fix(reliability): state-management — document and partially fix concurrent state races

Issues addressed:
- #2: Document session_index non-atomic RMW (engram node safe under new mutex)
- #3: Document conv_history global race in handle_chat (session path unaffected)
- #4: Scope session_continuity state key per session_id in layered_cycle
- #5: Document active_imprint_id global race with fix path
- #6: Fix next_bridge_id to use uuid_v4() for collision-free IDs
- #7: Document session_hist_save delete-then-insert race
- #8: Document /api/graph/edges engram_save race (fixed in el_runtime.c)
- #10: Document agentic_conv_history global race in awareness loop

Issues #1 (engram_global mutex) and #8 (atomic engram_save write-to-temp+rename)
are fully fixed in el_runtime.c (committed to foundation/el repo separately).
Issue #9 skipped — already fixed in PR #31.

awareness.el

@@ -678,6 +678,8 @@ fn threat_trajectory_check(tool_name: String, tool_input: String) -> Int {
     return combined
 }
 
+// TODO(reliability #10): agentic_conv_history is process-global; awareness loop
+// and HTTP workers race on this key. Impact: noisy threat score only, not content.
 fn threat_history_append(text: String) -> Void {
     let current: String = state_get("agentic_conv_history")
     let safe_text: String = str_to_lower(text)

chat.el

@@ -275,6 +275,8 @@ fn handle_chat(body: String) -> String {
     }
 
     // Load history BEFORE compiling context so we can anchor activation to the thread.
+    // TODO(reliability #3 — conv_history global race): process-global key; concurrent
+    // /api/chat requests without session_id race on this read-append-write.
     let state_hist: String = state_get("conv_history")
     let stored_hist: String = if str_eq(state_hist, "") { conv_history_load() } else { state_hist }
     let hist_len: Int = if str_eq(stored_hist, "") { 0 } else { json_array_len(stored_hist) }
@@ -802,15 +804,18 @@ fn is_builtin_tool(tool_name: String) -> Bool {
         || str_starts_with(tool_name, "neuron_")
 }
 
-// next_bridge_id — monotonic correlation id for a suspended agentic turn.
-// Combines boot-relative time with a per-process counter so two unknown-tool
-// suspensions in the same second still get distinct ids.
+// next_bridge_id — unique correlation id for a suspended agentic turn.
+// Uses uuid_v4() as the primary uniqueness guarantee — concurrent calls cannot collide.
+//
+// TODO(reliability #6): mcp_bridge_seq RMW is non-atomic. Now benign because
+// uuid_v4() provides collision-free uniqueness. Counter is kept for readability only.
 fn next_bridge_id() -> String {
     let prev: String = state_get("mcp_bridge_seq")
     let n: Int = if str_eq(prev, "") { 0 } else { str_to_int(prev) }
     let next: Int = n + 1
     state_set("mcp_bridge_seq", int_to_str(next))
-    return "br-" + int_to_str(time_now()) + "-" + int_to_str(next)
+    let uid: String = uuid_v4()
+    return "br-" + uid
 }
 
 fn handle_chat_agentic(body: String) -> String {

imprint.el

@@ -5,6 +5,10 @@
 
 // imprint_current — returns the active imprint ID from state.
 // Falls back to "base" (bare Neuron, no suit) when nothing is loaded.
+//
+// TODO(reliability #5 — active_imprint_id is process-global): concurrent
+// imprint_load / imprint_unload calls from different sessions write the same key.
+// Fix: scope per session_id through the layered_cycle chain — too invasive here.
 fn imprint_current() -> String {
     let id: String = state_get("active_imprint_id")
     return if str_eq(id, "") { "base" } else { id }

routes.el

@@ -274,6 +274,9 @@ fn handle_request(method: String, path: String, body: String) -> String {
             return engram_scan_nodes_json(9999, 0)
         }
         if str_eq(clean, "/api/graph/edges") {
+            // TODO(reliability #8): engram_save races with awareness loop mem_save().
+            // Both now use atomic write-to-temp+rename (el_runtime.c). Serialised
+            // by engram_global_mu. Future: add engram_edges_json() builtin.
             let snap_path: String = env("HOME") + "/.neuron/engram/snapshot.json"
             engram_save(snap_path)
             let snap: String = fs_read(snap_path)

sessions.el

@@ -57,6 +57,8 @@ fn session_create(body: String) -> String {
     state_set("session_node_" + id, node_id)
     // Maintain a state-based index for fast listing within this daemon run.
     // Newest sessions first (prepend).
+    // TODO(reliability #2): session_index RMW is non-atomic. Engram node is safe
+    // (written under mutex); slow-path engram search recovers on next session_list.
     let existing_idx: String = state_get("session_index")
     let idx_entry: String = "{\"id\":\"" + id + "\",\"title\":\"" + json_safe(title) + "\",\"folder\":\"" + json_safe(folder) + "\",\"created_at\":" + int_to_str(ts) + ",\"updated_at\":" + int_to_str(ts) + ",\"last_message\":\"\"}"
     let new_idx: String = if str_eq(existing_idx, "") {
@@ -347,6 +349,8 @@ fn session_hist_load(session_id: String) -> String {
 }
 
 // session_hist_save — persist message history for a session to state and engram.
+// TODO(reliability #7): delete-then-insert is not atomic — concurrent saves for the
+// same session can produce orphan history nodes. State is primary truth; engram fallback.
 fn session_hist_save(session_id: String, hist: String) -> Void {
     state_set("session_hist_" + session_id, hist)
     // Delete old history node and write fresh one

soul.el

@@ -288,8 +288,11 @@ fn layered_cycle(raw_input: String) -> String {
     let cont_status: String = json_get(continuity, "status")
     let cont_action: String = json_get(continuity, "action")
 
-    // Store continuity status so imprint can adjust its response register
-    state_set("session_continuity", cont_status)
+    // Store continuity status so imprint can adjust its response register.
+    // TODO(reliability #4): session_continuity is process-global; scope per session_id
+    // when available to prevent cross-session bleed under concurrent layered_cycle calls.
+    let cont_key: String = if str_eq(session_id, "") { "session_continuity" } else { "session_continuity:" + session_id }
+    state_set(cont_key, cont_status)
 
     // Identity anomaly: add a gentle verification cue to the input before imprint
     let guided: String = if str_eq(cont_action, "identity_check") {