fix(reliability): conversation history

chat.el

@@ -254,18 +254,39 @@ fn hist_append(hist: String, role: String, content: String) -> String {
     return "[" + inner + "," + entry + "]"
 }
 
+// hist_trim — drop the oldest two entries from a history JSON array.
+//
+// Issue #5 (BROKEN 20-TURN TRIM) + Issue #10 (OFF-BY-ONE): the original code uses
+// str_index_of to find '{"role":' markers by raw string scanning. If any message content
+// contains the literal string '{"role":' (e.g. the LLM quoted JSON), the marker search
+// lands inside a content value and the resulting slice is malformed. Additionally, the
+// function had no minimum-retained-count guard.
+//
+// Fix: use json_array_len / json_array_get to work at the structural level, immune to
+// content containing marker strings. Drop entries 0 and 1 (oldest user+assistant pair)
+// and rebuild from entry 2 onward. Minimum retained count: 2 entries (never over-trim).
 fn hist_trim(hist: String) -> String {
-    let inner: String = str_slice(hist, 1, str_len(hist) - 1)
-    let marker: String = "{\"role\":"
-    let i1: Int = str_index_of(inner, marker)
-    let tail1: String = str_slice(inner, i1 + 1, str_len(inner))
-    let i2: Int = str_index_of(tail1, marker)
-    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)) + "]"
+    let total: Int = json_array_len(hist)
+    // Safety: never trim below 2 entries. If already at or below the minimum, return unchanged.
+    if total <= 2 {
+        return hist
     }
-    return hist
+    // Drop entry 0 and entry 1 (oldest user+assistant pair). Rebuild from entry 2 onward.
+    let result: String = ""
+    let i: Int = 2
+    while i < total {
+        let entry: String = json_array_get(hist, i)
+        let result = if str_eq(result, "") {
+            entry
+        } else {
+            result + "," + entry
+        }
+        let i = i + 1
+    }
+    if str_eq(result, "") {
+        return hist
+    }
+    return "[" + result + "]"
 }
 
 // hist_trim_with_bell_guard — trim the history window exactly as hist_trim does, but
@@ -347,29 +368,72 @@ fn clean_llm_response(s: String) -> String {
 }
 
 // conv_history_persist — save conversation history to engram for cross-restart continuity.
-// Stores as a Conversation node. Overwrites by using consistent label "conv:history".
+// Stores as a Conversation node with label "conv:history".
+//
+// Issue #4 (OVERWRITE WITHOUT DELETE): engram_node_full behaviour on duplicate labels is
+// implementation-defined. If it appends rather than upserts, stale older nodes accumulate.
+// TODO: replace with explicit delete-then-create once engram exposes a label-scoped delete API.
+//
+// Issue #7 (DUAL STORAGE): auto_persist() also writes a per-turn Conversation node per turn.
+// Both run every turn for different purposes (rolling array vs. Q&A snapshot). Documented here.
 fn conv_history_persist(hist: String) -> Void {
     if str_eq(hist, "") { return "" }
     if str_eq(hist, "[]") { return "" }
-    let ts: Int = time_now()
+    // Issue #6 (PARTIAL-WRITE GUARD): refuse to persist a blob that is not a complete JSON
+    // array. A truncated write starting with '[' but missing ']' passes the old
+    // str_starts_with check and would overwrite a good node with a corrupt one.
+    if !str_starts_with(hist, "[") { return "" }
+    if !str_contains(hist, "]") { return "" }
     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
     )
+    // Issue #2 (SILENT FAILURE): surface write failures in logs rather than dropping silently.
+    if str_eq(node_id, "") {
+        println("[chat] conv_history_persist: engram_node_full returned empty — history node may be lost")
+    }
 }
 
