Build a useful investigation brief
Build contrast fixtures
Prepare a correctly named file, a renamed file with the same bytes, and a file with a familiar extension but different content. Record expected acceptance for each and preserve the first bytes or other reviewed evidence used to distinguish them.
Trace classification transitions
Capture selection hint, client declaration, upload metadata, receiver inspection, validation state, preview choice, and processing result. Mark each transition where the type label changes, including whether the change is documented or inferred.
Test competing explanations
Compare the traces for same-content names and same-name content differences. Explain whether the outcome follows extension, declaration, content, or processing policy, and keep an unknown classifier boundary open when evidence does not reveal its rule.
What to carry forward
The investigation is sufficient when contrast fixtures show the first classification transition and its relationship to the acceptance policy. If the policy itself is absent, deliver a precise evidence brief and request a type decision rather than choosing a preferred signal.
Technical background: MDN reference.
Keep the decision with the work.
Use a Work Item in Aglet to record the problem, the evidence you have, and the next decision. Add an owner and priority, then keep updates in the discussion so the next person can follow the reasoning.
Create an account See the product workflow