Most Aider tutorials assume you're using Sonnet for everything. For 60% of tasks, Haiku is fast enough and an order of magnitude cheaper. Here's the model-routing setup.
Aider 0.60 ships smarter architect mode and per-task model routing
Aider's latest release improves architect mode (planner + editor model split) and adds per-task model routing rules. Useful for cost-conscious heavy users.