[Bug] Model unexpectedly switched from Fable 5 to Opus 4.8 mid-session without user action

Bug Description
Mid way through a Fable 5 session, while doing a one hour long statistical model on heat related deaths in Europe vs the US, the ui switched to Opus 4.8 without any apparent reason. According to Claude its system prompt is still flagging it as Fable 5, but if I try and switch model with /model either to "Default (Opus 4.8)" or "Fable 5" I get a warning that this would have to re-send the whole conversation because it breaks cache. Currently the model selector is saying Opus 4.8

Environment Info

• Platform: darwin
• Terminal: tmux
• Version: 2.1.170
• Feedback ID: ad4cc230-e00e-4615-9080-339d3c47bae9

Errors

[]