What's New
Read-Only Mode
New -readonly flag / GOBUILDCACHE_READONLY env var that suppresses backend write operations (Put/Touch) while allowing reads (Get/Has) to pass through normally. This lets CI workers (e.g., PR builds) consume the shared S3 cache without polluting it. The local disk cache continues operating with full read-write access.
- Put and Touch become no-ops at the S3 layer — no async goroutines spawned
- Clear returns an error so destructive operations are never silently ignored
- Read-only stats reported in both human-readable and machine-readable output
Other
- Fix test workflow for fork: update actions, use local S3 tests