From abff4c2601968512291ca9a1157530a10fc0307a Mon Sep 17 00:00:00 2001
From: Ethan Harris <ethanwharris@gmail.com>
Date: Fri, 9 Dec 2022 12:28:24 +0000
Subject: [PATCH 01/17] Initial commit

---
 src/lightning_app/core/api.py | 41 ++++++++++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/src/lightning_app/core/api.py b/src/lightning_app/core/api.py
index e6f7b6ad0024c..d6d6c48804473 100644
--- a/src/lightning_app/core/api.py
+++ b/src/lightning_app/core/api.py
@@ -71,7 +71,6 @@ class SessionMiddleware:
 
 logger = Logger(__name__)
 
-
 # This can be replaced with a consumer that publishes states in a kv-store
 # in a serverless architecture
 
@@ -123,6 +122,27 @@ class StateUpdate(BaseModel):
     state: dict = {}
 
 
+class WorkStatus(BaseModel):
+    """The ``WorkStatus`` captures the status of a work according to the app."""
+
+    # The name of the work
+    name: str
+
+    # ``True`` when the work is running according to the app.
+    # Compute states in the cloud are owned by the platform.
+    is_running: bool
+
+
+class AppStatus(BaseModel):
+    """The ``AppStatus`` captures the current status of the app and its components."""
+
+    # ``True`` when the app UI is ready to be viewed
+    is_ui_ready: bool
+
+    # The statuses of ``LightningWork`` objects currently associated with this app
+    work_statuses: List[WorkStatus]
+
+
 openapi_tags = [
     {
         "name": OpenAPITags.APP_CLIENT_COMMAND,
@@ -326,6 +346,25 @@ async def upload_file(response: Response, filename: str, uploaded_file: UploadFi
     return f"Successfully uploaded '{filename}' to the Drive"
 
 
+@fastapi_service.get("/api/v1/status", response_class=JSONResponse)
+async def get_status(
+    response: Response,
+    x_lightning_session_uuid: Optional[str] = Header(None),
+    x_lightning_session_id: Optional[str] = Header(None),
+) -> Union[List, Dict]:
+    if x_lightning_session_uuid is None:
+        raise Exception("Missing X-Lightning-Session-UUID header")
+    if x_lightning_session_id is None:
+        raise Exception("Missing X-Lightning-Session-ID header")
+
+    if not ENABLE_PULLING_STATE_ENDPOINT:
+        response.status_code = status.HTTP_405_METHOD_NOT_ALLOWED
+        return {"status": "failure", "reason": "This endpoint is disabled."}
+
+    global app_spec
+    return app_spec or []
+
+
 @fastapi_service.get("/healthz", status_code=200)
 async def healthz(response: Response):
     """Health check endpoint used in the cloud FastAPI servers to check the status periodically."""

From 0aeddd61842af3ef545515c349c218923f4101a5 Mon Sep 17 00:00:00 2001
From: Ethan Harris <ethanwharris@gmail.com>
Date: Fri, 9 Dec 2022 19:21:36 +0000
Subject: [PATCH 02/17] Updates

---
 src/lightning_app/core/api.py                 | 59 ++++++++-----------
 src/lightning_app/core/app.py                 |  7 +++
 src/lightning_app/core/queues.py              |  5 ++
 src/lightning_app/runners/backends/backend.py |  1 +
 src/lightning_app/utilities/app_status.py     | 24 ++++++++
 5 files changed, 61 insertions(+), 35 deletions(-)
 create mode 100644 src/lightning_app/utilities/app_status.py

diff --git a/src/lightning_app/core/api.py b/src/lightning_app/core/api.py
index d6d6c48804473..075264258e782 100644
--- a/src/lightning_app/core/api.py
+++ b/src/lightning_app/core/api.py
@@ -34,6 +34,7 @@
 from lightning_app.core.queues import QueuingSystem
 from lightning_app.storage import Drive
 from lightning_app.utilities.app_helpers import InMemoryStateStore, Logger, StateStore
+from lightning_app.utilities.app_status import AppStatus
 from lightning_app.utilities.cloud import is_running_in_cloud
 from lightning_app.utilities.component import _context
 from lightning_app.utilities.enum import ComponentContext, OpenAPITags
@@ -66,6 +67,8 @@ class SessionMiddleware:
 lock = Lock()
 
 app_spec: Optional[List] = None
+app_status: Optional[AppStatus] = None
+
 # In the future, this would be abstracted to support horizontal scaling.
 responses_store = {}
 
@@ -76,10 +79,17 @@ class SessionMiddleware:
 
 
 class UIRefresher(Thread):
-    def __init__(self, api_publish_state_queue, api_response_queue, refresh_interval: float = 0.1) -> None:
+    def __init__(
+        self,
+        api_publish_state_queue,
+        api_response_queue,
+        app_status_queue,
+        refresh_interval: float = 0.1,
+    ) -> None:
         super().__init__(daemon=True)
         self.api_publish_state_queue = api_publish_state_queue
         self.api_response_queue = api_response_queue
+        self.app_status_queue = app_status_queue
         self._exit_event = Event()
         self.refresh_interval = refresh_interval
 
@@ -113,6 +123,12 @@ def run_once(self):
         except queue.Empty:
             pass
 
+        try:
+            global app_status
+            app_status = self.app_status_queue.get(timeout=0)
+        except queue.Empty:
+            pass
+
     def join(self, timeout: Optional[float] = None) -> None:
         self._exit_event.set()
         super().join(timeout)
@@ -122,27 +138,6 @@ class StateUpdate(BaseModel):
     state: dict = {}
 
 
-class WorkStatus(BaseModel):
-    """The ``WorkStatus`` captures the status of a work according to the app."""
-
-    # The name of the work
-    name: str
-
-    # ``True`` when the work is running according to the app.
-    # Compute states in the cloud are owned by the platform.
-    is_running: bool
-
-
-class AppStatus(BaseModel):
-    """The ``AppStatus`` captures the current status of the app and its components."""
-
-    # ``True`` when the app UI is ready to be viewed
-    is_ui_ready: bool
-
-    # The statuses of ``LightningWork`` objects currently associated with this app
-    work_statuses: List[WorkStatus]
-
-
 openapi_tags = [
     {
         "name": OpenAPITags.APP_CLIENT_COMMAND,
@@ -346,23 +341,16 @@ async def upload_file(response: Response, filename: str, uploaded_file: UploadFi
     return f"Successfully uploaded '{filename}' to the Drive"
 
 
-@fastapi_service.get("/api/v1/status", response_class=JSONResponse)
+@fastapi_service.get("/api/v1/status", response_class=AppStatus)
 async def get_status(
     response: Response,
-    x_lightning_session_uuid: Optional[str] = Header(None),
-    x_lightning_session_id: Optional[str] = Header(None),
 ) -> Union[List, Dict]:
-    if x_lightning_session_uuid is None:
-        raise Exception("Missing X-Lightning-Session-UUID header")
-    if x_lightning_session_id is None:
-        raise Exception("Missing X-Lightning-Session-ID header")
+    if app_status is None:
+        response.status_code = status.HTTP_404_NOT_FOUND
+        return {"status": "failure", "reason": "App status hasn't been reported yet."}
 
-    if not ENABLE_PULLING_STATE_ENDPOINT:
-        response.status_code = status.HTTP_405_METHOD_NOT_ALLOWED
-        return {"status": "failure", "reason": "This endpoint is disabled."}
-
-    global app_spec
-    return app_spec or []
+    global app_status
+    return app_status
 
