The diagram
Every HTTP response is a decision.
Send a request from the rail, or call this page's live URL with curl, and watch the flowchart decide the status one question at a time.
WebMacha sandbox
Under Classic rules, L13 checks If-Modified-Since without looking at the method, so this PUT is answered 304 Not Modified and never applied. Switch the rules to Modern and the same request gets 204 No Content, because RFC 9110 §13.1.3 says If-Modified-Since applies only to GET and HEAD, so L13 ignores it.
Decision flow
Decision path
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Request log
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