docs(16-01): complete Vite + React + Tailwind + shadcn/ui plan

Tasks completed: 2/2
- Create Vite + React + TypeScript project
- Configure Tailwind CSS and shadcn/ui

SUMMARY: .planning/phases/16-frontend-scaffold/16-01-SUMMARY.md

.planning/phases/16-frontend-scaffold/16-01-SUMMARY.md

@@ -0,0 +1,117 @@
+---
+phase: 16-frontend-scaffold
+plan: 01
+subsystem: ui
+tags: [vite, react, typescript, tailwindcss, shadcn-ui, postcss]
+
+# Dependency graph
+requires:
+  - phase: 15-frontend-wireframes
+    provides: UI design wireframes for dashboard, detail, and inbox screens
+provides:
+  - Vite + React + TypeScript project at packages/web/
+  - Tailwind CSS with shadcn/ui theming and cn() utility
+  - Path alias @/ for clean imports
+  - Dev server with tRPC proxy to backend
+  - npm workspaces linking packages/web
+affects: [16-frontend-scaffold remaining plans, 17-initiative-dashboard, 18-initiative-detail, 19-agent-inbox]
+
+# Tech tracking
+tech-stack:
+  added: [vite, react, react-dom, tailwindcss, postcss, autoprefixer, shadcn-ui, class-variance-authority, clsx, tailwind-merge, lucide-react, tailwindcss-animate, @tailwindcss/typography]
+  patterns: [npm workspaces monorepo, @/ path alias convention, shadcn/ui CSS variable theming]
+
+key-files:
+  created: [packages/web/package.json, packages/web/vite.config.ts, packages/web/tsconfig.json, packages/web/tsconfig.app.json, packages/web/index.html, packages/web/src/main.tsx, packages/web/src/App.tsx, packages/web/src/index.css, packages/web/postcss.config.js, packages/web/tailwind.config.ts, packages/web/components.json, packages/web/src/lib/utils.ts]
+  modified: [package.json, package-lock.json]
+
+key-decisions:
+  - "16-01: CSS import added to main.tsx (not in original Task 1 — required for Tailwind output)"
+  - "16-01: App.tsx uses cn() from @/lib/utils to verify both path alias and Tailwind integration in one shot"
+
+patterns-established:
+  - "@/ path alias: all imports from src/ use @/ prefix (shadcn convention)"
+  - "shadcn/ui CSS variables: HSL-based theming with light/dark mode via .dark class"
+
+# Metrics
+duration: 3min
+completed: 2026-02-04
+---
+
+# Phase 16 Plan 01: Vite + React + Tailwind + shadcn/ui Summary
+
+**Vite 6 + React 19 project with Tailwind CSS v3 theming and shadcn/ui component foundation in packages/web/**
+
+## Performance
+
+- **Duration:** 3 min
+- **Started:** 2026-02-04T17:55:00Z
+- **Completed:** 2026-02-04T18:02:00Z
+- **Tasks:** 2
+- **Files modified:** 14
+
+## Accomplishments
+- Vite + React + TypeScript project scaffolded in packages/web/ with dev server and tRPC proxy
+- Tailwind CSS v3 configured with PostCSS, autoprefixer, typography, and animate plugins
+- shadcn/ui theming with CSS custom properties (light + dark mode), components.json, and cn() utility
+- Path alias `@/` configured in both vite.config.ts and tsconfig.app.json
+- npm workspaces configured at root linking packages/web
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Create Vite + React + TypeScript project** - `99348e0` (feat)
+2. **Task 2: Configure Tailwind CSS and shadcn/ui** - `bb468e0` (feat)
+
+## Files Created/Modified
+- `packages/web/package.json` - Web package with React, Tailwind, shadcn deps
+- `packages/web/vite.config.ts` - Vite config with React plugin, @/ alias, tRPC proxy
+- `packages/web/tsconfig.json` - Root TS config extending tsconfig.app.json
+- `packages/web/tsconfig.app.json` - App TS config with @/ path mapping
+- `packages/web/index.html` - Vite entry HTML
+- `packages/web/src/main.tsx` - React root mount with CSS import
+- `packages/web/src/App.tsx` - Minimal component using cn() and Tailwind classes
+- `packages/web/src/index.css` - Tailwind directives + shadcn CSS variables (light/dark)
+- `packages/web/postcss.config.js` - PostCSS with tailwindcss and autoprefixer
+- `packages/web/tailwind.config.ts` - Tailwind config with shadcn color system and plugins
+- `packages/web/components.json` - shadcn/ui configuration
+- `packages/web/src/lib/utils.ts` - cn() utility combining clsx + tailwind-merge
+- `package.json` - Added workspaces and dev:web script
+- `package-lock.json` - Updated lockfile
+
+## Decisions Made
+- CSS import added to main.tsx during Task 2 (was missing from Task 1, required for Tailwind output in build)
+- App.tsx uses cn() from @/lib/utils to verify both path alias resolution and Tailwind integration simultaneously
+
+## Deviations from Plan
+
+### Auto-fixed Issues
+
+**1. [Rule 3 - Blocking] Added CSS import to main.tsx**
+- **Found during:** Task 2 verification (build had no CSS output)
+- **Issue:** main.tsx did not import index.css, so Tailwind directives were never processed and no CSS appeared in build output
+- **Fix:** Added `import "./index.css"` to main.tsx
+- **Files modified:** packages/web/src/main.tsx
+- **Verification:** Vite build now outputs CSS file with Tailwind resets and utility classes
+- **Committed in:** bb468e0 (Task 2 commit)
+
+---
+
+**Total deviations:** 1 auto-fixed (1 blocking)
+**Impact on plan:** Essential fix for Tailwind to function. No scope creep.
+
+## Issues Encountered
+None
+
+## User Setup Required
+None - no external service configuration required.
+
+## Next Phase Readiness
+- Frontend scaffold with Tailwind + shadcn/ui ready for component development
+- Next plan 16-02 (Shared Types Package) already completed
+- Ready for 16-03 (tRPC Client Wiring)
+
+---
+*Phase: 16-frontend-scaffold*
+*Completed: 2026-02-04*