 
 @fastapi_service.get("/healthz", status_code=200)
@@ -448,6 +436,7 @@ def start_server(
     api_publish_state_queue,
     api_delta_queue,
     api_response_queue,
+    app_status_queue,
     has_started_queue: Optional[Queue] = None,
     host="127.0.0.1",
     port=8000,
diff --git a/src/lightning_app/core/app.py b/src/lightning_app/core/app.py
index d9389ecd27e24..b051f8703b113 100644
--- a/src/lightning_app/core/app.py
+++ b/src/lightning_app/core/app.py
@@ -35,6 +35,7 @@
     _should_dispatch_app,
     Logger,
 )
+from lightning_app.utilities.app_status import AppStatus
 from lightning_app.utilities.commands.base import _process_requests
 from lightning_app.utilities.component import _convert_paths_after_init, _validate_root_flow
 from lightning_app.utilities.enum import AppStage, CacheCallsKeys
@@ -117,6 +118,7 @@ def __init__(
         self.api_response_queue: Optional[BaseQueue] = None
         self.api_publish_state_queue: Optional[BaseQueue] = None
         self.api_delta_queue: Optional[BaseQueue] = None
+        self.app_status_queue: Optional[BaseQueue] = None
         self.error_queue: Optional[BaseQueue] = None
         self.request_queues: Optional[Dict[str, BaseQueue]] = None
         self.response_queues: Optional[Dict[str, BaseQueue]] = None
@@ -140,6 +142,7 @@ def __init__(
         self.exception = None
         self.collect_changes: bool = True
 
+        self.status: Optional[AppStatus] = None
         # TODO: Enable ready locally for opening the UI.
         self.ready = False
 
@@ -535,6 +538,10 @@ def _update_is_headless(self) -> None:
 
             _handle_is_headless(self)
 
+    def _update_status(self) -> None:
+        # old_status = self.status
+        pass
+
     def _apply_restarting(self) -> bool:
         self._reset_original_state()
         # apply stage after restoring the original state.
diff --git a/src/lightning_app/core/queues.py b/src/lightning_app/core/queues.py
index db150a57eb098..5d04b5bc9027f 100644
--- a/src/lightning_app/core/queues.py
+++ b/src/lightning_app/core/queues.py
@@ -38,6 +38,7 @@
 CALLER_QUEUE_CONSTANT = "CALLER_QUEUE"
 API_STATE_PUBLISH_QUEUE_CONSTANT = "API_STATE_PUBLISH_QUEUE"
 API_DELTA_QUEUE_CONSTANT = "API_DELTA_QUEUE"
+APP_STATUS_QUEUE_CONSTANT = "APP_STATUS_QUEUE"
 API_REFRESH_QUEUE_CONSTANT = "API_REFRESH_QUEUE"
 ORCHESTRATOR_REQUEST_CONSTANT = "ORCHESTRATOR_REQUEST"
 ORCHESTRATOR_RESPONSE_CONSTANT = "ORCHESTRATOR_RESPONSE"
@@ -96,6 +97,10 @@ def get_api_delta_queue(self, queue_id: Optional[str] = None) -> "BaseQueue":
         queue_name = f"{queue_id}_{DELTA_QUEUE_CONSTANT}" if queue_id else DELTA_QUEUE_CONSTANT
         return self.get_queue(queue_name)
 
+    def get_app_status_queue(self, queue_id: Optional[str] = None) -> "BaseQueue":
+        queue_name = f"{queue_id}_{APP_STATUS_QUEUE_CONSTANT}" if queue_id else APP_STATUS_QUEUE_CONSTANT
+        return self.get_queue(queue_name)
+
     def get_orchestrator_request_queue(self, work_name: str, queue_id: Optional[str] = None) -> "BaseQueue":
         queue_name = (
             f"{queue_id}_{ORCHESTRATOR_REQUEST_CONSTANT}_{work_name}"
diff --git a/src/lightning_app/runners/backends/backend.py b/src/lightning_app/runners/backends/backend.py
index 54c1f9092bf0f..b4114286f8109 100644
--- a/src/lightning_app/runners/backends/backend.py
+++ b/src/lightning_app/runners/backends/backend.py
@@ -88,6 +88,7 @@ def _prepare_queues(self, app: "lightning_app.LightningApp"):
         app.error_queue = self.queues.get_error_queue(**kw)
         app.api_publish_state_queue = self.queues.get_api_state_publish_queue(**kw)
         app.api_delta_queue = app.delta_queue
+        app.app_status_queue = self.queues.get_app_status_queue(**kw)
         app.request_queues = {}
         app.response_queues = {}
         app.copy_request_queues = {}
diff --git a/src/lightning_app/utilities/app_status.py b/src/lightning_app/utilities/app_status.py
new file mode 100644
index 0000000000000..fc3fd9457ffa5
--- /dev/null
+++ b/src/lightning_app/utilities/app_status.py
@@ -0,0 +1,24 @@
+from typing import List
+
+from pydantic import BaseModel
+
+
+class WorkStatus(BaseModel):
+    """The ``WorkStatus`` captures the status of a work according to the app."""
+
+    # The name of the work
+    name: str
+
+    # ``True`` when the work is running according to the app.
+    # Compute states in the cloud are owned by the platform.
+    is_running: bool
+
+
+class AppStatus(BaseModel):
+    """The ``AppStatus`` captures the current status of the app and its components."""
+
+    # ``True`` when the app UI is ready to be viewed
+    is_ui_ready: bool
+
+    # The statuses of ``LightningWork`` objects currently associated with this app
+    work_statuses: List[WorkStatus]

From 2b683102736c1b5b3539f2f16d342a52caa4e247 Mon Sep 17 00:00:00 2001
From: Ethan Harris <ethanwharris@gmail.com>
Date: Wed, 14 Dec 2022 20:44:19 +0000
Subject: [PATCH 03/17] Updates

---
 src/lightning_app/core/api.py             | 17 ++++++---------
 src/lightning_app/core/app.py             | 26 ++++++++++++++---------
 src/lightning_app/core/work.py            |  6 +++---
 src/lightning_app/runners/multiprocess.py |  1 +
 src/lightning_app/utilities/app_status.py | 14 ++++++------
 src/lightning_app/utilities/enum.py       | 15 +------------
 6 files changed, 36 insertions(+), 43 deletions(-)

diff --git a/src/lightning_app/core/api.py b/src/lightning_app/core/api.py
index 075264258e782..5aaeee4511446 100644
--- a/src/lightning_app/core/api.py
+++ b/src/lightning_app/core/api.py
@@ -341,15 +341,12 @@ async def upload_file(response: Response, filename: str, uploaded_file: UploadFi
     return f"Successfully uploaded '{filename}' to the Drive"
 
 
-@fastapi_service.get("/api/v1/status", response_class=AppStatus)
-async def get_status(
-    response: Response,
-) -> Union[List, Dict]:
-    if app_status is None:
-        response.status_code = status.HTTP_404_NOT_FOUND
-        return {"status": "failure", "reason": "App status hasn't been reported yet."}
-
+@fastapi_service.get("/api/v1/status", response_model=AppStatus)
+async def get_status() -> AppStatus:
+    """Get the current status of the app and works."""
     global app_status
+    if app_status is None:
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="App status hasn't been reported yet.")
     return app_status
 
 
@@ -436,7 +433,7 @@ def start_server(
     api_publish_state_queue,
     api_delta_queue,
     api_response_queue,
-    app_status_queue,
+    app_status_queue: Optional[Queue] = None,
     has_started_queue: Optional[Queue] = None,
     host="127.0.0.1",
     port=8000,
@@ -458,7 +455,7 @@ def start_server(
 
     global_app_state_store.add(TEST_SESSION_UUID)
 
