diff --git a/docs/api/terminal.md b/docs/api/terminal.md
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+# Terminal API
+
+The Terminal API provides WebSocket-based terminal access to running tool instances.
+
+## WebSocket Endpoint
+
+### Connect to Terminal
+
+```
+GET /ws/tool-instances/{instance_id}/terminal
+```
+
+Establishes a WebSocket connection to an interactive terminal session inside a running tool instance container.
+
+**Authentication:** Requires valid session cookie.
+
+**Path Parameters:**
+- `instance_id` (string, UUID): The tool instance ID
+
+**Connection Flow:**
+1. Client connects to WebSocket endpoint
+2. Server authenticates user and verifies instance ownership
+3. Server creates or reattaches to existing terminal session
+4. Server sends `{"type": "status", "status": "connected"}` message
+5. Bidirectional communication begins
+
+**Message Types:**
+
+#### Client to Server
+
+**Terminal Input (bytes or string)**
+- Send raw bytes for terminal input (key presses)
+- Send text for terminal input (will be encoded as UTF-8)
+
+**Resize Command (JSON)**
+```json
+{
+  "type": "resize",
+  "cols": 80,
+  "rows": 24
+}
+```
+
+**Reset Command (JSON)**
+```json
+{
+  "type": "reset"
+}
+```
+Kills the current terminal session and starts a fresh one.
+
+**Pong Response (JSON)**
+```json
+{
+  "type": "pong"
+}
+```
+Sent automatically in response to server ping messages.
+
+#### Server to Client
+
+**Terminal Output (bytes)**
+Raw terminal output as binary data (Blob in browser).
+
+**Status Messages (JSON)**
+```json
+{"type": "status", "status": "connected"}
+{"type": "status", "status": "resetting"}
+```
+
+**Ping Messages (JSON)**
+```json
+{"type": "ping"}
+```
+Sent every 30 seconds to detect disconnections. Client should respond with `{"type": "pong"}`.
+
+### Session Persistence
+
+Terminal sessions persist across WebSocket disconnections:
+- When a client disconnects, the terminal session remains active
+- On reconnection, the client reattaches to the existing session
+- Buffered output is replayed to the client on reconnection
+- Sessions are cleaned up after 30 minutes of inactivity
+
+### Concurrent Connections
+
+Only one WebSocket connection is allowed per terminal session:
+- New connections close existing connections with code 4000
+- Previous client receives "New connection established" reason
+
+## HTTP Endpoints
+
+### Reset Terminal Session
+
+```
+POST /api/projects/{project_id}/repositories/{repo_id}/instances/{instance_id}/terminal/reset
+```
+
+Resets the terminal session for a tool instance, killing the current shell and starting fresh.
+
+**Authentication:** Required
+
+**Path Parameters:**
+- `project_id` (string, UUID): Project ID
+- `repo_id` (string, UUID): Repository ID
+- `instance_id` (string, UUID): Instance ID
+
+**Response:**
+```json
+{
+  "status": "success",
+  "message": "Terminal session reset successfully",
+  "instance_id": "...",
+  "session_id": "..."
+}
+```
+
+**Error Responses:**
+- `404 Not Found`: Instance not found
+- `400 Bad Request`: Instance is not running
+- `500 Internal Server Error`: Failed to reset terminal session
+
+## Error Codes
+
+WebSocket close codes:
+- `1000`: Normal closure
+- `4000`: Error/reset
+- `4001`: Invalid instance ID
+- `4003`: Unauthorized/Forbidden
+- `4004`: Instance not found or not running
+
+## Heartbeat
+
+The server sends ping messages every 30 seconds. If no ping is received for 60 seconds, the client should assume the connection is dead and reconnect.
diff --git a/docs/features/terminal-troubleshooting.md b/docs/features/terminal-troubleshooting.md
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+# Terminal Troubleshooting Guide
+
+## Common Issues
+
+### Cannot Connect to Terminal
+
+**Symptom:** Terminal shows "Connection closed" or "Error" status immediately.
