fix(react): keep PathnameProvider mounted so changing userId doesn't change hook count (#384)

[crossi-dev]

Fixes #384

Problem

FlowsProvider early-returns when userId isn't set yet:

if (!isProps(props)) return props.children;
return <PathnameProvider><FlowsProviderInner {...props} /></PathnameProvider>;

So while userId is null the children render outside PathnameProvider. When userId then changes to a string, PathnameProvider (which has useState/useEffect) is mounted into the tree at the same parent fiber for the first time — the render now runs more hooks than the previous one, and React throws "Rendered more hooks than during the previous render."

Fix

Keep PathnameProvider mounted at a stable position on every render, and switch the inner content instead:

return (
  <PathnameProvider>
    {isProps(props) ? <FlowsProviderInner {...props} /> : props.children}
  </PathnameProvider>
);

PathnameProvider's hooks now run on every render regardless of userId, so the hook count never changes across the null → string transition.

Verified

pnpm test
  workspaces/react   Test Suites: 1 passed   Tests: 3 passed
  workspaces/shared  Test Suites: 4 passed   Tests: 107 passed
  exit code: 0

I added 3 regression tests covering mount-with-userId, mount-without then set userId, and the reverse. The workspaces/react package had no component-test harness yet, so the PR also adds react-dom + @types/react-dom (devDeps) and "types": ["jest"] to its tsconfig — the minimal wiring needed to render the provider in a test. Happy to drop the test + that wiring and keep just the 4-line fix if you'd prefer a leaner diff.

---

Came across flows-sdk and noticed #384 had been open a while, so I fixed it. No strings attached — I'm with Choreless and we like contributing real fixes to projects we use. If it's useful and you ever want a hand with something larger, happy to help.

— Charles

[VojtechVidra]

Hi @crossi-dev and thanks for the PR! I do like the idea, keeping the React component tree the same with or without the userId would prevent the app from rerendering completely after SSR/SSG hydration.

However this PR seems incomplete to me. The <FlowsContext.Provider> is still rendered only with the userId defined. As a result I don't think the issue is actually solved.