runtime: engram_scan_nodes_by_type_json() filters at the engine

Added a typed scan function: walks the live nodes once, skips
transparent layers, keeps only entries whose node_type matches the
filter, sorts the survivors by salience, paginates. Header forward
decl in el_runtime.h so callers can find it.

Empty / NULL filter falls through to engram_scan_nodes_json so the
existing GET /api/nodes contract is preserved exactly.

This is what every list-X tool in the MCP wrapper has been wanting:
listProcesses returning only Process nodes, not all of them, without
the wrapper having to fetch + filter client-side.

el-compiler/runtime/el_runtime.c

@@ -4840,6 +4840,43 @@ el_val_t engram_scan_nodes_json(el_val_t limit, el_val_t offset) {
     return el_wrap_str(b.buf);
 }
 
+/* engram_scan_nodes_by_type_json — filter by node_type before paginating.
+ * Empty / NULL type_v falls back to the unfiltered scan (existing behaviour).
+ * Result is JSON array, salience-sorted, transparent layers skipped. */
+el_val_t engram_scan_nodes_by_type_json(el_val_t type_v, el_val_t limit, el_val_t offset) {
+    const char* type_filter = EL_CSTR(type_v);
+    if (!type_filter || !*type_filter) {
+        return engram_scan_nodes_json(limit, offset);
+    }
+    EngramStore* g = engram_get();
+    int64_t lim = (int64_t)limit; if (lim <= 0) lim = 100;
+    int64_t off = (int64_t)offset; if (off < 0) off = 0;
+    JsonBuf b; jb_init(&b);
+    jb_putc(&b, '[');
+    if (g->node_count == 0) { jb_putc(&b, ']'); return el_wrap_str(b.buf); }
+    int64_t* idx = malloc((size_t)g->node_count * sizeof(int64_t));
+    if (!idx) { jb_putc(&b, ']'); return el_wrap_str(b.buf); }
+    int64_t live = 0;
+    for (int64_t i = 0; i < g->node_count; i++) {
+        if (engram_layer_is_transparent(g->nodes[i].layer_id)) continue;
+        const char* nt = g->nodes[i].node_type;
+        if (!nt || strcmp(nt, type_filter) != 0) continue;
+        idx[live++] = i;
+    }
+    engram_sort_indices_by_salience(idx, live, g->nodes);
+    int64_t end = off + lim;
+    if (end > live) end = live;
+    int first = 1;
+    for (int64_t i = off; i < end; i++) {
+        if (!first) jb_putc(&b, ',');
+        engram_emit_node_json(&b, &g->nodes[idx[i]]);
+        first = 0;
+    }
+    free(idx);
+    jb_putc(&b, ']');
+    return el_wrap_str(b.buf);
+}
+
 el_val_t engram_neighbors_json(el_val_t node_id, el_val_t max_depth, el_val_t direction) {
     /* Re-implement here directly so we serialize without going through
      * the ElList path. Walks BFS to max_depth, emits {node, edge, hops}

el-compiler/runtime/el_runtime.h

@@ -27,10 +27,19 @@
  *   -lcurl     — required for the HTTP client (http_get, http_post, llm_*).
  *   -lpthread  — required for the HTTP server (one detached thread per
  *                connection, capped at 64 concurrent).
+ *   -loqs      — optional; required only when liboqs is installed and the
+ *                pq_* / sha3_256_hex entry points are needed. Detected at
+ *                compile time via __has_include(<oqs/oqs.h>).
+ *   -lcrypto   — optional; pulled in alongside -loqs. Used for X25519 in
+ *                pq_hybrid_* and HKDF-SHA256 derivation.
  *
  * Canonical compile command:
  *   cc -std=c11 -I el-compiler/runtime -lcurl -lpthread \
  *      -o <out> <prog>.c el-compiler/runtime/el_runtime.c
+ *
+ * With liboqs (post-quantum stack):
+ *   cc -std=c11 -I el-compiler/runtime -lcurl -lpthread -loqs -lcrypto \
+ *      -o <out> <prog>.c el-compiler/runtime/el_runtime.c
  */
 
