Removed-agent records kept no platform identity, so the fleet doctor
emitted an empty platform for removed rows and the Agent Doctor
uninstall handoff could never tighten to a single platform command.
Host and Docker removal now capture the agent's last-known reported
platform onto the removed record, and the fleet diagnostic resolves the
retained value through the same strict normalization as live subjects,
so /api/agents/diagnostics reports a platform for removed agents and
the handoff shipped in 4fc86ec18 scopes to one command automatically.
A retained value that does not normalize to a known platform still
yields an empty diagnostic platform rather than a guess, and removed
Kubernetes clusters retain nothing because the cluster report never
carries a platform. The field is additive and optional, so removed
lists serialized before it existed load unchanged. Monitoring contract
updated; proofs staged in agent_fleet_doctor_test.go and
monitor_host_agents_test.go.
rcourtman
671b159711