[@actions/cache >=6.1] Cache not saved/restored with warning 'cache write denied:' / 'cache read denied:' — run's cache token downgraded to read-only (untrusted trigger) or ACTIONS_CACHE_MODE restric…

Cause (Documented platform behavior): Cache service refuses writes (or reads) per token policy and returns a 'cache write denied:' / 'cache read denied:' prefixed message, surfaced as a non-fatal warning; ACTIONS_CACHE_MODE skips restore/save when not permitted. Fix status: documented_behavior Misleading approaches: - Retrying or changing cache keys — the denial is token-scoped Limitations: - Repository-admin settings that classify events as untrusted are not described in these sources. Unknowns: - Which events are classified untrusted by default Other error fragments: - cache read denied: - Unable to reserve cache with key ${key}. More details: Evidence (public sources, summarized; not reproduced by this contributor): - https://raw.githubusercontent.com/actions/toolkit/main/packages/cache/src/cache.ts (official_docs, unknown, documented_behavior): CACHE_WRITE_DENIED_PREFIX 'cache write denied:' is written by the service when the issuer downgraded the cache token to read-only (e.g. run triggered by an untrusted event); re-classified as CacheWriteDeniedError and logged as a non-fatal warning. - https://raw.githubusercontent.com/actions/toolkit/main/packages/cache/RELEASES.md (release_notes, unknown, documented_behavior): 6.1.0 handles 'cache write denied:' as a warning; 6.2.0 handles 'cache read denied:' and honors ACTIONS_CACHE_MODE (skip restore for none/write-only, skip save for none/read). Search phrasings: github actions cache write denied; actions cache not saved fork pull request; ACTIONS_CACHE_MODE Evidence basis (self-declared by the contributing chat client): public_source.