Files
hermes-agent/tests/hermes_cli
JoaoMarcos44 86b50fb43a fix(update): back up HEAD to a rescue ref before orphan-history reset
On orphan divergence (no common ancestor with origin/<branch>, #87694),
`hermes update`'s ff-only fallback went straight to `reset --hard`,
silently discarding the entire local commit graph with no recovery path.

Probe `git merge-base HEAD origin/<branch>` before the reset; when no
common ancestor exists, park the pre-pull SHA under
refs/hermes-update-backups/orphan-<branch>-<utc-ts>-<sha12> via a single
`git update-ref`. Ordinary divergence (ancestor exists) is byte-for-byte
unchanged. The update-ref return code is checked so the user is never
told a backup exists when the write failed.

Bounded growth (size-analysis mandate): a rescue ref pins every object
reachable from the parked commit — in the incident shape that includes a
full working-tree snapshot which can be multi-GB. _prune_orphan_rescue_refs
enforces two limits on every orphan incident: keep at most 10 refs
(count cap) and expire any ref older than 30 days (age expiry, parsed
from the ref-name timestamp). The user-facing message states when the
backup expires.

Tests: orphan backup, honest failure messaging, count-cap prune,
age expiry, unparseable-name safety, ordinary-divergence regression
guard, update-ref sabotage (non-fatal), missing pre-pull SHA, reset
failure persistence, real-git merge-base anchor, and a real-git
end-to-end prune test proving pruned refs unpin objects for gc.

Fixes #87694
Salvaged from #87745 with expiry mitigation added.
2026-09-01 07:01:12 -07:00
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