Match model identity across provider transports in replay cohorts

When constructing a historical Gemini replay cohort, classify traces using both transport provider and model identity. A filter limited to the native Google provider silently excludes Gemini calls routed through OpenRouter, understating reference coverage even when linked traces are intact. Preserve all linked trace records before filtering, distinguish missing linkage from an unrecognized provider, and verify the saved response belongs to the same image attempt. This repairs attribution; it does not turn model output into independent ground truth, and it should not include every OpenRouter model indiscriminately.

Applies when: model traffic moves between native APIs and routing providers while historical evaluation spans both. Keywords: Gemini OpenRouter OCR traces provider model replay attribution coverage