feature-development

A planning workflow for new software features that creates a written plan before coding begins. It includes reviews of the scope, user experience, technical approach, security, and testing.

In plain words
What is it for?
Use it to prepare a feature plan and review document. It helps teams agree on what to build, how it should work, and how it will be tested.
Why use it?
It prevents coding from starting before the feature’s requirements, risks, and test plan have been reviewed. It also keeps implementation separate from planning.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/pjuniszewski/cook/feature-development
Any agent
npx skills add PJuniszewski/cook --skill feature-development
Clone the repo
git clone --depth 1 https://github.com/PJuniszewski/cook

Made for: Claude Code, Codex.

Per session 17 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 7,101 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 98% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00017 $0.07101
Opus 5 $0.00009 $0.03550
Sonnet 5 $0.00003 $0.01420
Haiku 4.5 $0.00002 $0.00710

Measured 2d ago against content hash 9c836360e5e1, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

feature-development scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

98% identical to cook — 171 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/feature-development/SKILL.md · 1,169 lines

How it starts

The opening of the file, as written. The whole thing — 1,169 lines — stays where its author put it; the contents beside it link to each section on GitHub.

feature-development skill

⛔ CRITICAL: PLANNING ONLY - NO CODE

/cook produces ONLY an artifact file. Do NOT implement any code.

  • ❌ NO adding/modifying source files
  • ❌ NO creating classes, functions, or components
  • ❌ NO running implementation tests
  • ❌ NO writing actual code beyond file path references
  • ❌ NO "Implementation" step in todo list
  • ✅ ONLY produce the artifact file (cook/*.cook.md)

After cooking is complete, user will separately request implementation.

Correct todo list for /cook:

  1. Create artifact file (FIRST!)
  2. Product review - scope & acceptance criteria
  3. UX review - interaction design
  4. Architecture review - technical approach
  5. Security review - risk assessment
  6. QA review - test plan
  7. Finalize artifact

WRONG - do NOT include:

  • ❌ Implementation
  • ❌ Write code
  • ❌ Any coding step

⚡ IMMEDIATE FIRST ACTION - EXECUTE NOW

Your VERY FIRST tool call MUST be Write to create the artifact file.

Execute this Write call IMMEDIATELY:

Write(
  file_path="cook/<feature-slug>.<YYYY-MM-DD>.cook.md",
  content="<full skeleton below>"
)

BLOCKED ACTIONS until artifact exists:

  • ❌ Read (any file)
  • ❌ Glob/Grep (any search)
  • ❌ Task/Explore (any agent)
  • ❌ Bash (any command)

ONLY ALLOWED first action: Write artifact file.

A PreToolUse hook will BLOCK other tools until artifact exists.

# Cooking Result

## Dish
<1-2 sentence description of what we're building>

## Status
raw

## Cooking Mode
well-done

## Current Phase
Step 0.0 - Artifact Created

## Ownership
- Decision Owner: _TBD_
- Reviewers: _TBD_
- Approved by: _TBD_

---

# Phase 0 - Project Policy & Context

## Sources Scanned
| File | Status | Key Rules |
|------|--------|-----------|
| CLAUDE.md | _Pending_ | |
| README.md | _Pending_ | |
| .claude/agents/*.md | _Pending_ | |

## Hard Rules (must not be violated)
_Pending..._

## Preferred Patterns
_Pending..._

## Detected Conflicts
_Pending..._

## Policy Alignment Risk
_Pending..._

---

# Step 1 - Read the Order

## Feature Summary
_Pending..._

## Affected Modules/Components
| Module | Impact | Risk Level |
|--------|--------|------------|
| | | |

## Dependencies
_Pending..._

## Microwave Blocker Check
_Pending..._

---

# Step 2 - Ingredient Approval (Product Review)

## Product Decision
_Pending: Approved / Rejected / Deferred_

## Scope

### In Scope
- _Pending..._

### Out of Scope
- _Pending..._

### Non-goals
- _Pending..._

## User Value
_Pending..._

## Assumptions
- _Pending..._

---

# Step 3 - Presentation Planning (UX Review)

## UX Decision
_Pending: Required / Not Required_

## User Flow
_Pending..._

## UI Components Affected
| Component | Change Type | Notes |
|-----------|-------------|-------|
| | | |

## Accessibility Considerations
_Pending..._

---

# Step 4 - Implementation Plan

## Architecture Decision

### Selected Approach
_Pending..._

### Alternatives Considered
| Option | Pros | Cons | Decision |
|--------|------|------|----------|
| Option A | | | Rejected: _reason_ |
| Option B | | | **Selected**: _reason_ |

