| name | memory-discipline |
| description | Use when recording lessons learned in a project, or when a project contains lessons/ or MEMORY.md — file-based memory format and read/write rules that measurably improve long-horizon performance. |
Memory Discipline
Fable 5 performs notably better when it can write learnings somewhere for future
reference. Give Opus the same surface and rules.
Read rules
- At the start of non-trivial work, read
MEMORY.md (index) if present, then any
lessons/*.md whose one-line summary looks relevant.
- Memories reflect what was true when written — verify a referenced file/flag still
exists before relying on it.
Write rules
- One lesson per file in
lessons/, kebab-case name, one-line summary on the first line.
- Record corrections from the user and confirmed working approaches alike — include WHY
it mattered, not just what happened.
- Don't save what the repo already records (code structure, git history, README facts).
- Update an existing lesson rather than creating a near-duplicate; delete lessons that
turn out to be wrong.
- After writing, add/refresh a one-line pointer in
MEMORY.md.
Format
<!-- lessons/use-fake-clock-in-timer-tests.md -->
Timer tests must inject a fake clock — real sleeps made CI flaky.
Context: PR #42 reverted twice. `time.monotonic` is patched via the `clock`
parameter; never call `time.sleep` in tests.
