<skill name="apex:implement" phase="implement"> <overview> Implement the architecture from the plan phase. Build code, run tests, iterate until all validations pass.

Combines BUILDER (write code) and validation (run tests) in a tight loop. </overview>

<phase-model> phase_model: frontmatter: [research, plan, implement, rework, complete] rework: enabled db_role: [RESEARCH, ARCHITECT, BUILDER, BUILDER_VALIDATOR, REVIEWER, DOCUMENTER] legacy_db_role: [VALIDATOR] source_of_truth: gating: frontmatter.phase telemetry: db_role </phase-model> <phase-gate requires="plan|rework" sets="implement"> <reads-file>./.apex/tasks/[ID].md</reads-file> <requires-section>plan</requires-section> <appends-section>implementation</appends-section> </phase-gate> <principles> - **Follow the Plan**: The architecture was approved - implement it, don't redesign - **Pattern Discipline**: Only use patterns from the plan's pattern selection - **Fail Fast**: Run tests frequently, fix issues immediately - **No Guessing**: If spec is unclear, return to plan or ask user </principles> <initial-response> <if-no-arguments> I'll implement the planned architecture. Please provide the task identifier.

You can find active tasks in ./.apex/tasks/ or run with: /apex:implement [identifier] </if-no-arguments> <if-arguments>Load task file and begin implementation.</if-arguments> </initial-response>

<workflow> <step id="1" title="Load task and verify phase"> <instructions> 1. Read `./.apex/tasks/[identifier].md` 2. Verify frontmatter `phase: plan` OR `phase: rework` 3. Parse `<task-contract>` first and treat it as authoritative scope/ACs 4. Parse `<plan>` section, especially `<builder-handoff>` 5. If phase == rework, treat this as a Ship REJECT rework loop 6. If phase not in [plan, rework], refuse with: "Task is in [phase] phase. Expected: plan or rework"

Contract rules:

•Implementation MUST satisfy all AC-* or explicitly document unmet criteria
•If scope/ACs must change, append a <amendments><amendment ...> entry inside task-contract and bump its version </instructions>

