Validate unknown shapes at the boundary

When a value is unknown, do not manually prove its shape with a long anonymous chain of typeof, null, array, property, and key checks. Parse it once with a schema or use a domain-named type guard that owns the invariant.

Bad:

const empty =
  value !== null &&
  typeof value === "object" &&
  !Array.isArray(value) &&
  Object.keys(value).length === 0;

Better:

const EmptyBrowserFeedState = z.strictObject({});
const empty = EmptyBrowserFeedState.safeParse(value).success;

Do not extract the anonymous check chain into a single-use helper merely to hide it. A named guard is useful when it represents a real domain concept, centralizes the invariant, and narrows values for its callers.