The generated schemas compose with schemas imported from
@modelcontextprotocol/sdk/types.js (e.g. z.array(ContentBlockSchema)).
The SDK constructs its schemas via `import * as z from 'zod/v4'`, but
our generated schema.ts used `import { z } from "zod"` — which returns
the v3 API when the consumer has zod 3.25.x installed.
Mixing v3-created and v4-created schema instances throws at parse time
with errors like `keyValidator._parse is not a function` because zod v4
dropped the `_parse` / `_parseSync` internals that v3 wrappers call.
This was masked before #534 because zod was bundled — all schema
creation shared the same inlined zod copy. Externalizing zod exposed
the mismatch on consumers pinned to zod 3.x (e.g. anthropics/apps).
The `zod/v4` subpath is exported by both zod 3.25+ and zod 4.x, so the
existing peerDependency range `^3.25.0 || ^4.0.0` is preserved.
https://claude.ai/code/session_013xQUegrvVGct5xpqeSL5av
Co-authored-by: Claude <noreply@anthropic.com>
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