muse-dev-patterns

# muse-dev-patterns — the recurring slice discipline Distilled from 200+ loop fires (docs/goals/loops/*), the backlog's dedup ledger, and live sessions. `improve-muse` decides WHAT to build and drives the end-to-end cycle; THIS skill is the HOW at each step — the moves that kept working, and the failure classes each one exists to prevent. ## 1. When a gate/test fails: triage BEFORE fixing A red gate has exactly three causes. Fixing before classifying produces the worst class of bug — "fixing" the assertion when the product regressed, or "fixing" the product when the assertion went stale. 1. **Reproduce and read the determinism.** Run the failing case k=3–5 times. `0/5 with the identical wrong output` is STRUCTURAL (something in the path changed); `3/5` is stochastic (model variance, load, race). Structural failures deserve root-cause; stochastic ones deserve `MUSE_EVAL_REPEAT` and a look at thresholds/timeouts. 2. **Is it pre-existing? Prove it with stash.** `git stash && <run the failing test> && git stash pop` — if it fails on clean HEAD, it is main's rot, not your change. File it as its own T0 fix (never bundle it silently into your slice's commit). 3. **Date the flip.** `git log --format='%ci %h %s' -S '<changed token>' -- <file>` finds WHEN the behavior changed and WHICH commit did it. Read that commit's intent before touching anything. 4. **Classify: bug vs stale expectation.** If the flip commit was a DELIBERATE product improvement, th...