Feature Request: Add ListTasks tool for discovering background task IDs

Problem

Claude can start background tasks with Bash({ run_in_background: true }) but has no way to discover existing task IDs from previous conversations or sessions.

The /tasks CLI command shows running tasks to users, but there's no programmatic equivalent for Claude to call.

Current Limitation

What Claude can do:

• ✅ Start background tasks: Bash({ command: "./start.sh", run_in_background: true }) → returns task_id
• ✅ Check task output: TaskOutput({ task_id: "xyz" })
• ✅ Stop tasks: TaskStop({ task_id: "xyz" })

What Claude cannot do:

• ❌ List running tasks to discover task IDs
• ❌ Resume managing tasks from previous conversations
• ❌ Find tasks started by the user or other sessions

Current Workaround

Users must:

1. Run /tasks CLI command themselves
2. Manually provide task IDs to Claude
3. Or manage tasks entirely through the CLI

This creates a gap where background tasks persist across conversations, but Claude loses access to them without user intervention.

Proposed Solution

Add a ListTasks() tool (or GetRunningTasks()) that returns information about all running background tasks:

ListTasks()
// Returns:
[
  {
    task_id: "task-abc123",
    command: "./start.sh",
    status: "running",
    runtime: "65h 23m 11s",
    output_file: "/path/to/output",
    started_at: "2025-01-15T10:30:00Z"
  }
]

Use Cases

Cross-conversation continuity:

[Previous conversation]
User: "Start the backend server"
Claude: Bash({ command: "./start.sh", run_in_background: true })

[New conversation, context cleared]
User: "Stop the backend server"
Claude: ListTasks() → finds task_id → TaskStop({ task_id: "..." })

Task management:

User: "What's running in the background?"
Claude: ListTasks() → "You have ./start.sh running for 65 hours"

Cleanup:

User: "Stop all background tasks"
Claude: ListTasks() → StopTask for each

Consistency

This would align with the existing pattern:

• Users have /tasks CLI command
• Claude should have programmatic equivalent
• Other task tools (TaskOutput, TaskStop) already exist but require task_id

Evidence

See attached screenshot showing /tasks CLI output - this information exists in the system but isn't accessible to Claude programmatically.

!/tasks CLI output showing running background task

Priority

Impact: Medium-High

• Background tasks are a core feature
• Cross-conversation task management is currently broken
• Workaround exists but requires manual intervention

Effort: Likely Low

• /tasks command already implements the logic
• Just needs to be exposed as a tool with structured output