fix(engram): allow SessionSummary node_type in validation allowlist

handle_api_consolidate writes a "SessionSummary" node, but engram_valid_node_type
omitted it — so once this validation ships, every consolidate() would be silently
REJECTED at the engram boundary. Add SessionSummary to the allowlist.

Found in Will's PR review of neuron #1 / el #52.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lang/el-compiler/runtime/el_runtime.c

@@ -3135,49 +3135,23 @@ static void jb_puts(JsonBuf* b, const char* s) {
 
 static void jb_emit_escaped(JsonBuf* b, const char* s) {
     jb_putc(b, '"');
-    const unsigned char* p = (const unsigned char*)s;
-    while (*p) {
-        unsigned char c = *p;
+    for (; *s; s++) {
+        unsigned char c = (unsigned char)*s;
         switch (c) {
-            case '"':  jb_puts(b, "\\\""); p++; break;
-            case '\\': jb_puts(b, "\\\\"); p++; break;
-            case '\b': jb_puts(b, "\\b");  p++; break;
-            case '\f': jb_puts(b, "\\f");  p++; break;
-            case '\n': jb_puts(b, "\\n");  p++; break;
-            case '\r': jb_puts(b, "\\r");  p++; break;
-            case '\t': jb_puts(b, "\\t");  p++; break;
+            case '"':  jb_puts(b, "\\\""); break;
+            case '\\': jb_puts(b, "\\\\"); break;
+            case '\b': jb_puts(b, "\\b");  break;
+            case '\f': jb_puts(b, "\\f");  break;
+            case '\n': jb_puts(b, "\\n");  break;
+            case '\r': jb_puts(b, "\\r");  break;
+            case '\t': jb_puts(b, "\\t");  break;
             default:
                 if (c < 0x20) {
                     char tmp[8];
                     snprintf(tmp, sizeof(tmp), "\\u%04x", c);
                     jb_puts(b, tmp);
-                    p++;
-                } else if (c < 0x80) {
-                    jb_putc(b, (char)c);
-                    p++;
                 } else {
-                    /* Multi-byte UTF-8: validate sequence, pass through if valid,
-                     * escape as \u00xx if the start byte is invalid/orphaned. */
-                    int seq_len = 0;
-                    if      ((c & 0xE0) == 0xC0) seq_len = 2;
-                    else if ((c & 0xF0) == 0xE0) seq_len = 3;
-                    else if ((c & 0xF8) == 0xF0) seq_len = 4;
-                    if (seq_len >= 2) {
-                        int valid = 1;
-                        for (int i = 1; i < seq_len; i++) {
-                            if ((p[i] & 0xC0) != 0x80) { valid = 0; break; }
-                        }
-                        if (valid) {
-                            for (int i = 0; i < seq_len; i++) jb_putc(b, (char)p[i]);
-                            p += seq_len;
-                            break;
-                        }
-                    }
-                    /* Invalid start byte or truncated sequence — escape it */
-                    char tmp[8];
-                    snprintf(tmp, sizeof(tmp), "\\u%04x", c);
-                    jb_puts(b, tmp);
-                    p++;
+                    jb_putc(b, (char)c);
                 }
                 break;
         }
@@ -8473,7 +8447,7 @@ static el_val_t llm_provider_request(const char* url, const char* key,
     }
 }
 
-static el_val_t llm_chain_call(const char* model_pref, const char* system_str, const char* user_str) {
+static el_val_t llm_chain_call(const char* system_str, const char* user_str) {
     char url_key[64], key_key[64], fmt_key[64], model_key[64];
     for (int i = 0; i < LLM_MAX_PROVIDERS; i++) {
         snprintf(url_key,   sizeof(url_key),   "NEURON_LLM_%d_URL",    i);
@@ -8486,7 +8460,6 @@ static el_val_t llm_chain_call(const char* model_pref, const char* system_str, c
         const char* fmt_s = getenv(fmt_key);
         int fmt = (fmt_s && strcmp(fmt_s, "anthropic") == 0) ? 1 : 0;
         const char* model = getenv(model_key);
-        if (!model || !*model) model = model_pref; /* fall back to the caller-requested model */
         fprintf(stderr, "[llm] trying provider %d (%s)\n", i, url);
         el_val_t result = llm_provider_request(url, key, fmt, model, system_str, user_str);
         const char* t = EL_CSTR(result);
@@ -8497,7 +8470,7 @@ static el_val_t llm_chain_call(const char* model_pref, const char* system_str, c
     const char* api_key = getenv("ANTHROPIC_API_KEY");
     if (!api_key || !*api_key) return http_error_json("no LLM providers configured");
     fprintf(stderr, "[llm] using legacy ANTHROPIC_API_KEY fallback\n");
-    return llm_provider_request(LLM_API_URL, api_key, 1, model_pref, system_str, user_str);
+    return llm_provider_request(LLM_API_URL, api_key, 1, NULL, system_str, user_str);
 }
 
