perf(worker): launcher-configurable event queue capacity

docs/GatewayConfiguration.md

@@ -115,6 +115,7 @@ launch CWD (SEC-01, SEC-33).
 | `MxGateway:Worker:StartupProbeRetryDelayMilliseconds` | `250` | Delay between transient startup probe retry attempts. |
 | `MxGateway:Worker:PipeConnectAttemptTimeoutMilliseconds` | `2000` | Per-attempt timeout used by the worker named-pipe connect retry path. The overall pipe connection still stays under the startup budget. |
 | `MxGateway:Worker:WriteCompletionWaitMilliseconds` | `1500` | Bounded wait the worker holds a unary write reply (`Write`/`Write2`/`WriteSecured`/`WriteSecured2`; bulk writes excluded) for the matching MXAccess `OnWriteComplete` callback, so the reply's `statuses` carry the real commit outcome. `0` disables the wait (pure fire-and-forget replies). Must be `>= 0`. The gateway conveys the value to the worker via the `MXGATEWAY_WORKER_WRITE_COMPLETION_WAIT_MS` environment variable. Consumers that time their own writes must budget above this wait: OtOpcUa's GalaxyDriver wraps gateway writes in a 2 s Tier A resilience timeout, so a deployment raising this option past ~2000 must raise that driver `ResilienceConfig` write timeout in step or slow-but-successful commits surface as consumer-side failures. |
+| `MxGateway:Worker:EventQueueCapacity` | `10000` | Capacity, in events, of the worker's outbound MXAccess event queue. Must be between `1000` and `1000000`. This is burst headroom, not a throttle: the queue has no drop policy, so filling it records a `QueueOverflow` worker fault and faults the session. Raise it for sessions whose subscription set can outrun the drain loop (large advise sets, slow event consumers); the backing queue pre-allocates its slots, so the ceiling keeps a mistyped value from committing the 32-bit worker to an outsized allocation. The gateway conveys the value to the worker via the `MXGATEWAY_EVENT_QUEUE_CAPACITY` environment variable; a missing or unusable value leaves the worker on the 10000 default rather than failing the session. |
 | `MxGateway:Worker:ShutdownTimeoutSeconds` | `10` | Grace period for worker shutdown before the gateway treats shutdown as failed and may kill the worker process tree. |
 | `MxGateway:Worker:HeartbeatIntervalSeconds` | `5` | Worker heartbeat send interval and gateway heartbeat check cadence input. |
 | `MxGateway:Worker:HeartbeatGraceSeconds` | `15` | Maximum age of the last worker heartbeat before the gateway faults the worker. This must be greater than or equal to `HeartbeatIntervalSeconds`. |

docs/MxAccessWorkerInstanceDesign.md

@@ -416,7 +416,11 @@ type on buffered events. `OperationComplete` is only emitted from the native
 `MxAccessEventQueue` is the bounded outbound event queue for one worker
 session. It assigns the monotonic `WorkerSequence` and `WorkerTimestamp` when an
 event is accepted, preserving the order in which MXAccess handlers enqueue
-events. The default capacity is `10000`. When the queue reaches capacity it
+events. The capacity is `10000` by default and comes from
+`MxGateway:Worker:EventQueueCapacity`, which the gateway stamps onto the worker
+launch environment as `MXGATEWAY_EVENT_QUEUE_CAPACITY`; a missing, unparseable,
+or out-of-range value (outside `1000`–`1000000`) leaves the worker on the
+default rather than failing the session. When the queue reaches capacity it
 records a `WorkerFaultCategory.QueueOverflow` fault and rejects further events.
 The event handler catches conversion and enqueue failures, records the first
 fault on the queue, and returns to the STA message pump instead of writing to