soul: persist sessions across restarts via local snapshot

On startup, prefer the local engram snapshot if it has >50 nodes.
HTTP Engram is only used on first boot (no snapshot yet). This means
sessions, conversation history, and in-process state survive daemon
restarts.

awareness.el: sync source with compiled binary (periodic mem_save
on heartbeat was already in the binary but not in source).

Rebuilds soul.c with the new startup logic and ships updated binary.

awareness.el

@@ -440,6 +440,12 @@ fn awareness_run() -> Void {
         if should_beat {
             emit_heartbeat()
             state_set("soul.last_beat_ts", int_to_str(now_ts))
+            // Persist in-process Engram (sessions, memories, conversation nodes)
+            // to local snapshot so they survive restarts.
+            let snap_path: String = state_get("soul_snapshot_path")
+            if !str_eq(snap_path, "") {
+                mem_save(snap_path)
+            }
         }
 
         // Curiosity scan: idle-gated AND wall-clock based. Only fires when the

soul.el

@@ -251,11 +251,17 @@ println("[soul] boot - cgi=" + soul_cgi_id + " port=" + int_to_str(port))
 
 let using_http_engram: Bool = !str_eq(engram_url_raw, "")
 
-if using_http_engram {
-    // Bootstrap in-memory Engram store from the running HTTP Engram server.
-    // Fetch all nodes and edges, compose a snapshot JSON, write to a temp
-    // file, and load it. The HTTP Engram owns persistence — we do not save back.
-    println("[soul] engram -> HTTP " + engram_url_raw)
+// Always try local snapshot first. If it has content (>50 nodes) it was
+// previously seeded from HTTP Engram and is kept up-to-date by the awareness
+// loop — use it. This preserves sessions and memories across restarts.
+// HTTP Engram is only used for the very first boot (empty/absent snapshot).
+engram_load(snapshot)
+let local_node_count: Int = engram_node_count()
+let snapshot_usable: Bool = local_node_count > 50
+
+if using_http_engram && !snapshot_usable {
+    // First boot or empty/corrupt snapshot: seed from HTTP Engram.
+    println("[soul] engram -> HTTP " + engram_url_raw + " (no local snapshot, first boot)")
     let nodes_json: String = http_get(engram_url_raw + "/api/nodes?limit=10000")
     let edges_json: String = http_get(engram_url_raw + "/api/edges")
     let nodes_part: String = if str_eq(nodes_json, "") { "[]" } else { nodes_json }
@@ -266,9 +272,7 @@ if using_http_engram {
     engram_load(tmp_path)
     println("[soul] loaded from HTTP Engram - nodes=" + int_to_str(engram_node_count()) + " edges=" + int_to_str(engram_edge_count()))
 } else {
-    println("[soul] engram -> " + snapshot)
-    engram_load(snapshot)
-    println("[soul] loaded - nodes=" + int_to_str(engram_node_count()) + " edges=" + int_to_str(engram_edge_count()))
+    println("[soul] loaded from local snapshot - nodes=" + int_to_str(local_node_count) + " edges=" + int_to_str(engram_edge_count()))
 }
 
 load_identity_context()