The Payload Looked Like JSON for 48 Hours. Then a Strict Parser Hit NaN.
python
dev.to
Have you ever watched a downstream service reject a body that every local Python test called perfectly valid JSON? I just burned forty-eight hours on that mismatch, and the encoder was not lying to me in the way I expected. It was json.dumps, doing the documented default, while I silently assumed "JSON" meant RFC 8259 and nothing else. These field notes cover what I tried, what actually broke, and the small gate I will keep. Hour zero: the body looked fine The symptom was almost bori