Fix missing reasoningEffort telemetry for Claude models#309639
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The reasoningEffort telemetry property on response.success and response.error events was only reading from requestBody.reasoning?.effort (Responses API / OpenAI), missing Claude models which set effort via requestBody.output_config?.effort (Messages API). This adds a fallback to output_config.effort so both events capture the reasoning effort level regardless of which API path is used. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Pull request overview
Fixes missing reasoningEffort telemetry for Claude (Messages API) requests by reading effort from the correct request-body field, while preserving existing behavior for OpenAI (Responses API) requests.
Changes:
- Update
response.successtelemetry to readreasoningEffortfromrequestBody.reasoning?.effort ?? requestBody.output_config?.effort. - Update
response.errortelemetry to readreasoningEffortfromrequestBody.reasoning?.effort ?? requestBody.output_config?.effort.
Show a summary per file
| File | Description |
|---|---|
| extensions/copilot/src/extension/prompt/node/chatMLFetcherTelemetry.ts | Adds a fallback to capture reasoning effort from the Messages API payload shape (output_config.effort) for both success and error telemetry. |
Copilot's findings
- Files reviewed: 1/1 changed files
- Comments generated: 0
bhavyaus
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Apr 13, 2026
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Cherry-pick of #308325.
Problem
The
reasoningEfforttelemetry property onresponse.successandresponse.errorevents was only reading fromrequestBody.reasoning?.effort, which is set by the Responses API path (OpenAI models).Claude models use the Messages API path, which sets effort via
requestBody.output_config?.effortinstead. As a result, reasoning effort was silently missing from telemetry for all Claude model requests.Fix
Added a fallback:
requestBody.reasoning?.effort ?? requestBody.output_config?.efforton bothresponse.successandresponse.errortelemetry events so the effort level is captured regardless of which API path is used.Impact
response.success— now logsreasoningEffortfor Claude modelsresponse.error— now logsreasoningEffortfor Claude modelsreasoning.effortpath is checked first)