[Bug] Session unexpectedly downgrading to Claude Opus 4.8 from requested model Fable 5

[Nightsd01]

Bug Description
I have no idea why Fable 5 keeps downgrading my session to Opus 4.8. This project is literally just a harmless weekend project that has literally nothing to do with the security guardrails that you have in place. At the VERY WORST: Downgrade to Opus 5, not 4.8!!!!

Environment Info

• Platform: linux
• Terminal: vscode
• Version: 2.1.224
• Feedback ID: 5697ecc7-65e5-4ddd-89fa-1bd7a4071cc6

Errors

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[kolchurinvv]

same here
Environment Info

• Platform: linux nixos 26.04
• Terminal: tmux (ghostty)
• Version: 2.1.220