test: preserve user changes across failed pull retries

[LemieuxStrategicSolutions]

Adds two failure/retry regressions to #1215, following the remaining review cases from #1209:

• After a failed checkout leaves a binary conflict copy, a user edits that copy. The next snapshot and pull must retain those bytes in the working tree and merge tree, and preserve the remote attachment in a separately named copy.
• After a failed checkout, a user deletes the conflicted note. The next snapshot must commit that deletion before a new edit/delete merge. The test explicitly preserves the existing keep-the-edited-version policy: the remote note may return as a reported conflict, while the deletion remains in the local merge parent.

This is intentionally based on codex/git-sync-reliability so the diff contains only the added tests. It can be merged into #1215 or cherry-picked; it does not ask to merge the old recovery mechanism from #1209. The in-memory merge in #1215 avoids creating the MERGE_* state that mechanism would recover.

Validation passed: cargo test -p reflect-open git::merge_tests (11 tests, including both additions), cargo fmt --all --check, cargo clippy -p reflect-open --all-targets -- -D warnings, pnpm check, and pnpm build. These tests exercise deterministic checkout failure and retry; they do not claim physical-device kill testing or migration of pre-existing foreign Git merges.

Summary by CodeRabbit

• Bug Fixes
  • Improved merge recovery after a failed checkout when the worktree contains uncommitted changes.
  • Preserved edits to conflict copies and recorded file deletions before retrying a merge.
  • Ensured retried merges retain local changes while correctly surfacing incoming content conflicts.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Team

Run ID: 03c07fa4-d130-47d2-98c5-2bc8c19f8fb2

📥 Commits

Reviewing files that changed from the base of the PR and between 4780481 and e0eaf63.

📒 Files selected for processing (1)

• apps/desktop/src-tauri/src/git/merge_tests.rs

Included review availability: Your plan provides up to 4 included reviews per hour; 2 remain after this review.

---

Walkthrough

The change adds two regression tests for merge retries after failed checkouts. The tests cover edited conflict copies and deleted files, then verify preserved first-parent state, remote merge content, clean repository state, and resolved index conflicts.

Changes

Merge retry regressions

Layer / File(s)	Summary
Retry merge snapshot behavior apps/desktop/src-tauri/src/git/merge_tests.rs	Adds tests for preserving an edited conflict copy and snapshotting a deletion before retrying a merge. The tests verify the resulting conflict contents, first-parent trees, clean repository state, and absence of index conflicts.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to e0eaf

This adds regression coverage for preserving edited conflict copies and deleted notes across failed pull retries, with no production behavior changes or current merge-readiness risk identified.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: regression tests that verify user changes remain preserved across failed pull retries.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 1 files.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

_{Comment @coderabbitai help to get the list of available commands.}

[LemieuxStrategicSolutions]

@coderabbitai review

[coderabbitai]

✅ Action performed

Review finished.

Note: CodeRabbit is an incremental review system and does not re-review already reviewed commits. This command is applicable only when automatic reviews are paused.