vibe-parallel-task-decomposition

Large tasks are often collections of independent subtasks hiding behind a sequential mental model. Find the parallelism.

When to Use This Skill

• Facing a task with 5+ subtasks
• Multiple files need changes that don't depend on each other
• Implementation plan has steps that could run concurrently
• User asks to "speed this up" or "parallelize"

When NOT to Use This Skill

• Tasks with fewer than 3 subtasks
• All subtasks depend on each other sequentially
• Changes are all in the same file
• The overhead of coordination exceeds the benefit
• Long-running, multi-phase work with follow-ups (use vibe-workstream-orchestration)

Steps

1. List all subtasks from the plan or requirements

2. Build dependency graph — For each pair of tasks, ask:

   • Do they modify the same file? → dependent
   • Does task B need output from task A? → dependent
   • Do they share mutable state? → dependent
   • Otherwise → independent (can parallelize)

3. Group into batches:

   • Batch 0: Tasks with no dependencies (run first, in parallel)
   • Batch 1: Tasks that depend only on Batch 0 (run after Batch 0, in parallel)
   • Batch N: Continue until all tasks assigned

4. Set parallelism limit — Use the harness's native parallelism (subagents, background tasks, workflows, or cloud tasks) and respect its concurrency limits. Past a handful of concurrent streams, the integration and review cost usually outweighs the speedup, so 3–5 is a sensible default unless the tasks are trivially independent.

5. Isolate — Give each parallel stream its own worktree or branch if the harness supports isolation, so streams can't overwrite each other's files. Integrate afterwards with vibe-cherry-pick-integration.

6. Create dispatch plan:

Output Format

Parallel Task Decomposition

Total Tasks: X Batches: Y Max Parallelism: Z agents Estimated Speedup: ~Nx vs sequential

Dependency Graph

Task A ──→ Task D
Task B ──→ Task D
Task C (independent)
Task D ──→ Task F
Task E (independent)

Dispatch Plan

Batch	Tasks	Parallelism	Dependencies
0	A, B, C, E	4	None
1	D	1	A, B
2	F	1	D

Per-Task Assignments

• Task A: [files], [description], [acceptance test]
• Task B: [files], [description], [acceptance test]

Integration Order

After all batches complete, integrate in order: [A, B, C, E] → D → F