<mcp-checkpoint> ```javascript apex_task_checkpoint(taskId, "BUILDER_VALIDATOR: Starting implementation phase", 0.5) ``` </mcp-checkpoint> </step> <step id="2" title="Extract implementation directives"> <extract-from-plan> - `<builder-handoff><mission>` - What we're building - `<builder-handoff><core-architecture>` - The chosen approach - `<builder-handoff><pattern-guidance>` - Patterns to apply with locations - `<builder-handoff><implementation-order>` - Sequence of steps - `<builder-handoff><validation-gates>` - Checks after each step - `<builder-handoff><warnings>` - Critical risks to avoid - `<architecture-decision><files-to-modify>` - Existing files to change - `<architecture-decision><files-to-create>` - New files to add </extract-from-plan> <extract-from-contract> - `<task-contract><acceptance-criteria>` - AC-* to track and validate </extract-from-contract> <create-todo-list> Create TodoWrite items for each implementation step from the plan. </create-todo-list> </step> <step id="3" title="Pre-implementation verification"> <checks> - [ ] All files to modify exist and are readable - [ ] No syntax errors in current codebase (`npm run lint` or equivalent) - [ ] Tests currently passing (baseline) - [ ] Dependencies available </checks> <on-failure>Document blockers and ask user how to proceed.</on-failure> </step> <step id="4" title="Implementation loop"> <loop until="all steps complete AND all tests pass"> <builder-phase> <for-each-step> 1. **Read target files** fully before modifying 2. **Apply patterns** from plan's pattern-guidance 3. **Write code** following architecture decision 4. **Document pattern usage**: `# [PAT:ID] ★★★★☆ (X uses, Y% success)` 5. **Run syntax check** immediately after writing </for-each-step> <pattern-discipline> ONLY use patterns listed in `<plan><patterns><applying>`. DO NOT invent new pattern names. If you need a pattern not in the plan, document it as a gap. </pattern-discipline> <failure-prevention> Review `<plan><architecture-decision><risks>` before each step. Apply mitigations proactively. </failure-prevention> </builder-phase> <validator-phase> <after-each-step> 1. Run validation gate from plan 2. If passes, continue to next step 3. If fails, fix and retry (max 3 attempts per step) 4. After 3 failures, document issue and ask user </after-each-step> <validation-commands> - Syntax: `npm run lint` / `ruff check` / language-appropriate - Types: `tsc --noEmit` / `mypy` / language-appropriate - Unit tests: `npm test` / `pytest` / language-appropriate - Integration: As specified in plan </validation-commands> </validator-phase> <checkpoint-after-each-step> ``` apex_task_checkpoint(taskId, "Completed [step]: [summary]", confidence) ``` </checkpoint-after-each-step> </loop> </step> <step id="4.5" title="Pattern Evidence Gate"> <critical> Before running full validation, verify all patterns you intend to claim. </critical> <verification-checklist> For each pattern in `<patterns-used>`: 1. [ ] Pattern exists in `<plan><patterns><applying>` 2. [ ] Trust score matches what's in the plan 3. [ ] Location (file:line) is accurate and verifiable 4. [ ] Outcome is honest (worked|tweaked|failed) </verification-checklist> <evidence-collection> ```javascript // Record pattern usage evidence BEFORE validation for (const pattern of patterns_used) { apex_task_append_evidence(taskId, "pattern", `Applied ${pattern.id} at ${pattern.location}`, { pattern_id: pattern.id, file: pattern.file, line_start: pattern.line_start, line_end: pattern.line_end, outcome: pattern.outcome } ) } ``` </evidence-collection> <fabrication-check> IF any pattern in `<patterns-used>` is NOT in `<plan><patterns><applying>`: → REMOVE it from patterns-used → Document as "unplanned pattern discovered" → Do NOT claim it in apex_reflect

Unplanned patterns can be submitted as new_patterns in apex_reflect, but NOT as patterns_used (which updates trust scores). </fabrication-check> </step>

<step id="5" title="Comprehensive validation"> <critical> This is NOT optional. Run FULL test suite before completing. </critical> <spawn-validator> <agent type="apex:test-validator"> **Task ID**: [taskId] **Modified Files**: [list from implementation] **Predictions**: [from plan's risk section]

Run: Syntax → Formatting → Type check → Unit tests → Integration tests → Coverage

Return: Validation report comparing predictions vs reality </agent> </spawn-validator>

<decision-logic> IF any failures: → Return to builder-phase with issue list → Fix and re-run validation → Max 3 full cycles before escalating to user

IF only warnings: → Document for review phase → Proceed

IF all pass: → Proceed to write implementation section </decision-logic> </step>

<step id="6" title="Write implementation section to task file"> <output-format> Append to `<implementation>` section:

xml

<implementation>
<metadata>
  <timestamp>[ISO]</timestamp>
  <duration>[Time spent]</duration>
  <iterations>[Build-validate cycles]</iterations>
</metadata>

<files-modified>
  <file path="[path]">
    <changes>[Summary of what changed]</changes>
    <patterns-applied>
      <pattern id="PAT:X:Y">[How it was used]</pattern>
    </patterns-applied>
    <diff-summary>[Key additions/removals]</diff-summary>
  </file>
</files-modified>

<files-created>
  <file path="[path]">
    <purpose>[Why created]</purpose>
    <patterns-applied>[PAT:IDs]</patterns-applied>
    <test-file>[Corresponding test if any]</test-file>
  </file>
</files-created>

<validation-results>
  <syntax status="pass|fail">[Details]</syntax>
  <types status="pass|fail">[Details]</types>
  <tests status="pass|fail" passed="X" failed="Y" skipped="Z">[Details]</tests>
  <coverage>[Percentage if available]</coverage>
</validation-results>

