The 'a route can be unhealthy before it is unavailable' line is the whole thing, and it is not just an AI-routing problem. I hit the exact same trap on the infra side with a mirrored homelab: the standby node was technically up and passing a naive health check, so nothing failed over, but it was quietly behind and useless the moment I actualy needed it. Same late-fallback shape you describe, just in hardware. What finally fixed it for me was defining health by the outcome I cared about, is the replica caught up and serving, instead of 'did it respond'. Your workflow-outcome framing maps onto that perfectly. Nice clear writeup on the three states too, the half-open part is the one people skip and then wonder why they thrash.
The 'a route can be unhealthy before it is unavailable' line is the whole thing, and it is not just an AI-routing problem. I hit the exact same trap on the infra side with a mirrored homelab: the standby node was technically up and passing a naive health check, so nothing failed over, but it was quietly behind and useless the moment I actualy needed it. Same late-fallback shape you describe, just in hardware. What finally fixed it for me was defining health by the outcome I cared about, is the replica caught up and serving, instead of 'did it respond'. Your workflow-outcome framing maps onto that perfectly. Nice clear writeup on the three states too, the half-open part is the one people skip and then wonder why they thrash.