Keep diff mode and Git status refresh responsive

[yaacovcorcos]

User impact

• Switching the diff viewer between split and stacked mode now takes effect immediately and consistently.
• Git status no longer enters a stale invalidation loop while repository discovery resolves.
• Git mutations fail closed if the branch changes after the user sees status, and in-process mutations for linked worktrees are serialized by their common Git directory.
• Non-repository projects avoid unnecessary status polling while active repository status and diffs remain responsive.

Upstream provenance and disposition

• Synara donor: 807acfe3c784b41229b81c4b78957681ec8e6cb2.
• Disposition: Adapt. Scient reimplements the useful interaction and reliability behavior on its existing diff, Git React Query, Git service, checkpoint, automation, and provider seams.
• The adaptation adds a Scient-owned shared RPC authority overlay requiring expectedBranch for pull and stacked actions. It does not change the immutable released transport-contract source.
• No donor identity, storage, credential, telemetry, publication, updater, or release authority is imported.

Exact candidate

• Base: 1e03f8d638d991ad6e7c88c900f20d8a3ad27894
• Head: a46809b73fcf0f318209e258bbce0a5a81c40e9a
• Current main was incorporated by a normal conflict-free merge; no rebase or force push.

Verification at the exact head

• Focused web and transport: 168 passed.
• Shared mutation RPC: 2 passed.
• Focused server Git, manager, checkpoint, automation, and provider-reactor: 315 passed.
• bun run scient:upstream-check --intake: identity, format, lint with zero errors, all typechecks, complete bun run test, web/desktop/CLI builds, release smoke, and clean certification passed.
• Full web tests: 3,106 passed. Scripts: 215 passed, 4 skipped. Full server/CLI suite passed.
• Stable Chromium: 353 passed, 19 skipped. Geometry: 19 passed.
• git diff --check passed and the worktree remained clean.

Independent final reviews

Exactly three fresh read-only reviews inspected this exact head:

1. Correctness, reliability, concurrency, lifecycle, performance, and regression risk: no P0-P2 code findings.
2. Security, privacy, data loss, destructive Git behavior, RPC authority, credentials, migrations, updater, and release safety: no P0-P2 findings.
3. Architecture, maintainability, ownership, donor lineage, product design, UI coherence, responsive behavior, and accessibility: no P0-P2 code findings. The stale hosted-head/body P2 is resolved by this exact-head push and body update; hosted CI remains the final proof.

Nonblocking P3 limitations: direct pull branch-interleaving lacks a dedicated deterministic regression; the public frozen NativeApi type does not expose the stronger overlay even though production callers do; repository semaphores are retained for the server lifetime and long stacked operations can queue sibling-worktree mutations; no manual screenshot, keyboard, or screen-reader acceptance was performed.

Safety and rollback

• Pull remains fast-forward-only. Every UI-triggered pull or stacked action carries the caller-observed branch, which is revalidated server-side.
• Direct Git mutations, checkpoints, automation worktree operations, and provider branch rename/publish share common-directory serialization.
• No persistence migration, credential/session change, updater change, packaging change, or release-control change.
• Rollback is a single-PR revert.

Related intake PRs

• Crash-loop breaker: Bound repeated desktop backend crash restarts #126 (merged)
• New-chat project picker: Make the new-chat project heading interactive #128
• Parent recovery research record: ScientFactory/Scient#49

[yaacovcorcos]

Final integration refresh (2026-07-25): current main dab9b6d was merged normally into this branch; no rebase or force-push. Exact hosted head: 11a086a. Focused Git and diff reliability suites 116/116 passed. git diff --check passes and the task worktree is clean. Fresh hosted CI run https://github.com/ScientFactory/scient-desktop/actions/runs/30160244357 completed successfully, including format, lint, typecheck, full bun run test, stable browser, Linux geometry, desktop build/preload, release smoke, Linux and Windows HTML-preview smoke, and Windows process regression. No unresolved review threads remain. Existing documented manual limitations are unchanged and non-blocking. This candidate is integration-ready against main dab9b6d; this is not merge or release authorization.