[MartinCupela]

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Description of the changes, What, Why and How?

Linear: REACT-1363

What: removes the CustomCommandData interface and its root export.

Why: in v9, CustomCommandData fed CommandVariants, which typed CommandResponse.name and set, so a typo in a command name failed to compile. In v10, Command['name'] and Command['set'] come from the generated models as plain string, and nothing reads CustomCommandData. Augmenting it compiled but had no effect. Command names come from the server (built-in commands plus the app's own), so we don't type them. An app that wants a closed set of names declares its own union.

How:

• src/custom_types.ts and src/index.ts: interface and export removed.
• ai-docs/v10-breaking-changes.md (#custom-data-augmentation): a note that it is removed, a migration step, a row in "Removed: no replacement type", and updated counts in the type-rename section.
• ai-docs/ai-migration-v9-to-v10.md: the migration step, plus CustomCommandData added to the removed-type import regex and the verification grep. A leftover augmentation still compiles, so tsc alone won't find it.
• ai-docs/v10-followups.md: the follow-up is marked solved.
• .claude/skills/update-custom-mapping: the interface is no longer listed.

yarn types, yarn lint and yarn test pass.

Downstream:

• stream-chat-react: fix(types): remove DefaultCommandData and the CustomCommandData augmentation stream-chat-react#3380 removes its CustomCommandData augmentation and DefaultCommandData.
• stream-chat-react-native still augments CustomCommandData (package/src/types/stream-chat-common-custom-data.d.ts and two examples). That keeps compiling against this change, but has no effect and should be deleted.

Changelog

• Removed CustomCommandData. Command names (Command['name'], Command['set']) are string; delete augmentations of it.

Squash-merge footer

BREAKING CHANGE: CustomCommandData is no longer exported. Delete its augmentations and imports. A leftover augmentation still compiles and has no effect, so search for the name rather than relying on tsc. An app that wants a closed set of command names declares its own union. See ai-docs/v10-breaking-changes.md#custom-data-augmentation.