Refactor CompanionFrameServer for non-blocking message synchronization

- Changed the _get_companion_stats method to be asynchronous, improving responsiveness.
- Added a new async method _cmd_sync_next_message to handle message synchronization without blocking the event loop, enhancing performance during message processing.
- Introduced constants for response codes to streamline message handling in the CompanionFrameServer.

repeater/companion/frame_server.py

@@ -10,8 +10,16 @@ from __future__ import annotations
 
 import asyncio
 import logging
+import struct
 from typing import Optional
 
+from pymc_core.companion.constants import (
+    RESP_CODE_CHANNEL_MSG_RECV,
+    RESP_CODE_CHANNEL_MSG_RECV_V3,
+    RESP_CODE_CONTACT_MSG_RECV,
+    RESP_CODE_CONTACT_MSG_RECV_V3,
+    RESP_CODE_NO_MORE_MESSAGES,
+)
 from pymc_core.companion.frame_server import CompanionFrameServer as _BaseFrameServer
 from pymc_core.companion.models import QueuedMessage
 
@@ -83,6 +91,71 @@ class CompanionFrameServer(_BaseFrameServer):
             path_len=msg_dict.get("path_len", 0),
         )
 
+    # -----------------------------------------------------------------
+    # Non-blocking command overrides (keep event loop responsive)
+    # -----------------------------------------------------------------
+
+    async def _cmd_sync_next_message(self, data: bytes) -> None:
+        """Sync next message; run persistence read in thread so SQLite does not block."""
+        msg = self.bridge.sync_next_message()
+        if msg is None:
+            msg = await asyncio.to_thread(self._sync_next_from_persistence)
+        if msg is None:
+            self._write_frame(bytes([RESP_CODE_NO_MORE_MESSAGES]))
+            return
+        if msg.is_channel:
+            path_len_byte = msg.path_len if msg.path_len < 256 else 0xFF
+            txt_type = 0
+            text_bytes = (msg.text or "").rstrip("\x00").encode("utf-8", errors="replace")
+            if self._app_target_ver >= 3:
+                frame = (
+                    bytes(
+                        [
+                            RESP_CODE_CHANNEL_MSG_RECV_V3,
+                            0,
+                            0,
+                            0,
+                            msg.channel_idx,
+                            path_len_byte,
+                            txt_type,
+                        ]
+                    )
+                    + struct.pack("<I", msg.timestamp)
+                    + text_bytes
+                )
+            else:
+                frame = bytes(
+                    [
+                        RESP_CODE_CHANNEL_MSG_RECV,
+                        msg.channel_idx,
+                        path_len_byte,
+                        txt_type,
+                    ]
+                )
+                frame += struct.pack("<I", msg.timestamp) + text_bytes
+        else:
+            prefix = (
+                msg.sender_key[:6] if len(msg.sender_key) >= 6 else msg.sender_key.ljust(6, b"\x00")
+            )
+            path_len_byte = msg.path_len if msg.path_len < 256 else 0xFF
+            text_bytes = msg.text.encode("utf-8", errors="replace")
+            if self._app_target_ver >= 3:
+                frame = (
+                    bytes([RESP_CODE_CONTACT_MSG_RECV_V3, 0, 0, 0])
+                    + prefix
+                    + bytes([path_len_byte, msg.txt_type])
+                    + struct.pack("<I", msg.timestamp)
+                    + text_bytes
+                )
+            else:
+                frame = (
+                    bytes([RESP_CODE_CONTACT_MSG_RECV])
+                    + prefix
+                    + bytes([path_len_byte, msg.txt_type])
+                )
+                frame += struct.pack("<I", msg.timestamp) + text_bytes
+        self._write_frame(frame)
+
     @staticmethod
     def _contact_to_dict(c) -> dict:
         """Convert a Contact object to a persistence dict."""

repeater/main.py

@@ -651,7 +651,7 @@ class RepeaterDaemon:
 
         return stats
 
-    def _get_companion_stats(self, stats_type: int) -> dict:
+    async def _get_companion_stats(self, stats_type: int) -> dict:
         """Return stats dict for companion CMD_GET_STATS (format expected by frame_server + meshcore_py)."""
         from repeater.companion.constants import (
             STATS_TYPE_CORE,