 #pragma once
@@ -132,14 +141,83 @@ el_val_t  http_post_json(el_val_t url, el_val_t json_body);
 el_val_t  http_get_with_headers(el_val_t url, el_val_t headers_map);
 el_val_t  http_post_with_headers(el_val_t url, el_val_t body, el_val_t headers_map);
 el_val_t  http_post_form_auth(el_val_t url, el_val_t form_body, el_val_t auth_header);
+el_val_t  http_delete(el_val_t url);
 void      http_serve(el_val_t port, el_val_t handler);
 void      http_set_handler(el_val_t name);
 
+/* HTTP server v2 ─────────────────────────────────────────────────────────────
+ * Same dispatch model as http_serve, but the handler signature is widened:
+ *
+ *     el_val_t handler(method, path, headers_map, body)
+ *
+ * `headers_map` is an ElMap from lowercased header name → header value (both
+ * Strings). Repeated headers are joined with ", " per RFC 7230.
+ *
+ * Response value: the handler may return either
+ *   (a) a plain body string — same auto-content-type / 200-OK behaviour as
+ *       http_serve (3-arg) — or
+ *   (b) a response envelope built with `http_response(status, headers_json,
+ *       body)`. The runtime detects the envelope discriminator
+ *       `"el_http_response":1` at the start of the returned string and
+ *       unpacks status / headers / body before sending.
+ *
+ * The 3-arg http_serve(port, handler) remains supported unchanged for
+ * existing handlers (e.g. products/web/server.el): it dispatches with
+ * (method, path, body), hardcodes 200 OK, and auto-detects content type. */
+void      http_serve_v2(el_val_t port, el_val_t handler);
+void      http_set_handler_v2(el_val_t name);
+
+/* Build an HTTP response envelope. `headers_json` should be a JSON object
+ * literal like `{"WWW-Authenticate":"Basic"}` (or "" / "{}" for none). The
+ * returned string carries the discriminator `{"el_http_response":1,...}`
+ * which the runtime's send-path detects and unpacks. Detection happens
+ * uniformly inside http_send_response, so a 3-arg handler may also return
+ * an envelope. The 3-arg variant remains documented as a fixed 200-OK
+ * auto-content-type contract for legacy handlers that return plain bodies. */
+el_val_t  http_response(el_val_t status, el_val_t headers_json, el_val_t body);
+
+/* HTTP timeout — every libcurl request honors EL_HTTP_TIMEOUT_MS (default
+ * 60000ms). Read lazily on first use, so setting the env var any time before
+ * the first http_* call is sufficient.                                    */
+
+/* Streaming variants — write the response body straight to a file via
+ * libcurl's CURLOPT_WRITEFUNCTION = fwrite. These bypass the el_val_t string
+ * wrapper entirely, so binary payloads (audio/mpeg, image/png, etc.) survive
+ * embedded NUL bytes that would truncate a strlen()-based code path.
+ *
+ * Both honor EL_HTTP_TIMEOUT_MS, follow redirects, and accept the same
+ * `headers_map` shape as http_post_with_headers (ElMap of String→String).
+ *
+ * Return value: 1 on success (file fully written), 0 on any failure
+ * (network, file open, partial write). On failure the output file is removed
+ * so callers cannot mistake a partially-written file for a valid one. */
+el_val_t  http_post_to_file(el_val_t url, el_val_t body, el_val_t headers_map, el_val_t output_path);
+el_val_t  http_get_to_file(el_val_t url, el_val_t headers_map, el_val_t output_path);
+
+/* ── URL encoding ────────────────────────────────────────────────────────── */
+
+el_val_t  url_encode(el_val_t s);   /* RFC 3986 unreserved set */
+el_val_t  url_decode(el_val_t s);   /* '+' → space, %XX → byte  */
+
 /* ── Filesystem ──────────────────────────────────────────────────────────── */
 
