fix(recall): set threshold=25 in all engram_compile_ranked variants

chat.el

@@ -212,8 +212,8 @@ fn engram_compile_ranked(nodes_json: String, max_nodes: Int) -> String {
         while ci < total {
             let node: String = json_array_get(nodes_json, ci)
             let score: Int = engram_score_node(node)
-            // Threshold: includes moderately-relevant older nodes (score >= 15).
-            let above_thresh: Bool = score >= 15
+            // Threshold 25: sal=0.5 * imp=0.5 * recency=1.0 -> 50*50*100/10000 = 25.
+            let above_thresh: Bool = score >= 25
             let idx_marker: String = "|" + int_to_str(ci) + "|"
             let already_picked: Bool = str_contains(selected_indices, idx_marker)
             let is_better: Bool = score > best_score && above_thresh && !already_picked
@@ -1159,12 +1159,29 @@ fn handle_chat(body: String) -> String {
     state_set("conv_history", final_hist)
     conv_history_persist(final_hist)
 
-    // Automatic session-end summary: write/overwrite the SessionSummary node on each turn
-    // so process restarts always have a continuity snapshot (no shutdown hook needed).
-    // Uses autogenerate (no LLM) so it is cheap — the node is overwritten not appended.
-    let auto_sum: String = session_summary_autogenerate(final_hist)
-    if !str_eq(auto_sum, "") {
-        let discard_sum: String = session_summary_write(auto_sum)
+    // Session-end summary hook: write a dated SessionSummary node once per boot when
+    // the conversation reaches >= 5 user turns (10 hist entries = 5 user+assistant pairs).
+    // Uses a per-boot label ("session:summary:<boot_ts>") so summaries accumulate across
+    // sessions instead of overwriting a single global node. A state flag prevents rewriting
+    // on every subsequent turn once the threshold is crossed.
+    let final_hist_len: Int = json_array_len(final_hist)
+    if final_hist_len >= 10 {
+        let already_wrote: String = state_get("session_summary_written")
+        if str_eq(already_wrote, "") {
+            // Derive (or create) a stable boot-scoped session id.
+            let boot_id: String = state_get("session_boot_id")
+            let boot_id = if str_eq(boot_id, "") {
+                let new_id: String = int_to_str(time_now())
+                state_set("session_boot_id", new_id)
+                new_id
+            } else { boot_id }
+            let sess_label: String = "session:summary:" + boot_id
+            let auto_sum: String = session_summary_autogenerate(final_hist)
+            if !str_eq(auto_sum, "") {
+                let discard_sum: String = session_summary_write_dated(auto_sum, sess_label)
+                state_set("session_summary_written", "1")
+            }
+        }
     }
 
     let activation_nodes: String = engram_activate_json(message, 2)
@@ -2247,6 +2264,32 @@ fn session_summary_write(summary_text: String) -> String {
     return node_id
 }
 
+// session_summary_write_dated — write a SessionSummary node with a caller-supplied dated label.
+// Unlike session_summary_write, this does NOT delete old nodes — each session accumulates its
+// own node so engram_search_json("session:summary") can return multiple past sessions.
+// The label must be unique per session (e.g. "session:summary:<boot_ts>").
+fn session_summary_write_dated(summary_text: String, label: String) -> String {
+    if str_eq(summary_text, "") { return "" }
+    if str_eq(label, "") { return "" }
+    let safe_text: String = str_replace(summary_text, "\"", "'")
+    let trimmed: String = if str_len(safe_text) > 800 { str_slice(safe_text, 0, 800) } else { safe_text }
+    let ts: Int = time_now()
+    let ts_str: String = int_to_str(ts)
+    let content: String = "[session-summary] " + trimmed + " | ts:" + ts_str
+    let tags: String = "[\"SessionSummary\",\"session-summary\",\"previous-session\",\"consolidate\"]"
+    let node_id: String = engram_node_full(
+        content, "SessionSummary", label,
+        el_from_float(0.9), el_from_float(0.8), el_from_float(1.0),
+        "Episodic", tags
+    )
+    if str_eq(node_id, "") {
+        println("[chat] session_summary_write_dated: engram write failed — summary node lost (label=" + label + ")")
+        return ""
+    }
+    println("[chat] session_summary_write_dated: wrote SessionSummary (" + int_to_str(str_len(content)) + " chars) label=" + label + " -> " + node_id)
+    return node_id
+}
+
 // session_summary_autogenerate — build a minimal summary from conversation history without LLM.
 // Extracts user message snippets (first 80 chars each, up to 5 turns).
 // Used as the automatic session-end hook so every turn produces a continuity snapshot.