/model claude-opus-4-7 fails with "thinking.type.enabled" not supported error

Description

Switching to claude-opus-4-7 via the /model command fails with an API error about an unsupported thinking config format.

Error

API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"\"thinking.type.enabled\" is not supported for this model. Use \"thinking.type.adaptive\" and \"output_config.effort\" to control thinking behavior."},"request_id":"req_011Ca7eP18tycjccNePYz3Wy"}

Steps to reproduce

1. Start a session on any model (e.g. claude-sonnet-4-6)
2. Run /model claude-opus-4-7

Expected behavior

Model switches successfully.

Actual behavior

400 error — the harness appears to be sending thinking: { type: "enabled" } in the API request, but claude-opus-4-7 requires thinking: { type: "adaptive" } with output_config.effort instead.

Environment

• Claude Code version: 2.1.110
• OS: macOS Darwin 25.3.0