implement

Implement Command

Creates a minimal implementation that follows the existing patterns. One agent does the steps in order.

Usage

/sf:implement [--isolate] [SPECIFICATION_OR_PATH]

Context

Read the current branch. Check whether .sf/spec.md exists.

Input Resolution

1. If the skill has arguments: use them as a specification path or as inline requirements
2. Else if .sf/spec.md exists: use it
3. Else: ask the user where the specification is. Wait for the answer.

Execution

Step 1 — Learn

• Search the codebase for the closest existing pattern for this specification. Stop when you have one good example. Do not survey the whole repository.
• Write the example to .sf/research/pattern-example.md.

Step 2 — Implement

• Follow the pattern you found. No creativity.
• Write the simplest change that works. No abstractions for later. One feature at a time.
• Test that it works.
• Write .sf/implementation-summary.md.

Gate — Post-Implementation: run scripts/validate-implementation.sh, in this skill directory. If validate-implementation.sh fails (non-zero exit), check every criterion the spec meets, or finish the work it names. Do not report the implementation as done.

Output: Implementation + .sf/implementation-summary.md

If Step 1 finds no pattern: create the basic file structure the language expects, implement only the core requirement, and note in the summary: "No existing patterns found - used minimal approach".

Philosophy

This command enforces:

• Pattern consistency over creativity
• Working code over perfect code
• Minimal solution over extensible solution

On Claude Code

Claude Code has subagents. Use them for both steps.

Context arrives for free:

• Branch: !git branch --show-current 2>/dev/null

• Spec exists: !test -f .sf/spec.md && echo "yes" || echo "no"

• Parse $ARGUMENTS. --isolate is a Claude-only flag: strip it and set ISOLATE=true.

• Use the AskUserQuestion tool to ask for the specification location.

• Step 1: use the Agent tool with subagent_type="Explore" to find the pattern for $SPECIFICATION (request "medium" thoroughness in the prompt).

• Step 2: Task: implement-minimal with spec: $SPECIFICATION. If ISOLATE is true, add isolation: "worktree".

• Gate: bash ${CLAUDE_PLUGIN_ROOT}/scripts/validate-implementation.sh ${CLAUDE_PROJECT_DIR:+$CLAUDE_PROJECT_DIR/.sf}