'repository is corrupt' says a repository cannot be read, not what in it is unreadable -- and the walk that discovers it visits every artifact in the store, minutes on a large one. Whoever holds the broken repository was left bisecting it or attaching a debugger.

The derive now records which artifact it rejected and why; openRepo reports it, so every verb's open gets the name. Plain data, no allocation, so it survives the errdefer that tears down a half-built view. Repository.open clears it per attempt because callers declare a Repository undefined.

Also splits open's two identical diagnostics: deriving the view and reopening the log for materialization both printed the same line, which made a failure in one indistinguishable from the other. (#42) check-in: 37f746e59f user: dmestas tags: sub-manifest