---
phase: 16-frontend-scaffold
plan: 03
subsystem: ui
tags: [trpc, react-query, vite, typescript]

# Dependency graph
requires:
  - phase: 16-01
    provides: Vite + React + Tailwind project
  - phase: 16-02
    provides: Shared types package with AppRouter export
provides:
  - tRPC React Query client with type-safe hooks
  - React Query provider with sensible defaults
  - httpBatchLink configured for Vite dev proxy
affects: [17-initiative-dashboard, 18-initiative-detail, 19-agent-inbox]

# Tech tracking
tech-stack:
  added: ["@trpc/client", "@trpc/react-query", "@tanstack/react-query"]
  patterns: ["tRPC React Query provider wrapping", "httpBatchLink with Vite proxy"]

key-files:
  created: ["packages/web/src/lib/trpc.ts"]
  modified: ["packages/web/package.json", "packages/web/src/main.tsx", "packages/web/src/App.tsx"]

key-decisions:
  - "httpBatchLink URL set to /trpc (proxied by Vite in dev, same-origin in prod)"
  - "QueryClient defaults: refetchOnWindowFocus=false, retry=1"
  - "Temporary App.tsx with health check to prove tRPC connection"

patterns-established:
  - "tRPC client: createTRPCReact<AppRouter>() in lib/trpc.ts"
  - "Provider stack: trpc.Provider > QueryClientProvider > App"

# Metrics
duration: 2min
completed: 2026-02-04
---

# Phase 16 Plan 03: tRPC Client Wiring Summary

**tRPC React Query client wired to AppRouter with httpBatchLink, React Query provider, and health check verification**

## Performance

- **Duration:** 2 min
- **Started:** 2026-02-04
- **Completed:** 2026-02-04
- **Tasks:** 2
- **Files modified:** 4

## Accomplishments
- tRPC React Query client created with full AppRouter type inference
- React Query provider configured with sensible defaults (no refetch on focus, single retry)
- httpBatchLink configured for `/trpc` URL (Vite dev proxy forwards to backend at 127.0.0.1:3847)
- Temporary App.tsx with `trpc.health.useQuery()` proves end-to-end type-safe data fetching
- Vite build passes with full type checking

## Task Commits

Each task was committed atomically:

1. **Task 1: Install tRPC React Query dependencies** - `603d908` (feat)
2. **Task 2: Wire tRPC React Query client with providers** - `0d5645f` (feat)

## Files Created/Modified
- `packages/web/src/lib/trpc.ts` - tRPC React Query client with createTRPCReact<AppRouter> and httpBatchLink
- `packages/web/package.json` - Added @trpc/client, @trpc/react-query, @tanstack/react-query, @codewalk-district/shared
- `packages/web/src/main.tsx` - Root component with trpc.Provider and QueryClientProvider wrapping App
- `packages/web/src/App.tsx` - Temporary health check component using trpc.health.useQuery()

## Decisions Made
- httpBatchLink URL set to `/trpc` relying on Vite dev proxy (no absolute URL needed)
- QueryClient configured with refetchOnWindowFocus=false and retry=1 for development ergonomics
- tsconfig.app.json project references to shared package not needed (npm workspaces symlink handles resolution, skipLibCheck avoids third-party declaration issues)

## Deviations from Plan

None - plan executed exactly as written.

## Issues Encountered
None

## User Setup Required
None - no external service configuration required.

## Next Phase Readiness
- tRPC client fully operational with type-safe hooks
- All subsequent UI screens (dashboard, detail, inbox) can use `trpc.{procedure}.useQuery()` for data fetching
- Ready for 16-04: React Router Setup

---
*Phase: 16-frontend-scaffold*
*Completed: 2026-02-04*
