implement

name	implement
description	Implement a requested feature or behavior change from freeform instructions or a named proposal, report, or legacy blueprint. Use debug for unexplained failures, fix for supplied findings, and refine for behavior-preserving cleanup.
allowed-tools	Bash, Read, Write, Edit, Glob, Grep
argument-hint	[instructions|blueprint-slug-or-path]

Implement

Deliver the requested change with proportionate verification. Artifacts are optional inputs, never prerequisites.

@rules/blueprints.md, @rules/harness-compat.md, and @rules/artifact-readability.md apply.

Inputs

• Freeform request — use the conversation as the execution source.
• Explicitly named artifact path — store it in file and read that proposal, report, or legacy blueprint.
• Slug — resolve one unambiguous file with blueprint find --type proposal,report,spec,plan --match <slug>, then store its path in file.
• No artifact — proceed directly; do not search for or create one.

Explicitly invoking this skill with a draft proposal authorizes it. Set the proposal to approved and commit before source edits, using the artifact safety checks in step 3. Legacy artifacts require no particular status; explicit implementation is sufficient authorization. Use fix for a review artifact.

Workflow

1. Bound Work

Read applicable repository instructions and inspect git status --short before editing. Preserve unrelated work. Read the named artifact and relevant source, then extract scope, constraints, acceptance criteria, and verification. For freeform work, derive the smallest safe execution sequence.

2. Implement

For each cohesive change:

1. Read affected code and tests.
2. Confirm the expected behavior and important failure boundaries.
3. Make the smallest complete change without unrelated refactoring.
4. Add or update tests only where they protect realistic behavior.
5. Run the narrowest useful verification, then broader checks as risk warrants.
6. Inspect the resulting diff for scope, correctness, and accidental churn.

Continue through recoverable failures. Stop and report genuine blockers with the exact evidence or decision needed to proceed. Do not create a tracker or report artifact.

3. Update Source Artifact When Present

• Proposal: append concise changes and verification under ## Implementation Notes; set it to complete only after all acceptance criteria pass. Leave a partial implementation approved. Commit the notes first, then change and commit status separately.
• Legacy spec/plan: append implementation notes and preserve readable legacy status behavior.

Preserve artifact frontmatter and write below the closing ---. Before each artifact commit, run blueprint validate "$file", then blueprint commit <type> "$file". The CLI refuses a pre-existing blueprint index and stages only the exact file. Stop on failure. This does not authorize a source-code commit.

4. Report

Return the outcome, files changed, verification commands and results, and any remaining work or risk. Suggest $review or $commit only when useful.

Rules

• Freeform implementation requires no blueprint.
• A named proposal or report constrains scope but does not replace source inspection.
• Revalidate findings before changing code.
• Preserve unrelated working-tree changes and never stage or commit them.
• Do not create harness-native durable state.