Replace check-then-insert with atomic findOneAndUpdate upsert keyed on
externalId, plus a single E11000 retry fallback. Eliminates the duplicate
key race when two requests resolve the same gh_<id> concurrently.
When a GitHub repo is renamed and looked up by its new name, the lookup
by name misses but a record with the same externalId still exists,
causing E11000 on save. Fall back to a lookup by externalId before
creating a new document.
Fixes#500
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
When a user renamed the original GitHub repository, anonymous_github
kept calling oct.repos.get({owner, repo}) with the cached old name and
got 404, marking the link broken even though the repository still
existed at a new path.
Recover the numeric GitHub id from the dbModel's externalId
("gh_<id>"). On a 404 from the name-based lookup, fall back to
GET /repositories/<id>, which returns the renamed repo. The caller
already updates source.repositoryName from r.full_name afterwards.
Fixes#409.
tdurieux