 // conv_history_load — restore conversation history from engram on first access.
-// Returns the most recent "conv:history" node content, or "" if none found.
+//
+// Issue #1 (ASYMMETRIC PERSIST/LOAD): original code loaded only via vector search, which
+// is not symmetric with the label-based write in conv_history_persist. A cold or corrupt
+// vector index returns [] even when the node exists on disk. Fixed by trying a label-based
+// fetch (engram_get_node_by_label) first, falling back to vector search only when that fails.
+//
+// Issue #2 (SILENT LOAD FAILURE): all failure paths now emit a log line so history loss
+// is visible rather than silently treated as a first-turn conversation.
+//
+// Issue #6 (PARTIAL-WRITE GUARD): content must start with '[' AND contain ']' before
+// being accepted — a truncated write that starts with '[' but has no ']' would pass the
+// old str_starts_with check and cause downstream json_array_len to malfunction.
 fn conv_history_load() -> String {
+    // Primary: label-based fetch — symmetric with persist, immune to vector index drift.
+    let label_node: String = engram_get_node_by_label("conv:history")
+    let label_ok: Bool = !str_eq(label_node, "") && !str_eq(label_node, "null")
+    if label_ok {
+        let label_content: String = json_get(label_node, "content")
+        let label_valid: Bool = str_starts_with(label_content, "[") && str_contains(label_content, "]")
+        if label_valid {
+            return label_content
+        }
+        // Label node exists but content is invalid — partial write or corruption.
+        println("[chat] conv_history_load: label node found but content invalid — falling back to vector search")
+    }
+
+    // Fallback: vector search — covers nodes indexed before this fix, or on cold index.
     let results: String = engram_search_json("conv:history", 3)
     if str_eq(results, "") { return "" }
     if str_eq(results, "[]") { return "" }
     let node: String = json_array_get(results, 0)
     let content: String = json_get(node, "content")
-    // Validate it looks like a JSON array
-    if !str_starts_with(content, "[") { return "" }
+    // Issue #6: full partial-write guard — require both '[' prefix AND ']' presence.
+    if !str_starts_with(content, "[") || !str_contains(content, "]") {
+        println("[chat] conv_history_load: vector search result content invalid — treating as first turn")
+        return ""
+    }
     return content
 }
 
@@ -380,6 +444,13 @@ fn handle_chat(body: String) -> String {
     }
 
     // Load history BEFORE compiling context so we can anchor activation to the thread.
+    // Issue #3 (NO RECOVERY PATH): when conv_history_load() returns "" (corrupted node,
+    // missing embeddings, search failure), handle_chat treats it identically to a genuine
+    // first-turn conversation — no retry, no ID fallback, no caller signal. The old history
+    // node also sits as an orphaned entry in engram and is never cleaned up. The improvements
+    // in conv_history_load() (Issues #1, #2) reduce false negatives, but a full recovery path
+    // requires caller-level state changes too invasive for a targeted fix.
+    // TODO: add a load-failure signal to the response envelope so callers can surface it.
     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) }
@@ -500,6 +571,11 @@ fn handle_chat(body: String) -> String {
 
     // ISSUE 9: add safety_augment_system to primary /api/chat path.
     // handle_chat was the only LLM path missing bell directive injection.
+    // Safety augmentation on the main chat path. Previously only applied on the
+    // handle_chat_as_soul / handle_dharma_room_turn paths. The phrase-list bell
+    // detector (safety_augment_system) was absent from handle_chat, so a user
+    // expressing crisis in the primary conversational UI bypassed soft/hard
+    // directive injection entirely. Applying it here before every llm_call_system.
     let full_system = safety_augment_system(full_system, message)
 
     let raw_response: String = llm_call_system(model, full_system, message)
@@ -518,6 +594,11 @@ fn handle_chat(body: String) -> String {
     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.
+    // Issue #8 (NO MAX SIZE GUARD): the 20-turn count limit bounds entry count, but individual
+    // messages can be arbitrarily large (up to max_tokens = 4096 tokens each). At 20 turns the
+    // history blob can reach ~80KB before trim fires. engram_node_full has no apparent size cap.
+    // A byte-length cap would require truncating or summarising entries — too invasive here.
+    // TODO: add a byte-length cap (e.g. 32KB) that drops oldest entries until under limit.
     let final_hist: String = if json_array_len(updated_hist2) > 20 {
         hist_trim_with_bell_guard(updated_hist2)
     } else {
@@ -1035,12 +1116,23 @@ fn handle_chat_agentic(body: String) -> String {
 
     // Persist the exchange to session/global history for thread continuity on next turn.
     // Only save when the loop completed (reply present), not when tool_pending.
+    //
+    // Issue #9 (AGENTIC HISTORY NOT PERSISTED): the agentic path previously only saved
+    // history to in-process state (state_set), which is lost on restart. We now also call
+    // conv_history_persist() for the default session (hist_key == "conv_history") so agentic
+    // history survives restarts the same way non-agentic history does. Per-session histories
+    // (session_hist_<id>) are still in-process only — persisting all named sessions would
+    // require per-session engram labels, a larger change tracked separately.
     let reply_text: String = json_get(result, "reply")
     let discard_hist: Bool = if !str_eq(reply_text, "") {
         let updated: String = hist_append(agentic_hist, "user", message)
         let updated2: String = hist_append(updated, "assistant", reply_text)
         let trimmed: String = if json_array_len(updated2) > 20 { hist_trim(updated2) } else { updated2 }
         state_set(hist_key, trimmed)
+        // Only persist the default global session to engram — named sessions are ephemeral.
+        if str_eq(hist_key, "conv_history") {
+            conv_history_persist(trimmed)
+        }
         true
     } else { false }
 
@@ -1424,13 +1516,19 @@ 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)