Add script kill/abort mechanism — running scripts cannot be stopped

[Aryan1092raj]

@siddu-k

Summary

Once a script starts executing via /api/scripts/run, there is no way
to stop it from the UI or API. The only option is to kill the entire
DevShell process. This is a critical gap for long-running or hung scripts.

Current Behavior

• /api/scripts/run spawns a subprocess and streams output via SSE
• No process registry exists to track active run IDs
• No /api/scripts/kill endpoint exists
• proc.wait(timeout=10) in run_script() will silently throw
  subprocess.TimeoutExpired for any script that produces no output
  for 10+ seconds, crashing the stream unexpectedly

Expected Behavior

• Each script execution gets a unique run_id (already generated but unused for kill)
• A POST /api/scripts/kill endpoint accepts { "run_id": "..." } and
  terminates the process gracefully (proc.terminate() → proc.kill() fallback)
• Active terminal tabs in the UI show an Abort button while a script is running
• SSE stream sends a final { "type": "aborted" } event on kill

Proposed Fix

Backend (app.py):

# Global registry for active processes
active_processes = {}

# In run_script(), register the process:
active_processes[run_id] = proc

# New endpoint:
@app.route('/api/scripts/kill', methods=['POST'])
def kill_script():
    data = request.json
    run_id = data.get('run_id', '')
    proc = active_processes.get(run_id)
    if not proc:
        return jsonify({'error': 'Process not found'}), 404
    proc.terminate()
    try:
        proc.wait(timeout=3)
    except subprocess.TimeoutExpired:
        proc.kill()
    active_processes.pop(run_id, None)
    return jsonify({'success': True, 'run_id': run_id})


I noticed this issue 
Could u please assign this to me, i would like to work upon this

[MayurLochkar]

Bug Fix: Implement Script Abortion
Here is the draft description you requested detailing the solution, which you can use for your pull request or commit message:

📝 Title: Feature: Graceful Script Abortion via API and UI
🔍 Description
Previously, once a script started executing via /api/scripts/run, there was no way to terminate it without killing the entire DevShell process. This caused issues for long-running scripts, and the frontend stream would crash silently after 10 seconds if no output was generated due to an unhandled subprocess.TimeoutExpired.

This update resolves these issues by introducing a robust process registry, a new kill endpoint, and interactive abort controls in the terminal UI.

✨ Changes Made

1. Process Registry & Safe Timeout Handling (Backend - app.py)
   Created a global active_processes = {} dictionary to track executing scripts by their run_id.
   Modified run_script() to register the spawned process and safely remove it in a finally block.
   Caught subprocess.TimeoutExpired during proc.wait(timeout=10) to gracefully kill the process instead of crashing the stream.
   Injected proc.aborted = True flag to differentiate between natural exits and forced terminations, allowing the backend to stream a clean { "type": "aborted" } SSE event.

app.py (Excerpt)

active_processes[run_id] = proc
...
try:
proc.wait(timeout=10)
except subprocess.TimeoutExpired:
proc.kill()
proc.wait()

2. Kill Endpoint (Backend - app.py)
   Added POST /api/scripts/kill which uses the run_id to locate the process.
   Implements a graceful shutdown fallback: proc.terminate() -> wait(3s) -> proc.kill()

app.py (Excerpt)

@app.route('/api/scripts/kill', methods=['POST'])
def kill_script():
# ...
proc.aborted = True
proc.terminate()
try:
proc.wait(timeout=3)
except subprocess.TimeoutExpired:
proc.kill()
active_processes.pop(run_id, None)
return jsonify({'success': True, 'run_id': run_id})

3. Dynamic UI Abort Button (Frontend - ui/index.html & ui/app.js)
   Added an "Abort Script" button (#btn-abort) next to the clear button in the active terminal header.
   Extracted the run_id dynamically from the initial SSE system stream (Starting script execution... (ID: {run_id})).
   Maintained terminal state (state.activeRuns) so switching between tabs updates the visibility of the abort button correctly

// ui/app.js (Excerpt)
if (data.type === 'system') {
const match = data.content.match(/(ID: (.*?))/);
if (match) {
state.activeRuns[termId] = match[1];
if (termId === state.activeTerminalId) {
document.getElementById('btn-abort').style.display = 'inline-flex';
}
}
}

4. Stream Abort Event Handling
   Added handling for the aborted SSE event type to properly mark the run status as "Aborted" and log it gracefully to the terminal and debugger console without throwing unhandled exceptions.
   🏆 Why this is optimal
   Graceful Degradation: It attempts SIGTERM first before falling back to SIGKILL.
   Resource Safe: Process removal is guaranteed by Python finally blocks, preventing memory leaks in the process registry.
   Responsive UI: The Abort button only appears when a script is verified to be actively running in the backend and hides cleanly across multi-terminal tabs.

[Aryan1092raj]

Hi @siddu-k, I opened this issue and would like to work on the implementation. Could you please assign it to me before I start the PR?

[MayurLochkar]

please tell us “This issue has been assigned to whom?”

[siddu-k]

@Aryan1092raj assigned

[Aryan1092raj]

@Aryan1092raj assigned

Thanks for assigning this to me.
I will implement the abort flow, test it, and raise a PR.

[Aryan1092raj]

Hi @siddu-k ,

I have updated the PR and addressed the review feedback.

The implementation has been tested locally and the required checks are passing.

Please review it when you get time.

Thank you! #37