+
+**Solutions:**
+1. Verify the tool instance is running:
+   - Check instance status in the UI
+   - Start the instance if it's stopped
+   
+2. Check browser console for errors:
+   - Open browser DevTools (F12)
+   - Look for WebSocket connection errors
+   - Check for CORS or authentication errors
+
+3. Verify network connectivity:
+   - Ensure you can reach the API server
+   - Check if WebSocket connections are blocked by firewall/proxy
+   - Try accessing from a different network
+
+**If the issue persists:**
+- Reset the terminal session
+- Refresh the page
+- Check server logs for errors
+
+### Terminal Freezes or Becomes Unresponsive
+
+**Symptom:** Terminal accepts no input or stops updating.
+
+**Solutions:**
+1. **Reset the terminal:**
+   - Click the Reset button in the terminal header
+   - Confirm the reset action
+   - Wait for the new session to start
+
+2. **Check for stuck processes:**
+   - Try Ctrl+C to interrupt any running process
+   - If that doesn't work, reset the terminal
+
+3. **Browser issues:**
+   - Close and reopen the browser tab
+   - Clear browser cache and cookies
+   - Try a different browser
+
+### Output Not Showing
+
+**Symptom:** Commands execute but no output appears.
+
+**Solutions:**
+1. Check terminal focus:
+   - Click inside the terminal area
+   - Look for the cursor indicator
+
+2. Resize the terminal:
+   - The terminal may need a resize event to render properly
+   - Try resizing the browser window slightly
+
+3. Reset the terminal session
+
+### Reconnection Loop
+
+**Symptom:** Terminal keeps disconnecting and reconnecting repeatedly.
+
+**Solutions:**
+1. Check instance health:
+   - The instance may be unhealthy or restarting
+   - Check instance logs for errors
+
+2. Network stability:
+   - Unstable network causes repeated disconnections
+   - Try on a more stable connection
+
+3. Multiple tabs:
+   - Only one tab can connect to a terminal session
+   - Close other tabs with the same terminal open
+
+## Diagnostic Steps
+
+### Check WebSocket Connection
+
+1. Open browser DevTools (F12)
+2. Go to Network tab
+3. Filter by "WS" (WebSocket)
+4. Look for the terminal WebSocket connection
+5. Check:
+   - Connection status (should be 101 Switching Protocols)
+   - Messages tab for ping/pong traffic
+   - Any error messages in the connection
+
+### Verify Terminal Session
+
+To check if a terminal session exists on the server:
+
+```bash
+# Check server logs for session activity
+docker logs hq-api | grep -i "terminal"
+```
+
+Look for:
+- "Terminal session ready" - session created successfully
+- "Reattaching to existing terminal session" - reconnecting to existing session
+- "Cleaning up idle terminal session" - session expired
+
+### Test Basic Connectivity
+
+```bash
+# Test if the WebSocket endpoint is reachable
+curl -i -N \
+  -H "Connection: Upgrade" \
+  -H "Upgrade: websocket" \
+  -H "Sec-WebSocket-Key: test" \
+  -H "Sec-WebSocket-Version: 13" \
+  https://your-api-domain/ws/tool-instances/test/terminal
+```
+
+Expected: HTTP 400 (invalid instance ID) or redirect to auth
+
+## Error Codes
+
+### WebSocket Close Codes
+
+- **1000**: Normal closure - connection closed cleanly
+- **4000**: Generic error - check server logs
+- **4001**: Invalid instance ID - verify the instance exists
+- **4003**: Unauthorized - session expired or invalid
+- **4004**: Instance not running - start the instance first
+
+### HTTP Status Codes
+
+- **404**: Instance not found - verify instance ID
+- **400**: Instance not running - start the instance
+- **500**: Server error - check server logs
+
+## Resetting Everything
+
+If all else fails:
+
+1. **Reset terminal session:**
+   ```
+   POST /api/projects/{project_id}/repositories/{repo_id}/instances/{instance_id}/terminal/reset
+   ```
+
+2. **Restart the tool instance:**
+   - Stop the instance
+   - Start the instance again
+   - Reconnect to the terminal
+
+3. **Clear browser data:**
+   - Clear cookies for the domain
+   - Clear local storage
+   - Hard refresh the page (Ctrl+F5)
+
+## Getting Help
+
+If issues persist:
+
+1. Collect diagnostic information:
+   - Browser console logs
+   - Network tab WebSocket messages
+   - Server logs (`docker logs hq-api`)
+   - Instance status and health
+
+2. Check the [Terminal API documentation](/docs/api/terminal.md) for protocol details
+
+3. Report issues with:
+   - Steps to reproduce
+   - Expected vs actual behavior
+   - Browser and OS version
+   - Instance type and configuration
diff --git a/docs/features/terminal.md b/docs/features/terminal.md
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+# Terminal Sessions
+
+Terminal sessions provide interactive shell access to your running tool instances directly in the browser.
