## Problem
Closes#21780.
When editing a **Phones** field in Settings → Data Model, changing the
**Default Country Code** does not enable the Save button — the form
becomes dirty but never valid, so the change can't be saved.
## Root cause
The settings form validates `defaultValue` with the record-value
`phonesFieldValueSchema`, which requires non-null strings:
```ts
primaryPhoneNumber: z.string(),
primaryPhoneCountryCode: z.string(),
```
But a Phones default value can legitimately have **null** subfields — a
default country code with no default number. The backend normalizes
empty subfields to `null`
(`nullify-empty-phones-default-value.util.ts`), and the shared contract
`FieldMetadataDefaultValuePhones` is `string | null`. So an existing
field whose stored default has `primaryPhoneNumber: null` makes the form
**permanently invalid**: changing the country code preserves the null
number → `isValid` stays `false` → `canSave = isDirty && isValid` keeps
Save disabled.
The sibling **address** field doesn't have this bug because
`addressFieldValueSchema` already makes every subfield `.nullable()`.
Phones was simply inconsistent.
## Fix
Add a dedicated `phonesFieldDefaultValueSchema` with nullable subfields
(mirroring the address pattern and matching
`FieldMetadataDefaultValuePhones`) and use it in the Phones settings
form. The stricter record-value `phonesFieldValueSchema` is left
untouched, so record input/persistence/empty-checks are unaffected.
## Test plan
- [x] Unit test covering the partial-null default value (and asserting
the record-value schema still rejects it)
- [x] `nx typecheck twenty-front` clean
- [x] `nx lint:diff-with-main twenty-front` clean
- Manual: open a Phones field, set a Default Country Code and save,
re-open, change the country code → Save now enables.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
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Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
Thomas Trompette
a59ed80422
