Fix custom isUrl overrides for internal link shortcuts

[zbeyens]

Summary

Custom isUrl callbacks could not veto /... and #... link shortcuts because validateUrl returned early for internal paths and anchors before it ever consulted the configured validator.

This change only gives that veto power to real custom isUrl callbacks. The default platejs validator still preserves the existing internal-path and anchor-link behavior.

What Changed

• detect when the configured isUrl is a custom override instead of the default validator
• respect that custom validator for internal paths and anchor links
• add regression coverage for validateUrl and upsertLink
• add a patch changeset for @platejs/link

Testing

• bun test packages/link/src/lib/utils/validateUrl.spec.ts packages/link/src/lib/transforms/upsertLink.spec.tsx packages/link/src/lib/withLink.spec.tsx
• pnpm install
• pnpm turbo build --filter=./packages/link
• pnpm turbo typecheck --filter=./packages/link
• pnpm lint:fix
• pnpm check

Fixes #4591.

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🦋 Changeset detected

Latest commit: 7868135

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@platejs/link	Patch

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Project	Deployment	Actions	Updated (UTC)
plate	Ready	Preview, Comment	Mar 28, 2026 11:50pm