# Tracer bullet

Band: established — Settled. Documented by a primary source and not seriously disputed.
Group: How work is arranged
Implemented by: https://clickai.dev/skills/to-tickets

A thin slice that goes all the way through the system rather than a horizontal layer that goes nowhere alone. Hunt and Thomas's term, and explicitly not a prototype: prototyping generates disposable code, while tracer code is lean but complete and forms part of the final skeleton. Three tests: verifiable alone, PR-sized, ordered by what it unblocks. “Build the data layer” fails all three, because its acceptance criteria are always someone else's.

## See also

- [Issue-as-spec](https://clickai.dev/legend/issue-as-spec)
- [Task graph (dependency graph)](https://clickai.dev/legend/task-graph)
- [Spec-driven development](https://clickai.dev/legend/spec-driven-development)

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