Tighten infrastructure doc and align backup boundary wording

INFRASTRUCTURE.md

@@ -1,5 +1,17 @@
 # ZeroLagHub Infrastructure
 
+This file is the authoritative infrastructure inventory for the active environment.
+
+Use it for:
+- active host facts
+- bridge/network layout
+- VM/LXC inventory
+- backup/infrastructure ownership boundaries
+
+Do not use this file as a backlog.
+
+---
+
 ## Dedicated Server — GTHost Detroit (Active)
 
 **Hardware:** Supermicro 2029TP-HTR  
@@ -67,16 +79,18 @@
 
 ## DNS / Service Discovery Notes
 
-- `internal.zlh` is **not currently used** for active hot-path service discovery.
-- Prefer explicit env-configured IPs / addresses in runtime-critical paths.
-- DNS records may still exist historically or for reference, but should not be treated as the current source of truth for service routing.
+- `internal.zlh` is **not currently used** for active hot-path service discovery
+- Prefer explicit env-configured IPs / addresses in runtime-critical paths
+- DNS records may still exist historically or for reference, but should not be treated as the current source of truth for service routing
 
 ---
 
-## Backup Strategy
+## Backup Strategy / Ownership Boundary
 
-- **PBS (zlh-back 9017)** — primary backup for all VMs/LXCs on new host
-- **Backblaze B2 (zpack-migration bucket)** — offsite copy of critical data and old host backups
+- **PBS (`zlh-back`, 9017)** is the infrastructure backup layer for VMs/LXCs
+- offsite durability/sync belongs to the PBS/platform layer, not the agent implementation layer
+- agent-local Minecraft backups are app-aware rollback backups inside the workload/container scope
+- do not treat platform/PBS durability work as agent backup implementation work unless ownership changes
 - Old Denver host decommissioned Apr 2, 2026 — OS wiped, disks striped
 
 ---