-    refresher = UIRefresher(api_publish_state_queue, api_response_queue)
+    refresher = UIRefresher(api_publish_state_queue, api_response_queue, app_status_queue)
     refresher.setDaemon(True)
     refresher.start()
 
diff --git a/src/lightning_app/core/app.py b/src/lightning_app/core/app.py
index b051f8703b113..b348f439eb446 100644
--- a/src/lightning_app/core/app.py
+++ b/src/lightning_app/core/app.py
@@ -421,6 +421,7 @@ def run_once(self):
 
         self._update_layout()
         self._update_is_headless()
+        self._update_status()
         self.maybe_apply_changes()
 
         if self.checkpointing and self._should_snapshot():
@@ -488,14 +489,7 @@ def _run(self) -> bool:
         self._original_state = deepcopy(self.state)
         done = False
 
-        # TODO: Re-enable the `ready` property once issues are resolved
-        if not self.root.ready:
-            warnings.warn(
-                "One of your Flows returned `.ready` as `False`. "
-                "This feature is not yet enabled so this will be ignored.",
-                UserWarning,
-            )
-        self.ready = True
+        self.ready = self.root.ready
 
         self._start_with_flow_works()
 
@@ -539,8 +533,20 @@ def _update_is_headless(self) -> None:
             _handle_is_headless(self)
 
     def _update_status(self) -> None:
-        # old_status = self.status
-        pass
+        old_status = self.status
+
+        work_statuses = []
+        for work in breadth_first(self.root, types=(lightning_app.LightningWork,)):
+            work_statuses.append(work.status)
+
+        new_status = AppStatus(
+            is_ui_ready=self.ready,
+            work_statuses=work_statuses,
+        )
+
+        if new_status != old_status:
+            self.status = new_status
+            self.app_status_queue.put(self.status)
 
     def _apply_restarting(self) -> bool:
         self._reset_original_state()
diff --git a/src/lightning_app/core/work.py b/src/lightning_app/core/work.py
index 60d1ea62d8afb..6ac15a4a20610 100644
--- a/src/lightning_app/core/work.py
+++ b/src/lightning_app/core/work.py
@@ -12,13 +12,13 @@
 from lightning_app.storage.drive import _maybe_create_drive, Drive
 from lightning_app.storage.payload import Payload
 from lightning_app.utilities.app_helpers import _is_json_serializable, _LightningAppRef, is_overridden
+from lightning_app.utilities.app_status import WorkStatus
 from lightning_app.utilities.component import _is_flow_context, _sanitize_state
 from lightning_app.utilities.enum import (
     CacheCallsKeys,
     make_status,
     WorkFailureReasons,
     WorkStageStatus,
-    WorkStatus,
     WorkStopReasons,
 )
 from lightning_app.utilities.exceptions import LightningWorkException
@@ -267,8 +267,8 @@ def status(self) -> WorkStatus:
             latest_status = statuses[-1]
             if latest_status.get("reason") == WorkFailureReasons.TIMEOUT:
                 return self._aggregate_status_timeout(statuses)
-            return WorkStatus(**latest_status)
-        return WorkStatus(stage=WorkStageStatus.NOT_STARTED, timestamp=time.time())
+            return WorkStatus(name=self.name, **latest_status)
+        return WorkStatus(name=self.name, stage=WorkStageStatus.NOT_STARTED, timestamp=time.time())
 
     @property
     def statuses(self) -> List[WorkStatus]:
diff --git a/src/lightning_app/runners/multiprocess.py b/src/lightning_app/runners/multiprocess.py
index 673e8601043d7..7839ed9a96ecd 100644
--- a/src/lightning_app/runners/multiprocess.py
+++ b/src/lightning_app/runners/multiprocess.py
@@ -91,6 +91,7 @@ def dispatch(self, *args: Any, open_ui: bool = True, **kwargs: Any):
                     api_response_queue=self.app.api_response_queue,
                     api_publish_state_queue=self.app.api_publish_state_queue,
                     api_delta_queue=self.app.api_delta_queue,
+                    app_status_queue=self.app.app_status_queue,
                     has_started_queue=has_started_queue,
                     spec=extract_metadata_from_app(self.app),
                     root_path=self.app.root_path,
diff --git a/src/lightning_app/utilities/app_status.py b/src/lightning_app/utilities/app_status.py
index fc3fd9457ffa5..95248433d782f 100644
--- a/src/lightning_app/utilities/app_status.py
+++ b/src/lightning_app/utilities/app_status.py
@@ -1,17 +1,19 @@
-from typing import List
+from typing import List, Optional
 
 from pydantic import BaseModel
 
+from lightning_app.utilities.enum import WorkStageStatus
+
 
 class WorkStatus(BaseModel):
     """The ``WorkStatus`` captures the status of a work according to the app."""
 
-    # The name of the work
     name: str
-
-    # ``True`` when the work is running according to the app.
-    # Compute states in the cloud are owned by the platform.
-    is_running: bool
+    stage: WorkStageStatus
+    timestamp: float
+    reason: Optional[str] = None
+    message: Optional[str] = None
+    count: int = 1
 
 
 class AppStatus(BaseModel):
diff --git a/src/lightning_app/utilities/enum.py b/src/lightning_app/utilities/enum.py
index 11cd7fabc4299..e0d211d29ff27 100644
--- a/src/lightning_app/utilities/enum.py
+++ b/src/lightning_app/utilities/enum.py
@@ -1,5 +1,4 @@
 import enum
-from dataclasses import dataclass
 from datetime import datetime, timezone
 from typing import Optional
 
@@ -37,7 +36,7 @@ class WorkPendingReason(enum.Enum):
     REQUESTING_RESOURCE = "requesting_ressource"
 
 
-class WorkStageStatus:
+class WorkStageStatus(str, enum.Enum):
     NOT_STARTED = "not_started"
     STARTED = "started"
     STOPPED = "stopped"
@@ -47,18 +46,6 @@ class WorkStageStatus:
     FAILED = "failed"
 
 
-@dataclass
-class WorkStatus:
-    stage: WorkStageStatus
-    timestamp: float
-    reason: Optional[str] = None
-    message: Optional[str] = None
-    count: int = 1
-
-    def __post_init__(self):
-        assert self.timestamp > 0 and self.timestamp < (int(datetime.now().timestamp()) + 10)
-
-
 def make_status(stage: str, message: Optional[str] = None, reason: Optional[str] = None):
     status = {
         "stage": stage,

From 1f29503a7832324b7c47350ffe834de7153c5edc Mon Sep 17 00:00:00 2001
From: Ethan Harris <ethanwharris@gmail.com>
Date: Thu, 15 Dec 2022 15:55:40 +0000
Subject: [PATCH 04/17] Updates

---
 .../components/serve/streamlit.py             |  5 ++++
 src/lightning_app/core/app.py                 |  4 +--
 tests/tests_app/core/test_lightning_api.py    |  9 ++++++-
 tests/tests_app/core/test_lightning_flow.py   | 25 ++++++++++++-------
 4 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/src/lightning_app/components/serve/streamlit.py b/src/lightning_app/components/serve/streamlit.py
index 9b943a1708fa3..41a88dafbfe08 100644
--- a/src/lightning_app/components/serve/streamlit.py
+++ b/src/lightning_app/components/serve/streamlit.py
@@ -4,6 +4,7 @@
 import pydoc
 import subprocess
 import sys
+import time
 from typing import Any, Callable, Type
 
 from lightning_app.core.work import LightningWork
@@ -20,6 +21,8 @@ class ServeStreamlit(LightningWork, abc.ABC):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
 
