# 0013 — LESSONS.md for this repo

## What to build

Create `LESSONS.md` at the repo root. This file is the long-loop feedback mechanism for this repo — patterns noticed during active development get written here, and repeated patterns graduate to standing rules.

**File structure:**

```markdown
# Lessons

Patterns observed during development of this repo. Three or more entries on the same pattern → promote to CONTEXT.md (or the relevant instruction file) as a standing rule.

## [date] [short title]
[observation — what happened, what was learned, what should change]
```

**Graduation rule:** When three or more entries cover the same pattern, the human reviews and promotes the pattern to the appropriate standing location: CONTEXT.md for domain-level principles, `core/instructions/coding.md` for coding conventions, `core/instructions/git.md` for git conventions, or `core/instructions/testing.md` for testing conventions. The graduated entries are marked `[graduated → target file]` rather than deleted (audit trail).

**Who writes to it:** The session-handoff skill (Chunk 3) prompts LESSONS.md extraction before closing a session. The human may also write directly.

**What belongs here:** Non-obvious observations — a rule that was misapplied, a pattern that caused friction, a decision that turned out wrong in practice. Not summaries of what was built (that's git history) or planned changes (that's issues).

## Acceptance criteria

- [ ] `LESSONS.md` exists at repo root with the structure above
- [ ] Graduation rule is documented in the file header
- [ ] CONTEXT.md docs convention is updated to reference LESSONS.md as an artifact type

## Blocked by

None.