fix: allow user-defined interfaces as Server Props

[mattzcarey]

Summary

The Props generic on Server, getServerByName, and routePartykitRequest was bounded by Record<string, unknown>. Interfaces do not get implicit index signatures in TypeScript, so a well-typed interface fails that bound with:

Type 'MyProps' is not assignable to type 'Record<string, unknown>'.
  Index signature for type 'string' is missing in type 'MyProps'.

This surfaced downstream as cloudflare/agents#1886 (getAgentByName(ns, name, { props: config }) rejecting interface-typed props) — the agents SDK inherits these bounds through Server and getServerByName, so the root fix belongs here.

Fix — object bounds, no any, no casts

• Props extends object = Record<string, unknown> on Server, getServerByName, and routePartykitRequest. Interfaces satisfy object natively; defaults stay Record<string, unknown> so untyped usage still reads props values as unknown. Props is only ever treated as an opaque JSON bag at runtime (encodeProps/decodeProps already type it unknown), so nothing behavioral changes.
• T extends Server<Env, object> = Server<Env> on getServerByName/routePartykitRequest. Two things forced this: the #_props private field carries Props covariantly, so a subclass declaring interface Props failed the old Server<Env> constraint (whose Props silently pinned to the Record default); and the DO stub's setName parameter resolves from the constraint, so options.props wouldn't flow without it. The default stays Server<Env>, keeping the return type for untyped callers identical.

Repro / regression tests

New compile-time test packages/partyserver/src/tests/props.test-d.ts — typechecked by check:type but never executed (vitest only picks up *.test.ts). Written first and confirmed red on main with errors matching the report:

• Server declared with interface Props
• getServerByName / routePartykitRequest called with interface-typed props
• onStart receiving the interface type
• negative pins: primitives are still rejected as Props

Verification

npm run build && npm run check fully green (sherif, oxfmt, oxlint, all 42 typecheck projects, all workspace test suites).

Once this ships, cloudflare/agents can bump partyserver and loosen its own Props bounds without any bridging (supersedes the approach in cloudflare/agents#1906, closed in favor of fixing it here).

[changeset-bot]

🦋 Changeset detected

Latest commit: de5bc27

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

This PR includes changesets to release 1 package

Name	Type
partyserver	Patch

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hono-party

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partyfn

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partyserver

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partysocket

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partysub

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partysync

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partytracks

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partywhen

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y-partyserver

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commit: de5bc27