Add Live Status Model section - finalized agent health vs service runtime, DEV vs GAME semantics, UI mapping table

PORTAL_MIGRATION.md

@@ -87,3 +87,42 @@ These are intentional removals.
 - Servers page UX: 🔄 Active
 - System View page: ⏳ Next
 - Billing integration: ⏸ Deferred
+
+---
+
+## Live Status Model (Finalized)
+
+The portal consumes **aggregated live state** from the API.
+It does not directly query agents, Proxmox, or exporters.
+
+### Status Layers
+
+#### Host / Agent Health
+- Source: `GET /health` on agent
+- Cached in Redis
+- Determines host availability
+
+#### Service Runtime
+- GAME:
+  - Source: `GET /status`
+  - Reflects actual game server lifecycle
+- DEV:
+  - No service runtime
+  - Status inferred from host availability
+
+### UI Mapping
+
+| Container Type | Host Online | Agent State | UI Status |
+|---------------|------------|-------------|-----------|
+| DEV           | true       | n/a         | running   |
+| DEV           | false      | n/a         | offline   |
+| GAME          | true       | running     | running   |
+| GAME          | true       | idle        | stopped   |
+| GAME          | false      | n/a         | offline   |
+
+### Notes
+- "Idle" does **not** mean broken
+- Offline means host unreachable
+- UI refresh reflects Redis state, not instant agent changes
+
+This model intentionally mirrors Pterodactyl semantics.