Hey, this is a known issue. The mode state can get stuck if you switch between Ask and Agent in the same chat session. It’s not specific to GPT-5.4. It happens with other models too.
A workaround that works reliably is to open a new chat CMD + I and choose Agent mode from the start instead of switching modes in the same chat.
If you want to keep the context from your Ask session, you can also tell the model directly in your request: “You are in Agent mode. Edit the files directly.” Users say this usually unsticks it.
Similar reports for reference:
- Mode dropdown shows Agent but assistant is stuck in Plan/Ask mode
- Critical state isolation failure (Ask/Plan/Agent)
Let me know if the workaround helps.