Three silent drops on the way to a rented pod, all found while wiring Surya to
the model layer, all of the same shape: coderai accepted a field, forwarded a
reduced version of it, and the pod answered something plausible.

* Images. The front flattens multipart content to the literal text
  "[image_url content]" unless the backend claims vision, and only the llama.cpp
  backend ever did. So every page sent to a VLM served on RunPod — olmOCR in
  "model" mode, or Surya through a coderai-vllm pod — arrived as that
  placeholder, and the model answered fluently about nothing. A proxy is the
  wrong place to judge: forwarded, a text-only server returns a plain 400 and a
  VLM server reads the page.

* Structured output. Only {"type":"json_object"} survived, so a json_schema —
  the strict form current clients send, Surya's guided decoding among them — was
  dropped and the reply came back as free text the caller could not parse. The
  streamed path ignored the field entirely, json_object included.

* extra_args. Whitelisted per engine on a model's runpod block since pods
  shipped, parsed, stored, and never put on a command line. Setting it looked
  like tuning and did nothing, which is worse than refusing it: the pod boots,
  serves, and ignores the decision. A page-reading model wants prefix caching
  and the Qwen-VL pixel bounds, and until now the only way in was docker_args,
  which replaces the whole generated line.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PxYHWbCAjjjD7A1rhFKtaW