isRunningInTest check causes problems during agentic debugging

[hasanayan]

I sometimes let Claude Code use playwright-cli to debug issues on Storybook. However, since isRunningInTest considers HeadlessChrome a testing environment, the auto snapshots feature kicks in and my agent gets bamboozled by commands.setupVisSuite is not a function errors.

I am registering the addon as follows to avoid this issue:

const visAddon = addonVis({
  createMissingBaseline: true,
  auto: true,
});

// storybook-addon-vis reads any HeadlessChrome user agent as a test run, so its
// `beforeAll` reaches for vitest commands a plain browser has not got, and the
// preview fails to render. `__vitest_browser__` is the signal it wants;
// setup-vitest.ts asserts it is there when the suite really does run.
const vis: typeof visAddon = {
  ...visAddon,
  beforeAll: (...args) =>
    "__vitest_browser__" in globalThis
      ? visAddon.beforeAll?.(...args)
      : undefined,
};