nexus/.planning/milestones/v1.3-phases/26-pwa-performance/26-01-SUMMARY.md

phase	plan	subsystem	tags	requires	provides	affects	tech-stack	key-files	key-decisions	patterns-established	requirements-completed	duration	completed
26-pwa-performance	01	ui	react vite performance lazy-loading code-splitting bundle-optimization	phase provides 25-file-system Completed UI feature set that needed bundling optimization	React.lazy code splitting for all 37 page components in App.tsx Suspense boundary with Skeleton fallback for route transitions Manual vendor chunk splitting in Vite: vendor-react, vendor-router, vendor-query, vendor-markdown Reduced initial bundle load via route-level lazy splitting	26-02-PLAN 26-03-PLAN 26-04-PLAN	added patterns React.lazy with .then(m => ({ default: m.NamedExport })) pattern for named-export pages Suspense boundary wrapping Routes block for route-level loading fallback Vite manualChunks for stable vendor bundle caching	created modified ui/src/App.tsx ui/vite.config.ts	All 37 page components use named exports, so lazy imports use .then(m => ({ default: m.X })) module re-mapping Suspense boundary placed around Routes (not each Route) for single loading boundary vendor-react, vendor-router, vendor-query, vendor-markdown as manualChunks — no @mdxeditor/editor (avoids circular deps) OnboardingWizard kept as eager import — renders outside Routes, always needed for app shell	Named-export lazy pattern: lazy(() => import('./pages/X').then(m => ({ default: m.X }))) Suspense fallback uses Skeleton component from @/components/ui/skeleton	PERF-01 PERF-05	4min	2026-04-02

Phase 26 Plan 01: Lazy Loading and Vendor Chunk Splitting Summary

React.lazy code splitting for all 37 page components plus Vite manualChunks for react, react-dom, react-router-dom, @tanstack/react-query, react-markdown vendor bundles

Performance

• Duration: ~4 min
• Started: 2026-04-02T01:57:13Z
• Completed: 2026-04-02T02:01:00Z
• Tasks: 2
• Files modified: 2

Accomplishments

• Converted all 37 eager page imports in App.tsx to React.lazy with named-export re-mapping pattern
• Wrapped <Routes> with <Suspense> boundary using <Skeleton> fallback for route chunk loading
• Added build.rollupOptions.output.manualChunks to vite.config.ts producing 4 stable vendor chunks
• Build verified: 4 vendor chunks present in dist/assets/ with no circular dependency errors

Task Commits

1. Task 1: Convert App.tsx page imports to React.lazy with Suspense - da35021a (feat)
2. Task 2: Add manual vendor chunk splitting to Vite config - 31f25b34 (feat)

Files Created/Modified

• ui/src/App.tsx - Replaced 37 eager named-export page imports with React.lazy + Suspense boundary wrapping Routes
• ui/vite.config.ts - Added build.rollupOptions.output.manualChunks for vendor-react, vendor-router, vendor-query, vendor-markdown

Decisions Made

• All page files use export function PageName() named exports (not default exports), so lazy imports use .then(m => ({ default: m.X })) module re-mapping to satisfy React.lazy's default export requirement
• Suspense boundary placed at the outer <Routes> level rather than per-route — single loading state for any route chunk load
• @mdxeditor/editor intentionally excluded from manualChunks per plan guidance (complex internal imports risk circular dependency errors)
• rehype-highlight excluded (replaced by manual highlight.js usage in Phase 25)
• OnboardingWizard kept eager — renders outside <Routes> and is always present in the app shell

Deviations from Plan

None — plan executed exactly as written. The named-export lazy pattern was correctly anticipated by the plan in step 4 of Task 1.

Issues Encountered

None — build succeeded on first attempt with all 4 vendor chunks produced and no circular dependency errors.

User Setup Required

None — no external service configuration required.

Next Phase Readiness

• Route-level code splitting complete: each page loads as its own chunk on demand
• Vendor chunks cached separately from application code (stable browser caching for react, router, query, markdown)
• Ready for Plan 02 (service worker / PWA manifest) and Plan 03 (offline support)
• Main bundle still ~1.7 MB due to mermaid/cytoscape/katex; Plans 02-04 address further splitting or deferral

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Phase: 26-pwa-performance Completed: 2026-04-02