_build_ollama_payload sends options.temperature and options.num_predict
to /api/chat, but never options.num_ctx. Ollama defaults num_ctx to 2048
when the option is omitted, so prompts going to any Ollama backend are
silently truncated there regardless of the model's actual capability.
Thread the discovered context length through the three call sites
(llm_call, llm_call_async, stream_llm) and emit options.num_ctx when it
is known and positive. The builder filters out the DEFAULT_CONTEXT
fallback (128000) so we don't lie to Ollama about models whose window
we couldn't actually discover. The issue's literal 'when > 2048'
heuristic is dropped: a model with a real context smaller than 2048
would OOM if Ollama used its default, so we pass the real value
regardless of size. Matches how src/context_compactor.py uses the
same helper.
Sister fix to PR #753 — that PR teaches the compactor the right budget,
this one tells Ollama to actually use that budget on the way in.
a8a34bd22a