Update bug fix: prevent update from a stale workflow handle

temporalio/client.py

@@ -1882,11 +1882,6 @@ async def execute_update(
         .. warning::
            This API is experimental
 
-        .. warning::
-            WorkflowHandles created as a result of :py:meth:`Client.start_workflow` will
-            send updates to the latest workflow with the same workflow ID even if it is
-            unrelated to the started workflow.
-
         Args:
             update: Update function or name on the workflow.
             arg: Single argument to the update.
@@ -1994,11 +1989,6 @@ async def start_update(
         .. warning::
            This API is experimental
 
-        .. warning::
-            WorkflowHandles created as a result of :py:meth:`Client.start_workflow` will
-            send updates to the latest workflow with the same workflow ID even if it is
-            unrelated to the started workflow.
-
         Args:
             update: Update function or name on the workflow.
             arg: Single argument to the update.
@@ -2060,6 +2050,7 @@ async def _start_update(
             StartWorkflowUpdateInput(
                 id=self._id,
                 run_id=self._run_id,
+                first_execution_run_id=self.first_execution_run_id,
                 update_id=id,
                 update=update_name,
                 args=temporalio.common._arg_or_args(arg, args),
@@ -4728,6 +4719,7 @@ class StartWorkflowUpdateInput:
 
     id: str
     run_id: Optional[str]
+    first_execution_run_id: Optional[str]
     update_id: Optional[str]
     update: str
     args: Sequence[Any]
@@ -5360,6 +5352,7 @@ async def start_workflow_update(
                 workflow_id=input.id,
                 run_id=input.run_id or "",
             ),
+            first_execution_run_id=input.first_execution_run_id or "",
             request=temporalio.api.update.v1.Request(
                 meta=temporalio.api.update.v1.Meta(
                     update_id=input.update_id or str(uuid.uuid4()),

tests/worker/test_workflow.py

@@ -4425,6 +4425,53 @@ async def test_workflow_update_task_fails(client: Client, env: WorkflowEnvironme
         assert bad_validator_fail_ct == 2
 
 
+@workflow.defn
+class UpdateRespectsFirstExecutionRunIdWorkflow:
+    def __init__(self) -> None:
+        self.update_received = False
+
+    @workflow.run
+    async def run(self) -> None:
+        await workflow.wait_condition(lambda: self.update_received)
+
+    @workflow.update
+    async def update(self) -> None:
+        self.update_received = True
+
+
+async def test_workflow_update_respects_first_execution_run_id(
+    client: Client, env: WorkflowEnvironment
+):
+    # Start one workflow, obtain the run ID (r1), and let it complete. Start a second
+    # workflow with the same workflow ID, and try to send an update using the handle from
+    # r1.
+    workflow_id = f"update-respects-first-execution-run-id-{uuid.uuid4()}"
+    async with new_worker(client, UpdateRespectsFirstExecutionRunIdWorkflow) as worker:
+
+        async def start_workflow(workflow_id: str) -> WorkflowHandle:
+            return await client.start_workflow(
+                UpdateRespectsFirstExecutionRunIdWorkflow.run,
+                id=workflow_id,
+                task_queue=worker.task_queue,
+            )
+
+        wf_execution_1_handle = await start_workflow(workflow_id)
+        await wf_execution_1_handle.execute_update(
+            UpdateRespectsFirstExecutionRunIdWorkflow.update
+        )
+        await wf_execution_1_handle.result()
+        await start_workflow(workflow_id)
+
+        # Execution 1 has closed. This would succeed if the update incorrectly targets
+        # the second execution
+        with pytest.raises(RPCError) as exc_info:
+            await wf_execution_1_handle.execute_update(
+                UpdateRespectsFirstExecutionRunIdWorkflow.update
+            )
+        assert exc_info.value.status == RPCStatusCode.NOT_FOUND
+        assert "workflow execution not found" in str(exc_info.value)
+
+
 @workflow.defn
 class ImmediatelyCompleteUpdateAndWorkflow:
     def __init__(self) -> None: