Writing Plans

Overview

Write comprehensive implementation plans assuming the engineer has zero context for the codebase and questionable taste. Document everything they need to know: which files to touch for each task, code, testing, docs they might need to check, how to test it. Give them the whole plan as bite-sized tasks. DRY. YAGNI. TDD. Frequent commits.

Assume they are a skilled developer, but know almost nothing about the toolset or problem domain. Assume they don't know good test design very well.

Core principle: Plans must be executable without asking questions.

The Iron Law

NO VAGUE STEPS - EVERY STEP IS A SPECIFIC ACTION

"Add validation" is not a step. "Write test for empty email, run it, implement check, run it, commit" - that's 5 steps.

Bite-Sized Task Granularity

Each step is one action (2-5 minutes):

• "Write the failing test" - step
• "Run it to make sure it fails" - step
• "Implement the minimal code to make the test pass" - step
• "Run the tests and make sure they pass" - step
• "Commit" - step

Not a step:

• "Add authentication" (too vague)
• "Implement the feature" (multiple actions)
• "Test it" (which tests? how?)

Plan Document Header

Every plan MUST start with this header:

# [Feature Name] Implementation Plan

> **For Claude:** REQUIRED: Follow this plan task-by-task using TDD.
> **Design:** See `docs/plans/YYYY-MM-DD-<feature>-design.md` for full specification.

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

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

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

**Prerequisites:** [What must exist before starting]

---

Note: If a design document exists, always reference it in the header.

Task Structure

### Task N: [Component Name]

**Files:**
- Create: `exact/path/to/file.ts`
- Modify: `exact/path/to/existing.ts:123-145`
- Test: `tests/exact/path/to/test.ts`

**Step 1: Write the failing test**

```typescript
test('specific behavior being tested', () => {
  const result = functionName(input);
  expect(result).toBe(expected);
});

Step 2: Run test to verify it fails

Run: npm test tests/path/test.ts -- --grep "specific behavior" Expected: FAIL with "functionName is not defined"

Step 3: Write minimal implementation

function functionName(input: InputType): OutputType {
  return expected;
}

Step 4: Run test to verify it passes

Run: npm test tests/path/test.ts -- --grep "specific behavior" Expected: PASS

Step 5: Commit

git add tests/path/test.ts src/path/file.ts
git commit -m "feat: add specific feature"

## Context is King (Cole Medin Principle)

**The plan must contain ALL information for a single-pass implementation.**

A developer with zero codebase context should be able to execute the plan WITHOUT asking any questions.

### Context References Section (MUST READ!)

**Every plan MUST include a Context References section:**

```markdown
## Relevant Codebase Files

### Patterns to Follow
- `src/components/Button.tsx` (lines 15-45) - Component structure pattern
- `src/services/api.ts` (lines 23-67) - API service pattern

### Configuration Files
- `tsconfig.json` - TypeScript settings
- `.env.example` - Environment variables needed

### Related Documentation
- `docs/architecture.md#authentication` - Auth flow overview
- `README.md#running-tests` - Test commands

Why: Claude forgets context. External docs get stale. File:line references are always accurate.

Validation Levels

Match validation depth to plan complexity:

Include specific validation commands in each task step.

Requirements Checklist

Before writing a plan:

• Problem statement clear
• Users identified
• Functional requirements listed
• Non-functional requirements listed (performance, security, scale)
• Constraints documented
• Success criteria defined
• Existing code patterns understood
• Context References section prepared with file:line references

Risk Assessment Table

For each identified risk:

Score = Probability × Impact. Address risks with score > 8 first.

Risk-Based Testing Matrix

Match testing depth to task risk:

How to assess risk:

• How many files touched? (1 = low, 3+ = medium, cross-service = high)
• Is it auth/payments/security? (always high or critical)
• Is it user-facing? (medium minimum)
• Can it cause data loss? (high or critical)

Use this matrix when planning test steps. Don't over-test trivial changes. Don't under-test critical ones.

Functionality Flow Mapping

Before planning, document all flows:

User Flow:

1. User clicks [button]
2. System shows [form]
3. User enters [data]
4. System validates [input]
5. System saves [data]
6. System shows [confirmation]

Admin Flow:

1. Admin opens [dashboard]
2. Admin selects [item]
3. System shows [details]
4. Admin changes [setting]
5. System applies [change]

System Flow:

1. Request arrives at [endpoint]
2. Middleware validates [auth]
3. Controller calls [service]
4. Service queries [database]
5. Response returns [data]

Architecture Decision Records (ADR)

When comparing approaches, document the decision formally:

Use this format when a plan involves choosing between multiple valid approaches:

## ADR: [Decision Title]

**Context:** What situation or requirement prompted this decision?

**Decision:** What approach did we choose?

**Consequences:**
- **Positive:** [benefits of this choice]
- **Negative:** [tradeoffs we accept]
- **Alternatives Considered:** [what we didn't choose and why]

When to use ADR:

• Choosing between architectures (monolith vs microservices)
• Selecting libraries/frameworks (React vs Vue)
• Database decisions (SQL vs NoSQL)
• Authentication approaches (JWT vs sessions)

Save ADRs to: docs/decisions/ADR-NNN-title.md

Red Flags - STOP and Revise

If you find yourself:

• Writing "add feature" without exact file paths
• Skipping the test step
• Combining multiple actions into one step
• Using "etc." or "similar" instead of explicit steps
• Planning without understanding existing code patterns
• Creating steps that take more than 5 minutes
• Not including expected output for test commands

STOP. Revise the plan with more specific steps.

