Incorporate the upstream Gemma4 chat template refinements for tool-calling stability, turn closure, and multi-turn reasoning. This updates the native renderer and checked-in HF template fixtures to keep adjacent assistant/tool continuations in the same model turn, add the post-tool thought-channel cue when thinking is enabled, and match Google's default of not replaying historical thinking before a later user turn.
Also preserve null tool arguments through Gemma4 rendering/parsing and extend the Jinja2 parity coverage for these upstream behaviors.
Daniel Hiltgen
8a0016f826