Improve gateway reliability and dashboard docs

docs/gateway-process-design.md

@@ -361,13 +361,13 @@ worker startup, and removes the session if startup fails. A successful
 `OpenSession` attaches the ready `IWorkerClient` and transitions the session to
 `Ready`.
 
-Only `Ready` sessions accept command and event operations. `CloseSession` is
-idempotent for sessions still known to the registry: the first close shuts down
-the worker, and later closes return the final `Closed` state. Lease handling is
-exposed as a session hook so a monitor can close expired sessions without
-embedding lease policy in the worker client. Gateway shutdown walks the
-registry, closes each known session, and kills a worker if graceful shutdown
-fails.
+Only `Ready` sessions accept command and event operations. `CloseSession` shuts
+down the worker, disposes the worker client, and removes the session from the
+registry so closed sessions do not retain pipe or process handles. A later close
+for the same id returns `SessionNotFound`. Lease handling is exposed as a
+session hook so a monitor can close expired sessions without embedding lease
+policy in the worker client. Gateway shutdown walks the registry, closes each
+known session, and kills a worker if graceful shutdown fails.
 
 ## Worker Launch
 
@@ -813,6 +813,11 @@ It emits .NET `Meter` instruments for collectors and keeps a
 the dashboard needs current counters and queue depths without depending on a
 specific metrics exporter.
 
+Event metrics use low-cardinality tags such as event family. Per-session event
+counts are kept only in the in-process snapshot for active dashboard sessions
+and are purged when the session is removed. Worker event queue depth and gRPC
+event stream queue depth are reported as separate gauges.
+
 HTTP request handling uses `UseGatewayRequestLoggingScope()` to attach common
 structured log fields when request metadata is present:
 
@@ -842,6 +847,8 @@ Suggested configuration shape:
     },
     "Worker": {
       "ExecutablePath": "src/MxGateway.Worker/bin/x86/Release/MxGateway.Worker.exe",
+      "WorkingDirectory": null,
+      "RequiredArchitecture": "X86",
       "StartupTimeoutSeconds": 30,
       "StartupProbeRetryAttempts": 3,
       "StartupProbeRetryDelayMilliseconds": 250,
@@ -854,6 +861,7 @@ Suggested configuration shape:
     "Sessions": {
       "DefaultCommandTimeoutSeconds": 30,
       "MaxSessions": 64,
+      "MaxPendingCommandsPerSession": 128,
       "AllowMultipleEventSubscribers": false
     },
     "Events": {
@@ -869,6 +877,9 @@ Suggested configuration shape:
       "RecentFaultLimit": 100,
       "RecentSessionLimit": 200,
       "ShowTagValues": false
+    },
+    "Protocol": {
+      "WorkerProtocolVersion": 1
     }
   }
 }
@@ -888,6 +899,9 @@ diagnostics, so it redacts secret-related fields such as
 `Authentication:PepperSecretName` and does not include raw API keys or key
 material.
 
+The complete option reference, including defaults and validation rules, is in
+[Gateway Configuration](./GatewayConfiguration.md).
+
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