Claude VS Code Extension Reasoning Effort Slider Sends Inconsistent Values

The reasoning effort slider in the Claude VS Code extension has a bug that causes it to send inconsistent numeric values to the model. The slider label does not correspond to a stable numeric value, and the mapping is non-monotonic, meaning moving the slider "up" can actually send a lower number to the model.

Documented Inconsistencies

During a single testing session where the model was asked to report its reasoning_effort value after each slider change, the following inconsistencies were observed:

• High (session starting default): 99
• Max: 99
• High (moved back down): 19
• Medium: 85
• High (moved back up): 99
• Max (again): 50

The issue is documented in GitHub issue #41012 in the anthropics/claude-code repository. The bug report shows that the same slider position (like "High") can send different values (99 vs 19) depending on the slider's movement history, and higher slider positions don't necessarily correspond to higher numeric values.

For developers using the Claude VS Code extension, this means the reasoning effort control is currently unreliable. The model may be receiving different reasoning effort values than what the slider interface indicates, which could affect the quality and consistency of AI-generated code suggestions.