Summary

Continues the renderer startup-chain parallelization proposed in #7225 (proposal 2), on top of the merged #7266 (which fixed the main-process blocking — proposal 1). Two small changes to the renderer startup effect (App.tsx) and the worktree slice:

1. Overlap the sidebar-scope loads with the worktree scan. fetchProjectGroupsForAllHosts → fetchFolderWorkspacesForAllHosts previously ran serially before the per-repo git worktree list fan-out. They enumerate hosts via runtimeEnvironments.list and read neither the repos store nor worktrees, so once repos have landed they are independent of the scan. They now run concurrently with the worktree/lineage Promise.all, so a slow/unreachable remote host's scope RPCs (up to 15s each) no longer queue ahead of the scan. Ordering (folder-workspaces reads projectGroups) and the "all settle before hydrate" invariant are preserved.
2. Raise worktree refresh concurrency 5 → 8. Each repo's git worktree list is an independent main-process child, so a higher ceiling runs fewer sequential scan batches at startup on multi-core machines — the dominant renderer-chain cost from Slow startup and UI freezing issue analysis / 启动慢、界面卡顿问题分析 #7225. Still bounded so one UI moment can't launch every git probe at once.

User-visible effect: faster startup, most noticeably for users with many repos and/or a configured-but-unreachable remote host. No behavior or UI change otherwise.

Screenshots

No visual change. Verified via the ORCA_STARTUP_DIAGNOSTICS=1 startup timeline instead:

renderer-fetch-repos-done            durationMs=87
renderer-fetch-worktrees-done        durationMs=1     ← now overlapped with:
renderer-fetch-project-groups-done   durationMs=25
renderer-fetch-folder-workspaces-done durationMs=2

The four fetches complete within the same window (t≈2980–3000) instead of serializing.

Testing

• pnpm lint — oxlint clean on the changed files (App.tsx, worktrees.ts, worktrees.test.ts)
• pnpm typecheck — changed files type-clean (the 5 pre-existing TS6307 project-reference errors are also present on unmodified main, unrelated to this PR)
• pnpm test — ran the affected suites green: worktrees.test.ts (204 tests, incl. the two "bounds concurrent repo scans" tests now asserting against the exported WORKTREE_REFRESH_CONCURRENCY) and app-startup-routing.test.ts (14 tests)
• pnpm build — not run (renderer-only logic change, no build-surface impact)
• Updated the two concurrency-bound tests to reference the exported constant and use CONCURRENCY + 2 repos so the bound is still exercised (10 > 8)

AI Review Report

Reviewed with the AI agent; main risks checked:

• Store-write races: the two overlapped branches write disjoint keys (projectGroups/folderWorkspaces vs worktreesByRepo/detectedWorktreesByRepo/sortEpoch). Zustand set() stays atomic per key on the single-threaded event loop, so concurrency cannot cause a lost update. ✅
• Session/reconnect correctness: mapped the dependency graph — folderWorkspaces (consumed by session hydration + terminal reconnect to build validWorktreeIds/pendingReconnectWorktreeIds) and worktreesByRepo are both still fully awaited before the hydrate steps, so no persisted tab/terminal/editor state is dropped. fetchAllWorktrees reads only repos/settings/projectHostSetups (already loaded), not projectGroups/folderWorkspaces. ✅
• Error handling / unhandled rejections: the concurrent projectScopeChain promise is created and passed into Promise.all in the same synchronous tick (handler attached before any microtask can reject), and a rejection still propagates to the existing outer startup catch. Terminal behavior unchanged. ✅
• Concurrency change: affects parallelism only, not scan results (each repo scanned exactly once); still bounded.
• Cross-platform (macOS / Linux / Windows): no keyboard shortcuts, UI labels, file paths, or shell invocations touched. Both changes are platform-agnostic (JS promise ordering + a bound on main-process git child processes). Slow startup and UI freezing issue analysis / 启动慢、界面卡顿问题分析 #7225 is Windows-focused and this reduces its scan-batch count there. No Electron platform-specific surface touched.

Security Audit

Low surface. No new IPC handlers, command construction, path handling, auth, secrets, or dependency changes. The concurrency constant only bounds how many existing git worktree list child processes run in parallel (raised 5 → 8, still capped — no unbounded spawn). Reordering is pure in-renderer promise scheduling. No user input flows through the changed code. No follow-up required.

Notes

• Scoped deliberately to proposal 2 of Slow startup and UI freezing issue analysis / 启动慢、界面卡顿问题分析 #7225. Proposal 3 (lazy-loading non-critical IPC handlers) is the remaining lever and is not included here.
• SSH / remote-host use case is the primary beneficiary: an unreachable runtime host's 15s scope RPCs now overlap the worktree scan rather than blocking it.

🤖 Generated with Claude Code