[Bug] Effective context window reduced from 200k to 160k tokens

Bug Description
Hi Anthropic team,

We’d like to share some feedback regarding Claude Code and the effective context window.

We’ve observed that the usable context appears to have decreased to around 160,000 tokens, whereas it was previously closer to 200,000 tokens. This change has a noticeable impact on longer development sessions, as context is dropped earlier than before, requiring more frequent manual summarization or splitting of work.

Could you please clarify whether this reduction is intentional (e.g. reserved capacity for internal processing or generation), the result of a recent configuration change in Claude Code, or an unintended regression? It would also be helpful to understand the difference between the nominal context window and the practically usable one.

Thanks for your continued work on Claude Code — the large context capability is a key part of its value for complex, long-running workflows.

Best regards,
Roberto

Environment Info

• Platform: darwin
• Terminal: Apple_Terminal
• Version: 2.1.7
• Feedback ID: 41648571-176c-42da-acdd-f052ad388254

Errors

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