parallelize

name	parallelize
description	Fan out 2+ isolated, non-dependent tasks to parallel Engineer subagents. Validates isolation, creates per-task handoff files, updates state.json, and spawns agents. Use when the task list contains work that can run simultaneously.

Parallelize Skill

When to Use

• Manager identifies 2+ tasks that are isolated and non-dependent
• User runs /parallelize TASK-A TASK-B [TASK-C...]
• After foundation task completes and parallel streams are ready

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Step 1: Validate Isolation

Before spawning anything, verify ALL of these pass for the task set:

• Each task operates on separate directory trees (no shared files)
• No task in the set depends on another task in the set
• All tasks depend on the same prior-completed task (or have no dependencies)
• Each task has a distinct handoff filename
• Manager can track all via state.json array form

If any check fails: Block parallelization. Explain which tasks overlap or have unresolved dependencies. Ask user to refactor the task split before proceeding.

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Step 2: Create Per-Task Handoff Files

For each task, write a dedicated handoff file:

• Primary task → .agents/handoff.md
• Each additional task → .agents/handoff-TASK-X.md

Each file contains: task ID, title, description, acceptance criteria, relevant workspace context, and instructions for the Engineer to delete only their own handoff file on completion.

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Step 3: Update state.json

Switch handoff to array form:

"handoff": [
  { "task_id": "TASK-A", "status": "in_progress", "prompt_file": ".agents/handoff.md" },
  { "task_id": "TASK-B", "status": "in_progress", "prompt_file": ".agents/handoff-TASK-B.md" },
  { "task_id": "TASK-C", "status": "in_progress", "prompt_file": ".agents/handoff-TASK-C.md" }
]

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Step 4: Spawn Engineers

Use the Agent tool to spawn one Engineer subagent per task simultaneously (multiple Agent tool calls in a single response). Pass each agent its assigned handoff file as context.

Show the user the parallel dispatch summary:

Spawning [N] parallel Engineer subagents:

  🔧 Engineer A → TASK-A: [title]
  🔧 Engineer B → TASK-B: [title]
  🔧 Engineer C → TASK-C: [title]

All running simultaneously. Manager will aggregate results when complete.

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Step 5: Monitor and Aggregate

As each Engineer subagent completes:

1. Update state.json → mark their task completed
2. Update .agents/state.md dashboard
3. Check if any downstream tasks are now unblocked
4. Report to user: which tasks are done, which are still running, what's unblocked next

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Rules

• Never parallelize if isolation checklist has any failure
• If tasks share files with each other → block, ask user to refactor
• If a task in the set depends on another → block, explain the dependency chain
• Engineers delete only their own handoff file on completion — never touch parallel files
• For full isolation protocol, see .agents/parallelization-protocol.md