---
date: '2026-02-13T22:00:00Z'
author: claude-opus-4-6
session: unknown
type: handoff
importance: 0.6
tags: [handoff, ws6, rest-api, typebox, type-safety]
supersedes: null
signature: pending
---

# Handoff: TypeBox Type Provider Refactor (REST API)

## What Was Done This Session

- Evaluated Copilot's PR #156 (`copilot/refactor-rest-api-typebox-usage`) — determined it was unsalvageable: 60 commits behind main, used wrong Ory client API (`@ory/client` instead of `@ory/client-fetch`), broke signing-requests logic, sprayed `as any` across return statements
- Created fresh branch `claude/142-typebox-type-provider` from current main
- Added `@fastify/type-provider-typebox` to pnpm catalog and rest-api dependencies
- Converted all 9 route files to use `fastify.withTypeProvider<TypeBoxTypeProvider>()` pattern
- Removed ~30 manual `as` type assertions on `request.body`, `request.params`, `request.query`
- Created `DateTime` and `NullableDateTime` schema helpers using `Type.Unsafe<Date | string>()` to properly handle the Date/string mismatch between DB layer and JSON schema
- Rebased onto origin/main, resolved conflicts in hooks.ts and registration.ts (registration was refactored to use DBOS workflows)
- All verification passes: typecheck (0 errors), lint (0 errors), 175/175 tests pass

## What's Not Done Yet

- PR needs to be created (branch is pushed)
- Copilot's PR #156 should be closed after this one merges

## Current State

- Branch: `claude/142-typebox-type-provider`
- Tests: 175 passing, 0 failing
- Build: clean (full workspace typecheck passes)
- Net change: -32 lines, 12 files changed (excluding lockfile)

## Decisions Made

- **Per-route `withTypeProvider` pattern** over app-level configuration — this is the recommended Fastify approach and scopes type inference to each plugin
- **`Type.Unsafe<Date | string>()` for DateTime fields** — keeps JSON schema output as `{ type: "string", format: "date-time" }` (OpenAPI spec unchanged) while accepting `Date` objects from the DB layer. Fastify's `fast-json-stringify` handles `Date` → ISO string conversion at runtime
- **No `as any` casts** — Copilot used `as any` on ~10 return statements with eslint-disable comments. We solved the root cause instead (Date/string type mismatch in schemas)
- **Kept legitimate `as` assertions** — casts on `JSON.parse` results, Ory metadata (`unknown` type), and error objects in catch blocks are necessary and correct

## Open Questions

- `Type.Ref()` shows deprecation warnings in newer TypeBox versions — may need migration in a future session

## Where to Start Next

1. Create PR for this branch
2. Close PR #156
3. Consider addressing `Type.Ref` deprecation warnings project-wide
