# Implement

> Implement a piece of work based on a spec or set of tickets.

- Skill: `eszxcvfd/implement` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add eszxcvfd/implement`
- Raw SKILL.md: https://api.skillmd.com/api/skills/eszxcvfd/implement/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: eszxcvfd (https://skillmd.com/u/eszxcvfd)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/eszxcvfd/implement

---


Implement the work described by the user in the spec or tickets.

## Work Routing

Before writing production code, read the shared [`Work Routing`](../../WORK-ROUTING.md)
reference. It is the single source of truth for the exact project documents,
lane selection, plan ownership, and closeout rules; do not replace it with a
skill-local routing rule.

## Test Discipline

Tests protect a settled production contract; they do not choose architecture,
invent owners, or justify a production seam. Use test-first RED/GREEN only for
deterministic behavior whose contract and owner are already decided.

Do not add or retain production APIs, state, lifecycle branches, dependency
features, or instrumentation whose only consumer is a test or proof harness.

Delete tests whose only claim is a retired or forbidden name, source substring,
help text, file inventory, private call order, phase label, proof-registry
membership, or generated report shape unless that exact representation is a
public machine contract.

After every schema or protocol hard cut, audit every added or modified test and
fixture. Negative cases must protect current-contract invariants without naming
or hardcoding deleted fields, tags, widths, values, or other contracts; derive
invalid inputs from current constants and boundaries such as `WIDTH - 1` and
`WIDTH + 1`.

Use the diff to discover removed identifiers and values, then search current
code, tests, and fixtures for them. Never commit a legacy blacklist, tombstone
registry, or source-substring gate. A hard cut cannot close while historical
names or literals remain in current tests or fixtures.

Ask whether each test remains meaningful without Git history; delete or rewrite
one that only proves a dead contract is rejected. Also remove any production
API or state that exists only to make such behavior observable.

Prefer outcome-level tests at the owning boundary. A fixture that constructs a
parallel game/runtime model proves only the fixture and must not gate the
production implementation.

## Hard Cut Rules

When the governing repository docs identify the product as pre-publication,
breaking changes are mandatory and legacy versions are not supported. If that
phase is not explicit, record the bounded inference before applying this rule.

- Keep exactly one current schema, metadata, architecture, protocol, package
  identity, and compatibility-admission contract. Keep protocol/schema version
  `1` until first public shipment; replace Version 1 instead of introducing
  v2/v3.
- At schema, protocol, metadata, package-identity, and compatibility-admission
  boundaries, validate the current contract before mutation and reject input
  that does not match it. Do not interpret older data through a fallback. This
  rule does not prescribe a wider failure scope for faults after admission.
- Do not add legacy/current branches, dual read/write paths, compatibility
  facades, or migration-warning behavior.
- Update every current shipping producer, consumer, and generated artifact that
  is compiled, loaded, or otherwise consumed by the product/toolchain in the
  same contract change. Audit tests, fixtures, validators, reports, snapshots,
  mocks, and proof output independently; repository ownership alone does not
  make them synchronization peers.

Use /tdd where possible, at pre-agreed seams.

Run typechecking regularly, single test files regularly, and the full test suite once at the end.

Once done, use /code-review to review the work.

Commit your work to the current branch.