Fix Google Adapter

[nirvanatikku]

Gemini Adapter Rebuild — google-genai SDK v1.0+ Migration

Summary

Migrates the Gemini LLM adapter from the deprecated google-generativeai SDK to the modern google-genai (v1.0+) SDK, achieving full protocol parity with the OpenAI and Anthropic adapters. Fixes the broken LLMEngine Gemini integration that was dropping system prompts, tools, and conversation history.

Changes

Adapter (gemini_adapter.py)

• Rebuilt GeminiAdapter for the genai.Client pattern (client.models.generate_content / client.models.generate_content_stream) replacing legacy genai.configure() + GenerativeModel()
• Token counts (prompt, completion, total) from usage_metadata
• Finish reason mapping from candidates
• Function call tracking with provider-native IDs
• Streaming usage metadata recovery from final chunks
• Multi-turn GeminiChatSession with proper history management, including during streaming via _chat_stream_wrapper

LLM Engine (llm.py)

• Added _messages_to_gemini_contents() — converts OpenIntent messages to Gemini format (system → system_instruction, assistant → model role)
• Added _tools_to_gemini_format() — converts tool schemas to Gemini function declarations; returns [] for empty input
• Added raw provider fallback for Gemini in _call_raw_provider and _stream_raw_provider
• Updated _format_tools_for_provider for Gemini

Dependencies (pyproject.toml)

• google-generativeai>=0.4.0 → google-genai>=1.0.0 in gemini and all-adapters extras
• mypy overrides updated to google.genai

Docs & Frontend

• Default model names updated from gemini-1.5-pro / gemini-2.0-flash to gemini-3-flash
• Code examples updated to new SDK patterns across adapters.tsx, adapters.md, llm-adapters.md, llm-quickstart.md

Tests

• Added TestGeminiConversions (system extraction, no-system, multi-system, empty messages, tool format, empty tools)
• Added TestGeminiToolFormatConversion (protocol tool conversion, _format_tools_for_provider Gemini path)
• Updated model resolution tests for new model names
• All 105 tests pass

Version

• Bumped to 0.15.1 across pyproject.toml, __init__.py, MCP server package.json/index.ts, mkdocs.yml, home.html, changelogs, and frontend

CI

• ruff check . — pass
• ruff format --check . — pass
• mypy openintent --ignore-missing-imports — pass
• pytest -v — 105 passed