+        self.ready = False
+
         self._process = None
 
     @property
@@ -38,6 +41,7 @@ def build_model(self) -> Any:
         return None
 
     def run(self) -> None:
+        time.sleep(100)
         env = os.environ.copy()
         env["LIGHTNING_COMPONENT_NAME"] = self.name
         env["LIGHTNING_WORK"] = self.__class__.__name__
@@ -58,6 +62,7 @@ def run(self) -> None:
             ],
             env=env,
         )
+        self.ready = True
         self._process.wait()
 
     def on_exit(self) -> None:
diff --git a/src/lightning_app/core/app.py b/src/lightning_app/core/app.py
index 29b7d0b10de23..fc44378a1e8e1 100644
--- a/src/lightning_app/core/app.py
+++ b/src/lightning_app/core/app.py
@@ -493,7 +493,7 @@ def _run(self) -> bool:
 
         self._start_with_flow_works()
 
-        if self.ready and self.should_publish_changes_to_api and self.api_publish_state_queue:
+        if self.should_publish_changes_to_api and self.api_publish_state_queue:
             self.api_publish_state_queue.put(self.state_vars)
 
         self._reset_run_time_monitor()
@@ -503,7 +503,7 @@ def _run(self) -> bool:
 
             self._update_run_time_monitor()
 
-            if self.ready and self._has_updated and self.should_publish_changes_to_api and self.api_publish_state_queue:
+            if self._has_updated and self.should_publish_changes_to_api and self.api_publish_state_queue:
                 self.api_publish_state_queue.put(self.state_vars)
 
             self._has_updated = False
diff --git a/tests/tests_app/core/test_lightning_api.py b/tests/tests_app/core/test_lightning_api.py
index 04b89c927941a..a46eb4e9f9bbd 100644
--- a/tests/tests_app/core/test_lightning_api.py
+++ b/tests/tests_app/core/test_lightning_api.py
@@ -31,6 +31,7 @@
 from lightning_app.runners import MultiProcessRuntime
 from lightning_app.storage.drive import Drive
 from lightning_app.testing.helpers import _MockQueue
+from lightning_app.utilities.app_status import AppStatus
 from lightning_app.utilities.component import _set_frontend_context, _set_work_context
 from lightning_app.utilities.enum import AppStage
 from lightning_app.utilities.load_app import extract_metadata_from_app
@@ -197,7 +198,7 @@ def test_update_publish_state_and_maybe_refresh_ui():
 
     publish_state_queue.put(app.state_with_changes)
 
-    thread = UIRefresher(publish_state_queue, api_response_queue)
+    thread = UIRefresher(publish_state_queue, api_response_queue, None)
     thread.run_once()
 
     assert global_app_state_store.get_app_state("1234") == app.state_with_changes
@@ -225,13 +226,16 @@ def get(self, timeout: int = 0):
     change_state_queue = _MockQueue("change_state_queue")
     has_started_queue = _MockQueue("has_started_queue")
     api_response_queue = _MockQueue("api_response_queue")
+    app_status_queue = _MockQueue("app_status_queue")
     state = app.state_with_changes
     publish_state_queue.put(state)
+    app_status_queue.put(AppStatus(is_ui_ready=True, work_statuses=[]))
     spec = extract_metadata_from_app(app)
     ui_refresher = start_server(
         publish_state_queue,
         change_state_queue,
         api_response_queue,
+        app_status_queue=app_status_queue,
         has_started_queue=has_started_queue,
         uvicorn_run=False,
         spec=spec,
@@ -284,6 +288,9 @@ def get(self, timeout: int = 0):
             {"name": "main_4", "content": "https://te"},
         ]
 
+        response = await client.get("/api/v1/status")
+        assert response.json() == {"is_ui_ready": True, "work_statuses": []}
+
         response = await client.post("/api/v1/state", json={"state": new_state}, headers=headers)
         assert change_state_queue._queue[1].to_dict() == {
             "values_changed": {"root['vars']['counter']": {"new_value": 1}}
diff --git a/tests/tests_app/core/test_lightning_flow.py b/tests/tests_app/core/test_lightning_flow.py
index c8e9921f29eec..afbad586c6260 100644
--- a/tests/tests_app/core/test_lightning_flow.py
+++ b/tests/tests_app/core/test_lightning_flow.py
@@ -5,7 +5,7 @@
 from dataclasses import dataclass
 from functools import partial
 from time import time
-from unittest.mock import ANY, MagicMock
+from unittest.mock import ANY
 
 import pytest
 from deepdiff import DeepDiff, Delta
@@ -19,7 +19,7 @@
 from lightning_app.storage.path import _storage_root_dir
 from lightning_app.structures import Dict as LDict
 from lightning_app.structures import List as LList
-from lightning_app.testing.helpers import EmptyFlow, EmptyWork
+from lightning_app.testing.helpers import _MockQueue, EmptyFlow, EmptyWork
 from lightning_app.utilities.app_helpers import (
     _delta_to_app_state_delta,
     _LightningAppRef,
@@ -887,21 +887,28 @@ def run(self):
 
 
 def test_flow_ready():
-    """This test validates the api publish state queue is populated only once ready is True."""
+    """This test validates that the app status queue is populated correctly."""
+
+    mock_queue = _MockQueue("app_status_queue")
 
     def run_patch(method):
-        app.api_publish_state_queue = MagicMock()
-        app.should_publish_changes_to_api = False
+        app.app_status_queue = mock_queue
         method()
 
     app = LightningApp(FlowReady())
     app._run = partial(run_patch, method=app._run)
     MultiProcessRuntime(app, start_server=False).dispatch()
 
-    # Validates the state has been added only when ready was true.
-    state = app.api_publish_state_queue.put._mock_call_args[0][0]
-    call_hash = state["works"]["w"]["calls"]["latest_call_hash"]
-    assert state["works"]["w"]["calls"][call_hash]["statuses"][0]["stage"] == "succeeded"
+    # Run the app once to ensure it updates the queues
+    app.run_once()
+
+    first_status = mock_queue.get()
+    assert not first_status.is_ui_ready
+
+    last_status = mock_queue.get()
+    while len(mock_queue) > 0:
+        last_status = mock_queue.get()
+    assert last_status.is_ui_ready
 
 
 def test_structures_register_work_cloudcompute():

From 00f86fa1f4d9a44958234620d2fab7587d857530 Mon Sep 17 00:00:00 2001
From: Ethan Harris <ethanwharris@gmail.com>
Date: Thu, 15 Dec 2022 16:00:58 +0000
Subject: [PATCH 05/17] Remove debug

---
 src/lightning_app/components/serve/streamlit.py | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/lightning_app/components/serve/streamlit.py b/src/lightning_app/components/serve/streamlit.py
index 41a88dafbfe08..720139f93f25e 100644
--- a/src/lightning_app/components/serve/streamlit.py
+++ b/src/lightning_app/components/serve/streamlit.py
@@ -4,7 +4,6 @@
 import pydoc
 import subprocess
 import sys
-import time
 from typing import Any, Callable, Type
 
 from lightning_app.core.work import LightningWork
@@ -41,7 +40,6 @@ def build_model(self) -> Any:
         return None
 
     def run(self) -> None:
-        time.sleep(100)
         env = os.environ.copy()
         env["LIGHTNING_COMPONENT_NAME"] = self.name
         env["LIGHTNING_WORK"] = self.__class__.__name__

From ed6801d71e186223fd17a573e7320880d2367752 Mon Sep 17 00:00:00 2001
From: Ethan Harris <ethanwharris@gmail.com>
Date: Thu, 15 Dec 2022 16:03:09 +0000
Subject: [PATCH 06/17] Update comment