 el_val_t  fs_read(el_val_t path);
 el_val_t  fs_write(el_val_t path, el_val_t content);
 el_val_t  fs_list(el_val_t path);
+el_val_t  fs_exists(el_val_t path);
+el_val_t  fs_mkdir(el_val_t path);   /* mkdir -p, mode 0755                */
+
+/* Length-explicit binary write. `length` is an Int (el_val_t holding the
+ * byte count). The caller knows the length from context — typically because
+ * `bytes` came from base64_decode (which produces a magic-tagged binary
+ * buffer with embedded NULs possible) and the caller already tracks the
+ * decoded length, OR because the bytes came from a fixed-size source
+ * (sha256_bytes = 32, hmac_sha256_bytes = 32). Bypasses strlen entirely.
+ *
+ * Returns 1 on success, 0 on failure (invalid path, can't open, partial
+ * write, negative length). On partial-write failure, the file is removed
+ * so callers cannot read back a truncated artefact. */
+el_val_t  fs_write_bytes(el_val_t path, el_val_t bytes, el_val_t length);
 
 /* ── JSON ────────────────────────────────────────────────────────────────── */
 
@@ -153,6 +231,8 @@ el_val_t  json_get_bool(el_val_t json_str, el_val_t key);
 el_val_t  json_get_raw(el_val_t json_str, el_val_t key);
 el_val_t  json_set(el_val_t json_str, el_val_t key, el_val_t value);
 el_val_t  json_array_len(el_val_t json_str);
+el_val_t  json_array_get(el_val_t json_str, el_val_t index);
+el_val_t  json_array_get_string(el_val_t json_str, el_val_t index);
 
 /* ── Time ────────────────────────────────────────────────────────────────── */
 
@@ -223,9 +303,14 @@ el_val_t  list_range(el_val_t start, el_val_t end);
 
 el_val_t  bool_to_str(el_val_t b);
 
+/* ── Numeric parsing ─────────────────────────────────────────────────────── */
+
+el_val_t  parse_int(el_val_t s, el_val_t default_val);
+
 /* ── Process ─────────────────────────────────────────────────────────────── */
 
 void      exit_program(el_val_t code);
+el_val_t  getpid_now(void);
 
 /* ── CGI identity ─────────────────────────────────────────────────────────────
  * Called at the start of main() in CGI programs (those with a `cgi {}` block).
@@ -279,6 +364,19 @@ el_val_t  engram_node(el_val_t content, el_val_t node_type, el_val_t salience);
 el_val_t  engram_node_full(el_val_t content, el_val_t node_type, el_val_t label,
                            el_val_t salience, el_val_t importance, el_val_t confidence,
                            el_val_t tier, el_val_t tags);
+/* Layered consciousness — see el_runtime.c for the layered architecture
+ * design notes (search "Layered consciousness architecture"). The five
+ * canonical layers (safety / core-identity / domain-knowledge / imprint /
+ * suit) are seeded automatically; engram_add_layer extends the registry
+ * with imprint or suit overlays at runtime. Nodes default to layer 1
+ * (core-identity) when created via engram_node / engram_node_full. */
+el_val_t  engram_node_layered(el_val_t content, el_val_t node_type, el_val_t label,
+                              el_val_t salience, el_val_t certainty, el_val_t confidence,
+                              el_val_t status, el_val_t tags, el_val_t layer_id);
+el_val_t  engram_add_layer(el_val_t name, el_val_t priority, el_val_t suppressible,
+                           el_val_t transparent, el_val_t injectable);
+el_val_t  engram_remove_layer(el_val_t layer_id);
+el_val_t  engram_list_layers(void);
 el_val_t  engram_get_node(el_val_t id);
 void      engram_strengthen(el_val_t node_id);
 void      engram_forget(el_val_t node_id);
@@ -290,6 +388,8 @@ el_val_t  engram_edge_between(el_val_t from_id, el_val_t to_id);
 el_val_t  engram_neighbors(el_val_t node_id);
 el_val_t  engram_neighbors_filtered(el_val_t node_id, el_val_t max_depth, el_val_t direction);
 el_val_t  engram_edge_count(void);
+/* Three-pass activation: background fan-out → working-memory promotion →
+ * Layer 0 override. See "Three-pass activation" in el_runtime.c. */
 el_val_t  engram_activate(el_val_t query, el_val_t depth);
 el_val_t  engram_save(el_val_t path);
 el_val_t  engram_load(el_val_t path);
@@ -300,9 +400,16 @@ el_val_t  engram_load(el_val_t path);
 el_val_t  engram_get_node_json(el_val_t id);
 el_val_t  engram_search_json(el_val_t query, el_val_t limit);
 el_val_t  engram_scan_nodes_json(el_val_t limit, el_val_t offset);
+el_val_t  engram_scan_nodes_by_type_json(el_val_t node_type, el_val_t limit, el_val_t offset);
 el_val_t  engram_neighbors_json(el_val_t node_id, el_val_t max_depth, el_val_t direction);
 el_val_t  engram_activate_json(el_val_t query, el_val_t depth);
 el_val_t  engram_stats_json(void);
+el_val_t  engram_list_layers_json(void);
+/* engram_compile_layered_json — produce a prompt-ready text block split
+ * into "[LAYER 0 — STRUCTURAL]" (non-suppressible layers, sacred fire)
+ * and "[ENGRAM CONTEXT]" (standard suppressible layers). Returns "" if
+ * no nodes promoted to working memory. */
+el_val_t  engram_compile_layered_json(el_val_t intent, el_val_t depth);
 
