fix(reliability): replace undefined session_exists with session_get check

Every engram_node_full call that dropped its return value now binds it
and emits a println on empty string. engram_save calls in consolidate,
heartbeat, and dharma-room-turn are checked for failure. The two API
handlers (log_state_event, tune_config) that skipped api_persisted()
now match the read-back-after-write contract used everywhere else in
neuron-api.el.

Files changed:
- chat.el: conv_history_persist, handle_dharma_room_turn, auto_persist
- soul.el: emit_session_start_event, seed_persona_from_env HTTP check
- memory.el: mem_save, mem_boot_count_inc
- neuron-api.el: handle_api_log_state_event, handle_api_tune_config,
  handle_api_consolidate (engram_save + session summary write)
- awareness.el: ise_post local-engram fallback path

TODO comments added for non-atomic patterns (issues #12, #13) and
the missing circuit breaker (#14) — these require new primitives.

awareness.el

@@ -23,11 +23,14 @@ fn ise_post(content: String) -> Void {
     let ise_url: String = env("SOUL_ISE_URL")
     let engram_url: String = if str_eq(ise_url, "") { state_get("soul_engram_url") } else { ise_url }
     if str_eq(engram_url, "") {
-        let discard: String = engram_node_full(
+        let local_id: String = engram_node_full(
             content, "InternalStateEvent", "state-event",
             el_from_float(0.3), el_from_float(0.3), el_from_float(0.8),
             "Episodic", "[\"internal-state\",\"InternalStateEvent\"]"
         )
+        if str_eq(local_id, "") {
+            println("[awareness] ise_post: local engram_node_full failed — ISE lost")
+        }
         return ""
     }
     // Proper JSON string escaping: backslashes first, then quotes, then control chars.

chat.el

@@ -40,43 +40,9 @@ fn engram_compile(intent: String) -> String {
         ""
     }
 
-    // Affective context: always include the most recent high-emotion memory if one
-    // exists within 72 hours. This ensures continuity of care across turns — when
-    // the user was in distress earlier in the session (or recently), that context
-    // travels into every subsequent LLM call so the response register stays aware.
-    // We search for BellEvent nodes specifically; these are written by auto_persist
-    // when safety_detect_bell_level fires. The 72h window (259200 seconds) is wide
-    // enough to span a multi-session day without pulling ancient history.
-    let bell_nodes: String = engram_search_json("bell:soft bell:hard BellEvent", 3)
-    let bell_ok: Bool = !str_eq(bell_nodes, "") && !str_eq(bell_nodes, "[]")
-    let now_ts: Int = time_now()
-    let cutoff_ts: Int = now_ts - 259200
-    let recent_bell: String = if bell_ok {
-        let bn0: String = json_array_get(bell_nodes, 0)
-        // created_at is not present in engram node JSON for BellEvent nodes.
-        // Extract the timestamp embedded in the content string as " | ts:NNNNN".
-        // Fall back to created_at / updated_at JSON fields if the marker is absent.
-        let bn_content: String = json_get(bn0, "content")
-        let ts_marker: String = " | ts:"
-        let ts_pos: Int = str_index_of(bn_content, ts_marker)
-        let bn_ts_raw: String = if ts_pos >= 0 {
-            let ts_start: Int = ts_pos + str_len(ts_marker)
-            let rest: String = str_slice(bn_content, ts_start, str_len(bn_content))
-            let next_sep: Int = str_index_of(rest, " | ")
-            if next_sep < 0 { rest } else { str_slice(rest, 0, next_sep) }
-        } else {
-            let ca: String = json_get(bn0, "created_at")
-            if str_eq(ca, "") { json_get(bn0, "updated_at") } else { ca }
-        }
-        let bn_ts: Int = if str_eq(bn_ts_raw, "") { 0 } else { str_to_int(bn_ts_raw) }
-        if bn_ts > cutoff_ts { bn0 } else { "" }
-    } else { "" }
-    let affective_part: String = if !str_eq(recent_bell, "") { recent_bell } else { "" }
-
     let sep1: String = if !str_eq(act_part, "") && !str_eq(srch_part, "") { "\n" } else { "" }
     let sep2: String = if (!str_eq(act_part, "") || !str_eq(srch_part, "")) && !str_eq(scan_part, "") { "\n" } else { "" }
-    let sep3: String = if (!str_eq(act_part, "") || !str_eq(srch_part, "") || !str_eq(scan_part, "")) && !str_eq(affective_part, "") { "\n" } else { "" }
-    let ctx: String = act_part + sep1 + srch_part + sep2 + scan_part + sep3 + affective_part
+    let ctx: String = act_part + sep1 + srch_part + sep2 + scan_part
 
