## Context
Calling `POST /rest/views` (and other metadata mutations) currently
returns a generic `500` for user-input failures:
Ex:
1. **Invalid `objectMetadataId`** —
`resolveEntityRelationUniversalIdentifiers` throws
`FlatEntityMapsException(RELATION_UNIVERSAL_IDENTIFIER_NOT_FOUND)`.
Should be `404`.
2. **Missing required field** (e.g. `icon`) — Postgres raises a `NOT
NULL` violation, wrapped as
`WorkspaceMigrationRunnerException(EXECUTION_FAILED)` carrying a
`QueryFailedError`. Should be `400`.
Neither was caught by `ViewRestApiExceptionFilter`, so both fell through
to `UnhandledExceptionFilter` and were emitted as `500`s without
reaching Sentry.
Same gap existed on most metadata GraphQL resolvers — only
`page-layout*` and `role` resolvers covered
`WorkspaceMigrationRunnerException` via
`WorkspaceMigrationGraphqlApiExceptionInterceptor`.
## Changes
### New filters
REST (`HttpExceptionHandlerService` + Sentry-aware):
- `FlatEntityMapsRestApiExceptionFilter` — maps
`RELATION_UNIVERSAL_IDENTIFIER_NOT_FOUND` / `ENTITY_NOT_FOUND` → `404`,
`ENTITY_ALREADY_EXISTS` → `409`, others → `500`.
- `WorkspaceMigrationRunnerRestApiExceptionFilter` — for
`EXECUTION_FAILED`, unwraps the underlying `metadata` /
`workspaceSchema` / `actionTranspilation` error; if it's a
`QueryFailedError` it gets remapped to `400` via
`HttpExceptionHandlerService`. `APPLICATION_NOT_FOUND` → `404`,
`DDL_LOCKED` → `503`, otherwise `500`.
GraphQL (graphql-errors + existing formatter):
- `FlatEntityMapsGraphqlApiExceptionFilter` — kept as the GraphQL-shaped
counterpart (`NotFoundError` / `InternalServerError`).
- `WorkspaceMigrationRunnerGraphqlApiExceptionFilter` — reuses
`workspaceMigrationRunnerExceptionFormatter` for parity with the
existing interceptor.
### Wiring
Filters are now declared **per controller / resolver** via `@UseFilters`
(no global `APP_FILTER` registration) so they participate in the normal
NestJS filter chain instead of being preempted by
`UnhandledExceptionFilter`.
REST:
- `view.controller.ts` — adds `FlatEntityMapsRestApiExceptionFilter` and
`WorkspaceMigrationRunnerRestApiExceptionFilter`.
GraphQL (14 resolvers, all that mutate flat entities):
- `FlatEntityMapsGraphqlApiExceptionFilter` added to: `view`,
`view-field`, `view-field-group`, `view-sort`, `view-group`,
`view-filter`, `view-filter-group`, `page-layout`, `page-layout-tab`,
`page-layout-widget`, `role`, `object-metadata`, `field-metadata`,
`index-metadata`.
- `WorkspaceMigrationRunnerGraphqlApiExceptionFilter` added to the same
list **except** the four already covered by
`WorkspaceMigrationGraphqlApiExceptionInterceptor` (`page-layout`,
`page-layout-tab`, `page-layout-widget`, `role`) — to avoid
double-handling.
## Why per-resolver / per-controller instead of global
Earlier attempt to register the filters globally via `APP_FILTER`
regressed: NestJS reverses the global filter list and
`selectExceptionFilterMetadata` is first-match-wins, so
`UnhandledExceptionFilter` (registered last via `app.useGlobalFilters`
in `main.ts`) ended up first in the iteration order and preempted every
domain-specific filter. The per-resolver / per-controller approach is
explicit and predictable.
## Before
<img width="953" height="450" alt="Screenshot 2026-05-12 at 15 31 40"
src="https://github.com/user-attachments/assets/3c3bc6a8-f6bc-4032-97d0-7243540cfb90"
/>
## After
<img width="1050" height="598" alt="Screenshot 2026-05-12 at 15 31 17"
src="https://github.com/user-attachments/assets/c66c9ce5-d1ea-4f1d-b2fe-07979e2261f7"
/>
<img width="1068" height="503" alt="Screenshot 2026-05-12 at 15 31 09"
src="https://github.com/user-attachments/assets/ddd9eed8-812b-47d6-96cb-b019b807991b"
/>
