Concurrency

Flow-Next supports parallel work because task state is repo-local and tasks declare dependencies.

Safe parallelism

• Different specs on different branches
• Independent tasks from the same spec
• Worktrees for isolation
• Soft claims to avoid duplicate work

Worker isolation

/flow-next:work dispatches worker subagents with fresh context per task. Each worker re-anchors against the spec, task, and git state before editing.

Coordination rule

If two tasks touch the same high-churn module, prefer serial execution or split the module boundary first.

Solo developer

Solo concurrency is mostly about not losing context:

/flow-next:work fn-1
/flow-next:impl-review fn-1
/flow-next:work fn-2

Keep one spec in active implementation unless the second spec is truly isolated. If you switch, re-anchor before editing: read the spec, ready tasks, branch diff, and current review receipts.

Team execution

Teams can run multiple workers when the graph supports it:

flowchart LR
  Spec["Reviewed spec"] --> API["Worker 1: API"]
  Spec --> UI["Worker 2: UI"]
  Spec --> Docs["Worker 3: docs"]
  API --> Review["Impl review"]
  UI --> Review
  Docs --> Review

The tech lead should decide boundaries before launching parallel work. Product should not need to coordinate merge conflicts; product should review whether the implemented behavior matches the spec.

Worktree pattern

Use a worktree per independent task cluster when multiple agents need to edit simultaneously:

Worktree	Scope
fn-12-api	Server contract, tests
fn-12-ui	Client integration using agreed contract
fn-12-docs	Docs and examples

Merge back through the same spec branch and run /flow-next:spec-completion-review after integration. The completion review is where cross-task drift is caught.

Signals to stop parallelizing

• Two workers repeatedly touch the same files.
• Review findings mention conflicting assumptions.
• A task needs a product answer that is not in the spec.
• Tests only pass in one worktree.
• The PR body cannot explain acceptance coverage cleanly.

When these show up, serialize the risky part and improve the spec before restarting.