Summary

• Adds finer startup/session tracing for native window phases, API command pressure, and historical-session restore frames.
• Defers post-interactive local workspace refresh pressure while keeping remote workspace behavior unchanged.
• Restores local historical sessions with the latest 8 turns first, keeps remote restore at 3 turns, and hydrates full history after latest content paints or a bounded timeout.
• Splits large completed model rounds for virtual rendering, defers expensive markdown syntax highlighting, and preserves active/streaming/recent tool output behavior.
• Keeps a history loading overlay until the latest turn has readable text in the viewport, then lets full history hydrate in the background.
• Strengthens the performance E2E guard to check usable latest text, naked blank gaps, placeholder coverage, and input anchoring.
• Fixes review-found edge cases: full hydrate preserves turns appended after partial restore, the history overlay blocks click-through activation, searching a partially loaded session releases full hydrate early, saved custom themes restore before first React paint, and tail-restored recommendation context uses the backend turn index.
• Limits API payload byte estimation to explicit perf trace mode so default startup/session timing is not polluted by observer-side object traversal.
• Shows global turn numbers for partial historical tail restores while keeping previous/next navigation bounded to already loaded turns.

Updates #949. This PR does not close the issue; native startup outliers remain open follow-up work.

Performance Data

Current PR head after P2 safety amend: 8b90809d, base f46113e6. The release-fast performance data below was collected before the review-safety amend on head b0747d4a against base 8318ab32; the latest amend adds functional safeguards and focused tests, and does not claim a new performance delta. The large-session fixture has 80 turns with markdown, code blocks, tables, tools, and visible latest-turn narrative text.

Key End-To-End Results

Historical Session Viewport Quality

Startup Outlier Analysis

This PR should not be read as a startup win. The latest startup run still shows work before the interactive shell:

Risks And Functional Impact

• Local historical session first restore now requests up to 8 latest turns instead of 3. This improves latest-context rendering, but can increase first payload for very heavy turns.
• Remote historical restore intentionally stays at 3 turns to avoid changing remote compatibility or payload behavior in this PR.
• Complete history still hydrates in the background. Fast scrolling into older history before hydrate completes can still wait on that background load.
• During tail restore, some auxiliary consumers can temporarily see only the loaded tail in dialogTurns. This PR protects the main chat viewport, search hydration release, appended-turn merge, and recommendation context turn index, but it does not introduce a global explicit partial-session model.
• Searching while full history is pending now releases full hydrate early. Until hydrate completes, search results still reflect loaded content only; this is a bounded transient state rather than a permanent partial-search boundary.
• The history overlay blocks pointer activation behind the loading state while preserving the normal wheel/scroll path. Touch-drag interaction during the very short overlay period is intentionally not treated as an actionable message interaction.
• Model-round chunking is limited to completed, terminal, non-streaming rounds without active/recent tools. Live streaming and active tool output should keep existing behavior. Large historical model rounds may briefly show an inline loading marker while earlier/later groups render progressively.
• Inactive local workspace rows defer git refresh until activation or menu open. The first menu open for an inactive local workspace can briefly show git-dependent worktree actions in a loading/disabled state. Remote workspace behavior is intentionally unchanged.
• Saved custom themes are now restored before first React paint when bootstrap cannot resolve them. This preserves theme experience, but custom-theme users can pay one extra themes config read during before-render initialization; built-in and system theme startup paths stay on the bootstrap path.
• Default API trace keeps timing, bridge, pressure, and command data, but no longer computes request/response byte estimates unless BITFUN_PERF_TRACE_ENABLED is set. This avoids observer overhead in normal runs; payload-size investigations must explicitly enable perf trace mode.
• Partial historical session headers now display global turn numbers. Previous/next controls intentionally navigate only inside the loaded range until full hydrate completes; unloaded older turns are not exposed as jump targets during the transient partial state.
• Startup outliers are not fixed here. The issue remains open for native window lifecycle and startup invoke-pressure follow-up.

Verification

• After rebase to f46113e6:
  • pnpm --dir src/web-ui run test:run src/infrastructure/theme/core/ThemeService.test.ts src/app/startup/startupPerformanceContract.test.ts: 27 passed.
  • pnpm --dir src/web-ui run test:run src/flow_chat/store/FlowChatStore.test.ts src/flow_chat/components/modern/ModernFlowChatContainer.history-state.test.tsx: 44 passed.
  • pnpm --dir src/web-ui run type-check.
  • git diff --check gcwing/main...HEAD.
• P2 safety amend on 8b90809d:
  • pnpm --dir src/web-ui run test:run src/infrastructure/api/service-api/ApiClient.test.ts src/flow_chat/components/modern/ModernFlowChatContainer.history-state.test.tsx: 21 passed.
  • pnpm run type-check:web.
  • git diff --check.
• Earlier PR verification before review-safety amend:
  • pnpm run lint:web
  • pnpm --dir src/web-ui run type-check
  • pnpm --dir src/web-ui run test:run src/flow_chat/components/modern/VirtualMessageList.layout.test.ts src/flow_chat/components/modern/modelRoundProgressiveRender.test.ts src/flow_chat/components/modern/ModernFlowChatContainer.history-state.test.tsx src/flow_chat/store/modernFlowChatStore.test.ts src/flow_chat/store/FlowChatStore.test.ts src/shared/utils/startupTrace.test.ts src/infrastructure/theme/core/ThemeService.test.ts src/app/startup/startupPerformanceContract.test.ts
  • pnpm --dir src/web-ui run test:run src/app/components/NavPanel/sections/workspaces/workspaceGitRefreshOptions.test.ts src/infrastructure/api/service-api/ApiClient.test.ts src/infrastructure/api/adapters/tauri-adapter.test.ts src/shared/utils/logger.test.ts
  • pnpm --dir src/web-ui run test:run src/flow_chat/store/FlowChatStore.test.ts src/flow_chat/components/modern/ModernFlowChatContainer.history-state.test.tsx src/component-library/components/Markdown/Markdown.test.tsx
  • pnpm run desktop:build:release-fast
  • pnpm run check:repo-hygiene
  • cargo test -p bitfun-core load_session_tail_turns -- --nocapture
  • cargo test -p bitfun-core restore_session_view -- --nocapture
  • Release-fast E2E after the overlay fix: 3 first-open runs, 2 warm-reopen runs, and 1 startup run.