Some models (observed with an abliterated Qwen variant) answer a request
they judge "politically sensitive" with hedging refusal language instead of
erroring or returning blank — neither of which the existing blank-response
or schema-validation retry triggers catch, so the refusal just passed
through as a normal result.
Adds a hybrid detector to _llm/retry.py: a free lexical/regex pass catches
blatant refusals ("I cannot generate...") without any network call; a
response that's short and/or hedge-y enough to be ambiguous additionally
gets an embedding-similarity check against canonical refusal exemplars, via
a new optional LLMProvider.embed() (Ollama's /api/embed, llama-server's
/v1/embeddings) — deliberately model-agnostic to the backend, since this is
a model-behavior concern, not a backend one. A detected refusal is treated
exactly like a blank response or validation failure: retried with a bumped
seed (existing next_seed()/RETRY_BACKOFF_SECS machinery), never returned to
the caller.
Wired into all four retry loops: OllamaProvider.chat()/chat_structured(),
LlamaCppProvider.chat(), and the shared _llm/chat.py chat_structured() used
by LlamaCppProvider.chat_structured(). New OllamaOptionRefusalRetry node
(same composable OLLAMA_OPTIONS chain as OllamaOptionDisableThinking)
configures it: enabled toggle, optional embedding_model (blank = lexical-
only), similarity threshold.
Claude-Session: https://claude.ai/code/session_01YArD9ZjBWKsAvazmS48amA
Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>
