Snap Plan

Read a GitHub issue → identify durable decisions → draft tracer-bullet phases → post as issue comment. Issue-type agnostic — works on PRDs or individual slices; plan depth scales to issue scope.

1. Get the issue

If issue URL/number in conversation context, use it. Otherwise ask. Fetch with gh issue view <number>.

2. Explore codebase

Understand current architecture, existing patterns, integration layers. Focus on what's relevant to the issue — module boundaries, dependency graphs, test infrastructure.

Use subagents for deep exploration of unfamiliar areas.

3. Identify durable architectural decisions

Before phasing, lock down decisions unlikely to change across implementation:

• Route structures / URL patterns
• Database schema shape
• Key data models and abstractions
• Auth/authz approach
• Third-party service boundaries

These anchor the plan — every phase references them.

4. Draft tracer-bullet phases

Break the issue into vertical slices. Each phase is a thin end-to-end path through ALL layers — never a horizontal slice of one layer.

• Each slice delivers a narrow but COMPLETE path (schema → API → logic → UI → tests)
• Completed slice is demoable or verifiable standalone
• Prefer many thin slices over few thick ones
• Include durable decisions (routes, schemas, model names) — exclude volatile details (file paths, function names)
• Order simplest-to-most-complex; first phase is the tracer bullet (thinnest possible end-to-end proof)

5. Quiz user

Present breakdown as numbered list. Per phase: title, what it covers, what it builds, acceptance criteria.

Ask: granularity right? Merge or split any phases? Iterate until approved.

6. Post as issue comment

Post approved plan as comment on the source issue via gh issue comment.

## Durable Decisions
- **Routes:** ...
- **Schema:** ...
- **Key models:** ...

---

## Phase 1: [Title] (tracer bullet)
**Covers:** [user stories / requirements from source issue]
### What to build
[End-to-end behavior, not layer-by-layer]
### Acceptance criteria
- [ ] ...

---

## Phase 2: [Title]
...

Principles

• Vertical over horizontal. Every phase is end-to-end, never one-layer-deep.
• Durable over volatile. Plan references routes/schemas/models, not file paths.
• Tracer bullet first. Thinnest possible proof that the path works.