Make spec type tests catch .optional() missing args too

[felixweinberger]

We have tests covering adherence to schema.ts with our Zod types, but these don't catch if we're missing optional params.

Example: #1295

Would be great to be able to catch such cases too so our internal SDK types include both required and optional params from the spec.

[rechedev9]

I've implemented a solution for this in PR #1652.

Approach

Added 151 compile-time key-parity assertions using three utility types:

• KnownKeys<T> — strips index signatures, keeping only named keys
• AssertExactKeys<A, B> — resolves to true when key sets match; produces a descriptive error type on mismatch
• Assert<T extends true> — forces a compile error on mismatch

Every sdkTypeChecks entry now has a corresponding assertion that fails at pnpm typecheck time if the SDK type has extra or missing keys relative to the spec.

Coverage: 151 of 174 entries. 23 excluded with documentation (15 union types where key enumeration isn't meaningful, 8 primitive aliases).

Discovered mismatches

The new assertions immediately caught 7 genuine SDK/spec key differences:

SDK Type	Issue
PromptReference	Missing title from spec
Resource	Missing size from spec
PromptArgument	Missing title from spec
ResourceLink	Missing size from spec
ClientCapabilities	Missing extensions from spec
ServerCapabilities	Missing extensions from spec
RequestMetaObject	Extra io.modelcontextprotocol/related-task not in spec

These are documented with @ts-expect-error — when the SDK catches up, the directive itself errors, prompting removal.

Zero runtime overhead. Single file changed.