The diagram
Every HTTP response is a decision.
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WebMacha sandbox
The client's If-Match tag is correct, so G11 passes, but under Classic rules the flow goes on to check If-Unmodified-Since at H12, finds the resource changed after that date, and refuses with 412. Switch the rules to Modern and the same request gets 204 No Content, because RFC 9110 §13.2.2 says If-Unmodified-Since is ignored when If-Match is present, so H10 answers no.
Decision flow
Decision path
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Request log
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