Validate cutover and browser-bundle age before RCA

Before attributing a post-merge failure to new client behavior, establish three times separately: page or bundle load, deployment success and health, and request execution. A session opened before cutover may retain an old browser bundle after the new server is healthy, so “tested after merge” does not prove the new client ran.

Confirm a versioned client diagnostic or deployment identifier when available. Absence of an upstream request proves only that execution stopped before that boundary, not which client predicate blocked it.