Add status to StartWorkflowExecutionResponse (#580)

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<!-- Describe what has changed in this PR -->
**What changed?**

Added field `WorkflowExecutionStatus status` to
`StartWorkflowExecutionResponse`.

<!-- Tell your future self why have you made these changes -->
**Why?**

To align Update-with-Start's behavior with a regular Update. A regular
Update returns its outcome from a closed Workflow, to make
Update-with-Start do the same thing, it needs to returns a successful
response in that case. But that would tell the user that a running
Workflow exists. To help the user distinguish whether UwS operated on a
closed or running workflow, this field is introduced.

<!-- Are there any breaking changes on binary or code level? -->
**Breaking changes**

No.

<!-- If this breaks the Server, please provide the Server PR to merge
right after this PR was merged. -->
**Server PR**

temporalio/temporal#7656

Author: stephanos

openapi/openapiv2.json

@@ -10083,7 +10083,8 @@
             "$ref": "#/definitions/v1ExecuteMultiOperationResponseResponse"
           }
         }
-      }
+      },
+      "description": "IMPORTANT: For [StartWorkflow, UpdateWorkflow] combination (\"Update-with-Start\") when both\n  1. the workflow update for the requested update ID has already completed, and\n  2. the workflow for the requested workflow ID has already been closed,\nthen you'll receive\n  - an update response containing the update's outcome, and\n  - a start response with a `status` field that reflects the workflow's current state."
     },
     "v1ExecuteMultiOperationResponseResponse": {
       "type": "object",
@@ -13782,6 +13783,10 @@
           "type": "boolean",
           "description": "If true, a new workflow was started."
         },
+        "status": {
+          "$ref": "#/definitions/v1WorkflowExecutionStatus",
+          "description": "Current execution status of the workflow. Typically remains WORKFLOW_EXECUTION_STATUS_RUNNING\nunless a de-dupe occurs or in specific scenarios handled within the ExecuteMultiOperation (refer to its docs)."
+        },
         "eagerWorkflowTask": {
           "$ref": "#/definitions/v1PollWorkflowTaskQueueResponse",
           "description": "When `request_eager_execution` is set on the `StartWorkflowExecutionRequest`, the server - if supported - will\nreturn the first workflow task to be eagerly executed.\nThe caller is expected to have a worker available to process the task."

openapi/openapiv3.yaml

@@ -7380,6 +7380,13 @@ components:
           type: array
           items:
             $ref: '#/components/schemas/ExecuteMultiOperationResponse_Response'
+      description: |-
+        IMPORTANT: For [StartWorkflow, UpdateWorkflow] combination ("Update-with-Start") when both
+           1. the workflow update for the requested update ID has already completed, and
+           2. the workflow for the requested workflow ID has already been closed,
+         then you'll receive
+           - an update response containing the update's outcome, and
+           - a start response with a `status` field that reflects the workflow's current state.
     ExecuteMultiOperationResponse_Response:
       type: object
       properties:
@@ -11011,6 +11018,21 @@ components:
         started:
           type: boolean
           description: If true, a new workflow was started.
+        status:
+          enum:
+            - WORKFLOW_EXECUTION_STATUS_UNSPECIFIED
+            - WORKFLOW_EXECUTION_STATUS_RUNNING
+            - WORKFLOW_EXECUTION_STATUS_COMPLETED
+            - WORKFLOW_EXECUTION_STATUS_FAILED
+            - WORKFLOW_EXECUTION_STATUS_CANCELED
+            - WORKFLOW_EXECUTION_STATUS_TERMINATED
+            - WORKFLOW_EXECUTION_STATUS_CONTINUED_AS_NEW
+            - WORKFLOW_EXECUTION_STATUS_TIMED_OUT
+          type: string
+          description: |-
+            Current execution status of the workflow. Typically remains WORKFLOW_EXECUTION_STATUS_RUNNING
+             unless a de-dupe occurs or in specific scenarios handled within the ExecuteMultiOperation (refer to its docs).
+          format: enum
         eagerWorkflowTask:
           allOf:
             - $ref: '#/components/schemas/PollWorkflowTaskQueueResponse'

temporal/api/workflowservice/v1/request_response.proto

@@ -221,6 +221,9 @@ message StartWorkflowExecutionResponse {
     string run_id = 1;
     // If true, a new workflow was started.
     bool started = 3;
+    // Current execution status of the workflow. Typically remains WORKFLOW_EXECUTION_STATUS_RUNNING
+    // unless a de-dupe occurs or in specific scenarios handled within the ExecuteMultiOperation (refer to its docs).
+    temporal.api.enums.v1.WorkflowExecutionStatus status = 5;
     // When `request_eager_execution` is set on the `StartWorkflowExecutionRequest`, the server - if supported - will
     // return the first workflow task to be eagerly executed.
     // The caller is expected to have a worker available to process the task.
@@ -1805,6 +1808,12 @@ message ExecuteMultiOperationRequest {
     }
 }
 
+// IMPORTANT: For [StartWorkflow, UpdateWorkflow] combination ("Update-with-Start") when both
+//   1. the workflow update for the requested update ID has already completed, and
+//   2. the workflow for the requested workflow ID has already been closed,
+// then you'll receive
+//   - an update response containing the update's outcome, and
+//   - a start response with a `status` field that reflects the workflow's current state.
 message ExecuteMultiOperationResponse {
     repeated Response responses = 1;