Writing Plans

Skill — Writing Plans

When this skill activates

Any task that requires producing an implementation plan, task decomposition, step-by-step instructions, or structured execution guide. This includes feature plans, migration plans, refactoring plans, and any multi-step work breakdown.

Mandatory actions when this skill is active

Before writing any plan

1. Gather complete context. Read:
   • The specification or requirement being planned for.
   • The current codebase structure (file paths, existing patterns).
   • Any constraints (tech stack, timeline, dependencies on other work).
2. Identify the scope boundary. What is IN the plan vs OUT of scope?
3. Identify dependencies. Which steps depend on other steps? Which can be parallel?

EXPLORE — Structured Codebase Discovery (run BEFORE plan authoring)

Adapted from the PRP EXPLORE protocol (PRPs-agentic-eng by Wirasm). This is a discovery discipline that PRECEDES authoring the MindForge XML/structured plan — it does NOT replace the plan format. The output of EXPLORE feeds the plan's Context, Files, and Details sections with real, cited patterns.

Golden Rule: If you would need to search the codebase during implementation, capture that knowledge NOW, during EXPLORE.

The 8 Search Categories

Search the codebase directly (grep, find, file reads) for each category. Do NOT skip a category by assuming — confirm it against the actual repository.

1. Existing Patterns — Architectural patterns already in use (repository, service, controller, middleware, hook, etc.) in the area you'll modify.
2. Similar Features — Existing features that resemble the planned one. The closest analogue is the single most valuable reference.
3. Conventions — How files, functions, variables, classes, and exports are named and organized in the relevant area.
4. Dependencies — Packages, imports, and internal modules used by similar features. Note versions where they matter.
5. Tests — How similar features are tested: test file locations, naming, setup/teardown, fixtures, and assertion style.
6. Configs — Relevant config files, environment variables, and feature flags.
7. Error Handling — How errors are caught, propagated, logged, and surfaced to users in similar code paths.
8. Integration Points — Entry points, data flow, state changes, and the contracts/interfaces the new code must honor.

Patterns to Mirror (capture as file:line snippet references)

For each category that yields a concrete convention, record a Patterns to Mirror entry. Every entry MUST cite a real file:line source and quote the actual snippet — never paraphrase, never invent:

## Patterns to Mirror

### NAMING_CONVENTION
// SOURCE: src/services/userService.ts:1-5
[actual snippet copied from the file]

### ERROR_HANDLING
// SOURCE: src/middleware/errorHandler.ts:10-25
[actual snippet copied from the file]

### TEST_STRUCTURE
// SOURCE: tests/services/userService.test.ts:1-30
[actual snippet copied from the file]

These mirrored snippets get folded into the plan's Details blocks so the executor writes code indistinguishable from existing code.

The "No Prior Knowledge" Gate (MANDATORY before authoring)

The plan must be executable by someone with NO prior knowledge of this repo. Therefore:

• Every convention the plan references MUST be cited from the actual codebase (a real file:line + snippet). If you cannot cite it, you have not explored enough — go search.
• NEVER invent a convention, path, type, or import. If the codebase does not establish it, the plan does not assume it.
• If a needed pattern genuinely does not exist yet, say so explicitly and define the new convention in the plan (rather than pretending it already exists).

Gate check: Before moving from EXPLORE to plan authoring, confirm — "Could a developer who has never seen this repo implement every step using ONLY this plan, without searching or asking?" If not, the EXPLORE pass is incomplete.

During plan writing

Core Principle: NO PLACEHOLDERS

Every step in the plan must contain complete, executable instructions. A plan fails its purpose if the executor has to figure out what goes in a placeholder.

Bad (placeholder):

3. Add the authentication middleware to the routes.

Good (complete):

3. Add authentication middleware to API routes.
   File: src/middleware/auth.ts
   Create a new middleware function:
   - Import `verifyJWT` from `src/lib/jwt.ts`
   - Extract the `Authorization` header, strip "Bearer " prefix
   - Call `verifyJWT(token)` — if it throws, return 401 with `{ error: "Invalid token" }`
   - If valid, attach `req.user = decoded` and call `next()`

   File: src/routes/api.ts
   - Import `authMiddleware` from `src/middleware/auth.ts`
   - Add `router.use("/api/v1/protected", authMiddleware)` before the route definitions
     on line ~45 (after the public routes, before the protected group)

   Verify: Run `curl -H "Authorization: Bearer invalid" localhost:3000/api/v1/protected/me`
   Expected: 401 response with `{"error": "Invalid token"}`