---
 src/lightning_app/core/flow.py | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/src/lightning_app/core/flow.py b/src/lightning_app/core/flow.py
index 302ba344320d1..25fae44cd29d0 100644
--- a/src/lightning_app/core/flow.py
+++ b/src/lightning_app/core/flow.py
@@ -255,10 +255,7 @@ def __getattr__(self, item):
 
     @property
     def ready(self) -> bool:
-        """Not currently enabled.
-
-        Override to customize when your App should be ready.
-        """
+        """Override to customize when your App should be ready."""
         flows = self.flows
         return all(flow.ready for flow in flows.values()) if flows else True
 

From 41ee98708a874b870bec29e1f9054dd09428526d Mon Sep 17 00:00:00 2001
From: Ethan Harris <ethanwharris@gmail.com>
Date: Thu, 15 Dec 2022 17:52:36 +0000
Subject: [PATCH 07/17] Update examples/app_boring/app.py

Co-authored-by: thomas chaton <thomas@grid.ai>
---
 examples/app_boring/app.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/app_boring/app.py b/examples/app_boring/app.py
index dafa87b5406d2..78a9b1c819f06 100644
--- a/examples/app_boring/app.py
+++ b/examples/app_boring/app.py
@@ -45,7 +45,7 @@ def __init__(self):
 
     @property
     def ready(self) -> bool:
-        return self.source_work.has_succeeded and self.dest_work.is_running
+        return self.dest_work.is_running
 
     def run(self):
         self.source_work.run()

From 30f12114d4df5a24014d25ad2624e92b91c41c4f Mon Sep 17 00:00:00 2001
From: Ethan Harris <ethanwharris@gmail.com>
Date: Fri, 16 Dec 2022 14:01:20 +0000
Subject: [PATCH 08/17] Remove app status queue

---
 src/lightning_app/core/api.py                 | 15 +++--------
 src/lightning_app/core/app.py                 | 13 +++++-----
 src/lightning_app/core/queues.py              |  5 ----
 src/lightning_app/runners/backends/backend.py |  1 -
 src/lightning_app/runners/multiprocess.py     |  1 -
 src/lightning_app/runners/runtime.py          |  2 +-
 src/lightning_app/testing/helpers.py          |  3 +++
 tests/tests_app/core/test_lightning_api.py    |  7 ++----
 tests/tests_app/core/test_lightning_flow.py   | 25 +++++++++++++------
 9 files changed, 32 insertions(+), 40 deletions(-)

diff --git a/src/lightning_app/core/api.py b/src/lightning_app/core/api.py
index 8a2b912a6b2b6..73d7274631a69 100644
--- a/src/lightning_app/core/api.py
+++ b/src/lightning_app/core/api.py
@@ -83,13 +83,11 @@ def __init__(
         self,
         api_publish_state_queue,
         api_response_queue,
-        app_status_queue: Optional[Queue],
         refresh_interval: float = 0.1,
     ) -> None:
         super().__init__(daemon=True)
         self.api_publish_state_queue = api_publish_state_queue
         self.api_response_queue = api_response_queue
-        self.app_status_queue = app_status_queue
         self._exit_event = Event()
         self.refresh_interval = refresh_interval
 
@@ -107,7 +105,8 @@ def run(self):
 
     def run_once(self):
         try:
-            state = self.api_publish_state_queue.get(timeout=0)
+            global app_status
+            state, app_status = self.api_publish_state_queue.get(timeout=0)
             with lock:
                 global_app_state_store.set_app_state(TEST_SESSION_UUID, state)
         except queue.Empty:
@@ -123,13 +122,6 @@ def run_once(self):
         except queue.Empty:
             pass
 
-        if self.app_status_queue is not None:
-            try:
-                global app_status
-                app_status = self.app_status_queue.get(timeout=0)
-            except queue.Empty:
-                pass
-
     def join(self, timeout: Optional[float] = None) -> None:
         self._exit_event.set()
         super().join(timeout)
@@ -434,7 +426,6 @@ def start_server(
     api_publish_state_queue,
     api_delta_queue,
     api_response_queue,
-    app_status_queue: Optional[Queue] = None,
     has_started_queue: Optional[Queue] = None,
     host="127.0.0.1",
     port=8000,
@@ -456,7 +447,7 @@ def start_server(
 
     global_app_state_store.add(TEST_SESSION_UUID)
 
-    refresher = UIRefresher(api_publish_state_queue, api_response_queue, app_status_queue)
+    refresher = UIRefresher(api_publish_state_queue, api_response_queue)
     refresher.setDaemon(True)
     refresher.start()
 
diff --git a/src/lightning_app/core/app.py b/src/lightning_app/core/app.py
index fc44378a1e8e1..2826edb47533f 100644
--- a/src/lightning_app/core/app.py
+++ b/src/lightning_app/core/app.py
@@ -118,7 +118,6 @@ def __init__(
         self.api_response_queue: Optional[BaseQueue] = None
         self.api_publish_state_queue: Optional[BaseQueue] = None
         self.api_delta_queue: Optional[BaseQueue] = None
-        self.app_status_queue: Optional[BaseQueue] = None
         self.error_queue: Optional[BaseQueue] = None
         self.request_queues: Optional[Dict[str, BaseQueue]] = None
         self.response_queues: Optional[Dict[str, BaseQueue]] = None
@@ -153,6 +152,7 @@ def __init__(
         self.checkpointing: bool = False
 
         self._update_layout()
+        self._update_status()
 
         self.is_headless: Optional[bool] = None
 
@@ -494,7 +494,7 @@ def _run(self) -> bool:
         self._start_with_flow_works()
 
         if self.should_publish_changes_to_api and self.api_publish_state_queue:
-            self.api_publish_state_queue.put(self.state_vars)
+            self.api_publish_state_queue.put((self.state_vars, self.status))
 
         self._reset_run_time_monitor()
 
@@ -504,7 +504,7 @@ def _run(self) -> bool:
             self._update_run_time_monitor()
 
             if self._has_updated and self.should_publish_changes_to_api and self.api_publish_state_queue:
-                self.api_publish_state_queue.put(self.state_vars)
+                self.api_publish_state_queue.put((self.state_vars, self.status))
 
             self._has_updated = False
 
@@ -536,14 +536,13 @@ def _update_status(self) -> None:
         for work in breadth_first(self.root, types=(lightning_app.LightningWork,)):
             work_statuses.append(work.status)
 
-        new_status = AppStatus(
+        self.status = AppStatus(
             is_ui_ready=self.ready,
             work_statuses=work_statuses,
         )
 
-        if new_status != old_status:
-            self.status = new_status
-            self.app_status_queue.put(self.status)
+        if self.status != old_status:
+            self._has_updated = True
 
     def _apply_restarting(self) -> bool:
         self._reset_original_state()
diff --git a/src/lightning_app/core/queues.py b/src/lightning_app/core/queues.py
index 5d04b5bc9027f..db150a57eb098 100644
--- a/src/lightning_app/core/queues.py
+++ b/src/lightning_app/core/queues.py
@@ -38,7 +38,6 @@
 CALLER_QUEUE_CONSTANT = "CALLER_QUEUE"
 API_STATE_PUBLISH_QUEUE_CONSTANT = "API_STATE_PUBLISH_QUEUE"
 API_DELTA_QUEUE_CONSTANT = "API_DELTA_QUEUE"
-APP_STATUS_QUEUE_CONSTANT = "APP_STATUS_QUEUE"
 API_REFRESH_QUEUE_CONSTANT = "API_REFRESH_QUEUE"
 ORCHESTRATOR_REQUEST_CONSTANT = "ORCHESTRATOR_REQUEST"
 ORCHESTRATOR_RESPONSE_CONSTANT = "ORCHESTRATOR_RESPONSE"
@@ -97,10 +96,6 @@ def get_api_delta_queue(self, queue_id: Optional[str] = None) -> "BaseQueue":
         queue_name = f"{queue_id}_{DELTA_QUEUE_CONSTANT}" if queue_id else DELTA_QUEUE_CONSTANT
         return self.get_queue(queue_name)
 
