From 654e59b45e87ef9258808522afce0601c554b69b Mon Sep 17 00:00:00 2001
From: Peter Holloway <peter.holloway@diamond.ac.uk>
Date: Thu, 2 Apr 2026 17:38:20 +0100
Subject: [PATCH] fix: Check plan outcome when calling Plan objects

When using the client.plans.plan_name() approach to running plans, the
task status returned by the server was not being checked so that plans
failing did not raise exceptions on the client side.

Checking the task status also allows values returned by plans to be
accessed easily if they were serializable.
---
 src/blueapi/client/client.py | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/src/blueapi/client/client.py b/src/blueapi/client/client.py
index c5b41ff45e..417d7df01c 100644
--- a/src/blueapi/client/client.py
+++ b/src/blueapi/client/client.py
@@ -6,7 +6,7 @@
 from functools import cached_property
 from itertools import chain
 from pathlib import Path
-from typing import Self
+from typing import Any, Self
 
 from bluesky_stomp.messaging import MessageContext, StompClient
 from bluesky_stomp.models import Broker
@@ -38,7 +38,7 @@
 )
 from blueapi.utils import deprecated
 from blueapi.worker import WorkerEvent, WorkerState
-from blueapi.worker.event import ProgressEvent, TaskStatus
+from blueapi.worker.event import ProgressEvent, TaskError, TaskResult, TaskStatus
 from blueapi.worker.task_worker import TrackableTask
 
 from .event_bus import AnyEvent, EventBusClient, OnAnyEvent
@@ -141,13 +141,17 @@ def __init__(self, name, model: PlanModel, client: "BlueapiClient"):
         self._client = client
         self.__doc__ = model.description
 
-    def __call__(self, *args, **kwargs):
+    def __call__(self, *args, **kwargs) -> Any:
         req = TaskRequest(
             name=self.name,
             params=self._build_args(*args, **kwargs),
             instrument_session=self._client.instrument_session,
         )
-        self._client.run_task(req)
+        match self._client.run_task(req):
+            case TaskStatus(result=TaskResult(result=res)):
+                return res
+            case TaskStatus(result=TaskError(type=typ, message=msg)):
+                raise PlanFailedError(typ, msg)
 
     @property
     def help_text(self) -> str:
@@ -744,3 +748,9 @@ def login(self, token_path: Path | None = None):
                 auth.start_device_flow()
             else:
                 print("Server is not configured to use authentication!")
+
+
+class PlanFailedError(Exception):
+    def __init__(self, typ: str, message: str):
+        super().__init__(message)
+        self._type = typ