+
+## Persistent Sessions
+
+Terminal sessions are **persistent** - they survive browser refreshes, network interruptions, and tab switches.
+
+### How It Works
+
+- When you open a terminal, a shell session starts inside the tool instance container
+- If you close the browser or lose connection, the session keeps running
+- When you reconnect, you reattach to the same session with all previous output preserved
+- Sessions automatically clean up after 30 minutes of inactivity
+
+### Reconnecting
+
+If your connection drops:
+1. The terminal shows "Reconnecting..." status
+2. The client automatically attempts to reconnect with exponential backoff
+3. On successful reconnection, buffered output is replayed
+4. You can continue working where you left off
+
+## Resetting the Terminal
+
+If your terminal becomes unresponsive or you want a fresh start:
+
+1. Click the **Reset** button in the terminal header
+2. Confirm the reset action
+3. The current shell is killed and a new one starts
+4. All terminal history is cleared
+
+**Note:** Resetting only affects the terminal session, not the tool instance itself. Any files you've created remain intact.
+
+## Mobile Terminal
+
+On mobile devices, the terminal includes:
+- Special keys panel (Ctrl, Alt, Tab, arrows, etc.)
+- Font size controls
+- Auto-hiding header for maximum screen space
+- Touch-friendly interface
+
+## Keyboard Shortcuts
+
+Standard terminal shortcuts work as expected:
+- `Ctrl+C`: Send interrupt signal
+- `Ctrl+D`: Send EOF (close shell if empty)
+- `Ctrl+L`: Clear screen
+- `Ctrl+Z`: Suspend process
+
+Special keys can be accessed via the special keys panel on mobile or by using modifier combinations.
+
+## Troubleshooting
+
+### Connection Issues
+
+**"Connection closed" error:**
+- The tool instance may have stopped - check the instance status
+- Network issues - the client will auto-reconnect
+- Session timeout - sessions expire after 30 minutes of inactivity
+
+**Terminal not responding:**
+- Try resetting the terminal using the Reset button
+- Check if the tool instance is still running
+- Refresh the page to force reconnection
+
+### Display Issues
+
+**Text not visible:**
+- Adjust font size using +/- buttons
+- Check if the terminal has focus (click inside it)
+- Try resizing the browser window
+
+**Characters not appearing:**
+- Ensure the terminal has focus
+- Check if a modifier key is stuck (Ctrl, Alt)
+- Reset the terminal if stuck
+
+## Session Limits
+
+- **One connection per terminal:** Only one browser tab can connect to a terminal session at a time. Opening a new connection closes the old one.
+- **30-minute idle timeout:** Sessions without activity are automatically cleaned up
+- **Buffer size:** Up to 10KB of output is buffered for replay on reconnection
diff --git a/openspec/changes/persistent-terminal-sessions/tasks.md b/openspec/changes/persistent-terminal-sessions/tasks.md
index a234a6e..65ec048 100644
--- a/openspec/changes/persistent-terminal-sessions/tasks.md
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@@ -59,6 +59,6 @@
 
 ## 8. Documentation
 
-- [ ] 8.1 Update API documentation with new reset endpoint
-- [ ] 8.2 Update user documentation about persistent terminals
-- [ ] 8.3 Add troubleshooting guide for terminal issues
+- [x] 8.1 Update API documentation with new reset endpoint
+- [x] 8.2 Update user documentation about persistent terminals
+- [x] 8.3 Add troubleshooting guide for terminal issues