merge runtime/channels — MPMC buffered channels, channel_pipeline, channel_fan_out

el-compiler/runtime/el_runtime.h

@@ -751,6 +751,39 @@ 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);
 
+/* ── Threading seed primitives ────────────────────────────────────────────────
+ * These are the low-level C primitives that back thread.el and channel.el.
+ * El programs call them via their El wrappers (spawn, join, __mutex_new, etc.)
+ * rather than directly.
+ *
+ * __thread_create(fn_name, arg) — dlsym-resolves fn_name, spawns pthread,
+ *   returns a slot index (Int) usable with __thread_join.
+ * __thread_join(tid)            — joins the thread, returns its String result.
+ * __mutex_new()                 — allocates a mutex, returns handle (Int).
+ * __mutex_lock(m)               — locks mutex m (blocks until available).
+ * __mutex_unlock(m)             — unlocks mutex m.                           */
+
+el_val_t __thread_create(el_val_t fn_name, el_val_t arg);
+el_val_t __thread_join(el_val_t tid);
+el_val_t __mutex_new(void);
+void     __mutex_lock(el_val_t m);
+void     __mutex_unlock(el_val_t m);
+
+/* ── Channel seed primitives ─────────────────────────────────────────────────
+ * Buffered MPMC channels. All values are Strings; handles are Ints.
+ *
+ * __channel_new(capacity)   — create channel; cap=0 means unbounded.
+ * __channel_send(ch, msg)   — push msg; blocks if bounded and full.
+ * __channel_recv(ch)        — pop msg; blocks until available; "" on closed+empty.
+ * __channel_try_recv(ch)    — non-blocking pop; "" if empty.
+ * __channel_close(ch)       — mark closed; wakes all blocked recvers/senders. */
+
+el_val_t __channel_new(el_val_t capacity);
+void     __channel_send(el_val_t ch, el_val_t msg);
+el_val_t __channel_recv(el_val_t ch);
+el_val_t __channel_try_recv(el_val_t ch);
+void     __channel_close(el_val_t ch);
+
 #ifdef __cplusplus
 }
 #endif