Plan Mode

When triggered, switch into planning mode: analyze the task, produce a structured plan, and wait for explicit user approval before writing any code or making changes.

The core philosophy: think deeply, communicate clearly, execute only when aligned.

When to Enter Plan Mode

• User explicitly requests it (/plan, "plan this", "think first", etc.)
• Task touches 3+ files or components
• Task involves architecture decisions, new patterns, or breaking changes
• Task is ambiguous and could be approached multiple ways
• Task involves infrastructure, CI/CD, database changes, or migrations
• You're unsure about the right approach

Plan Output Structure

Produce a plan with these sections. Adapt depth to task complexity — a small bug fix needs a lighter plan than a new feature.

1. Understanding (What)

Restate the task in your own words to confirm understanding. Call out any ambiguities or assumptions you're making. This catches misalignment early.

## Understanding
[Restate the goal in 2-3 sentences]

**Assumptions:**
- [List anything you're assuming that wasn't explicitly stated]

**Open questions:**
- [List anything you need clarified before proceeding]

If there are open questions that would significantly change the approach, STOP here and ask the user before continuing with the plan. Don't build a full plan on shaky assumptions.

2. Approach Options (How)

For non-trivial tasks, present 2-3 distinct approaches. For simple tasks, present one recommended approach with brief justification.

For each option include:

• Summary: One-line description
• How it works: Key implementation steps (keep high-level, not line-by-line)
• Pros: Why this approach is good
• Cons: Tradeoffs and risks
• Effort estimate: Relative complexity (small / medium / large)

End with a clear recommendation and why.

## Approach Options

### Option A: [Name]
**Summary:** [One line]
**How it works:** [3-5 bullet points, high-level]
**Pros:** [What's good about this]
**Cons:** [Tradeoffs]
**Effort:** [small / medium / large]

### Option B: [Name]
...

**Recommendation:** Option [X] because [reason tied to project context].

3. Task Breakdown (Steps)

Break the chosen (or recommended) approach into concrete, ordered steps. Each step should be small enough to verify independently. Group related steps into phases.

## Task Breakdown

### Phase 1: [Name, e.g. "Setup / Preparation"]
- [ ] Step 1.1: [Concrete action]
- [ ] Step 1.2: [Concrete action]
  **Checkpoint:** [What should be true after this phase — a testable condition]

### Phase 2: [Name, e.g. "Core Implementation"]
- [ ] Step 2.1: [Concrete action]
- [ ] Step 2.2: [Concrete action]
  **Checkpoint:** [Testable condition]

### Phase 3: [Name, e.g. "Verification & Cleanup"]
- [ ] Step 3.1: [Concrete action]
- [ ] Step 3.2: [Concrete action]
  **Checkpoint:** [Testable condition]

Guidelines for good steps:

• Each step modifies 1-2 files at most
• Steps are ordered so the project stays in a working state after each phase
• Include test/verification steps, not just implementation
• Checkpoints are concrete and testable ("tests pass", "server starts", "endpoint returns 200")

4. Risk Assessment

Identify what could go wrong and how to mitigate it. Focus on risks specific to this task, not generic software risks.

## Risks

| Risk | Likelihood | Impact | Mitigation |
|------|-----------|--------|------------|
| [Specific thing that could go wrong] | low/med/high | low/med/high | [How to prevent or handle it] |

Always consider:

• Breaking changes: Will this break existing functionality? Which consumers/callers are affected?
• Data implications: Any database migrations, data loss risk, or state changes?
• Rollback: If this goes wrong, how hard is it to undo?
• Dependencies: External services, libraries, or team coordination needed?

5. Files & Scope

List the files that will be created, modified, or deleted. This helps the user understand the blast radius.

## Affected Files
- **Create:** `path/to/new-file.ts` — [purpose]
- **Modify:** `path/to/existing-file.ts` — [what changes]
- **Delete:** `path/to/old-file.ts` — [why]

6. Approval Gate

Always end the plan with an explicit request for approval. Never proceed to implementation without it.

## Ready to Execute?

Plan is complete. Please review and let me know:
- ✅ **Approve** — proceed with implementation
- 🔄 **Revise** — adjust the approach (tell me what to change)
- ❓ **Clarify** — answer open questions first
- ❌ **Cancel** — abort this task

Saving the Plan

After generating the plan, save it to a plans/ directory in the project root before requesting approval.

File naming convention: plans/YYYY-MM-DD-<short-slug>.md

Examples:

• plans/2026-02-25-auth-refactor.md
• plans/2026-02-25-add-search-endpoint.md
• plans/2026-02-25-fix-race-condition.md

The slug should be a concise, kebab-case summary of the task (3-5 words max).

File contents: The full plan output (all sections) as a markdown document. Add a YAML frontmatter block at the top:

---
task: "[One-line task description]"
status: proposed  # proposed → approved → in-progress → completed → cancelled
created: YYYY-MM-DD
approach: "[Name of chosen/recommended approach]"
---

Status updates: Update the status field in the frontmatter as the task progresses. If the plan is revised after feedback, append a ## Revision Log section at the bottom rather than overwriting the original plan — this preserves the decision history.

Create the plans/ directory if it doesn't exist. If a .gitignore exists and the user hasn't indicated whether plans should be tracked in git, ask.

Execution After Approval

Once approved, follow the task breakdown step by step. After each phase checkpoint:

• Briefly report what was completed
• Confirm the checkpoint condition is met
• Proceed to the next phase (or flag if something unexpected came up)

If during execution you discover something that contradicts the plan (unexpected complexity, a better approach, a blocker), pause and re-plan rather than silently deviating.

Scaling the Plan to Task Size

Not every task needs a full plan. Scale the depth:

Small tasks (bug fix, config change, typo):

• Understanding + single approach + file list + approval gate
• Skip options comparison and risk table
• 1-2 minutes of planning

Medium tasks (new endpoint, component, small feature):

• Full plan structure
• 2 approach options
• Basic risk assessment
• 3-5 minutes of planning

Large tasks (new feature, refactor, migration, infrastructure):

• Full plan with detailed options
• Comprehensive risk table
• Consider suggesting the work be split into multiple PRs/phases
• Include dependency graph if components interact
• 5-10 minutes of planning

Anti-Patterns to Avoid

• Plan theater: Don't produce a 500-line plan for renaming a variable. Match depth to complexity.
• Vague steps: "Implement the feature" is not a step. "Add handleSubmit function to LoginForm.tsx that validates inputs and calls POST /api/auth" is a step.
• Optimistic risk assessment: If a migration could lose data, say so plainly. Don't bury risks.
• Planning in circles: If you've laid out the plan and the user approved, execute. Don't re-plan unless something changes.
• Assumption hiding: Surface your assumptions explicitly. The most dangerous assumptions are the ones nobody stated.