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Split, Each & Parallel

Most real workflows decompose work into tasks and process each one. Gump handles this with split + each and optionally parallel.

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Split + Each

A step with type: split produces tasks. The each: block declares the steps to execute per task. 
steps:
  - name: decompose
    type: split
    get:
      prompt: "Decompose {spec} into independent tasks."
    run:
      agent: claude-opus
    gate: [schema]
    each:
      - name: impl
        type: code
        get:
          prompt: |
            Implement: {task.description}
            Files: {task.files}
        run:
          agent: claude-sonnet
        gate: [compile, test]
        retry:
          - exit: 3

      - name: smoke
        type: code
        get:
          prompt: "Run smoke tests and fix any issues."
          session: from: impl
        run:
          agent: {impl.agent}
        gate: [compile, test]
        retry:
          - exit: 2
The each: block is a mini-workflow executed per task. Steps within each: are sequential by default. Each task gives access to {task.name}, {task.description}, {task.files}. Tasks are processed sequentially by default. Each task’s sub-steps run in the worktree, results are committed, and the next task starts from the updated state.

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Parallel tasks

Add parallel: true on the split step to process tasks simultaneously: 
- name: decompose
  type: split
  parallel: true
  get:
    prompt: |
      Decompose {spec} into independent tasks with strictly disjoint blast radii.
  run:
    agent: claude-opus
  gate: [schema]
  each:
    - name: impl
      type: code
      ...
Each task gets its own worktree. Agents work simultaneously. Merge is sequential in declaration order. File conflict = fatal.

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The MECE requirement

Parallel execution requires tasks with strictly disjoint blast radii. If two tasks modify the same file, the merge creates a Git conflict and the run stops. Your split prompt should enforce this.

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Parallel groups (without split)

You can also parallelize steps without a split: 
- name: reviews
  parallel: true
  steps:
    - name: arch-review
      type: validate
      get:
        prompt: "Review architecture..."
      run:
        agent: claude-opus

    - name: security-review
      type: validate
      get:
        prompt: "Review security..."
      run:
        agent: gemini
Each branch gets its own worktree. Merge sequential by order. Conflict = fatal.