The custom/Ollama provider profile had no default_max_tokens, so no
max_tokens was sent on requests and Ollama fell back to its internal
num_predict=128 — truncating responses after a few tokens with
finish_reason='length' (#39281, e.g. gemma4).
max_tokens resolution is ephemeral > user model.max_tokens > profile
default, so this is only a floor used when the user hasn't set their own
cap. Set it to 65536 (matching the qwen-oauth tier) rather than a
conservative value, since users can always override per-model.
Fixes#39281
09ec26c66a