Plan Structure Template

# Plan: [Feature/Task Name]

## Context
[1-3 sentences: WHY this work exists. Link to spec/ticket if applicable.]

## Scope
- IN: [What this plan covers]
- OUT: [What is explicitly excluded]

## Prerequisites
- [ ] [Anything that must be true before starting step 1]

## Steps

### Step 1: [Verb + Object] (estimated: Xmin)
**What**: [One sentence summary]
**Files**:
- `path/to/file.ts` — [what changes]
- `path/to/other.ts` — [what changes]

**Details**:
[Complete instructions with exact code patterns, not pseudocode]

**Verify**: [Exact command or check to confirm this step worked]
Expected: [What success looks like]

---

### Step 2: [Verb + Object] (estimated: Xmin)
**Depends on**: Step 1
...

## Verification (End-to-End)
[How to verify the entire plan was executed correctly]

## Rollback
[How to undo this work if something goes wrong]

Step Design Rules

1. Bite-sized: Each step is independently verifiable. If you cannot verify a step without completing the next step, merge them or restructure.
2. Atomic: Each step makes one logical change. "Add the model AND the migration AND the API route AND the tests" is four steps, not one.
3. Ordered by dependency: Steps that depend on previous steps come after them. Independent steps are noted as parallelizable.
4. Specific file paths: Every step names exact files. Never say "the config file" when you mean src/config/database.ts.
5. Include the WHY: If a step has a non-obvious reason, explain it inline. The executor should never wonder "why are we doing this?"
6. Verification after every step: Each step ends with a concrete check. Prefer runnable commands (npm test, curl, grep) over subjective checks ("looks right").

Handling Complexity

• If a step has > 10 lines of instructions: Split it into sub-steps (1a, 1b, 1c).
• If a plan has > 15 steps: Group into phases with phase-level verification gates.
• If there are conditional paths ("if X then do Y, else do Z"): Write both paths explicitly. Note the decision criteria clearly.
• If a step requires research ("find the best library for X"): That is a separate pre-plan task. Plans should not contain open-ended research.

Estimations

• Include time estimates per step (in minutes).
• Be realistic: include time for verification and debugging.
• Total plan time = sum of steps + 20% buffer for unexpected issues.
• If total exceeds 4 hours: break into multiple plans with clear handoff points.

Dependencies and Parallelism

• Mark each step with Depends on: Step N or Depends on: None (parallelizable).
• Group parallelizable steps explicitly:

  ### Steps 3-5 (parallelizable — no dependencies between them)
  

• Never leave implicit dependencies. If step 4 silently requires step 3's output, make it explicit.

After writing the plan

1. Self-review with the "zero context" test: Could someone unfamiliar with this codebase follow these steps and produce a working result? If any step requires knowledge not in the plan, add it.
2. Check for placeholder language: Search for words like "appropriate", "relevant", "as needed", "etc.", "similar to". Replace each with specifics.
3. Verify file paths exist: Every path referenced in the plan should be a real file (or explicitly marked as "create new file").
4. Confirm verification steps are runnable: Each verify command should work copy-pasted into a terminal.

Plan quality anti-patterns to flag

• "Update the configuration as appropriate" (what configuration? what value?)
• "Add error handling" (what errors? what handling? what response?)
• "Refactor the module" (which module? what pattern? what is the target state?)
• "Write tests" (what tests? what cases? what assertions?)
• Steps without verification (how do you know it worked?)
• Steps that combine 3+ unrelated changes (should be split)
• Vague time estimates ("a while", "some time") instead of minutes
• Missing rollback plan (what if step 7 fails and you need to undo steps 1-6?)

Self-check before task completion

Before marking a task done when this skill was active:

• Every step has specific file paths (no "the relevant file").
• Every step has a verification check with expected output.
• No placeholder language ("as needed", "appropriate", "etc.").
• Dependencies between steps are explicit.
• Time estimates are included per step.
• A zero-context reader could follow the plan without asking questions.
• Rollback instructions are included.
• Plan scope (IN/OUT) is clearly defined.
• If > 15 steps, organized into phases with phase-level gates.
• All file paths verified to exist (or marked as "new file").
• EXPLORE ran across all 8 search categories before authoring.
• Patterns to Mirror captured as real file:line snippets (no invented conventions).
• "No Prior Knowledge" gate passes — every referenced convention is cited from the codebase.