fix sendmessage

source/scheduler.c

@@ -1065,12 +1065,38 @@ const char *JS_SendMessage(JSContext *ctx, WotaBuffer *wb)
   if (!wb || !wb->data || wb->size == 0)
     return "Empty WOTA buffer";
 
-  size_t byte_len = wb->size * sizeof(uint64_t);
-  blob *msg = blob_new(byte_len * 8);
-  if (!msg) return "Could not allocate blob";
+  /* Wrap the caller's payload in the engine protocol envelope:
+     {type: "user", data: <payload>}
+     The header takes ~6 words; pre-allocate enough for header + payload. */
+  WotaBuffer envelope;
+  wota_buffer_init(&envelope, wb->size + 8);
+  wota_write_record(&envelope, 2);
+  wota_write_text(&envelope, "type");
+  wota_write_text(&envelope, "user");
+  wota_write_text(&envelope, "data");
 
-  blob_write_bytes(msg, wb->data, byte_len);
+  /* Append the caller's pre-encoded WOTA payload words directly. */
+  size_t need = envelope.size + wb->size;
+  if (need > envelope.capacity) {
+    size_t new_cap = envelope.capacity ? envelope.capacity * 2 : 8;
+    while (new_cap < need) new_cap *= 2;
+    envelope.data = realloc(envelope.data, new_cap * sizeof(uint64_t));
+    envelope.capacity = new_cap;
+  }
+  memcpy(envelope.data + envelope.size, wb->data,
+         wb->size * sizeof(uint64_t));
+  envelope.size += wb->size;
+
+  size_t byte_len = envelope.size * sizeof(uint64_t);
+  blob *msg = blob_new(byte_len * 8);
+  if (!msg) {
+    wota_buffer_free(&envelope);
+    return "Could not allocate blob";
+  }
+
+  blob_write_bytes(msg, envelope.data, byte_len);
   blob_make_stone(msg);
+  wota_buffer_free(&envelope);
 
   const char *err = send_message(ctx->id, msg);
   if (!err) {