Group of 2 Under the hood
Prompt-cache telemetry now notes whether it has been over 5 minutes or over 1 hour since the last assistant message
What
Both the cache-read-token diagnostic event and the prompt-cache break/invalidation diagnosis call now include lastAssistantMsgOver5minAgo and lastAssistantMsgOver1hAgo boolean fields, computed from how long ago the last assistant message was sent. The cache-read event also gains an is1hCacheTTL field, and both gain a querySource field.
Why Knowing how long it has been since the last assistant message helps explain why a prompt cache was or was not reused (caches can expire after a period of inactivity), making cache-behavior diagnostics easier to interpret.