feat: add thinking indicator via emoji reaction

README.md

@@ -90,6 +90,7 @@ LOG_LEVEL="info"                     # Logging level (default: info)
    - `chat:write` — Post messages and thread replies
    - `channels:history` — Read messages in public channels
    - `groups:history` — Read messages in private channels (if needed)
+   - `reactions:write` — Add/remove emoji reactions (thinking indicator)
 4. Subscribe to these **Events**:
    - `app_mention` — Trigger on @mentions
    - `message.channels` — Listen for thread replies

src/bender/config.py

@@ -20,6 +20,7 @@ class Settings(BaseSettings):
     # Optional
     bender_workspace: Path = Path.cwd()
     bender_api_port: int = 8080
+    bender_timeout: int = 300
     log_level: str = "info"
 
     # Optional: API key for authenticating external HTTP requests

src/bender/slack_handler.py

@@ -12,6 +12,24 @@
 
 logger = logging.getLogger(__name__)
 
+THINKING_EMOJI = "hourglass_flowing_sand"
+
+
+async def _add_reaction(client, channel: str, timestamp: str, emoji: str) -> None:
+    """Add a reaction to a message, silently ignoring errors."""
+    try:
+        await client.reactions_add(channel=channel, name=emoji, timestamp=timestamp)
+    except Exception:
+        logger.debug("Could not add reaction %s", emoji, exc_info=True)
+
+
+async def _remove_reaction(client, channel: str, timestamp: str, emoji: str) -> None:
+    """Remove a reaction from a message, silently ignoring errors."""
+    try:
+        await client.reactions_remove(channel=channel, name=emoji, timestamp=timestamp)
+    except Exception:
+        logger.debug("Could not remove reaction %s", emoji, exc_info=True)
+
 
 def register_handlers(app: AsyncApp, settings: Settings, sessions: SessionManager) -> None:
     """Register Slack event handlers on the bolt app."""
@@ -27,7 +45,7 @@ async def handle_reaction_removed(event: dict) -> None:
         pass
 
     @app.event("app_mention")
-    async def handle_mention(event: dict, say) -> None:
+    async def handle_mention(event: dict, say, client) -> None:
         """Handle new @Bender mentions — create session and invoke Claude Code."""
         text = _strip_mention(event.get("text", ""))
         thread_ts = event.get("ts", "")
@@ -41,19 +59,23 @@ async def handle_mention(event: dict, say) -> None:
 
         session_id = await sessions.create_session(thread_ts)
 
+        await _add_reaction(client, channel, thread_ts, THINKING_EMOJI)
         try:
             response = await invoke_claude(
                 prompt=text,
                 workspace=settings.bender_workspace,
                 session_id=session_id,
+                timeout=settings.bender_timeout,
             )
             await _post_response(say, response.result, thread_ts)
         except ClaudeCodeError as exc:
             logger.error("Claude Code invocation failed: %s", exc)
             await say(text=f"Sorry, something went wrong: {exc}", thread_ts=thread_ts)
+        finally:
+            await _remove_reaction(client, channel, thread_ts, THINKING_EMOJI)
 
     @app.event("message")
-    async def handle_message(event: dict, say) -> None:
+    async def handle_message(event: dict, say, client) -> None:
         """Handle thread replies — resume existing session if one exists."""
         # Ignore bot messages to avoid loops
         if event.get("bot_id") or event.get("subtype"):
@@ -74,19 +96,24 @@ async def handle_message(event: dict, say) -> None:
             return
 
         channel = event.get("channel", "")
+        message_ts = event.get("ts", "")
         logger.info("Thread reply in channel=%s thread=%s", channel, thread_ts)
 
+        await _add_reaction(client, channel, message_ts, THINKING_EMOJI)
         try:
             response = await invoke_claude(
                 prompt=text,
                 workspace=settings.bender_workspace,
                 session_id=session_id,
                 resume=True,
+                timeout=settings.bender_timeout,
             )
             await _post_response(say, response.result, thread_ts)
         except ClaudeCodeError as exc:
             logger.error("Claude Code invocation failed: %s", exc)
             await say(text=f"Sorry, something went wrong: {exc}", thread_ts=thread_ts)
+        finally:
+            await _remove_reaction(client, channel, message_ts, THINKING_EMOJI)
 
 
 def _strip_mention(text: str) -> str: