0.3.0

[0.3.0] — 2026-09-09

A behaviour change and one public type change, both in the same area. Notes:
docs/releases/0.3.0.md.

Changed

• A refused declaration no longer unmounts your application. It was re-thrown from the provider's
  render, so an author who forgot to install a validator got a blank page — with the console message
  naming the exact import sitting underneath a tree that no longer rendered. MCP is a second control
  interface onto one application, and a misconfigured second interface must not take down the first.
  What has not changed is that the declaration is refused: the tool is absent from tools/list
  and callable by nobody. The refusal is now scoped to the declaration that earned it, so the other
  tools on the page survive it — previously one unvalidated tool cost you every tool.
• onRegistration carries every refused declaration, with the code that says which: a missing
  validator, a duplicate name, a foreign name, a reserved prefix. It previously carried only the
  reserved prefix. A development build also writes the refusal to the console with the declaration
  site, for an author who wired no observer.
• McpRegistrationEvent#prefix is optional. It is meaningless for three of the four causes, and a
  required field a consumer has to ignore is worse than an absent one. A TypeScript consumer reading
  event.prefix must now handle undefined — the one source change this release asks of you.
• onUnexpectedState still receives what it received before. Its documentation no longer says setup
  failures throw, because they do not.

Fixed

• The documentation pages that described the old behaviour — the design page, the API reference, the
  troubleshooting page, the state and dependency pages — say what happens now.