implement

name	implement
effort	xhigh
description	Feature implementation phase. Invoke with `/implement #<issue>` or when user says 'implement', 'work on issue #', 'start coding'. Clears context, fetches issue, enters plan mode, then implements with TDD. Gates to /submit when complete.

Feature Implementation Phase

Guide the development process from issue to tested, reviewable code.

Usage

/implement #<issue_number>
/implement <issue_number>

Example:

/implement #123

Also triggers on:

• "implement #123"
• "work on issue #123"
• "let's work on #123"
• "start coding #123"

Workflow Overview

Step 1: Clear context (fresh start)
Step 2: Fetch issue content
Step 3: Create feature branch
Step 4: Enter plan mode → write implementation plan
Step 5: GATE              ← "Plan approved?"
Step 6: Implement (TDD)
Step 7: QA (tests + code review)
Step 8: GATE              ← "Ready for review?"

Workflow Steps

Step 1: Clear Context

Start fresh to avoid context pollution from the spec phase.

Suggest to user:

Starting implementation for #<issue_number>.
Recommend clearing context for a fresh start: /clear

Or we can continue in this session if you prefer.

If user agrees, they run /clear and re-invoke /implement #<issue_number>. If user prefers to continue, proceed to Step 2.

Step 2: Fetch Issue Content

Retrieve the issue to understand requirements:

GitHub:

gh issue view $ISSUE_NUM --json title,body,labels

GitLab:

glab issue view $ISSUE_NUM

Parse and extract:

• Requirements (from PM phase)
• Architecture decisions (from architect phase)
• Acceptance criteria (checklist)
• UX constraints (from designer phase)

Step 3: Create Feature Branch

Check if branch already exists:

ISSUE_NUM="$1"
EXISTING_BRANCH=$(git branch -a | grep -E "(feature|fix|hotfix)/${ISSUE_NUM}-" | head -1 | xargs)

if [ -n "$EXISTING_BRANCH" ]; then
    git checkout "$EXISTING_BRANCH"
    echo "Switched to existing branch: $EXISTING_BRANCH"
else
    bash scripts/create_feature_branch.sh $ISSUE_NUM feature <brief-description>
fi

Step 4: Enter Plan Mode

CRITICAL: Enter plan mode to create an implementation plan before writing code.

Use the EnterPlanMode tool, then:

1. If implementing a Django feature, read ~/.claude/docs/django.md for design principles to align against
2. Explore the codebase based on architecture from the issue
3. Identify files to create/modify
4. Map each task to its TDD cycle (failing test → minimal code → refactor)
5. Write a step-by-step implementation plan

Plan should include:

• Files to create/modify (with full paths)
• Order of implementation (dependencies first)
• For each task: the test to write first, then the implementation
• Key code patterns to follow from existing codebase
• Acceptance criteria mapped to implementation tasks

TDD is the default. Every task in the plan should specify what test gets written first. If any task genuinely cannot be test-driven (e.g., pure UI layout, config-only changes, infrastructure wiring), it MUST be explicitly marked in the plan with a reason. These exceptions will be flagged to the user at the plan approval gate.

Write the plan to the plan file (path provided by plan mode).

Step 5: GATE - Plan Approved

Use ExitPlanMode to present the plan for user approval.

DO NOT write any code until user approves the plan.

If user requests changes → update the plan and re-present. If user approves → proceed to Step 6.

Step 6: Implementation Loop

Execute the approved plan using TDD:

1. Write a failing test for the first task
2. Run the test — confirm it fails
3. Implement the minimal code to make it pass
4. Run the test — confirm it passes
5. Refactor if needed
6. Commit (test and implementation together)
7. Repeat for the next task

TDD Exception Gate: If you encounter a task where TDD is not feasible and it was not already flagged in the plan, you MUST stop and use AskUserQuestion before proceeding:

⚠️ TDD Exception

Task: <description of the task>
Reason TDD isn't feasible: <explanation>
Proposed approach: <tests-after / manual verification / etc.>

Proceed without TDD for this task?
- Yes → Continue with proposed approach
- No → Let's discuss an alternative

Do NOT silently skip TDD. Writing all tests at the end is not acceptable without explicit human acknowledgment.

Commit format:

git commit -m "$(cat <<'EOF'
<Type> #<issue>: <Brief description>

<Why explanation>

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[e-mail]>
EOF
)"

Commit types: Fix, Add, Update, Refactor, Remove, Docs, Test, Chore

Step 7: QA

Run tests:

# Swift/iOS
swift test

# Python
pytest

# React Native
npm run test

Run code reviewer:

Domain	Reviewer
Swift	swift-swiftui-reviewer agent
Python	python-code-reviewer skill
React Native	react-native-reviewer skill

TDD compliance check: Review the commit history for this branch. Tests should appear in commits alongside their implementation code, not lumped together at the end. If all tests were written after all implementation, flag this to the user — TDD was not followed.

Manual QA (if needed):

• Build and run the app
• Test the feature manually
• Verify acceptance criteria from the issue

Address any issues before proceeding.

Step 8: GATE - Ready for Review

CRITICAL: STOP and ask user before proceeding to submit phase.

Use AskUserQuestion:

✅ Implementation complete!

Branch: feature/<issue>-<description>
Commits: <count> commits
Tests: ✓ passing
Code review: ✓ no critical issues

Ready for code review?
- Yes → Continue to /submit
- No → Continue working or run more tests

When user confirms "Yes": Invoke the submit skill:

Skill tool: skill="submit"

Commit Quality Standards

Every commit MUST:

1. Start with a type prefix (Fix, Add, Update, etc.)
2. Reference the issue number (#123)
3. Have subject under 72 characters
4. Explain "why" in the body (not just "what")

See references/commit_message_format.md for examples.

Git Hooks

Install hooks to enforce standards (once per repo):

bash scripts/setup_git_hooks.sh

Error Handling

Situation	Action
Issue not found	Ask user for correct issue number
Branch conflict	Ask user how to resolve
Tests failing	Fix before gating to submit
Code review issues	Fix before proceeding

Resources

scripts/

• create_feature_branch.sh - Creates properly named branches
• pre_commit_hook.sh - Blocks commits to main/master
• commit_msg_hook.sh - Validates commit message format
• setup_git_hooks.sh - Installs all git hooks

references/

• commit_message_format.md - Commit message guidelines and examples

Next Phase

After implementation is complete and user confirms, chains to → /submit