Add Nexus service definition for worker commands

Adds a nexusrpc.yaml file defining the temporal.api.worker.v1.WorkerService
for server-to-worker communication via Nexus. Uses $goRef to reference
proto-generated types.

Author: rkannan82

temporal/api/worker/v1/worker_service.nexusrpc.yaml

@@ -0,0 +1,25 @@
+# yaml-language-server: $schema=https://raw.githubusercontent.com/nexus-rpc/nexus-rpc-gen/main/schemas/nexus-rpc-gen.json
+#
+# Nexus service definition for server-to-worker communication.
+# See worker_nexus_service_commands.proto for protocol details and conventions.
+#
+# Task queue format: /temporal-sys/worker-commands/{namespace}/{worker_grouping_key}
+
+nexusrpc: 1.0.0
+
+services:
+  temporal.api.worker.v1.WorkerService:
+    description: >
+      Internal Nexus service for server-to-worker communication.
+      Used by the Temporal server to send commands to workers.
+    operations:
+      cancel-activities:
+        description: >
+          Cancels running activities on a worker. The server sends this when
+          activities need to be cancelled (e.g., workflow cancellation or
+          explicit activity cancellation).
+        input:
+          $goRef: "go.temporal.io/api/worker/v1.CancelActivitiesRequest"
+        output:
+          $goRef: "go.temporal.io/api/worker/v1.CancelActivitiesResponse"
+