mechanism-not-instancelisted

# Mechanism, not instance Authority: CLAUDE.md "Standing lessons" 08-19 (#506-#509: a second generator, a second call site, a second derivation), 09-01 (#566: a guard written against a spelling), 09-02 (#572: fixed in the cache, not at the two call sites); `docs/harness/ARCHAEOLOGY.md` for the guard that already names the lesson. Ask, and write the answers into ISSUE.md: 1. **Does the fix belong one layer down?** If the call site was reproducing an authority's logic (a skip list, a path rule, a cache contract, a version read), fix the authority so the tool written next inherits it. A per-consumer patch arms the trap again. 2. **What other spellings of this input exist?** `find_references` on the fixed symbol and its callers; the qualified form, the aliased form, the second transport, the other OS's separator. A test per spelling found. Also: **run the reintroduced defect against the new test** (Practice 9, non-vacuity). A guard green only against the fixed tree may be measuring nothing. And when an OLD test turns red, check whether it was the defect's witness before changing the code back.