fix(restart): preserve channel metadata across /restart so reply lands in thread

cmd_restart only persisted channel + chat_id across the os.execv boundary, so
when the new process announced "Restart completed" the OutboundMessage had
no Slack thread_ts and the reply fell back to the channel root.

Serialize msg.metadata into NANOBOT_RESTART_NOTIFY_METADATA, restore it on the
RestartNotice, and forward it to OutboundMessage so the completion message
follows the same routing as the original /restart invocation.

Made-with: Cursor

nanobot/utils/restart.py

@@ -2,12 +2,15 @@
 
 from __future__ import annotations
 
+import json
 import os
 import time
-from dataclasses import dataclass
+from dataclasses import dataclass, field
+from typing import Any
 
 RESTART_NOTIFY_CHANNEL_ENV = "NANOBOT_RESTART_NOTIFY_CHANNEL"
 RESTART_NOTIFY_CHAT_ID_ENV = "NANOBOT_RESTART_NOTIFY_CHAT_ID"
+RESTART_NOTIFY_METADATA_ENV = "NANOBOT_RESTART_NOTIFY_METADATA"
 RESTART_STARTED_AT_ENV = "NANOBOT_RESTART_STARTED_AT"
 
 
@@ -16,6 +19,7 @@ class RestartNotice:
     channel: str
     chat_id: str
     started_at_raw: str
+    metadata: dict[str, Any] = field(default_factory=dict)
 
 
 def format_restart_completed_message(started_at_raw: str) -> str:
@@ -30,11 +34,20 @@ def format_restart_completed_message(started_at_raw: str) -> str:
     return f"Restart completed{elapsed_suffix}."
 
 
-def set_restart_notice_to_env(*, channel: str, chat_id: str) -> None:
+def set_restart_notice_to_env(
+    *, channel: str, chat_id: str, metadata: dict[str, Any] | None = None,
+) -> None:
     """Write restart notice env values for the next process."""
     os.environ[RESTART_NOTIFY_CHANNEL_ENV] = channel
     os.environ[RESTART_NOTIFY_CHAT_ID_ENV] = chat_id
     os.environ[RESTART_STARTED_AT_ENV] = str(time.time())
+    if metadata:
+        try:
+            os.environ[RESTART_NOTIFY_METADATA_ENV] = json.dumps(metadata, default=str)
+        except (TypeError, ValueError):
+            os.environ.pop(RESTART_NOTIFY_METADATA_ENV, None)
+    else:
+        os.environ.pop(RESTART_NOTIFY_METADATA_ENV, None)
 
 
 def consume_restart_notice_from_env() -> RestartNotice | None:
@@ -42,9 +55,23 @@ def consume_restart_notice_from_env() -> RestartNotice | None:
     channel = os.environ.pop(RESTART_NOTIFY_CHANNEL_ENV, "").strip()
     chat_id = os.environ.pop(RESTART_NOTIFY_CHAT_ID_ENV, "").strip()
     started_at_raw = os.environ.pop(RESTART_STARTED_AT_ENV, "").strip()
+    metadata_raw = os.environ.pop(RESTART_NOTIFY_METADATA_ENV, "").strip()
     if not (channel and chat_id):
         return None
-    return RestartNotice(channel=channel, chat_id=chat_id, started_at_raw=started_at_raw)
+    metadata: dict[str, Any] = {}
+    if metadata_raw:
+        try:
+            parsed = json.loads(metadata_raw)
+        except (TypeError, ValueError):
+            parsed = None
+        if isinstance(parsed, dict):
+            metadata = parsed
+    return RestartNotice(
+        channel=channel,
+        chat_id=chat_id,
+        started_at_raw=started_at_raw,
+        metadata=metadata,
+    )
 
 
 def should_show_cli_restart_notice(notice: RestartNotice, session_id: str) -> bool: