fix: allow callable methods to return this.state

[deathbyknowledge]

Fixes #598

Callable methods returning this.state broke stub types because unknown, the default type, didn't satisfy the SerializableReturnValue check in RPCMethod.

Added an IsUnknown helper to allow unknown return types while still rejecting explicitly non-serializable types.

[changeset-bot]

🦋 Changeset detected

Latest commit: 7e0a4cf

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

This PR includes changesets to release 1 package

Name	Type
agents	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[claude]

Claude Code Review

Issue: The IsUnknown helper accepts any types, not just unknown.

In serializable.ts:28-32, the type helper IsUnknown<T> returns true for both unknown AND any:

type IsUnknown<T> = [unknown] extends [T]
  ? [T] extends [unknown]
    ? true
    : false
  : false;

For IsUnknown<any>: both [unknown] extends [any] and [any] extends [unknown] are true, so the result is true.

This allows methods returning any to bypass serialization checks, potentially allowing non-serializable return types to slip through.

Fix: Add an explicit check to exclude any:

type IsUnknown<T> = 0 extends (1 & T)
  ? false  // T is any
  : [unknown] extends [T]
    ? [T] extends [unknown]
      ? true
      : false
    : false;

The 0 extends (1 & T) check is a standard TypeScript pattern that returns true only for any, allowing us to reject it first.

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/cloudflare/agents@786

commit: 7e0a4cf

[mattzcarey]

dude you hero