 /* ── LLM (Anthropic API client) ─────────────────────────────────────────────
  * All functions call https://api.anthropic.com/v1/messages with the API key
@@ -329,6 +436,83 @@ void      llm_register_tool(el_val_t name, el_val_t handler_fn_name);
 el_val_t  args(void);
 void      el_runtime_init_args(int argc, char** argv);
 
+/* ── Crypto primitives ─────────────────────────────────────────────────────
+ * SHA-256, HMAC-SHA-256, and base64 (standard + URL-safe).
+ * Self-contained — no OpenSSL/libcrypto dependency. The implementations are
+ * adapted from public-domain reference code (Brad Conte / RFC 4648).
+ *
+ * Bytes-returning variants (sha256_bytes, hmac_sha256_bytes) return a string
+ * value whose contents are raw binary; callers usually feed these into
+ * base64_encode. Note that el_val_t strings are NUL-terminated by convention,
+ * so the binary payload may contain embedded NULs — pass it directly into
+ * base64_encode (which uses an explicit length) rather than treating it as
+ * a printable C string.
+ *
+ * The "base64" variants emit/accept RFC 4648 standard alphabet with padding.
+ * The "base64url" variants use URL-safe alphabet (`-`/`_`) with no padding,
+ * as used in JWTs.                                                           */
+
+el_val_t  sha256_hex(el_val_t input);
+el_val_t  sha256_bytes(el_val_t input);
+el_val_t  hmac_sha256_hex(el_val_t key, el_val_t message);
+el_val_t  hmac_sha256_bytes(el_val_t key, el_val_t message);
+el_val_t  base64_encode(el_val_t input);
+el_val_t  base64_decode(el_val_t input);
+el_val_t  base64url_encode(el_val_t input);
+el_val_t  base64url_decode(el_val_t input);
+
+/* Length-aware variants (internal — exposed for the rare caller that already
+ * has a known-length binary buffer and doesn't want to round-trip through
+ * a NUL-terminated el_val_t string). Sha256_bytes and hmac_sha256_bytes feed
+ * these implicitly. */
+el_val_t  el_sha256_bytes_n(const unsigned char* data, size_t len);
+el_val_t  el_base64_encode_n(const unsigned char* data, size_t len, int url_safe);
+
+/* ── Post-quantum primitives (liboqs-backed) ────────────────────────────────
+ * All inputs/outputs hex-encoded. Algorithm choices:
+ *   Signature: CRYSTALS-Dilithium-3   (NIST level 3, balanced)
+ *   KEM:       CRYSTALS-Kyber-768     (NIST level 3)
+ *   Hash:      SHA3-256 (Keccak)      (PQ-aware protocols favour SHA3 over SHA2)
+ *
+ * If liboqs is not linked (detected via __has_include(<oqs/oqs.h>) at compile
+ * time), the pq_* entry points return a JSON-shaped error string so callers
+ * fail loudly rather than silently fall back to classical schemes:
+ *   {"error":"liboqs not linked, post-quantum primitives unavailable"}
+ *
+ * The hybrid handshake pairs X25519 with Kyber-768 per NIST PQ guidance and
