Standard Schema matcher incompatible with Effect

[samhh]

Describe the bug

Effect's Schema implements Standard Schema interop as a class atop its own constructs, causing Vitest's internal isStandardSchema type guard to fail.

• https://effect.website/docs/schema/standard-schema/
• https://standardschema.dev/ (listed here as implementing the spec)
• https://github.com/vitest-dev/vitest/blob/main/packages/expect/src/jest-utils.ts#L810

I'm assuming it's the typeof obj === 'object' given both the fact that Schema uses a class under the hood and the fact that interop can be achieved by spreading Effect's output, as per the repro.

Reproduction

import { Schema } from 'effect';
import { describe, expect, it } from 'vitest';

describe('repro', () => {
  it('fails', () => {
    expect('foo').toEqual(
      expect.schemaMatching(Schema.standardSchemaV1(Schema.String)),
    );
  });

  it('succeeds', () => {
    expect('foo').toEqual(
      expect.schemaMatching({ ...Schema.standardSchemaV1(Schema.String) }),
    );
  });
});

System Info

System:
    OS: macOS 26.1
    CPU: (12) arm64 Apple M2 Pro
    Memory: 842.14 MB / 32.00 GB
    Shell: 4.1.2 - /Users/sam/.nix-profile/bin/fish
  Binaries:
    Node: 22.21.1 - /nix/store/icgwxxfs13q1y864dd9ln86scp5659mw-nodejs-22.21.1/bin/node
    npm: 10.9.4 - /nix/store/icgwxxfs13q1y864dd9ln86scp5659mw-nodejs-22.21.1/bin/npm
    pnpm: 10.15.0 - /nix/store/zxr2z04s11vsmdx5ybdnyld2kllvlq61-pnpm-10.20.0/bin/pnpm
  Browsers:
    Firefox Developer Edition: 144.0
    Safari: 26.1

Used Package Manager

pnpm

Validations

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• Read the Contributing Guidelines.
• Read the docs.
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• The provided reproduction is a minimal reproducible example of the bug.

[hi-ogawa]

Interesting. I think it would be nice if standard schema has explicit mention of runtime aspect of spec such like typeof and also property is enumerable or not, etc. though probably practically it should just support anything as long as schema['~standard'].validate exists.

I moved the repro to stackblitz https://stackblitz.com/edit/vitest-dev-vitest-9y6lqaoa?file=test%2Fbasic.test.ts