Rationalization Prevention

Output Format

# [Feature Name] Implementation Plan

> **For Claude:** REQUIRED: Follow this plan task-by-task using TDD.

**Goal:** [One sentence]

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

**Tech Stack:** [Technologies]

**Prerequisites:** [Requirements]

---

## Phase 1: Foundation

### Task 1: [First Component]

**Files:**
- Create: `src/path/file.ts`
- Test: `tests/path/file.test.ts`

**Step 1:** Write failing test
[code block with test]

**Step 2:** Run test, verify fails
Run: `[command]`
Expected: FAIL

**Step 3:** Implement
[code block with implementation]

**Step 4:** Run test, verify passes
Run: `[command]`
Expected: PASS

**Step 5:** Commit
```bash
git add [files]
git commit -m "feat: [description]"

Task 2: [Second Component]

...

Risks

Success Criteria

• All tests pass
• Feature works as specified
• No regressions
• Code reviewed

## Save the Plan (MANDATORY)

**Two saves are required - plan file AND memory update:**

### Step 1: Save Plan File (Use Write tool - NO PERMISSION NEEDED)

First create directory

Bash(command="mkdir -p docs/plans")

Then save plan using Write tool (permission-free)

Write(file_path="docs/plans/YYYY-MM-DD--plan.md", content="[full plan content from output format above]")

Then commit (separate commands to avoid permission prompt)

Bash(command="git add docs/plans/*.md") Bash(command="git commit -m 'docs: add implementation plan'")

### Step 2: Update Memory (CRITICAL - Links Plan to Memory)

**Use Edit tool (NO permission prompt):**

First read existing content

Read(file_path=".claude/cc10x/activeContext.md")

Then use Edit to replace (matches first line, replaces entire content)

Edit(file_path=".claude/cc10x/activeContext.md", old_string="# Active Context", new_string="# Active Context

Current Focus

Plan created for [feature]. Ready for execution.

Recent Changes

• Plan saved to docs/plans/YYYY-MM-DD--plan.md

Next Steps

1. Execute plan at docs/plans/YYYY-MM-DD--plan.md
2. Follow TDD cycle for each task
3. Update progress.md after each task

Active Decisions

Plan Reference

Execute: docs/plans/YYYY-MM-DD-<feature>-plan.md

Last Updated

[current date/time]")

**Also append to progress.md using Edit:**

Read(file_path=".claude/cc10x/progress.md")

Edit(file_path=".claude/cc10x/progress.md", old_string="[last section heading]", new_string="[last section heading]

Plan Created

• Plan saved - docs/plans/YYYY-MM-DD--plan.md")

**WHY BOTH:** Plan files are artifacts. Memory is the index. Without memory update, next session won't know the plan exists.

**This is non-negotiable.** Memory is the single source of truth.

## Task-Based Execution Tracking

After saving plan, create execution tasks for tracking progress:

### Step 1: Create Parent Task

TaskCreate({ subject: "Execute: {feature} Plan", description: "Plan file: docs/plans/YYYY-MM-DD-{feature}-plan.md\n\n{brief_plan_summary}", activeForm: "Executing {feature} plan" })

Returns parent_task_id

### Step 2: Create Phase Tasks with Dependencies

For each phase in plan:

TaskCreate({ subject: "Phase 1: {phase_title}", description: "From plan: docs/plans/YYYY-MM-DD-{feature}-plan.md\n\n{phase_details}", activeForm: "Working on {phase_title}" })

Returns phase_1_id

TaskCreate({ subject: "Phase 2: {phase_title}", description: "From plan: docs/plans/YYYY-MM-DD-{feature}-plan.md\n\n{phase_details}", activeForm: "Working on {phase_title}" }) TaskUpdate({ taskId: phase_2_id, addBlockedBy: [phase_1_id] })

Continue for all phases...

### Step 3: Store Task IDs in Memory

Update `.claude/cc10x/progress.md` with task IDs:

Edit(file_path=".claude/cc10x/progress.md", old_string="## Current Workflow", new_string="## Current Workflow PLAN → Execution

Active Workflow Tasks

Last Updated: {timestamp}")

**WHY:** Tasks enable resume capability across sessions. If conversation compacts or session ends, TaskList() will show where to continue.

## Execution Handoff

After saving the plan, offer execution choice:

**"Plan complete and saved to `docs/plans/<filename>.md`. Two execution options:**

**1. Subagent-Driven (this session)** - Fresh subagent per task, review between tasks, fast iteration

**2. Manual Execution** - Follow plan step by step, verify each step

**Which approach?"**

## Remember

- Exact file paths always
- Complete code in plan (not "add validation")
- Exact commands with expected output
- DRY, YAGNI, TDD, frequent commits
- Each step = one action (2-5 minutes)
- No assumptions about context