[Bug] Cross-model session resumption ignores target model budget, reports misleading spend limit error

Bug Description

• Bug: Cross-model session resumption — attempting to --resume a Sonnet session with --model haiku fails with misleading "monthly spend limit" error
• Expected: Either transparently switch to Haiku's budget, or block with clear error saying "cannot resume Sonnet session as Haiku"
• Actual: Uses exhausted Sonnet budget instead, even though it reports being on Haiku 4.5
• Reproducer: COS_END_HEADLESS=1 claude --model haiku --dangerously-skip-permissions --resume '27d0dd9c-7c56-4a62-9604-a637ea72b56b' -p '/cos end' (when

original session was Sonnet with exhausted budget

Environment Info

• Platform: linux
• Terminal: wsl-Ubuntu
• Version: 2.1.161
• Feedback ID: 7f3472ca-9671-48e0-9dc7-9f18b6d6aacc

Errors

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