The plan-without-action re-prompt at
`studio/backend/core/inference/llama_cpp.py` fires when the model
emits intent-only language ("first I'll ...", "let me ...") without
calling a tool. Previously the heuristic only checked an intent regex
and a 2000-char length cap. The same intent words occur in long
explanations that accompany REAL code or markup, so a complete reply
like "First, let me set up pygame. ```python ... ```" still tripped
the re-prompt, and the synthetic follow-up ("STOP. Do NOT write code
or explain.") wiped the user-visible answer.
Reproduced at scale in a 900-run sweep across 15 Qwen3.5/3.6 GGUF
configs: prompts that emit code or markup (Create a Python game,
Create a Flappy Bird game, weather dashboard HTML, sloth SVG)
landed empty `final_text` for the majority of seeds even on the
strongest configs.
Fix adds a `_HAS_ANSWER_ARTIFACT` regex covering:
- closed code fences (```...```)
- HTML pages (<!doctype, <html)
- complete SVG (<svg...</svg>)
- 2+ item numbered lists
and a `and not _HAS_ANSWER_ARTIFACT.search(_stripped)` guard on the
re-prompt condition. Plan-only stalls still re-prompt; complete
responses no longer do.
13 new unit tests in `test_llama_cpp_reprompt_guard.py` pin both
directions (artifact present -> no re-prompt; plan-only -> still
re-prompts).
