---
id: T01
parent: S01
milestone: M002
provides: []
requires: []
affects: []
key_files: ["engine/main.py", "app/vite.config.ts", "app/src/types/engine.ts", "app/src/api/engine.ts", "app/src/api/__tests__/engine.test.ts", "app/src/App.tsx", "app/src/test-setup.ts", "app/tsconfig.app.json"]
key_decisions: ["Allow all CORS origins for dev with comment to restrict in production", "API client functions throw on non-ok responses with status + detail text", "Use vitest globals + jsdom environment for test ergonomics"]
patterns_established: []
drill_down_paths: []
observability_surfaces: []
duration: ""
verification_result: "Ran `cd app && npx vitest run --reporter=verbose` — all 9 tests pass (3 per API function: getPresets, traceImage, simplifyVector). Ran `cd app && npx tsc --noEmit` — zero TypeScript errors."
completed_at: 2026-03-26T05:05:22.615Z
blocker_discovered: false
---

# T01: Added CORSMiddleware to engine, scaffolded Vite+React+TS app with dev proxy, and built typed API client with 9 passing tests

> Added CORSMiddleware to engine, scaffolded Vite+React+TS app with dev proxy, and built typed API client with 9 passing tests

## What Happened
---
id: T01
parent: S01
milestone: M002
key_files:
  - engine/main.py
  - app/vite.config.ts
  - app/src/types/engine.ts
  - app/src/api/engine.ts
  - app/src/api/__tests__/engine.test.ts
  - app/src/App.tsx
  - app/src/test-setup.ts
  - app/tsconfig.app.json
key_decisions:
  - Allow all CORS origins for dev with comment to restrict in production
  - API client functions throw on non-ok responses with status + detail text
  - Use vitest globals + jsdom environment for test ergonomics
duration: ""
verification_result: passed
completed_at: 2026-03-26T05:05:22.627Z
blocker_discovered: false
---

# T01: Added CORSMiddleware to engine, scaffolded Vite+React+TS app with dev proxy, and built typed API client with 9 passing tests

**Added CORSMiddleware to engine, scaffolded Vite+React+TS app with dev proxy, and built typed API client with 9 passing tests**

## What Happened

Added CORSMiddleware to engine/main.py allowing all origins for dev. Scaffolded app/ as a Vite+React+TS project with dev proxy forwarding /engine to localhost:8000. Created TypeScript interfaces matching all engine preset JSON structures and API response shapes. Built typed API client with getPresets(), traceImage(), and simplifyVector() functions that support AbortSignal cancellation and throw descriptive errors on failure. Wrote 9 unit tests covering URL/method correctness, FormData construction, AbortSignal passthrough, and error handling. All tests pass, zero TypeScript errors.

## Verification

Ran `cd app && npx vitest run --reporter=verbose` — all 9 tests pass (3 per API function: getPresets, traceImage, simplifyVector). Ran `cd app && npx tsc --noEmit` — zero TypeScript errors.

## Verification Evidence

| # | Command | Exit Code | Verdict | Duration |
|---|---------|-----------|---------|----------|
| 1 | `cd app && npx vitest run --reporter=verbose` | 0 | ✅ pass | 895ms |
| 2 | `cd app && npx tsc --noEmit` | 0 | ✅ pass | 2000ms |


## Deviations

Added @types/node as dev dependency (not in plan) for Node.js type resolution. Added vitest/globals to tsconfig.app.json types array for global test functions. Added test-setup.ts for jest-dom matchers.

## Known Issues

None.

## Files Created/Modified

- `engine/main.py`
- `app/vite.config.ts`
- `app/src/types/engine.ts`
- `app/src/api/engine.ts`
- `app/src/api/__tests__/engine.test.ts`
- `app/src/App.tsx`
- `app/src/test-setup.ts`
- `app/tsconfig.app.json`


## Deviations
Added @types/node as dev dependency (not in plan) for Node.js type resolution. Added vitest/globals to tsconfig.app.json types array for global test functions. Added test-setup.ts for jest-dom matchers.

## Known Issues
None.
