The gemma-4 native call:NAME{…} heuristic could eat legitimate text: the content
stripper removed ANY call:/response:{…} span with no tool-name restriction, so a
coding reply containing e.g. call:foo{…} in prose or a snippet got silently
deleted; and with no tools declared the parser matched any call:word{.

Add a 3-way mode, resolved per-model (models.json "gemma_tool_parser") over the
global models.gemma_tool_parser (default "restricted"):
  * full       - parse & strip every call:/response: span (old behavior)
  * restricted - only when NAME is a declared tool; legit call:foo{…} prose/code
                 is preserved, real declared-tool calls still parse & strip
  * off        - disable the gemma heuristic entirely (bigger models that emit
                 standard structured tool calls)

resolve_gemma_tool_mode() + a centralized strip_gemma_native() now gate both the
parse (GemmaParser, via the dispatcher) and the strip (ModelParserAdapter and the
streaming ToolCallParser, which now stashes the declared tool names from
extract_tool_calls so 'restricted' works on the streaming finalizer too).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RdMufYvtTbtGDWsiZVoXce