The model selection for title generation works as follows (prompt.ts:1956-1960): 1. If the title agent has an explicit model configured — that model is used. 2. Otherwise, it tries Provider.getSmallModel(providerID) — which picks a "small" model from the same provider as the current session, using this priority list (provider.ts:1396-1402): - claude-haiku-4-5 / claude-haiku-4.5 / 3-5-haiku / 3.5-haiku - gemini-3-flash / gemini-2.5-flash - gpt-5-nano - (Copilot adds gpt-5-mini at the front; opencode provider uses only gpt-5-nano) 3. If no small model is found — it falls back to the same model currently being used for the session. So by default, title generation uses a cheaper/faster small model from the same provider (e.g., Haiku if on Anthropic, Flash if on Google, nano if on OpenAI), and if none are available, it just uses whatever model the user is chatting with. You can also override this entirely by configuring a model on the title agent.