fix(build): give the existence cache a per-minor view of the slot #191
2026-09-01
fix(build): give the existence cache a per-minor view of the slot
#189 stopped per-minor objects from pruning the candidate list, which was right, but s3_cache.rds is derived from the same file_names. The cache handed to build_binary_package() therefore contained no per-minor object at all, its 'not present in the remote bucket' check answered not-present for every one, and a restarted run recompiled everything it had already built: amd64/resolute attempted 8683 packages, compiled 8683, and reported 'already exists in S3' three times. The two consumers need opposite views of one listing, and conflating them was wrong in both directions. The candidate list must ignore per-minor objects or a package present under one minor prunes itself from every other minor's work. The existence cache must not ignore them or the work is redone. The cache now keeps paths relative to the slot and build-all.R selects the part matching its pass: <minor>/ for a per-minor pass, the flat slot plus Archive/ for the primary. build_binary_package() compares basenames and cannot tell 4.4/curl from curl, so the choice has to be made where the running R minor is known. A cache written before this change holds bare basenames; filtering those by path would select nothing and trigger the very rebuild this prevents, so they are used unfiltered and #190's staleness check replaces them on the next pipeline.