bridge: auto-start from start.sh, survive agent restarts

- start.sh: clean stale sockets before launch (fuser check)
- start.sh: start bridge in tmux with restart loop before pi
- bridge: don't crash if no pi socket on startup (resolve lazily)
- bridge: refreshSocket() before every send, not just after errors
- bridge: reply 'agent starting up' instead of erroring when pi not ready

Fixes the bug where a systemctl restart kills the bridge and it never
comes back because the LLM has to remember to run a startup checklist.

Author: benvinegar

slack-bridge/bridge.mjs

@@ -188,15 +188,20 @@ const app = new App({
   socketMode: true,
 });
 
-let socketPath = findSessionSocket(process.env.PI_SESSION_ID);
-console.log(`🔌 Using pi session socket: ${socketPath}`);
+let socketPath = null;
+try {
+  socketPath = findSessionSocket(process.env.PI_SESSION_ID);
+  console.log(`🔌 Using pi session socket: ${socketPath}`);
+} catch {
+  console.log(`⏳ No pi session socket found yet — will resolve when first message arrives`);
+}
 
 /** Re-resolve the socket path (handles session restarts). */
 function refreshSocket() {
   try {
     socketPath = findSessionSocket(process.env.PI_SESSION_ID);
   } catch {
-    // keep current — will fail on next send with a clear error
+    socketPath = null;
   }
 }
 
@@ -233,6 +238,13 @@ async function handleMessage(userMessage, event, say) {
   } catch {}
 
   try {
+    // Always re-resolve the socket before sending (handles agent restarts)
+    refreshSocket();
+    if (!socketPath) {
+      await say({ text: "⏳ Agent is starting up — try again in a moment.", thread_ts: event.ts });
+      return;
+    }
+
     // Wrap the message with security boundaries before sending to agent
     const contextMessage = wrapExternalContent({
       text: userMessage,
@@ -263,7 +275,7 @@ async function handleMessage(userMessage, event, say) {
     } catch {}
   } catch (err) {
     console.error("Error:", err.message);
-    refreshSocket(); // try to reconnect on next message
+    refreshSocket();
     await say({ text: `❌ Error: ${err.message}`, thread_ts: event.ts });
   }
 }
@@ -299,6 +311,12 @@ app.event("message", async ({ event, say }) => {
       threadTs: event.ts,
     });
     try {
+      // Re-resolve socket before sending
+      refreshSocket();
+      if (!socketPath) {
+        console.log("⏳ Sentry alert dropped — agent not ready yet");
+        return;
+      }
       // Fire and forget — don't wait for agent response, don't reply in channel
       await enqueue(() => sendToAgent(socketPath, contextMessage));
     } catch (err) {

start.sh

@@ -33,6 +33,44 @@ umask 077
 # Redact any secrets that leaked into session logs
 ~/runtime/bin/redact-logs.sh 2>/dev/null || true
 
+# Clean stale session sockets from previous runs
+SOCKET_DIR="$HOME/.pi/session-control"
+if [ -d "$SOCKET_DIR" ]; then
+  echo "Cleaning stale session sockets..."
+  for sock in "$SOCKET_DIR"/*.sock; do
+    [ -e "$sock" ] || continue
+    # If no process has the socket open, it's stale
+    if ! fuser "$sock" &>/dev/null 2>&1; then
+      rm -f "$sock"
+    fi
+  done
+  # Clean broken alias symlinks
+  for alias in "$SOCKET_DIR"/*.alias; do
+    [ -L "$alias" ] || continue
+    target=$(readlink "$alias")
+    if [ ! -e "$SOCKET_DIR/$target" ] && [ ! -e "$target" ]; then
+      rm -f "$alias"
+    fi
+  done
+fi
+
+# Start Slack bridge in the background (before pi, so it's ready for messages).
+# The bridge resolves the pi session socket lazily — it will wait for the
+# control-agent to come up and create its socket before forwarding messages.
+if [ -n "${SLACK_BOT_TOKEN:-}" ] && [ -n "${SLACK_APP_TOKEN:-}" ]; then
+  # Kill any existing bridge
+  tmux kill-session -t slack-bridge 2>/dev/null || true
+  echo "Starting Slack bridge..."
+  tmux new-session -d -s slack-bridge \
+    "export PATH=$HOME/.varlock/bin:$HOME/opt/node-v22.14.0-linux-x64/bin:\$PATH && \
+     cd ~/runtime/slack-bridge && \
+     while true; do \
+       varlock run --path ~/.config/ -- node bridge.mjs; \
+       echo '⚠️  Bridge exited (\$?), restarting in 5s...'; \
+       sleep 5; \
+     done"
+fi
+
 # Set session name (read by auto-name.ts extension)
 export PI_SESSION_NAME="control-agent"