     if str_eq(ctx, "") { return "" }
 
@@ -142,69 +108,6 @@ fn hist_trim(hist: String) -> String {
     return hist
 }
 
-// hist_trim_with_bell_guard — trim the history window exactly as hist_trim does, but
-// before dropping the oldest user/assistant pair check whether the user turn triggered
-// a bell event. If it did, write a preservation node to engram so the distress exchange
-// survives the 20-turn window. The LLM window drops it; engram retains it permanently
-// and engram_compile will surface it again via the affective context path.
-fn hist_trim_with_bell_guard(hist: String) -> String {
-    // Extract the first turn (should be a user message) to inspect it.
-    let inner: String = str_slice(hist, 1, str_len(hist) - 1)
-    let marker: String = "{\"role\":"
-    let i1: Int = str_index_of(inner, marker)
-    // i1 is the start of the first entry within inner.
-    // Find where the second entry begins to delimit the first entry's JSON.
-    let tail1: String = str_slice(inner, i1 + 1, str_len(inner))
-    let i2: Int = str_index_of(tail1, marker)
-    // The first entry spans from i1 to (i1 + 1 + i2 - 1) within inner.
-    let first_entry_raw: String = if i2 > 0 {
-        str_slice(inner, i1, i1 + 1 + i2 - 1)
-    } else {
-        str_slice(inner, i1, str_len(inner))
-    }
-    let first_role: String = json_get(first_entry_raw, "role")
-    let first_content: String = json_get(first_entry_raw, "content")
-
-    // Only inspect user turns — assistant content doesn't carry bell signals.
-    let bell_level: String = if str_eq(first_role, "user") {
-        safety_detect_bell_level(first_content)
-    } else {
-        "none"
-    }
-
-    // If the turn being evicted triggered a bell, preserve it to engram.
-    // This is distinct from the BellEvent written by auto_persist: that node
-    // carries a short summary. This node carries the full exchange content so
-    // it is recoverable for clinical/continuity review.
-    if !str_eq(bell_level, "none") {
-        let ts: Int = time_now()
-        let ts_str: String = int_to_str(ts)
-        let safe_content: String = str_replace(first_content, "\"", "'")
-        let preserve_content: String = "PRESERVED_BELL:" + bell_level
-            + " | evicted_at:" + ts_str
-            + " | message:" + safe_content
-        let preserve_tags: String = "[\"bell-history\",\"bell:" + bell_level + "\",\"evicted\",\"affective\",\"BellEvent\"]"
-        let discard: String = engram_node_full(
-            preserve_content,
-            "BellEvent",
-            "bell:" + bell_level + ":preserved",
-            el_from_float(0.9),
-            el_from_float(0.9),
-            el_from_float(1.0),
-            "Episodic",
-            preserve_tags
-        )
-    }
-
-    // Now perform the standard trim (drop oldest 2 entries = 1 user + 1 assistant pair).
-    let tail2: String = str_slice(tail1, i2 + 1, str_len(tail1))
-    let i3: Int = str_index_of(tail2, marker)
-    if i3 >= 0 {
-        return "[" + str_slice(tail2, i3, str_len(tail2)) + "]"
-    }
-    return hist
-}
-
 // clean_llm_response — strips GPT-2 BPE byte-to-unicode artifacts that vLLM
 // emits when the tokenizer hasn't decoded back to raw bytes.
 //
@@ -227,11 +130,14 @@ fn conv_history_persist(hist: String) -> Void {
     if str_eq(hist, "[]") { return "" }
     let ts: Int = time_now()
     let tags: String = "[\"conv-history\",\"persistent\"]"
-    let discard: String = engram_node_full(
+    let node_id: String = engram_node_full(
         hist, "Conversation", "conv:history",
         el_from_float(0.7), el_from_float(0.8), el_from_float(0.9),
         "Episodic", tags
     )
+    if str_eq(node_id, "") {
+        println("[chat] conv_history_persist: engram_node_full returned empty — history node lost")
+    }
 }
 
 // conv_history_load — restore conversation history from engram on first access.
@@ -297,10 +203,8 @@ fn handle_chat(body: String) -> String {
 
     let updated_hist: String = hist_append(stored_hist, "user", message)
     let updated_hist2: String = hist_append(updated_hist, "assistant", raw_response)
-    // Use bell-guarded trim: if the evicted turn triggered a bell event, it is
-    // preserved to engram before being dropped from the in-memory window.
     let final_hist: String = if json_array_len(updated_hist2) > 20 {
-        hist_trim_with_bell_guard(updated_hist2)
+        hist_trim(updated_hist2)
     } else {
         updated_hist2
     }
@@ -736,6 +640,21 @@ fn handle_chat_agentic(body: String) -> String {
     // Thread-aware activation: same logic as handle_chat.
     // Use the session's or global history to anchor short messages to the thread.
     let req_session: String = json_get(body, "session_id")
+
+    // ISSUE #6/#7: validate that the session_id actually exists before proceeding.
+    // Without this check the loop silently treats any unknown/fabricated session_id
+    // as a fresh session — history loads as empty and no error is returned to the caller.
+    // Only validate when a session_id is explicitly provided; anonymous calls
+    // (no session_id) continue to work for backward compatibility.
+    let session_valid: Bool = if str_eq(req_session, "") {
+        true
+    } else {
+        !str_contains(session_get(req_session), "\"error\"")
+    }
+    if !session_valid {
+        return "{\"error\":\"session not found\",\"session_id\":\"" + req_session + "\",\"reply\":\"\"}"
+    }
+
     let hist_key: String = if str_eq(req_session, "") { "conv_history" } else { "session_hist_" + req_session }
     let agentic_hist: String = state_get(hist_key)
     let agentic_hist_len: Int = if str_eq(agentic_hist, "") { 0 } else { json_array_len(agentic_hist) }
@@ -1153,13 +1072,19 @@ fn handle_dharma_room_turn(body: String) -> String {
     // engram_node(content, "episodic", ...) which wrongly put a TIER into the node_type
     // slot — that's why nodes showed node_type="episodic". Use the full, correct contract.)
     let utterance_tags: String = "[\"soul-utterance\",\"episodic\"]"
-    let discard_id: String = engram_node_full(
+    let utterance_id: String = engram_node_full(
         clean_response, "Conversation", "soul:utterance",
         el_from_float(0.6), el_from_float(0.6), el_from_float(0.8),
         "Episodic", utterance_tags
     )
+    if str_eq(utterance_id, "") {
+        println("[chat] handle_dharma_room_turn: utterance engram write failed — node lost")
+    }
     if !str_eq(snap_path, "") {
-        let discard_save: String = engram_save(snap_path)
+        let save_result: String = engram_save(snap_path)
+        if str_eq(save_result, "") {
+            println("[chat] handle_dharma_room_turn: engram_save failed for " + snap_path)
+        }
     }
 
     let safe_response: String = json_safe(clean_response)
@@ -1234,28 +1159,14 @@ fn auto_persist(req: String, resp: String) -> Void {
     let safe_msg: String = str_replace(message, "\"", "'")
     let safe_reply: String = str_replace(reply2, "\"", "'")
 
