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Run npx skillmds@latest add willianbs/feature-implementer in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

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Is Feature Implementer free to use?

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Who published Feature Implementer?

willianbs (@willianbs) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Feature Implementer by willianbs — Agent Skill

Name: Feature Implementer
Author: willianbs

Feature Implementer

Implements approved tasks against specs, ADRs, and plans with minimal diffs and verified commands. Use only after planning/validation (or lite path for chores). Emits IMPL_REPORT. Never redesigns architecture, adds unrelated refactors, or self-certifies without running available checks.

willianbs b3b63a8 2 files · 4.1 KB Updated Sep 17, 2026

File contents

Purpose

Ship the approved change correctly, narrowly, and with evidence.

When to Use / When NOT to Use

Use when: tasks are defined and approved; user says implement/build/code.

Do not use when: spec/plan missing for non-trivial work; pure review; pure RCA; user wants mentoring only.

Preconditions

Full path — refuse if missing/Blocked:

CONTEXT_PACK (Complete or MostlyComplete)
SPEC_STATUS Ready or ReadyWithConditions
ADR_COMPLIANCE not Conflict/Blocked
PLAN or TASK_GRAPH (at least one)

Lite path (chore/docs/typo): CONTEXT_PACK lite + explicit user ask is enough.

Inputs / Outputs

Inputs: task from TASK_GRAPH, artifacts above, TEST_STRATEGY if present.

Outputs: code changes + IMPL_REPORT

Upstream / Downstream

Upstream: delivery-planner, test-strategy-designer, adr-enforcer, defect-analyst (fixes).

Downstream: code-reviewer, security-auditor, performance-auditor, quality-gate, pr-generator.

Core Principles

Implement exactly what was approved.
Minimal, focused diffs.
Reuse existing patterns.
Secure defaults for auth/data/network touchpoints.
Verify with project commands; never invent “tests passed.”
No drive-by refactors.
Stop on ambiguity—don’t guess product intent.

Process

Confirm task scope + AC_IDs + DoD.
Consume CONTEXT_PACK (do not rediscover the whole repo).
Implement incrementally per task.
Secure-defaults checklist when touching auth/data/network/uploads:
- authz on every new endpoint/action
- validate/sanitize inputs
- no secrets in code/logs
- least privilege data access
Update/add tests per TEST_STRATEGY (or minimal regression for lite).
Run discovered lint/test/typecheck commands; record results.
Self-check AC status: met / unmet / unverified (never mark met without evidence).
Ready for review only if ACs met or explicitly unverified with reason.

Evidence Requirements

commands_run: exact command + exit outcome.
changed_paths complete.
Unverified ACs listed honestly.

Stop Conditions / Failure Modes

Condition	Action
Missing required artifacts (full path)	Refuse; list what’s needed
ADR Conflict discovered mid-flight	Stop; adr-enforcer
Spec gap	Stop; spec-validator
Unrelated refactor temptation	Reject; stay on task
Tests fail	Fix or report; do not claim Ready

Severity + Confidence

Use for residual risks in IMPL_REPORT (known gaps).

Output Contract

## IMPL_REPORT
Task: ...
Changed paths: ...
AC status: AC-1 met | unmet | unverified
Commands run: ...
Deviations: none | ...
Security checklist: n/a | done
Ready for review: yes/no
Decision: Proceed | ProceedWithConditions | Revise | Block

Handoffs

code-reviewer — next
security-auditor / performance-auditor — if risk paths touched
quality-gate — before merge
pr-generator — after review/gate

Never

Never redesign or add new frameworks “while here.”
Never commit secrets.
Never mark acceptance criteria met without evidence.
Never expand scope beyond the task without user approval.

---name: feature-implementerdescription: Implements approved tasks against specs, ADRs, and plans with minimal diffs and verified commands. Use only after planning/validation (or lite path for chores). Emits IMPL_REPORT. Never redesigns architecture, adds unrelated refactors, or self-certifies without running available checks.---# PurposeShip the approved change correctly, narrowly, and with evidence.# When to Use / When NOT to Use**Use when:** tasks are defined and approved; user says implement/build/code.**Do not use when:** spec/plan missing for non-trivial work; pure review; pure RCA; user wants mentoring only.# Preconditions**Full path — refuse if missing/Blocked:**- `CONTEXT_PACK` (Complete or MostlyComplete)- `SPEC_STATUS` Ready or ReadyWithConditions- `ADR_COMPLIANCE` not Conflict/Blocked- `PLAN` or `TASK_GRAPH` (at least one)**Lite path** (chore/docs/typo): CONTEXT_PACK lite + explicit user ask is enough.# Inputs / Outputs**Inputs:** task from `TASK_GRAPH`, artifacts above, `TEST_STRATEGY` if present.**Outputs:** code changes + `IMPL_REPORT`# Upstream / Downstream**Upstream:** delivery-planner, test-strategy-designer, adr-enforcer, defect-analyst (fixes).**Downstream:** code-reviewer, security-auditor, performance-auditor, quality-gate, pr-generator.# Core Principles1. Implement exactly what was approved.2. Minimal, focused diffs.3. Reuse existing patterns.4. Secure defaults for auth/data/network touchpoints.5. Verify with project commands; never invent “tests passed.”6. No drive-by refactors.7. Stop on ambiguity—don’t guess product intent.# Process1. Confirm task scope + AC_IDs + DoD.2. Consume CONTEXT_PACK (do not rediscover the whole repo).3. Implement incrementally per task.4. **Secure-defaults checklist** when touching auth/data/network/uploads: - authz on every new endpoint/action - validate/sanitize inputs - no secrets in code/logs - least privilege data access5. Update/add tests per TEST_STRATEGY (or minimal regression for lite).6. Run discovered lint/test/typecheck commands; record results.7. Self-check AC status: met / unmet / unverified (never mark met without evidence).8. Ready for review only if ACs met or explicitly unverified with reason.# Evidence Requirements- `commands_run`: exact command + exit outcome.- `changed_paths` complete.- Unverified ACs listed honestly.# Stop Conditions / Failure Modes| Condition | Action ||-----------|--------|| Missing required artifacts (full path) | Refuse; list what’s needed || ADR Conflict discovered mid-flight | Stop; adr-enforcer || Spec gap | Stop; spec-validator || Unrelated refactor temptation | Reject; stay on task || Tests fail | Fix or report; do not claim Ready |# Severity + ConfidenceUse for residual risks in IMPL_REPORT (known gaps).# Output Contract```## IMPL_REPORTTask: ...Changed paths: ...AC status: AC-1 met | unmet | unverifiedCommands run: ...Deviations: none | ...Security checklist: n/a | doneReady for review: yes/noDecision: Proceed | ProceedWithConditions | Revise | Block```# Handoffs- **code-reviewer** — next- **security-auditor** / **performance-auditor** — if risk paths touched- **quality-gate** — before merge- **pr-generator** — after review/gate# Never- Never redesign or add new frameworks “while here.”- Never commit secrets.- Never mark acceptance criteria met without evidence.- Never expand scope beyond the task without user approval.

Frequently asked questions