When running in agent mode (e.g., --agent carmack) in a workspace with
detected languages, inject agent+language-specific prompts from
prompts/langs/<agent>.<lang>.md at the end of the system prompt.
Changes:
- Add AGENT_LANGUAGE_PROMPTS static array for compile-time embedding
- Add get_agent_language_prompt() to look up specific agent+lang combos
- Add get_agent_language_prompts_for_workspace_with_langs() that returns
both content and matched languages for display
- Update agent_mode.rs to inject prompts and show which languages loaded
- Display format: '✓ carmack: racket language guidance'
- Add tests for new functionality
Uses the same detect_languages() mechanism as regular language prompts
to avoid code-path aliasing.
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