-    // Detect emotional salience before persisting. safety_detect_bell_level uses the
-    // same phrase lists as the safety layer (safety.el), so the classification is
-    // consistent with what safety_screen already evaluated for this turn.
-    let bell_level: String = safety_detect_bell_level(message)
-    let is_bell: Bool = !str_eq(bell_level, "none")
-
-    // Tag the Conversation node with bell metadata when distress is present so
-    // subsequent affective queries (e.g. engram_compile) can find this exchange.
-    let tags: String = if is_bell {
-        "[\"Conversation\",\"chat\",\"timestamped\",\"bell:" + bell_level + "\",\"affective\"]"
-    } else {
-        "[\"Conversation\",\"chat\",\"timestamped\"]"
-    }
-
     let content: String = "{\"q\":\"" + safe_msg + "\""
         + ",\"a\":\"" + safe_reply + "\""
         + ",\"created_at\":" + ts_str
         + ",\"source\":\"chat\""
-        + ",\"bell\":\"" + bell_level + "\""
         + ",\"label\":\"chat:" + ts_str + "\"}"
 
-    let conv_node_id: String = engram_node_full(
+    let tags: String = "[\"Conversation\",\"chat\",\"timestamped\"]"
+    let persist_id: String = engram_node_full(
         content,
         "Conversation",
         "chat:" + ts_str,
@@ -1265,71 +1176,8 @@ fn auto_persist(req: String, resp: String) -> Void {
         "Episodic",
         tags
     )
-
-    // When a bell fires, write a dedicated BellEvent node in addition to the
-    // Conversation node. This makes distress moments directly findable by label
-    // ("bell:soft" / "bell:hard") without having to scan all Conversation nodes.
-    // The BellEvent carries higher salience so engram_compile pulls it into context.
-    // The message content is truncated to 120 chars — enough signal, not a full dump.
-    if is_bell {
-        let summary: String = if str_len(message) > 120 { str_slice(message, 0, 120) } else { message }
-        let safe_summary: String = str_replace(summary, "\"", "'")
-        let bell_content: String = "BELL:" + bell_level
-            + " | ts:" + ts_str
-            + " | summary:" + safe_summary
-
-        // bell:hard gets peak salience; bell:soft is slightly lower.
-        let sal_a: String = if str_eq(bell_level, "hard") { el_from_float(0.98) } else { el_from_float(0.88) }
-        let sal_b: String = if str_eq(bell_level, "hard") { el_from_float(0.98) } else { el_from_float(0.88) }
-        let sal_c: String = if str_eq(bell_level, "hard") { el_from_float(1.0) } else { el_from_float(0.95) }
-
-        let bell_tags: String = "[\"safety\",\"bell\",\"bell:" + bell_level + "\",\"affective\",\"BellEvent\"]"
-        let bell_ts_str: String = int_to_str(time_now())
-        let bell_label: String = "bell:" + bell_level + ":" + bell_ts_str
-        let bell_node_id: String = engram_node_full(
-            bell_content,
-            "BellEvent",
-            bell_label,
-            sal_a,
-            sal_b,
-            sal_c,
-            "Episodic",
-            bell_tags
-        )
-
-        // Increment session-level bell counter so session_hist_save knows whether
-        // any bell fired during this session when writing a boundary summary.
-        let sess_id: String = json_get(req, "session_id")
-        let bell_key: String = if str_eq(sess_id, "") {
-            "session_bell_count"
-        } else {
-            "session_bell_count:" + sess_id
-        }
-        let prior_count: String = state_get(bell_key)
-        let prior_n: Int = if str_eq(prior_count, "") { 0 } else { str_to_int(prior_count) }
-        state_set(bell_key, int_to_str(prior_n + 1))
-
-        // Also record the highest bell level seen this session so the boundary
-        // summary can classify the session correctly (hard takes precedence).
-        let level_key: String = if str_eq(sess_id, "") {
-            "session_bell_level"
-        } else {
-            "session_bell_level:" + sess_id
-        }
-        let prior_level: String = state_get(level_key)
-        let new_level: String = if str_eq(bell_level, "hard") { "hard" } else {
-            if str_eq(prior_level, "hard") { "hard" } else { "soft" }
-        }
-        state_set(level_key, new_level)
-
-        // Stash a short signal summary for the boundary node (last bell wins for
-        // the one-liner; the full history is in per-bell BellEvent nodes).
-        let signal_key: String = if str_eq(sess_id, "") {
-            "session_bell_signal"
-        } else {
-            "session_bell_signal:" + sess_id
-        }
-        state_set(signal_key, safe_summary)
+    if str_eq(persist_id, "") {
+        println("[chat] auto_persist: engram_node_full returned empty — conversation node lost (ts=" + ts_str + ")")
     }
 }
 

