Momento/.agent/skills/wds-5-agentic-development/steps-e/step-04-implement.md

---
name: 'step-04-implement'
description: 'Implement changes incrementally, verifying at each step'

# File References
nextStepFile: './step-05-verify-and-document.md'
---

# Step 4: Implement

## STEP GOAL:

Implement changes incrementally, verifying at each step.

## MANDATORY EXECUTION RULES (READ FIRST):

### Universal Rules:

- 🛑 NEVER generate content without user input
- 📖 CRITICAL: Read the complete step file before taking any action
- 🔄 CRITICAL: When loading next step with 'C', ensure entire file is read
- 📋 YOU ARE A FACILITATOR, not a content generator
- ✅ YOU MUST ALWAYS SPEAK OUTPUT in your Agent communication style with the config `{communication_language}`

### Role Reinforcement:

- ✅ You are an Implementation Partner guiding structured development activities
- ✅ If you already have been given a name, communication_style and persona, continue to use those while playing this new role
- ✅ We engage in collaborative dialogue, not command-response
- ✅ You bring software development methodology expertise, user brings domain knowledge and codebase familiarity
- ✅ Maintain clear and structured tone throughout

### Step-Specific Rules:

- 🎯 Focus only on implementing each planned commit, testing after each, and ensuring backward compatibility
- 🚫 FORBIDDEN to skip verification points or proceed with broken tests
- 💬 Approach: Execute each planned step methodically — implement, self-check, test, commit
- 📋 Backward compatibility must be verified at every commit

## EXECUTION PROTOCOLS:

- 🎯 All planned steps implemented with passing tests and backward compatibility
- 💾 Update dialog file with implementation progress after each commit
- 📖 Reference the implementation plan from Step 3 and verification points
- 🚫 Do not proceed to next commit if current one is broken

## CONTEXT BOUNDARIES:

- Available context: Scope from Step 1; risks from Step 2; implementation plan from Step 3
- Focus: Incremental implementation following the plan
- Limits: Only implement what is in the plan — no scope creep
- Dependencies: Step 3 must be complete (plan exists)

## Sequence of Instructions (Do not deviate, skip, or optimize)

### 1. Create Feature Branch

- Branch from the current working branch
- Use a descriptive name: `feature/<short-description>` or `evolve/<feature-name>`
- Commit the branch before making changes

### 2. Implement Incrementally Per Plan

For each planned commit:

1. **Read the plan** — What does this step require?
2. **Implement** — Write the code for this step only
3. **Self-check** — Does this change stay within its planned scope?
4. **Test** — Run relevant tests, verify the step works
5. **Commit** — Clean commit with descriptive message

### 3. Test After Each Step

- Run the verification point defined in Step 03
- If automated tests exist, run them after each commit
- If modifying existing features, verify they still work (baseline comparison)
- Do not proceed to the next step if the current one is broken

### 4. Ensure Backward Compatibility at Each Commit

At every commit, ask:
- Does the existing functionality still work?
- Can an existing user do everything they could before?
- Are any existing API consumers affected?
- If a commit breaks backward compatibility, either fix it or add a feature flag

### 5. Use Feature Flags if Needed

When the plan calls for feature flags:
- Implement the flag check early (before building the feature behind it)
- Default to "off" — new feature is hidden until explicitly enabled
- Ensure the "off" path is identical to the pre-change behavior
- Test both flag states: on (new behavior) and off (old behavior)

### 6. Verify Checklist

- [ ] Feature branch created
- [ ] Each planned step implemented and committed separately
- [ ] Tests pass after each commit
- [ ] Backward compatibility verified at each commit
- [ ] Feature flags implemented correctly (if applicable)
- [ ] Dialog file updated with implementation progress

### 7. Present MENU OPTIONS

Display: "**Select an Option:** [C] Continue to Step 5: Verify and Document"

#### Menu Handling Logic:
- IF C: Update design log, then load, read entire file, then execute {nextStepFile}
- IF Any other comments or queries: help user respond then [Redisplay Menu Options]

#### EXECUTION RULES:
- ALWAYS halt and wait for user input after presenting menu
- ONLY proceed to next step when user selects 'C'
- User can chat or ask questions - always respond and then redisplay menu options

## CRITICAL STEP COMPLETION NOTE

ONLY WHEN all planned steps are implemented, tested, and committed with backward compatibility verified will you then load and read fully `{nextStepFile}` to execute.

---

## 🚨 SYSTEM SUCCESS/FAILURE METRICS

### ✅ SUCCESS:
- Feature branch created
- Each planned step implemented and committed separately
- Tests pass after each commit
- Backward compatibility verified at each commit
- Feature flags implemented correctly (if applicable)
- Dialog file updated with implementation progress

### ❌ SYSTEM FAILURE:
- Proceeding to next step with broken tests
- Not verifying backward compatibility
- Implementing outside the planned scope
- Not testing feature flag on/off states

**Master Rule:** Skipping steps, optimizing sequences, or not following exact instructions is FORBIDDEN and constitutes SYSTEM FAILURE.