Description
Claude Code (latest versions) now sends a context_management field in the Anthropic /v1/messages request body. The Copilot backend doesn't recognise this field and rejects the request with a 400 error.
This affects Claude Opus 4.6 and likely Sonnet 4.6. Haiku 4.5 is unaffected (Claude Code doesn't send the field for that model).
Error
[FAIL] 400 POST /v1/messages claude-opus-4-6 → claude-opus-4.6 (3x) 809ms ↑141.3KB: HTTP 400: context_management: Extra inputs are not permitted
Environment
- copilot-api: v0.7.23 (@hsupu/copilot-api)
- Claude Code: latest
- Model: claude-opus-4.6 via Copilot
Suggested Fix
Strip the context_management field from the request body before forwarding to the Copilot Anthropic endpoint, similar to how orphaned tool blocks and other unsupported fields are already filtered.
Workaround
Setting CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS=1 on the Claude Code side may suppress the field, but this is client-side and may disable other features.
Description
Claude Code (latest versions) now sends a
context_managementfield in the Anthropic/v1/messagesrequest body. The Copilot backend doesn't recognise this field and rejects the request with a 400 error.This affects Claude Opus 4.6 and likely Sonnet 4.6. Haiku 4.5 is unaffected (Claude Code doesn't send the field for that model).
Error
Environment
Suggested Fix
Strip the
context_managementfield from the request body before forwarding to the Copilot Anthropic endpoint, similar to how orphaned tool blocks and other unsupported fields are already filtered.Workaround
Setting
CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS=1on the Claude Code side may suppress the field, but this is client-side and may disable other features.