Is the meal timestamp consumed time or logged time?

The meal timestamp reflects whatever the upstream provider returns.

The meal timestamp reflects whatever the upstream provider returns. No nutrition provider reliably separates time consumed from time logged; many return only daily-level nutrition or log/entry time.

When a provider (e.g. MyFitnessPal) returns no per-meal consumed_at, Terra anchors the entry to start-of-day with a small millisecond offset to keep ordering. So a 00:00:00.00X timestamp means no time was recorded, not a real midnight meal.

The most dependable signal for meal timing is the meal_type field (e.g. 1=breakfast, 3=lunch, 5=dinner, 6=snack), which you can map to configurable time windows on your side.