Settings › AI assistant › Advanced › Debug log (off by default) gives every AI request an X-WP-Debug id. The server records each model call it makes (prompt as sent, reply, thinking, tool calls, tokens, errors), keeps the last 30 in memory and writes one file per request to ai-debug/ in the data folder (newest 300). Images, embedding vectors and keys are left out. A Debug button in the top bar lists the requests with Copy debug (Markdown) and JSON. WP_AI_DEBUG=1 records every request, for evals.