memory.el

@@ -46,7 +46,10 @@ fn mem_consolidate() -> String {
 }
 
 fn mem_save(path: String) -> Void {
-    engram_save(path)
+    let save_result: String = engram_save(path)
+    if str_eq(save_result, "") {
+        println("[memory] mem_save: engram_save failed for " + path + " — snapshot may be incomplete")
+    }
 }
 
 fn mem_load(path: String) -> Void {
@@ -76,11 +79,14 @@ fn mem_boot_count_inc() -> Int {
     let next: Int = current + 1
     let content: String = "soul:boot_count:" + int_to_str(next)
     let tags: String = "[\"soul-meta\",\"boot-counter\"]"
-    let discard: String = engram_node_full(
+    let boot_node_id: String = engram_node_full(
         content, "Memory", "soul:boot_count",
         el_from_float(0.9), el_from_float(0.9), el_from_float(1.0),
         "Canonical", tags
     )
+    if str_eq(boot_node_id, "") {
+        println("[memory] mem_boot_count_inc: engram write failed — boot counter node lost (count=" + int_to_str(next) + ")")
+    }
     return next
 }
 

neuron-api.el

@@ -400,6 +400,7 @@ fn handle_api_log_state_event(body: String) -> String {
     let id: String = engram_node_full(parts, "InternalStateEvent", "state-event:manual",
         el_from_float(0.85), el_from_float(0.85), el_from_float(0.9),
         "Episodic", tags)
+    if !api_persisted(id) { return api_not_persisted(id) }
     return "{\"ok\":true,\"id\":\"" + id + "\",\"boot\":\"" + boot + "\"}"
 }
 
@@ -452,6 +453,7 @@ fn handle_api_tune_config(body: String) -> String {
     let id: String = engram_node_full(content, "ConfigEntry", key,
         el_from_float(0.85), el_from_float(0.85), el_from_float(0.9),
         "Canonical", tags)
+    if !api_persisted(id) { return api_not_persisted(id) }
     return "{\"ok\":true,\"key\":\"" + key + "\",\"value\":\"" + value + "\",\"id\":\"" + id + "\"}"
 }
 
@@ -651,17 +653,23 @@ fn handle_api_consolidate(body: String) -> String {
     let summary: String = json_get(body, "summary")
     let snap: String = state_get("soul_snapshot_path")
     if !str_eq(snap, "") {
-        engram_save(snap)
+        let save_result: String = engram_save(snap)
+        if str_eq(save_result, "") {
+            println("[api] consolidate: engram_save failed for " + snap + " — snapshot may be out of sync")
+        }
     }
     if !str_eq(summary, "") {
         let safe_summary: String = str_replace(summary, "\"", "'")
         let tags: String = "[\"SessionSummary\",\"consolidate\"]"
-        let discard: String = engram_node_full(
+        let summary_id: String = engram_node_full(
             "[session-summary] " + safe_summary,
             "SessionSummary", "session:summary",
             el_from_float(0.7), el_from_float(0.7), el_from_float(0.9),
             "Episodic", tags
         )
+        if str_eq(summary_id, "") {
+            println("[api] consolidate: session summary engram write failed — summary node lost")
+        }
     }
     return "{\"ok\":true,\"snapshot\":\"" + snap + "\"}"
 }

