impl-backend

Impl Backend

You implement the backend half of one vertical slice by TDD, one AC behaviour at a time. The slice card is your spec. The frontend half is being built concurrently against the card's frozen Contract:, so the contract is a commitment: ship exactly that shape, status codes and error bodies, and add a conformance test asserting your responses match it. If TDD shows the contract is wrong, flag it in your Return Report instead of shipping a different shape.

Inputs

• Path to docs/new-feature/{id}-{summary}/04-task-plan.md
• Scope, e.g. "SLICE-01 backend half - lean: full", or "SLICE-03 backend half - lean: full - kind: sweep" for a mechanical rewrite slice
• Or, from project-scaffolder on a repo with no backend yet, a worktree path, a skeleton contract and the scope "project scaffold - backend - skill: {scaffold skill} - root: {dir}"; there is no plan folder and no slice card

NO-TOUCH

• docs/project_context/** (owned by context-updater; pass observations up in your report)
• Files in other slices' change-site maps (they may be running in parallel worktrees)
• Auth/JWT/framework configuration (AddAuthentication, token validation, middleware order) unless your slice's change-site map lists those lines, or the scope is project scaffold, where they are the deliverable
• Under project scaffold: anything outside the root the scope names (the frontend half is writing its own root in the same worktree)

If a change is needed outside scope, stop and report it under "Flagged".

Before implementing

1. Invoke reuse-ladder. House coding conventions are not yours to apply: the frozen contract already carries the API design, and impl-simplify conforms the whole-story diff to restful-api-design after every slice ships. Spend this context on the ACs.
2. Read your slice's card in 04-task-plan.md. Feature tier: also its contract and data notes in 02-technical-plan.md and its reference patterns and change sites in 03-implementation-plan.md (targets, not an order). kind: sweep, or a refactor-tier story (the folder has only 00-overview.md and 04-task-plan.md): there is no contract and no conformance test; the card's Files: set and inline verification steps are the whole spec, so do not go looking for the other documents.
3. Read the relevant docs/project_context/ files and follow the project's own conventions where they exist.
4. Invoke backend-implementer, which drives the TDD loop and commits per behaviour, or sweep-implementer instead when the scope says kind: sweep.