fix: retry cleared object database pack slots#2726
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The fix is very lean and updates `load_one()` to do the same as its sibling function, which triggers a refresh of its internal index and it can recover just fine. --- agent Store::load_pack() assumed a non-stable handle could not retain a pack id after its slot was cleared. Disk consolidation can move a replacement index into a free slot without advancing the generation, leaving the old marker valid enough to reach the cleared slot and panic. Add a regression that loads an index without its pack, renames the index/pack pair to model an external repack, refreshes through a second handle, and then reads through the stale handle. This deterministically reproduced the single-index panic without invoking fetch or needing threads. Treat cleared slots as stale lookup misses in both single-index and multi-pack-index paths, including the recheck under the slot lock. Existing find logic then reloads indices and retries the object lookup. Co-authored-by: GPT 5.6 <codex@openai.com>
Sebastian Thiel (Byron)
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This section is for Byron only. Models continuing this PR must not add, remove, check, uncheck, rename, or reorder checkboxes here.
Everything below this line was generated by Codex GPT-5.
Created by Codex on behalf of Byron. Byron will review before this is ready to merge.
Fixes #2723
Summary
Reproduction
The test loads an index while leaving its pack unopened, renames the index/pack pair to model an external repack, refreshes the shared store through a second handle, and reads the same object through the stale first handle. Before the fix this panicked at the single-index cleared-slot assertion; afterward it reloads the moved index and finds the object.
Git baseline
Current git.git at a23bace963d508bd96983cc637131392d3face18 uses packfile_store_reprepare() in packfile.c to clear initialization and rescan the pack directory.
Validation