Parallel Implementation Plan

Create an implementation-ready plan that uses meaningful agent parallelism without introducing edit races.

Core principles

Explain the feature before explaining agent orchestration.
Parallelize independent files and concerns, not arbitrary subtasks.
Give every concurrent writer an exclusive file allowlist.
Place a single-writer integration barrier after concurrent edits.
Tell lane agents that peer scopes are not their responsibility; the integrator will reconcile all lanes.
Run independent verification lanes concurrently and keep them source-read-only.
Consolidate fixes through one writer, then rerun affected checks in parallel.
Use an Economy-by-default model budget and never inherit the parent's model for fan-out workers.
Run only explicitly named unit-test files during the agent workflow; leave broad suites to CI unless the user authorizes escalation.
Prefer the fewest agents that capture the natural parallelism. More agents are not automatically better.