Understanding Aider: Models and Modes Simplified

Based on the discussion in the Discord chat, there seems to be confusion about how Aider's models and modes interact. Let me clarify the key points:

The Basics: Models vs. Modes

First, let's distinguish between two core concepts:

• Models: The AI engines that do the work (o3-mini, claude-3-5-sonnet, etc.)
• Modes: Different ways of interacting with Aider (/code, /architect, /ask, /help)

Common Questions Answered

1. "What model is used in each mode?"

When you run: aider --architect --model o3-mini --reasoning-effort high --editor-model sonnet

| Mode | What Happens | Models Used | |------|-------------|------------| | /architect | First thinks about solution, then edits files (after asking you) | Thinking: o3-mini<br>Editing: sonnet | | /code | Directly makes code edits | Thinking: o3-mini<br>Editing: sonnet | | /ask | Answers questions without editing files | Only o3-mini |

2. "Is the architect a separate model?"

No - "architect" is just a mode, not a separate model. It uses your main model (o3-mini in this example) for planning, then your editor model (sonnet) for making changes.

3. "What happens to context between models?"

This is a key issue many users face:

• In /architect mode, when the editor model is called, it only receives the architect's last solution, not your full conversation history
• If you press "n" (reject the edits) and ask a follow-up question, the context might feel disconnected
• This is an intentional design choice to focus the editor model, but it can be frustrating

4. "What's the best workflow to maintain context?"

• For back-and-forth discussion before implementation: Use /ask mode
• For direct implementation: Use /code mode with your full context
• For complex planning followed by implementation: Use /architect mode but be prepared to provide comprehensive context in follow-ups

5. "Why use this complex setup instead of a single model?"

• Cost efficiency: Use a cheaper model for planning, more expensive model for precise edits
• Specialization: Some models are better at reasoning (o3-mini), others at code editing (sonnet)
• It's completely optional! Most users can start with a single model setup

Simple Mental Model

Think of it this way:

• Your --model is your "thinking brain"
• Your --editor-model is your "typing hands"
• Different modes (/architect, /code, /ask) are just different ways of using these components

For beginners, using just one model for everything is perfectly fine and avoids these complexities entirely!