Orchestrator can complete tasks prematurely without verifying todo completion

[0xMink]

Bug Description

In orchestrator mode, the model can call attempt_completion even when:

1. No todo list exists (no plan was created)
2. Todo items remain incomplete (pending or in_progress)

The existing preventCompletionWithOpenTodos setting defaults to false, making it opt-in. Orchestrator mode relies on structured delegation through todo lists, so completion without verifying the plan is structurally premature.

After context condensation, the model may lose visibility of outstanding work and attempt completion early. While a separate PR (#11434) addresses the visibility side by including the todo list in the system prompt, completion enforcement is still needed.

Expected Behavior

In orchestrator mode:

• Completion should be blocked if no todo list exists
• Completion should be blocked if any todo items are not completed
• This should apply regardless of the global preventCompletionWithOpenTodos setting

Impact

Orchestrator mode is designed for multi-step coordination. Premature completion means delegated subtasks may be abandoned or their results never synthesized.

[roomote]

I've analyzed this issue and here's my proposed implementation plan:

Problem

In AttemptCompletionTool.execute() (src/core/tools/AttemptCompletionTool.ts), the todo-list completion check is gated behind the preventCompletionWithOpenTodos setting which defaults to false. This means orchestrator mode -- which fundamentally relies on structured delegation through todo lists -- can complete prematurely when:

1. No todo list exists (no plan was created)
2. Todo items remain incomplete (pending or in_progress)

Proposed Solution

Modify src/core/tools/AttemptCompletionTool.ts to add orchestrator-specific enforcement that applies regardless of the global setting:

1. After the existing preventCompletionWithOpenTodos check (lines 52-68), add a new check:

   • Use await task.getTaskMode() to determine the current mode
   • If mode is "orchestrator", enforce stricter rules:
     • Block completion if no todo list exists (task.todoList is undefined or empty array) -- the orchestrator should always create a plan before completing
     • Block completion if any todos are incomplete (status is not "completed") -- same as the existing check but unconditionally applied
   • Return an appropriate error message explaining the orchestrator must create and complete all plan items before finishing

2. The existing preventCompletionWithOpenTodos behavior for non-orchestrator modes remains unchanged.

Add tests in src/core/tools/__tests__/attemptCompletionTool.spec.ts:

• Test: orchestrator mode blocks completion when no todo list exists (regardless of setting)
• Test: orchestrator mode blocks completion when todos are incomplete (regardless of setting)
• Test: orchestrator mode allows completion when all todos are completed
• Test: non-orchestrator modes are unaffected (existing behavior preserved)

Code sketch

// In AttemptCompletionTool.execute(), after the existing preventCompletionWithOpenTodos check:
const taskMode = await task.getTaskMode()
const isOrchestratorMode = taskMode === "orchestrator"

if (isOrchestratorMode) {
    if (!task.todoList || task.todoList.length === 0) {
        task.consecutiveMistakeCount++
        task.recordToolError("attempt_completion")
        pushToolResult(formatResponse.toolError(
            "Orchestrator mode requires a todo list before completing. Create a plan with update_todo_list first."
        ))
        return
    }
    if (task.todoList.some((todo) => todo.status !== "completed")) {
        task.consecutiveMistakeCount++
        task.recordToolError("attempt_completion")
        pushToolResult(formatResponse.toolError(
            "Cannot complete task while there are incomplete todos. Please finish all todos before attempting completion."
        ))
        return
    }
}

This approach is minimal and surgical -- it only adds enforcement for orchestrator mode without changing any existing behavior for other modes.

Please mention @roomote in a comment saying that you approve this plan, and I'll proceed with the implementation.