union_index_records() keeps a carried flat record when that object is recorded
safe and drops it otherwise. Objects uploaded before that record existed have no
verdict, so they are dropped. A full re-index removed roughly 2000 records per
per-minor index -- 16398 across the 4.4 indexes, 20076 across 4.5, 15532 across
4.6 -- each resolving to CRAN source for clients the routing serves correctly.
This inspects the objects already in the bucket and writes the verdict, which is
what restores that coverage.
The question is decided by symbols rather than heuristics: a binary fails at
dyn.load() under minor M exactly when it references a symbol M does not export,
and the volatile set is derived by diffing the R builds installed in the image.
This change will:
- add local/backfill-flat-safety.R, inspecting each compiled flat object and
recording whether it loads under every installed minor
- refuse to run where fewer than two R minors are installed, since every verdict
would then read "safe" for want of anything to compare
- skip packages with no compiled code, which cannot fail this way
- add a manual .crow workflow over the same slot matrix as reindex.yaml