### Trade-offs
- Sacrificing: _what we give up_
- Gaining: _what we get_

## Patch Plan

### Files to Modify
| File | Change | Risk |
|------|--------|------|
| | | |

### Commit Sequence
1. _commit message_
2. _commit message_

### High-risk Areas
- _area needing extra attention_

---

# Step 5 - QA Review

## Test Plan

### Test Cases
| # | Scenario | Given | When | Then |
|---|----------|-------|------|------|
| 1 | Happy path | | | |
| 2 | Edge case | | | |
| 3 | Error case | | | |

### Edge Cases
- _edge case 1_
- _edge case 2_

### Acceptance Criteria
- [ ] Given _context_, when _action_, then _result_
- [ ] Given _context_, when _action_, then _result_

### Regression Checks
- _existing feature to verify_

---

# Step 6 - Security Review

## Security Status
- Reviewed: _yes/no_
- Risk level: _low/medium/high_

## Security Checklist
| Check | Status | Notes |
|-------|--------|-------|
| Input validation | _Pending_ | |
| Auth/authz | _Pending_ | |
| Data exposure | _Pending_ | |
| Injection vectors | _Pending_ | |

## Issues Found
_Pending..._

---

# Step 7 - Documentation

## Documentation Updates
| File | Change Needed |
|------|---------------|
| | |

## New Documentation Needed
_Pending..._

---

# Risk Management

## Pre-mortem (3 scenarios required)
| # | What Could Go Wrong | Likelihood | Impact | Mitigation |
|---|---------------------|------------|--------|------------|
| 1 | | | | |
| 2 | | | | |
| 3 | | | | |

## Rollback Plan
1. _step 1_
2. _step 2_

## Blast Radius
- Affected users/modules: _list_
- Feature flag: _yes/no (name)_
- Rollout strategy: _immediate/gradual/canary_

---

# Decision Log

| Date | Phase | Decision | Rationale |
|------|-------|----------|-----------|
| <today> | Step 0.0 | Artifact created | Starting cook flow |

Read the full file on GitHub · 1,169 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 1,169 lines · 17 tokens per session scan A 9c836360e5e1

Subscribe to this mod's changes

feature-development is a skill published in the GitHub repository PJuniszewski/cook (13 stars, last pushed 6mo ago), licensed MIT. It adds 17 tokens to every session and 7,101 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 98% identical to cook, differing in 171 lines, and is treated as a copy.

Related

Other skills, from other repositories

performance-optimization

Optimizes application performance across frontend, backend, queries, and databases. Use when performance requirements exist, when you suspect performance regressions, when Core Web Vitals or load times need improvement, when N+1 query patterns need fixing, or when profiling reveals bottlenecks.

addyosmani/agent-skills · 59 tokens

doubt-driven-development

Subjects every non-trivial decision to a fresh-context adversarial review before it stands. Use when correctness matters more than speed, when working in unfamiliar code, when stakes are high (production, security-sensitive logic, irreversible operations), or any time a confident output would be cheaper to verify now…

addyosmani/agent-skills · 67 tokens

test-driven-development

Drives development with tests. Use when implementing any logic, fixing any bug, or changing any behavior. Use when you need to prove that code works, when a bug report arrives, or when you're about to modify existing functionality.

addyosmani/agent-skills · 50 tokens

ci-cd-and-automation

Automates CI/CD pipeline setup. Use when setting up or modifying build and deployment pipelines. Use when you need to automate quality gates, configure test runners in CI, or establish deployment strategies.

addyosmani/agent-skills · 45 tokens

context-engineering

Optimizes agent context setup. Use when starting a new session, when agent output quality degrades, when switching between tasks, or when you need to configure rules files and context for a project.

addyosmani/agent-skills · 43 tokens

git-workflow-and-versioning

Structures git workflow practices. Use when making any code change. Use when committing, branching, resolving conflicts, opening or reviewing a pull request (PR), pushing to a remote, or when you need to organize work across multiple parallel streams. Use when cutting a release, choosing a semantic version bump…

addyosmani/agent-skills · 74 tokens