Browser Mode leaks a manual mock across spec files when the same module is mocked via two ids

[A-kirami]

Describe the bug

This repro is pure TypeScript. Vue components are not required.

src/probe.spec.ts registers two manual mocks for the same logical module using two different raw ids:

• vi.mock('~/modal', ...)
• vi.mock('./modal', ...)

src/target.spec.ts does not register any mock. It only imports another module that touches ~/modal again.

Both spec files pass when run individually, but when they run in the same Browser Mode process, the second file fails after the first file passes:

[vitest] There was an error when mocking a module
[birpc] rpc is closed, cannot call "resolveManualMock"

This looks like a Browser Mode mock lifecycle bug. During the second file import, Vitest appears to still try resolving the manual mock registered in the previous file, even though the second file did not register that mock.

Reproduction

Repository repro:

A-kirami/vitest-browser-manual-mock

Commands:

bun vitest run --config vite.config.ts --no-cache src/probe.spec.ts
bun vitest run --config vite.config.ts --no-cache src/target.spec.ts
bun vitest run --config vite.config.ts --no-cache --reporter verbose src/probe.spec.ts src/target.spec.ts

Notes:

• --no-cache is important here because Vitest's sequencer uses cached file stats and durations to sort files.
• With cache enabled, the non-mocking file can run first and hide the problem.
• With --no-cache, the repro behaves like a fresh run and the failing order stays stable.

Expected behavior:

• src/probe.spec.ts passes alone
• src/target.spec.ts passes alone
• both specs also pass when run together in the same Browser Mode process

Actual behavior:

• the single-file runs pass
• the combined run fails after src/probe.spec.ts passes

Additional observation:

On a fresh run, vitest list also fails:

bun vitest list --config vite.config.ts --no-cache src/probe.spec.ts src/target.spec.ts

with:

Mock /src/modal.ts wasn't registered. This is probably a Vitest error. Please, open a new issue with reproduction.

System Info

System:
  OS: Windows 11 10.0.26200
  CPU: (20) x64 12th Gen Intel(R) Core(TM) i7-12700H
  Memory: 6.99 GB / 31.63 GB
Binaries:
  Node: 23.5.0
  npm: 10.9.2
  bun: 1.3.10
  Deno: 2.1.4
Browsers:
  Edge: Chromium (140.0.3485.54)
  Internet Explorer: 11.0.26100.7309
npmPackages:
  @vitest/browser-playwright: 4.1.0
  playwright:1.58.2
  vite: 7.3.1
  vitest: 4.1.0

Used Package Manager

bun

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