> Host: Codex CLI — This skill was designed for Claude Code and adapted for Codex. > Cross-reference commands use installed skill names in Codex rather than /octo:* slash commands. > Use the active Codex shell and subagent tools. Do not claim a provider, model, or host subagent is available until the current session exposes it. > For host tool equivalents, see skills/blocks/codex-host-adapter.md.

Writing Plans

MANDATORY COMPLIANCE — DO NOT SKIP

When this skill is invoked, you MUST produce a full implementation plan following the structure below. You are PROHIBITED from:

• Skipping the plan and jumping straight to implementation
• Producing a vague outline instead of the zero-context plan format
• Deciding the task is "simple enough" to not need a plan
• Omitting file paths, complete code, test instructions, or verification steps

The user asked for a plan, not an implementation. Write the plan first.

Your first output line MUST be: 🐙 **CLAUDE OCTOPUS ACTIVATED** - Implementation Planning

Overview

Write comprehensive implementation plans assuming the engineer has zero context for the codebase and questionable taste.

Document everything: which files to touch, complete code, how to test, how to verify.

Principles: DRY. YAGNI. TDD. Frequent commits.

Plan Document Structure

Header (Required)

markdown
# [Feature Name] Implementation Plan

**Goal:** [One sentence describing what this builds]

**Architecture:** [2-3 sentences about approach]

**Tech Stack:** [Key technologies/libraries]

**Estimated Time:** [X tasks × 5 min = Y minutes]


## Prerequisites

- [ ] [Any setup needed before starting]
- [ ] [Dependencies to install]
- [ ] [Files that must exist]

Task Granularity

Each task is ONE action (2-5 minutes):

| Good (Single Action) | Bad (Multiple Actions) | |---------------------|------------------------| | "Write the failing test" | "Write tests and implement" | | "Run test to verify it fails" | "Make it work" | | "Implement minimal code to pass" | "Add the feature" | | "Commit with message" | "Finish the feature" |

Task Template

markdown
### Task N: [Component Name]

**Files:**
- Create: `exact/path/to/new-file.ts`
- Modify: `exact/path/to/existing.ts` (lines 45-67)
- Test: `tests/exact/path/to/test.spec.ts`

**Step 1: Write failing test**

// tests/exact/path/to/test.spec.ts describe('ComponentName', () => { it('should do specific thing', () => { const result = functionName(input); expect(result).toBe(expected); }); });

**Step 2: Run test to verify it fails**

npm test tests/exact/path/to/test.spec.ts

Expected output:

FAIL: expected 'expected' but got undefined

**Step 3: Implement minimal code**

// exact/path/to/new-file.ts export function functionName(input: InputType): OutputType { // Minimal implementation return expected; }

**Step 4: Run test to verify it passes**

npm test tests/exact/path/to/test.spec.ts

Expected output:

PASS: 1/1 tests passed

**Step 5: Commit**

git add tests/exact/path/to/test.spec.ts exact/path/to/new-file.ts git commit -m "feat(component): add specific functionality"

Example: Complete Task

markdown
### Task 3: Add Email Validation

**Files:**
- Create: `src/validators/email.ts`
- Test: `tests/validators/email.spec.ts`

**Step 1: Write failing test**

// tests/validators/email.spec.ts import { validateEmail } from '../src/validators/email';

describe('validateEmail', () => { it('returns error for empty email', () => { const result = validateEmail(''); expect(result).toEqual({ valid: false, error: 'Email required' }); });

it('returns error for invalid format', () => { const result = validateEmail('not-an-email'); expect(result).toEqual({ valid: false, error: 'Invalid email format' }); });

it('returns valid for correct email', () => { const result = validateEmail('user@example.com'); expect(result).toEqual({ valid: true }); }); });

**Step 2: Run test to verify it fails**

npm test tests/validators/email.spec.ts

Expected: `Cannot find module '../src/validators/email'`

**Step 3: Implement minimal code**

// src/validators/email.ts interface ValidationResult { valid: boolean; error?: string; }

export function validateEmail(email: string): ValidationResult { if (!email || !email.trim()) { return { valid: false, error: 'Email required' }; }

const emailRegex = /^^\s@]+@^\s@]+\.^\s@]+$/; if (!emailRegex.test(email)) { return { valid: false, error: 'Invalid email format' }; }

return { valid: true }; }

**Step 4: Run test to verify it passes**

npm test tests/validators/email.spec.ts

Expected: `PASS: 3/3 tests passed`

**Step 5: Commit**

git add src/validators/email.ts tests/validators/email.spec.ts git commit -m "feat(validators): add email validation with tests"

Integration with Claude Octopus

Using Octopus for Plan Execution

After creating a plan, offer execution options:

markdown
## Execution Options

**1. Sequential (this session)**
Execute tasks one by one with verification between each.

**2. Parallel (octopus tangle)**
Use Claude Octopus to parallelize independent tasks:

${HOME}/.claude-octopus/plugin/scripts/orchestrate.sh tangle "Execute implementation plan for feature]"

**3. Full workflow (octopus embrace)**
Research → Define → Implement → Deliver:

${HOME}/.claude-octopus/plugin/scripts/orchestrate.sh embrace "Implement feature] per plan"

Plan Storage (Claude Code v2.1.10)

Claude Octopus uses session-aware plan storage. Plans are automatically saved to:

~/.claude-octopus/plans/${CLAUDE_SESSION_ID}/YYYY-MM-DD-feature-name.md

This integrates with Claude Code's plansDirectory setting. To customize:

json
// settings.json
{
  "plansDirectory": "~/.claude-octopus/plans"
}

For project-local plans, save to docs/plans/:

bash
mkdir -p docs/plans
# docs/plans/2026-01-17-user-authentication.md

Checklist for Good Plans

• ] Each task is 2-5 minutes (single action)
• ] Exact file paths (not "in the utils folder")
• ] Complete code (not "add validation logic")
• ] Exact commands with expected output
• ] TDD: test before implementation
• ] Commit after each task

Common Mistakes

| Mistake | Fix | |---------|-----| | "Add the validation" | Show exact code | | "Update the tests" | Show exact test code | | "In the config file" | config/app.config.ts line 23 | | "Run the tests" | npm test path/to/specific.spec.ts | | Large tasks (30+ min) | Break into 2-5 min steps | | No verification | Add "Run X, expect Y" |

When to Create Plans

| Scenario | Use Plan? | |----------|-----------| | Multi-step feature (3+ tasks) | Yes | | Simple bug fix (1 task) | No, just do it | | Uncertain scope | Yes (clarifies thinking) | | Delegation to subagent | Yes (zero-context execution) | | Complex refactoring | Yes | | Config change | No |

Related Skills

• test-driven-development - Each task follows TDD cycle
• verification-before-completion - Verify each step
• finishing-branch - After all tasks complete

The Bottom Line

Plan exists → Engineer with zero context can execute
Otherwise → Not a complete plan

Exact paths. Complete code. Verification steps. No assumptions.