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 Editing: sonnet
`/code`	Directly makes code edits	Thinking: o3-mini 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!

garyblankenship/aider-models.md