-    def get_app_status_queue(self, queue_id: Optional[str] = None) -> "BaseQueue":
-        queue_name = f"{queue_id}_{APP_STATUS_QUEUE_CONSTANT}" if queue_id else APP_STATUS_QUEUE_CONSTANT
-        return self.get_queue(queue_name)
-
     def get_orchestrator_request_queue(self, work_name: str, queue_id: Optional[str] = None) -> "BaseQueue":
         queue_name = (
             f"{queue_id}_{ORCHESTRATOR_REQUEST_CONSTANT}_{work_name}"
diff --git a/src/lightning_app/runners/backends/backend.py b/src/lightning_app/runners/backends/backend.py
index b4114286f8109..54c1f9092bf0f 100644
--- a/src/lightning_app/runners/backends/backend.py
+++ b/src/lightning_app/runners/backends/backend.py
@@ -88,7 +88,6 @@ def _prepare_queues(self, app: "lightning_app.LightningApp"):
         app.error_queue = self.queues.get_error_queue(**kw)
         app.api_publish_state_queue = self.queues.get_api_state_publish_queue(**kw)
         app.api_delta_queue = app.delta_queue
-        app.app_status_queue = self.queues.get_app_status_queue(**kw)
         app.request_queues = {}
         app.response_queues = {}
         app.copy_request_queues = {}
diff --git a/src/lightning_app/runners/multiprocess.py b/src/lightning_app/runners/multiprocess.py
index e951a8092c4fc..e5d34fb76800f 100644
--- a/src/lightning_app/runners/multiprocess.py
+++ b/src/lightning_app/runners/multiprocess.py
@@ -91,7 +91,6 @@ def dispatch(self, *args: Any, open_ui: bool = True, **kwargs: Any):
                     api_response_queue=self.app.api_response_queue,
                     api_publish_state_queue=self.app.api_publish_state_queue,
                     api_delta_queue=self.app.api_delta_queue,
-                    app_status_queue=self.app.app_status_queue,
                     has_started_queue=has_started_queue,
                     spec=extract_metadata_from_app(self.app),
                     root_path=self.app.root_path,
diff --git a/src/lightning_app/runners/runtime.py b/src/lightning_app/runners/runtime.py
index ab552f136fde0..d9bf372428894 100644
--- a/src/lightning_app/runners/runtime.py
+++ b/src/lightning_app/runners/runtime.py
@@ -122,7 +122,7 @@ def terminate(self) -> None:
                         self._add_stopped_status_to_work(work)
 
                     # Publish the updated state and wait for the frontend to update.
-                    self.app.api_publish_state_queue.put(self.app.state)
+                    self.app.api_publish_state_queue.put((self.app.state, self.app.status))
 
                 for thread in self.threads + self.app.threads:
                     thread.join(timeout=0)
diff --git a/src/lightning_app/testing/helpers.py b/src/lightning_app/testing/helpers.py
index cb21d314145ff..18aae8140d930 100644
--- a/src/lightning_app/testing/helpers.py
+++ b/src/lightning_app/testing/helpers.py
@@ -136,6 +136,9 @@ def __len__(self):
     def __repr__(self) -> str:
         return f"{self.__class__.__name__}({self._queue})"
 
+    def __bool__(self) -> bool:
+        return True
+
 
 class EmptyFlow(LightningFlow):
     """A LightningFlow that implements all abstract methods to do nothing.
diff --git a/tests/tests_app/core/test_lightning_api.py b/tests/tests_app/core/test_lightning_api.py
index a46eb4e9f9bbd..edf5fd7afc852 100644
--- a/tests/tests_app/core/test_lightning_api.py
+++ b/tests/tests_app/core/test_lightning_api.py
@@ -196,7 +196,7 @@ def test_update_publish_state_and_maybe_refresh_ui():
     publish_state_queue = _MockQueue("publish_state_queue")
     api_response_queue = _MockQueue("api_response_queue")
 
-    publish_state_queue.put(app.state_with_changes)
+    publish_state_queue.put((app.state_with_changes, None))
 
     thread = UIRefresher(publish_state_queue, api_response_queue, None)
     thread.run_once()
@@ -226,16 +226,13 @@ def get(self, timeout: int = 0):
     change_state_queue = _MockQueue("change_state_queue")
     has_started_queue = _MockQueue("has_started_queue")
     api_response_queue = _MockQueue("api_response_queue")
-    app_status_queue = _MockQueue("app_status_queue")
     state = app.state_with_changes
-    publish_state_queue.put(state)
-    app_status_queue.put(AppStatus(is_ui_ready=True, work_statuses=[]))
+    publish_state_queue.put((state, AppStatus(is_ui_ready=True, work_statuses=[])))
     spec = extract_metadata_from_app(app)
     ui_refresher = start_server(
         publish_state_queue,
         change_state_queue,
         api_response_queue,
-        app_status_queue=app_status_queue,
         has_started_queue=has_started_queue,
         uvicorn_run=False,
         spec=spec,
diff --git a/tests/tests_app/core/test_lightning_flow.py b/tests/tests_app/core/test_lightning_flow.py
index afbad586c6260..57dfb076a7149 100644
--- a/tests/tests_app/core/test_lightning_flow.py
+++ b/tests/tests_app/core/test_lightning_flow.py
@@ -889,25 +889,34 @@ def run(self):
 def test_flow_ready():
     """This test validates that the app status queue is populated correctly."""
 
-    mock_queue = _MockQueue("app_status_queue")
+    mock_queue = _MockQueue("api_publish_state_queue")
 
     def run_patch(method):
-        app.app_status_queue = mock_queue
+        app.should_publish_changes_to_api = True
+        app.api_publish_state_queue = mock_queue
         method()
 
+    state = {"done": False}
+
+    def lagged_run_once(method):
+        """Ensure that the full loop is run after the app exits."""
+        new_done = method()
+        if state["done"]:
+            return True
+        state["done"] = new_done
+        return False
+
     app = LightningApp(FlowReady())
     app._run = partial(run_patch, method=app._run)
+    app.run_once = partial(lagged_run_once, method=app.run_once)
     MultiProcessRuntime(app, start_server=False).dispatch()
 
-    # Run the app once to ensure it updates the queues
-    app.run_once()
-
-    first_status = mock_queue.get()
+    _, first_status = mock_queue.get()
     assert not first_status.is_ui_ready
 
-    last_status = mock_queue.get()
+    _, last_status = mock_queue.get()
     while len(mock_queue) > 0:
-        last_status = mock_queue.get()
+        _, last_status = mock_queue.get()
     assert last_status.is_ui_ready
 
 

From 312c571c644a6f50238a744499ec1bd6c0f0007c Mon Sep 17 00:00:00 2001
From: Ethan Harris <ethanwharris@gmail.com>
Date: Fri, 16 Dec 2022 15:05:01 +0000
Subject: [PATCH 09/17] Fixes

