X_CONFIG_READER_PIN_UNEXPLAINED
Means
an AppConfig leaf key is pinned with a blank reason
Typical cause
Object.hasOwn asked whether a row EXISTS and never whether it said anything, so a key pinned with an empty string silenced the rule outright — the waiver axiom 3 refuses. Both tables in the file are guarded, CONFIG_READER_PINS and CONFIG_AMBIGUOUS_PINS
Fix
write who reads the key — a file under packages/, or a surface outside this repo — in scripts/lib/config-reader-pins.ts; or delete the key from packages/core/src/config.ts and from defaults()