Post-Migration Cleanup

Handles frontend/caller migration from legacy Pages Router to v2 App Router routes. This is Phase 13+ work — all v2 API routes must already exist before running this workflow.

Scope: Frontend callers, mutation hooks, legacy helpers, and legacy types ONLY. No API route creation (the recollect-api-migrator agent handles that).

Per-Route Workflow

Execute these steps in order for each route being cleaned up. Each step prevents a specific class of dead code or broken references.

1. Update the Mutation Hook

Import types from the v2 route file instead of apiTypes.ts. Point postApi to the v2 URL.

// Before
import { type LegacyPayload } from "@/types/apiTypes";
postApi<LegacyResponse>("/api/old/path", payload);

// After
import {
	type EntityPayload,
	type EntityResponse,
} from "@/app/api/v2/domain/endpoint/route";
postApi<EntityResponse>("/api/v2/domain/endpoint", payload);

If the v2 route uses a different payload/response shape, update the hook’s optimistic updater and cache structure to match.

2. Update All Frontend Usage Sites

Search for every file importing the old hook:

ast-grep --lang tsx -p 'useOldHookName' src/  # Replace useOldHookName with the actual hook name

Update each site:

• Import the new hook
• Adjust any destructured return values
• Update payload construction if the shape changed

3. Remove Legacy Helper from supabaseCrudHelpers

Open src/async/supabaseCrudHelpers/index.ts and remove the legacy function. Remove any imports that become unused.

This prevents dead code from accumulating in the crud helpers barrel.

4. Remove Legacy Type from apiTypes.ts

Open src/types/apiTypes.ts and remove the legacy payload/response type. Types now live in the v2 route’s schema.ts.

This ensures a single source of truth for types.

5. Delete Old Files

Use trash (never rm) to remove:

trash src/pages/api/{entity}/{endpoint}.ts             # Old Pages Router route
trash src/async/mutationHooks/{entity}/use{OldHook}.ts # Old mutation hook (if separate)

6. Verify

Run both checks — they catch different classes of issues:

pnpm lint:types # Catches broken imports, type mismatches
pnpm lint:knip  # Catches orphaned exports, unused code

Fix any issues before marking the route as complete.

Routing Table

Error Handling Patterns to Preserve

When updating hooks, preserve these error handling patterns from the v2 routes:

Duplicate detection (23505): The v2 route returns { data: null, error: "Duplicate name" } with status 409. Hooks should handle this in onError or show a toast.

Authorization (403): The v2 route returns { data: null, error: "User is not the owner" } with status 403. Hooks should roll back optimistic updates on this.

Server error (500): Automatically captured by Sentry in the v2 route. Hooks should show a generic error toast.

Common Issues

Unused Import Warnings

After removing legacy code, ESLint flags orphaned imports:

pnpm fix:prettier src/async/supabaseCrudHelpers/index.ts
pnpm fix:prettier src/types/apiTypes.ts

Knip Unused Export Warnings

New types aren’t consumed yet → ensure all usage sites import from the v2 route file, not apiTypes.ts.

Type Mismatches

If the v2 response shape differs from legacy (e.g., nullable fields added, phantom fields removed), update the hook’s generic parameters and optimistic updater accordingly.

Cache Key Changes

If the v2 route serves a different data shape, the React Query cache key may need updating. Check src/utils/constants.ts for the correct key constant.

Success Criteria

Route cleanup is complete when:

• Mutation hook imports types from v2 route file
• Mutation hook points postApi to v2 URL
• All frontend usage sites updated to new hook
• Legacy helper removed from supabaseCrudHelpers/index.ts
• Legacy type removed from apiTypes.ts
• Old Pages Router file deleted with trash
• Old mutation hook deleted with trash (if applicable)
• pnpm lint:types passes
• pnpm lint:knip passes (no unused exports)