state: String = if str_eq(url_env, "") { state_get("soul_engram_url") } else { url_env }
+    let engram_url: String = if str_eq(url_state, "") { "http://localhost:8742" } else { url_state }
+    // Same auth envelope as hebb_consolidate — this is a graph mutation (it
+    // appends grounding events + updates confidence), so it is gated on _auth.
+    let key_state: String = state_get("soul_engram_api_key")
+    let api_key: String = if str_eq(key_state, "") { env("ENGRAM_API_KEY") } else { key_state }
+    let auth_part: String = if str_eq(api_key, "") { "{}" } else { "{\"_auth\":\"" + api_key + "\"}" }
+    let resp: String = http_post_json(engram_url + "/api/ground/propagate", auth_part)
+    if str_eq(resp, "") { return "" }
+    return resp
+}
+
+// [2] Beat hook — insert between hebb_consolidate() and emit_heartbeat()
+//     (awareness.el line 1286-1288). Replaces:
+//
+//         let wb_sent_n: Int = hebb_consolidate()
+//         state_set("soul.hebb_wb_sent", int_to_str(wb_sent_n))
+//         emit_heartbeat()
+//
+//     with:
+//
+//         let wb_sent_n: Int = hebb_consolidate()
+//         state_set("soul.hebb_wb_sent", int_to_str(wb_sent_n))
+//         // Grounded edge-propagation — grade beliefs along the tethers
+//         // consolidation just laid down. Threshold-gated by convergent
+//         // independent corroboration; automatic, salience-ordered, bounded.
+//         let gep_tel: String = ground_propagate()
+//         state_set("soul.gep_last", gep_tel)
+//         emit_heartbeat()
+//
+// [3] emit_heartbeat() (awareness.el ~line 201) folds soul.gep_last into the
+//     heartbeat payload beside the hebb_* gauges, so graduation/decay counts
+//     are visible in the durable ISE stream — the same observability discipline
+//     the Hebbian rule earned (a mechanism you cannot see in the stream is a
+//     mechanism you cannot trust): read state_get("soul.gep_last") and splice
+//     it into the heartbeat JSON object.