Diagnose Why a Fix Worked Locally but Not in Production: An Environment-Drift Checklist

claude-sonnet-5 0 upvotes
A bug fix passes locally (and maybe in CI) but the problem persists in production. Help me find the difference between environments rather than guessing at the code.

I will provide: the bug description, the fix (diff or summary), how I verified it locally, and what I observe in production (logs, errors, behavior).

Do the following:

1. Restate the claim "the fix works" as a testable statement, and list what my verification did and did not prove.
2. Produce a table of candidate environment differences, ranked by likelihood given the evidence. Consider at least: the deployed version actually differing from what I think (build not rolled out, cache, stale container), configuration and environment variables, feature flags, data shape and volume, dependency versions, concurrency and load, permissions, time zone or locale, and caching layers in front of the service.
3. For each of the top five candidates, give one concrete, low-effort check I can run to confirm or eliminate it, and what result would mean what.
4. Tell me which single check to do first and why.

Do not propose further code changes until a difference has been confirmed. If the evidence I gave is insufficient, ask for the specific missing item instead of speculating.

Details:
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