Consider setting tool_choice='required' globally when tools are present #73

Background

While fixing a ConsecutiveMistakeError regression for DeepSeek V4 thinking models (PostHog issue 019e08dc), we found that Task.ts always passes tool_choice: "auto" when tools are present — allowing the model to return a plain text response instead of calling a tool.

For DeepSeek V4 thinking models this caused 24 production ConsecutiveMistakeError events (20 from deepseek-v4-pro, 4 from deepseek-v4-flash) where the model repeatedly returned text without calling any tool, hitting the 3-strike mistake limit.

Earlier provider-specific fix idea

Originally scoped for PR #72: override "auto" → "required" inside DeepSeekHandler.createMessage when isThinkingModel is true and tools are present. PR #72 was later narrowed to DeepSeek V4 E2E coverage only, so that provider behavior change still needs its own follow-up.

Holistic fix

Roo Code's architecture requires every turn to end with a tool call — attempt_completion is always included as a tool. tool_choice: "auto" is semantically incorrect here; "required" is the right value for all providers.

Proposed change: Update Task.ts to pass tool_choice: "required" wherever it currently passes "auto" (main task loop + condensing calls), and remove the DeepSeek-specific override.

Before doing this, verify:

• Anthropic already maps "required" → "any" ✅
• OpenAI supports "required" ✅
• OpenRouter passes it through ✅
• Gemini, Bedrock, Vertex, and other providers in the codebase handle "required" correctly
• No provider silently ignores "required" in a way that causes regressions

Why deferred

Higher blast radius than a provider-specific fix. If another provider exhibits similar no_tools_used flakiness in the meantime, add a targeted override (same pattern as the originally proposed DeepSeek-specific override) and note it here before the holistic fix lands.