Bug: MAX_TASK_WORKERS Is Ignored

[malys]

Summary

MAX_TASK_WORKERS does not appear to be respected.

I configured:

MAX_TASK_WORKERS=1

but Claude Code Studio still starts and runs 2 task sessions concurrently.

Version

• Claude Code Studio: v7.x

Current Behavior

Configuration:

MAX_TASK_WORKERS=1

Expected:

1 running task at a time

Observed:

2 tasks running simultaneously

Steps to Reproduce

1. Configure:

MAX_TASK_WORKERS=1

2. Restart Claude Code Studio.
3. Queue multiple Kanban tasks.
4. Observe task execution.

Actual Behavior

Two tasks are executed in parallel despite the configured limit.

Expected Behavior

When:

MAX_TASK_WORKERS=1

only a single worker should be active.

Additional tasks should remain queued until the running task completes.

Questions

• Is MAX_TASK_WORKERS currently implemented?
• Does it only apply to specific task types?
• Are delegated agents excluded from this limit?
• Is there another configuration overriding this value?

Suggested Improvement

Add visibility in the UI:

Task Workers

Running: 1 / 1
Queued: 4

and log the resolved value at startup:

MAX_TASK_WORKERS=1

Impact

• Unexpected parallel execution.
• Higher resource consumption.
• Higher token/quota consumption.
• Difficult to control task concurrency.

Priority

High

[Lexus2016]

Fixed in main (commits 89090e5 and f23470a).

Root Cause

MAX_TASK_WORKERS previously guarded the independent task launch path only (else branch). Any task carrying an assigned session_id — including chain members and tasks attached to an existing chat — was started outside this cap, limited solely by per-session and per-workdir locks. As a result, multiple chains or session-bound tasks ran concurrently even with MAX_TASK_WORKERS=1.

Fix

1. Global Cap: Moved the concurrency check in processQueue() before the execution branch so that running >= MAX_TASK_WORKERS serves as a strict global ceiling on active child processes across all task varieties.
2. Startup Visibility: The resolved MAX_TASK_WORKERS value is now logged at server startup (taskWorkers: MAX_TASK_WORKERS), allowing verification of effective configuration and catching any parsing fallbacks.
3. Regression Test Suite: Added comprehensive test coverage in test/task-workers.test.js (12 passing tests) verifying global cap behavior across independent tasks, chain tasks, and mixed queues.