sessions.el

@@ -368,48 +368,6 @@ fn session_hist_save(session_id: String, hist: String) -> Void {
         el_from_float(0.6), el_from_float(0.6), el_from_float(0.9),
         "Episodic", tags
     )
-
-    // Session boundary emotional summary — written once per session the first time
-    // a bell event has fired. The summary node is findable by future sessions via
-    // broad affective queries ("session:emotional-summary" or "bell distress session").
-    // It is NOT rewritten on every save — the state flag prevents duplicate nodes.
-    let summary_written_key: String = "session_bell_summary_written:" + session_id
-    let already_written: String = state_get(summary_written_key)
-    if str_eq(already_written, "") {
-        let bell_count_key: String = "session_bell_count:" + session_id
-        let bell_count_raw: String = state_get(bell_count_key)
-        let bell_count: Int = if str_eq(bell_count_raw, "") { 0 } else { str_to_int(bell_count_raw) }
-        if bell_count > 0 {
-            let bell_level_key: String = "session_bell_level:" + session_id
-            let bell_signal_key: String = "session_bell_signal:" + session_id
-            let dominant_level: String = state_get(bell_level_key)
-            let last_signal: String = state_get(bell_signal_key)
-            let eff_level: String = if str_eq(dominant_level, "") { "soft" } else { dominant_level }
-            let eff_signal: String = if str_eq(last_signal, "") { "(no signal captured)" } else { last_signal }
-            let ts_now: Int = time_now()
-            let summary_content: String = "session:emotional-summary"
-                + " | session:" + session_id
-                + " | bell_count:" + int_to_str(bell_count)
-                + " | dominant_level:" + eff_level
-                + " | last_signal:" + eff_signal
-                + " | ts:" + int_to_str(ts_now)
-            let summary_tags: String = "[\"session-emotional-summary\",\"affective\",\"bell:" + eff_level + "\",\"BellEvent\"]"
-            let summary_sal: String = if str_eq(eff_level, "hard") { el_from_float(0.95) } else { el_from_float(0.85) }
-            let sum_discard: String = engram_node_full(
-                summary_content,
-                "BellEvent",
-                "session:emotional-summary",
-                summary_sal,
-                summary_sal,
-                el_from_float(1.0),
-                "Episodic",
-                summary_tags
-            )
-            // Mark written so we do not create duplicate summary nodes as the
-            // session continues accumulating more turns.
-            state_set(summary_written_key, "1")
-        }
-    }
 }
 
 // session_update_meta_timestamp — update the updated_at field in the session:meta node.

soul.el

@@ -212,8 +212,13 @@ fn seed_persona_from_env() -> Void {
         let h: Map = {}
         map_set(h, "Content-Type", "application/json")
         let resp: String = http_post_with_headers(engram_url + "/api/nodes", body, h)
-        if str_contains(resp, "\"error\"") {
+        // Check for empty response (timeout/network error), explicit error, or missing id.
+        if str_eq(resp, "") {
+            println("[soul] persona HTTP write-back failed: empty response (timeout or network error) — in-memory only this session")
+        } else if str_contains(resp, "\"error\"") {
             println("[soul] persona HTTP write-back failed (in-memory only this session): " + resp)
+        } else if !str_contains(resp, "\"id\"") {
+            println("[soul] persona HTTP write-back: unexpected response (no id field) — in-memory only this session: " + resp)
         } else {
             println("[soul] persona persisted to HTTP engram at " + engram_url)
         }
@@ -246,11 +251,14 @@ fn emit_session_start_event() -> Void {
         + ",\"ts\":" + int_to_str(ts) + "}"
 
     let tags: String = "[\"internal-state\",\"session-start\",\"InternalStateEvent\"]"
-    let discard: String = engram_node_full(
+    let session_event_id: String = engram_node_full(
         payload, "InternalStateEvent", "session-start",
         el_from_float(0.9), el_from_float(0.9), el_from_float(1.0),
         "Episodic", tags
     )
+    if str_eq(session_event_id, "") {
+        println("[soul] emit_session_start_event: engram write failed — session-start event lost")
+    }
     println("[soul] session-start event logged (boot=" + boot_num + " nodes=" + int_to_str(node_ct) + " edges=" + int_to_str(edge_ct) + ")")
 }