react-doctor/no-hydration-branch-on-browser-global

Render the same initial branch on the server and client instead of branching on a browser global during hydration.

Validation prompt

Confirm the detector match and collect the required evidence before deciding whether an edit is warranted.

Fires when initial rendered output branches on browser-only state such as window, document, navigator, storage, media queries, or a local helper or useMemo value derived from those globals. Confirm that the branch runs during render and can select different server and client output. The detector excludes branches under suppressHydrationWarning, but that is only safe for an unavoidable one-level text or attribute mismatch: it does not suppress structural hydration errors or make React patch mismatched content.

Evidence boundary

The diagnostic proves only that the detector’s modeled source pattern matched. It does not prove runtime impact, product intent, rendered failure, or that one remediation is correct.

Establish the environment, repository policy, exceptions, and required rendered or runtime evidence before deciding the occurrence.

Record one outcome:

• Confirmed failure: The required evidence establishes the violation.
• Rejected: A documented exception or false-positive predicate applies.
• Needs evidence: Named evidence can still be collected.
• Unavailable: Required evidence cannot be collected in this run.
• Waived with evidence: An authorized, scoped exception applies to an established failure.
• Observation: The review records an optional tradeoff without claiming a defect.

A waiver records its scope, authority, evidence, and review condition. It is not a pass or false positive.

Default severity is registry metadata. Use the occurrence’s JSON severity after repository configuration when ordering real findings.

Fix prompt

Apply this candidate correction only after the required evidence confirms the risk.

Render one stable initial structure on both the server and first client render. For a subscribable browser value, use useSyncExternalStore(subscribe, getSnapshot, getServerSnapshot) with an explicit server snapshot. Use suppressHydrationWarning only on the exact element with an unavoidable text or attribute mismatch, never to excuse different elements, child structure, or missing nodes. Use a mount gate only when no stable snapshot or server-compatible initial output can express the behavior.

Repository-wide copy prompt

Use this repository-wide prompt only after validating each occurrence. For one occurrence, use the guidance above.