+ * CNSA 2.0. Combined shared secret is HKDF-SHA256(x25519_ss || kyber_ss).
+ * Even if Kyber falls, X25519 holds; if X25519 falls under quantum attack,
+ * Kyber holds. SHA3-256 also remains usable independent of liboqs (the
+ * Keccak permutation is PQ-OK as a primitive). */
+
+el_val_t  pq_keygen_signature(void);
+el_val_t  pq_sign(el_val_t secret_key_hex, el_val_t message);
+el_val_t  pq_verify(el_val_t public_key_hex, el_val_t message, el_val_t signature_hex);
+
+el_val_t  pq_kem_keygen(void);
+el_val_t  pq_kem_encaps(el_val_t public_key_hex);
+el_val_t  pq_kem_decaps(el_val_t secret_key_hex, el_val_t ciphertext_hex);
+
+el_val_t  pq_hybrid_keygen(void);
+el_val_t  pq_hybrid_handshake(el_val_t remote_pub_combined);
+
+el_val_t  sha3_256_hex(el_val_t input);
+
+/* ── AEAD: AES-256-GCM (libcrypto-backed) ───────────────────────────────────
+ * Symmetric authenticated encryption used to wrap envelopes after a KEM
+ * handshake. Caller MUST supply a 32-byte key (64 hex chars) — typically the
+ * Kyber-768 / hybrid shared_secret, optionally normalized via SHA3-256.
+ *
+ * aead_encrypt returns a JSON map {"nonce":"...","ciphertext":"..."} where
+ * ciphertext is the AES-256-GCM output with the 16-byte auth tag appended.
+ * Nonce is a fresh 12-byte CSPRNG draw — callers never pick the nonce, which
+ * structurally rules out the GCM nonce-reuse footgun.
+ *
+ * aead_decrypt returns the plaintext String, or "" on any failure (including
+ * auth-tag mismatch). Callers MUST check for "" before trusting the result. */
+el_val_t  aead_encrypt(el_val_t key_hex, el_val_t plaintext);
+el_val_t  aead_decrypt(el_val_t key_hex, el_val_t nonce_hex, el_val_t ciphertext_hex);
+
 /* ── Native VM builtin aliases (for compiled El source) ─────────────────────
  * These match the El VM's native_* builtins so that El source compiled
  * to C can call the same names without modification.                */
@@ -355,6 +539,16 @@ el_val_t  get(el_val_t list, el_val_t index);      /* el_list_get    */
 el_val_t  map_get(el_val_t map, el_val_t key);     /* el_map_get     */
 el_val_t  map_set(el_val_t map, el_val_t key, el_val_t value); /* el_map_set */
 
+/* ── OTLP/HTTP Observability ─────────────────────────────────────────────── */
+/* See bottom of el_runtime.c for the implementation.
+ * Configured by env vars OTLP_ENDPOINT, OTEL_SERVICE_NAME, OTEL_SERVICE_VERSION.
+ * No-op when OTLP_ENDPOINT is unset. Drop-on-failure semantics. */
+el_val_t emit_log(el_val_t level, el_val_t msg, el_val_t fields_json);
+el_val_t emit_metric(el_val_t name, el_val_t value, el_val_t tags_json);
+el_val_t trace_span_start(el_val_t name);
+el_val_t trace_span_end(el_val_t span_handle);
+el_val_t emit_event(el_val_t name, el_val_t duration_ms);
+
 #ifdef __cplusplus
 }
 #endif