---
 src/lightning_app/utilities/app_status.py    |  4 +---
 src/lightning_app/utilities/enum.py          |  2 +-
 tests/tests_app/storage/test_orchestrator.py | 12 ++++++------
 tests/tests_app/storage/test_path.py         |  2 +-
 tests/tests_app/utilities/test_proxies.py    | 13 +++++++------
 5 files changed, 16 insertions(+), 17 deletions(-)

diff --git a/src/lightning_app/utilities/app_status.py b/src/lightning_app/utilities/app_status.py
index 95248433d782f..5184fb1ea291c 100644
--- a/src/lightning_app/utilities/app_status.py
+++ b/src/lightning_app/utilities/app_status.py
@@ -2,14 +2,12 @@
 
 from pydantic import BaseModel
 
-from lightning_app.utilities.enum import WorkStageStatus
-
 
 class WorkStatus(BaseModel):
     """The ``WorkStatus`` captures the status of a work according to the app."""
 
     name: str
-    stage: WorkStageStatus
+    stage: str
     timestamp: float
     reason: Optional[str] = None
     message: Optional[str] = None
diff --git a/src/lightning_app/utilities/enum.py b/src/lightning_app/utilities/enum.py
index e0d211d29ff27..4c92ffba3db11 100644
--- a/src/lightning_app/utilities/enum.py
+++ b/src/lightning_app/utilities/enum.py
@@ -36,7 +36,7 @@ class WorkPendingReason(enum.Enum):
     REQUESTING_RESOURCE = "requesting_ressource"
 
 
-class WorkStageStatus(str, enum.Enum):
+class WorkStageStatus:
     NOT_STARTED = "not_started"
     STARTED = "started"
     STOPPED = "stopped"
diff --git a/tests/tests_app/storage/test_orchestrator.py b/tests/tests_app/storage/test_orchestrator.py
index ca671e6b93704..4b391a890f1a9 100644
--- a/tests/tests_app/storage/test_orchestrator.py
+++ b/tests/tests_app/storage/test_orchestrator.py
@@ -39,7 +39,7 @@ def test_orchestrator():
 
     # orchestrator is now waiting for a response for copier in Work A
     assert "work_b" in orchestrator.waiting_for_response
-    assert not request_queues["work_a"]
+    assert len(request_queues["work_a"]) == 0
     assert request in copy_request_queues["work_a"]
     assert request.destination == "work_b"
 
@@ -54,7 +54,7 @@ def test_orchestrator():
 
     # orchestrator processes confirmation and confirms to the pending request from Work B
     orchestrator.run_once("work_a")
-    assert not copy_response_queues["work_a"]
+    assert len(copy_response_queues["work_a"]) == 0
     assert response in response_queues["work_b"]
     assert not orchestrator.waiting_for_response
     orchestrator.run_once("work_b")
@@ -71,7 +71,7 @@ def test_orchestrator():
     assert response.exception is None
 
     # all queues should be empty
-    assert all(not queue for queue in request_queues.values())
-    assert all(not queue for queue in response_queues.values())
-    assert all(not queue for queue in copy_request_queues.values())
-    assert all(not queue for queue in copy_response_queues.values())
+    assert all(len(queue) == 0 for queue in request_queues.values())
+    assert all(len(queue) == 0 for queue in response_queues.values())
+    assert all(len(queue) == 0 for queue in copy_request_queues.values())
+    assert all(len(queue) == 0 for queue in copy_response_queues.values())
diff --git a/tests/tests_app/storage/test_path.py b/tests/tests_app/storage/test_path.py
index 3cd501f7344c8..2310b8034c303 100644
--- a/tests/tests_app/storage/test_path.py
+++ b/tests/tests_app/storage/test_path.py
@@ -606,7 +606,7 @@ def test_path_response_not_matching_reqeuest(tmpdir):
         path.get()
 
     # simulate a response that has a different hash than the request had
-    assert not response_queue
+    assert len(response_queue) == 0
     response.path = str(path)
     response.hash = "other_hash"
     response_queue.put(response)
diff --git a/tests/tests_app/utilities/test_proxies.py b/tests/tests_app/utilities/test_proxies.py
index 4b8a5f25f71e3..a53d8e85a3d37 100644
--- a/tests/tests_app/utilities/test_proxies.py
+++ b/tests/tests_app/utilities/test_proxies.py
@@ -250,6 +250,7 @@ def __call__(self):
                 state = deepcopy(self.work.state)
                 self.work._calls[call_hash]["statuses"].append(
                     {
+                        "name": self.work.name,
                         "stage": WorkStageStatus.FAILED,
                         "reason": WorkFailureReasons.TIMEOUT,
                         "timestamp": time.time(),
@@ -547,7 +548,7 @@ def run(self, use_setattr=False, use_containers=False):
     # 1. Simulate no state changes
     ##############################
     work.run(use_setattr=False, use_containers=False)
-    assert not delta_queue
+    assert len(delta_queue) == 0
 
     ############################
     # 2. Simulate a setattr call
@@ -563,16 +564,16 @@ def run(self, use_setattr=False, use_containers=False):
     assert len(observer._delta_memory) == 1
 
     # The observer should not trigger any deltas being sent and only consume the delta memory
-    assert not delta_queue
+    assert len(delta_queue) == 0
     observer.run_once()
-    assert not delta_queue
+    assert len(delta_queue) == 0
     assert not observer._delta_memory
 
     ################################
     # 3. Simulate a container update
     ################################
     work.run(use_setattr=False, use_containers=True)
-    assert not delta_queue
+    assert len(delta_queue) == 0
     assert not observer._delta_memory
     observer.run_once()
     observer.run_once()  # multiple runs should not affect how many deltas are sent unless there are changes
@@ -591,7 +592,7 @@ def run(self, use_setattr=False, use_containers=False):
 
     delta = delta_queue.get().delta.to_dict()
     assert delta == {"values_changed": {"root['vars']['var']": {"new_value": 3}}}
-    assert not delta_queue
+    assert len(delta_queue) == 0
     assert len(observer._delta_memory) == 1
     observer.run_once()
 
@@ -599,7 +600,7 @@ def run(self, use_setattr=False, use_containers=False):
     assert delta["values_changed"] == {"root['vars']['dict']['counter']": {"new_value": 2}}
     assert delta["iterable_item_added"] == {"root['vars']['list'][1]": 1}
 
-    assert not delta_queue
+    assert len(delta_queue) == 0
     assert not observer._delta_memory
 
 

From cb6baffbfeb39fcdb447d7e387d9077a5ade5d63 Mon Sep 17 00:00:00 2001
From: Ethan Harris <ethanwharris@gmail.com>
Date: Fri, 16 Dec 2022 15:07:25 +0000
Subject: [PATCH 10/17] Update

---
 src/lightning_app/core/app.py        | 4 ++--
 src/lightning_app/testing/helpers.py | 3 ---
 2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/src/lightning_app/core/app.py b/src/lightning_app/core/app.py
index 2826edb47533f..f23ab3ccc223c 100644
--- a/src/lightning_app/core/app.py
+++ b/src/lightning_app/core/app.py
@@ -493,7 +493,7 @@ def _run(self) -> bool:
 
         self._start_with_flow_works()
 
-        if self.should_publish_changes_to_api and self.api_publish_state_queue:
+        if self.should_publish_changes_to_api and self.api_publish_state_queue is not None:
             self.api_publish_state_queue.put((self.state_vars, self.status))
 
         self._reset_run_time_monitor()
@@ -503,7 +503,7 @@ def _run(self) -> bool:
 
             self._update_run_time_monitor()
 
-            if self._has_updated and self.should_publish_changes_to_api and self.api_publish_state_queue:
+            if self._has_updated and self.should_publish_changes_to_api and self.api_publish_state_queue is not None:
                 self.api_publish_state_queue.put((self.state_vars, self.status))
 
             self._has_updated = False
diff --git a/src/lightning_app/testing/helpers.py b/src/lightning_app/testing/helpers.py
index 18aae8140d930..cb21d314145ff 100644
--- a/src/lightning_app/testing/helpers.py
+++ b/src/lightning_app/testing/helpers.py
@@ -136,9 +136,6 @@ def __len__(self):
     def __repr__(self) -> str:
         return f"{self.__class__.__name__}({self._queue})"
 
-    def __bool__(self) -> bool:
-        return True
-
 
 class EmptyFlow(LightningFlow):
     """A LightningFlow that implements all abstract methods to do nothing.

