Writing PRDs

PRDs live in docs/prd/ and follow a consistent format. Each new feature gets a PRD before implementation.

PRDs capture a decision at a point in time. As the project evolves, implementations may diverge from the original PRD — that's expected. Don't update old PRDs to match current code. Instead, write a new PRD when the direction changes.

File Naming

PRDs are numbered sequentially: 001-vision.md, 002-mvp.md, 003-prompt.md, etc. Use the next available number.

Required Sections

Follow the structure of existing PRDs (read one from docs/prd/ for reference). At minimum:

markdown

# PRD-NNN: Title

**Depends on:** [NNN-name.md](./NNN-name.md)

## Summary
One paragraph explaining what this change does.

## Motivation
Why this change is needed. What problem it solves.

## Changes
### Subsection per change area
Details of what changes, with examples and diagrams where helpful.

## Files
| File | Action |
|------|--------|
| `path/to/file.go` | Created — description |
| `path/to/other.go` | Modified — description |

## Acceptance Criteria
- [ ] Criterion 1
- [ ] Criterion 2
- [ ] `make build`, `make lint`, `make test` all pass

After Creating

Update docs/prd/README.md to add a row to the index table:

markdown

| [NNN](NNN-title.md) | Title |

Conventions

•Depends on links to the prerequisite PRD
•Files table lists every file that will be created or modified
•Acceptance criteria uses checkboxes — checked off as implementation progresses
•Always include make build, make lint, make test as a criterion
•Keep the summary concise — motivation section has the detail