Add Chat class with configurable modes

[koaning]

Summary

• Refactors the procedural chat() function into a Chat class for better state management
• Adds support for configurable modes (e.g., "plan", "normal", "debug") with different tool sets
• Implements conversation replay when switching modes to maintain context
• Adds new slash commands: /mode <name> and /modes
• Maintains full backward compatibility with existing chat() function

Key Features

• Mode System: Users can configure different modes with different tool subsets
• Mode Switching: /mode <name> command switches modes and replays conversation history
• UI Enhancements: Mode indicators in prompts, mode-aware help text
• Backward Compatible: Existing usage patterns continue to work unchanged

API Examples

# Existing usage (still works)
chat(tools=[tool1, tool2])

# New Chat class (equivalent)
Chat(tools=[tool1, tool2]).run()

# New with modes
Chat(
    tools={
        "normal": [read_tool, write_tool, edit_tool],
        "plan": [read_tool, glob_tool, grep_tool]  # Read-only
    },
    mode_switch_messages={
        "plan": "You are now in plan mode. You can read and analyze but not write files."
    },
    initial_mode="normal"
).run()

Test Plan

• Chat class initialization with various configurations
• Mode switching logic with tool filtering
• Backward compatibility with existing chat() function
• New slash commands (/mode, /modes)
• UI mode indicators and feedback

🤖 Generated with Claude Code