<acceptance-criteria-status>
  <criterion id="AC-1" status="met|not-met">[Evidence or reason]</criterion>
</acceptance-criteria-status>

<patterns-used>
  <pattern id="PAT:X:Y" location="file:line" outcome="worked|tweaked|failed">
    [Notes on usage]
  </pattern>
</patterns-used>

<issues-encountered>
  <issue resolved="true|false">
    <description>[What happened]</description>
    <resolution>[How fixed, or why unresolved]</resolution>
  </issue>
</issues-encountered>

<deviations-from-plan>
  <deviation>
    <planned>[What plan said]</planned>
    <actual>[What we did instead]</actual>
    <reason>[Why deviation was necessary]</reason>
  </deviation>
</deviations-from-plan>

<reviewer-handoff>
  <summary>[What was built]</summary>
  <key-changes>[Most important modifications]</key-changes>
  <test-coverage>[What's tested]</test-coverage>
  <known-limitations>[Edge cases, TODOs]</known-limitations>
  <patterns-for-reflection>[Patterns to report in apex_reflect]</patterns-for-reflection>
</reviewer-handoff>

<next-steps>
Run `/apex:ship [identifier]` to review and finalize.
</next-steps>
</implementation>

</output-format> <update-frontmatter> Set `phase: implement` and `updated: [ISO timestamp]` </update-frontmatter> <mcp-calls> ```javascript // Update task phase in database apex_task_update({ id: taskId, phase: "BUILDER_VALIDATOR", // Telemetry for build+validate completion handoff: reviewer_handoff_content, confidence: 0.85, files: [...files_modified, ...files_created] })

// Record implementation summary as evidence apex_task_append_evidence(taskId, "learning", "Implementation complete: " + summary, { files_modified: files_modified.length, files_created: files_created.length, patterns_applied: patterns_used.length, tests_passed: validation_results.tests.passed, iterations: metadata.iterations } )

// Checkpoint for phase completion apex_task_checkpoint(taskId, "BUILDER_VALIDATOR: Implementation complete, ready for review", 0.85)

code

</mcp-calls>
</step>

</workflow>

<critical-requirements>

<pattern-fabrication-prevention>
YOU CANNOT FABRICATE PATTERNS.

Only claim patterns that exist in `<plan><patterns><applying>`.
In `<patterns-used>`, only list patterns from the plan.
Pattern IDs claimed here will be validated during `/apex:ship`.

VIOLATION: Claiming "PAT:NEW:THING" that was never in the plan
CONSEQUENCE: apex_reflect will reject, trust scores become meaningless
</pattern-fabrication-prevention>

<syntax-gate>
Before completing implementation:
- Run linting
- Check for common errors (double async, missing brackets)
- Fix ALL syntax errors before proceeding
- DO NOT transition to ship with syntax errors
</syntax-gate>

<contract-gate>
Before finishing:
- Confirm all AC-* are met, or explicitly mark any unmet criteria with reasons
- If contract scope/ACs changed, record an amendment with rationale and bump contract version
</contract-gate>

<spec-unclear-protocol>
If implementation reveals spec ambiguity:
1. Document the ambiguity
2. Ask user for clarification
3. If architectural change needed, note it for plan revision
4. Do NOT guess and implement wrong thing
</spec-unclear-protocol>

</critical-requirements>

<success-criteria>
- All implementation steps from plan completed
- All validation gates passed
- Full test suite passing
- No syntax errors
- Acceptance criteria status reported for all AC-*
- Patterns used are from plan only (Pattern Evidence Gate passed)
- Deviations documented with reasons
- Task file updated at ./.apex/tasks/[ID].md
- apex_task_checkpoint called at start, per-step, and end
- apex_task_append_evidence called for pattern usage
- apex_task_update called with db_role: BUILDER_VALIDATOR
</success-criteria>

<next-phase>
`/apex:ship [identifier]` - Review, document, and reflect
</next-phase>

</skill>