probo / rules

---
description: Use Relay @required to make expected-present nullable fields non-null
globs: "**/*.tsx"
alwaysApply: false
---

# Use `@required` for expected-present fields

GraphQL schemas mark many fields nullable defensively, but at a given call site
you usually **expect** a value. When a field is nullable in the schema but the
component cannot meaningfully render without it, annotate it with `@required` so
the **generated type is non-null**. This keeps typing consistent: callers stop
threading `?.` / `?? ""` / `!` through code that always expects data, and a
genuinely-missing value becomes a real signal instead of a silently-empty UI.

Choose the action by what should happen when the value is actually absent:

- `@required(action: THROW)` — the value is an invariant for this view (a page's
  root entity, the `currentTrustCenter` a portal is built around). A null throws
  on read and propagates to the nearest error boundary. Field becomes non-null.
- `@required(action: LOG)` — a missing value should degrade gracefully: the null
  bubbles to the nearest `@required` ancestor (or nulls the fragment data) and
  Relay logs it. Use when the surrounding UI can render a fallback.
- `@required(action: NONE)` — bubble nullability without logging; rarely needed.

```graphql
# GOOD — the view is built around this entity; THROW makes it non-null
currentTrustCenter @required(action: THROW) {
  organization {
    name                    # already String! — no @required needed
    logo { downloadUrl }    # legitimately optional — leave nullable
  }
}
```

```tsx
// GOOD — non-null typing falls out of @required; no defensive chaining
const { organization } = data.currentTrustCenter;
const logoUrl = organization.logo?.downloadUrl ?? undefined; // logo stays optional
```

Do NOT use `@required` to silence nullability on fields that are *genuinely*
optional (avatar, logo, optional description) — those keep their nullable type
and get a real empty/fallback state. Do NOT use the `THROW` as control flow for
an expected-empty case (it is an error path, not a branch). Do NOT annotate
fields the schema already declares non-null (`String!`, `Organization!`).

See `contrib/claude/relay.md` (Fragments → Required fields).

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