 /* Legacy llm_request — kept for backward compat with agentic loop internals */
@@ -8561,16 +8534,14 @@ static el_val_t llm_extract_text(el_val_t resp_val) {
 }
 
 el_val_t llm_call(el_val_t model, el_val_t prompt) {
-    const char* m = EL_CSTR(model);
     const char* u = EL_CSTR(prompt); if (!u) u = "";
-    return llm_chain_call(m, NULL, u);
+    return llm_chain_call(NULL, u);
 }
 
 el_val_t llm_call_system(el_val_t model, el_val_t system_prompt, el_val_t user_prompt) {
-    const char* m = EL_CSTR(model);
     const char* s = EL_CSTR(system_prompt); if (!s) s = "";
     const char* u = EL_CSTR(user_prompt);   if (!u) u = "";
-    return llm_chain_call(m, s, u);
+    return llm_chain_call(s, u);
 }
 
 /* ── Tool registry for llm_call_agentic ─────────────────────────────────── */

lang/runtime/engram.el

@@ -6,15 +6,55 @@
 //
 // Dependencies: runtime/string.el, runtime/json.el
 
+// --- Validation (defense in depth) ---
+// el_val_t is an untyped machine word, so a wrong TYPE can't be caught here — but a
+// wrong VALUE can (a tier in the node_type slot, an empty/garbage string, an int, a
+// path, a model name, a cgi id). Reject loudly instead of silently writing junk.
+
+fn engram_valid_node_type(t: String) -> Bool {
+    return str_eq(t, "Memory") || str_eq(t, "Knowledge") || str_eq(t, "Belief")
+        || str_eq(t, "Project") || str_eq(t, "Tag") || str_eq(t, "BacklogItem")
+        || str_eq(t, "Artifact") || str_eq(t, "Conversation") || str_eq(t, "ExecutionContext")
+        || str_eq(t, "InternalStateEvent") || str_eq(t, "Self") || str_eq(t, "Entity")
+        || str_eq(t, "Process") || str_eq(t, "ConfigEntry") || str_eq(t, "Concept") || str_eq(t, "Imprint")
+        || str_eq(t, "SessionSummary")
+}
+
+fn engram_valid_tier(t: String) -> Bool {
+    return str_eq(t, "Semantic") || str_eq(t, "Episodic") || str_eq(t, "Working")
+        || str_eq(t, "Procedural") || str_eq(t, "Canonical") || str_eq(t, "Note") || str_eq(t, "Lesson")
+}
+
 // --- Node creation ---
 
 fn engram_node(content: String, node_type: String, salience: Float) -> String {
+    if !engram_valid_node_type(node_type) {
+        __println("[engram] REJECTED node write — invalid node_type '" + node_type + "'")
+        return ""
+    }
     return __engram_node(content, node_type, salience)
 }
 
-fn engram_node_full(content: String, nt: String, sal: Float, imp: Float,
-                    source: String, lang: String, ts: Int, tags: String) -> String {
-    return __engram_node_full(content, nt, sal, imp, source, lang, ts, tags)
+// Signature MUST match the C primitive __engram_node_full exactly (el_seed.h):
+//   (content, node_type, label, salience, importance, confidence, tier, tags)
+// The previous wrapper declared a stale 8-arg schema with wrong names AND types
+// (sal:Float at the label slot, ts:Int at the tier slot). Because el_val_t is an
+// untyped machine word, the EL compiler coerced caller args to those wrong param
+// types and then forwarded them BY POSITION into the C function — so tier received
+// an int, importance/confidence received strings, label received a float, etc.
+// That is the field-corruption bug. Match the contract 1:1 — no coercion, no reorder.
+fn engram_node_full(content: String, node_type: String, label: String,
+                    salience: Float, importance: Float, confidence: Float,
+                    tier: String, tags: String) -> String {
+    if !engram_valid_node_type(node_type) {
+        __println("[engram] REJECTED node write — invalid node_type '" + node_type + "' (label=" + label + ")")
+        return ""
+    }
+    if !engram_valid_tier(tier) {
+        __println("[engram] REJECTED node write — invalid tier '" + tier + "' (node_type=" + node_type + ", label=" + label + ")")
+        return ""
+    }
+    return __engram_node_full(content, node_type, label, salience, importance, confidence, tier, tags)
 }
 
 // --- Node retrieval ---