@greptileai review

Greptile Summary

This PR adds a concurrency limit for the gptodo spawn command to prevent overwhelming the system with unlimited background agents. The implementation adds a --max-concurrent option (default 4) that checks running sessions before spawning new ones, reconciling session state with actual tmux sessions to ensure accuracy.

Key Changes:

• Added --max-concurrent parameter to spawn_cmd and _execute_task_agent
• Implemented session reconciliation logic that verifies tmux session state before counting
• Added helpful user feedback when limit is reached, showing running agents and suggesting the kill command
• Created test_subagent.py with comprehensive tests for session management (save, load, list, error handling)

Test Coverage:
The new test file covers session CRUD operations but does not test the concurrency limiting logic itself. The PR description notes manual testing is required to verify the concurrency behavior.

Confidence Score: 4/5

• Safe to merge with minor considerations
• The implementation is straightforward and follows good practices. The reconciliation logic correctly verifies actual tmux session state. However, the concurrency limiting logic itself lacks automated test coverage (only session management is tested), and there's a potential edge case with race conditions if multiple spawn commands run simultaneously.
• No files require special attention - the implementation is clean and well-structured

Important Files Changed

Flowchart

flowchart TD
    A[User calls: gptodo spawn task-id] --> B{Check if background mode?}
    B -->|Yes| C{max_concurrent > 0?}
    B -->|No| H[Execute task agent]
    C -->|Yes| D[List sessions with status=running]
    C -->|No| H
    D --> E[Reconcile with tmux state]
    E --> F[Loop through running sessions]
    F --> G{check_session still running?}
    G -->|Yes| I[Add to actually_running list]
    G -->|No| F
    I --> J{len >= max_concurrent?}
    J -->|Yes| K[Display warning message]
    K --> L[List running sessions]
    L --> M[Show kill command hint]
    M --> N[Return early]
    J -->|No| H
    H --> O[Find task]
    O --> P[Build prompt]
    P --> Q[Spawn agent]

_{Last reviewed commit: 5d32970}