From 5c0ec054bf3dbd76bf076b5e1f6dfecfe75f7b40 Mon Sep 17 00:00:00 2001
From: Ethan Harris <ethanwharris@gmail.com>
Date: Fri, 16 Dec 2022 15:13:33 +0000
Subject: [PATCH 11/17] Switch to 503

---
 src/lightning_app/core/api.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/lightning_app/core/api.py b/src/lightning_app/core/api.py
index 73d7274631a69..4a439fa87bd82 100644
--- a/src/lightning_app/core/api.py
+++ b/src/lightning_app/core/api.py
@@ -339,7 +339,9 @@ async def get_status() -> AppStatus:
     """Get the current status of the app and works."""
     global app_status
     if app_status is None:
-        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="App status hasn't been reported yet.")
+        raise HTTPException(
+            status_code=status.HTTP_503_SERVICE_UNAVAILABLE, detail="App status hasn't been reported yet."
+        )
     return app_status
 
 

From 1f83edf4a46362c0133453012a0401c148c8f09b Mon Sep 17 00:00:00 2001
From: Ethan Harris <ethanwharris@gmail.com>
Date: Fri, 16 Dec 2022 19:31:51 +0000
Subject: [PATCH 12/17] Add comment

---
 src/lightning_app/core/app.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/lightning_app/core/app.py b/src/lightning_app/core/app.py
index f23ab3ccc223c..453206bed8293 100644
--- a/src/lightning_app/core/app.py
+++ b/src/lightning_app/core/app.py
@@ -541,6 +541,8 @@ def _update_status(self) -> None:
             work_statuses=work_statuses,
         )
 
+        # If the work statuses changed, the state delta will trigger an update.
+        # If ready has changed, we trigger an update manually.
         if self.status != old_status:
             self._has_updated = True
 

From 7f6df16d3b319215f8e65c2420c79f1b87c3803b Mon Sep 17 00:00:00 2001
From: Ethan Harris <ethanwharris@gmail.com>
Date: Mon, 19 Dec 2022 11:03:09 +0000
Subject: [PATCH 13/17] Cleanup

---
 tests/tests_app/core/test_lightning_api.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/tests_app/core/test_lightning_api.py b/tests/tests_app/core/test_lightning_api.py
index edf5fd7afc852..1117eeff4df02 100644
--- a/tests/tests_app/core/test_lightning_api.py
+++ b/tests/tests_app/core/test_lightning_api.py
@@ -198,7 +198,7 @@ def test_update_publish_state_and_maybe_refresh_ui():
 
     publish_state_queue.put((app.state_with_changes, None))
 
-    thread = UIRefresher(publish_state_queue, api_response_queue, None)
+    thread = UIRefresher(publish_state_queue, api_response_queue)
     thread.run_once()
 
     assert global_app_state_store.get_app_state("1234") == app.state_with_changes

From 593f86799ae534ef38917312298fa5ccf2b37ffe Mon Sep 17 00:00:00 2001
From: Ethan Harris <ethanwharris@gmail.com>
Date: Mon, 19 Dec 2022 11:20:29 +0000
Subject: [PATCH 14/17] Updates

---
 src/lightning_app/core/app.py             | 4 ++--
 src/lightning_app/core/work.py            | 4 ++--
 src/lightning_app/utilities/app_status.py | 5 ++---
 3 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/src/lightning_app/core/app.py b/src/lightning_app/core/app.py
index 453206bed8293..dfce2097ec5a0 100644
--- a/src/lightning_app/core/app.py
+++ b/src/lightning_app/core/app.py
@@ -532,9 +532,9 @@ def _update_is_headless(self) -> None:
     def _update_status(self) -> None:
         old_status = self.status
 
-        work_statuses = []
+        work_statuses = {}
         for work in breadth_first(self.root, types=(lightning_app.LightningWork,)):
-            work_statuses.append(work.status)
+            work_statuses[work.name] = work.status
 
         self.status = AppStatus(
             is_ui_ready=self.ready,
diff --git a/src/lightning_app/core/work.py b/src/lightning_app/core/work.py
index 84838f76cedb0..d99df13d4f933 100644
--- a/src/lightning_app/core/work.py
+++ b/src/lightning_app/core/work.py
@@ -309,8 +309,8 @@ def status(self) -> WorkStatus:
             latest_status = statuses[-1]
             if latest_status.get("reason") == WorkFailureReasons.TIMEOUT:
                 return self._aggregate_status_timeout(statuses)
-            return WorkStatus(name=self.name, **latest_status)
-        return WorkStatus(name=self.name, stage=WorkStageStatus.NOT_STARTED, timestamp=time.time())
+            return WorkStatus(**latest_status)
+        return WorkStatus(stage=WorkStageStatus.NOT_STARTED, timestamp=time.time())
 
     @property
     def statuses(self) -> List[WorkStatus]:
diff --git a/src/lightning_app/utilities/app_status.py b/src/lightning_app/utilities/app_status.py
index 5184fb1ea291c..92a474a7918eb 100644
--- a/src/lightning_app/utilities/app_status.py
+++ b/src/lightning_app/utilities/app_status.py
@@ -1,4 +1,4 @@
-from typing import List, Optional
+from typing import Dict, Optional
 
 from pydantic import BaseModel
 
@@ -6,7 +6,6 @@
 class WorkStatus(BaseModel):
     """The ``WorkStatus`` captures the status of a work according to the app."""
 
-    name: str
     stage: str
     timestamp: float
     reason: Optional[str] = None
@@ -21,4 +20,4 @@ class AppStatus(BaseModel):
     is_ui_ready: bool
 
     # The statuses of ``LightningWork`` objects currently associated with this app
-    work_statuses: List[WorkStatus]
+    work_statuses: Dict[str, WorkStatus]

From c3c54535e58ceb0490418cbb48ddff3c42fc84bc Mon Sep 17 00:00:00 2001
From: Ethan Harris <ethanwharris@gmail.com>
Date: Mon, 19 Dec 2022 11:32:06 +0000
Subject: [PATCH 15/17] Fix

---
 tests/tests_app/core/test_lightning_api.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/tests_app/core/test_lightning_api.py b/tests/tests_app/core/test_lightning_api.py
index 56272b4218726..adad9fba932e0 100644
--- a/tests/tests_app/core/test_lightning_api.py
+++ b/tests/tests_app/core/test_lightning_api.py
@@ -227,7 +227,7 @@ def get(self, timeout: int = 0):
     has_started_queue = _MockQueue("has_started_queue")
     api_response_queue = _MockQueue("api_response_queue")
     state = app.state_with_changes
-    publish_state_queue.put((state, AppStatus(is_ui_ready=True, work_statuses=[])))
+    publish_state_queue.put((state, AppStatus(is_ui_ready=True, work_statuses={})))
     spec = extract_metadata_from_app(app)
     ui_refresher = start_server(
         publish_state_queue,
@@ -286,7 +286,7 @@ def get(self, timeout: int = 0):
         ]
 
         response = await client.get("/api/v1/status")
-        assert response.json() == {"is_ui_ready": True, "work_statuses": []}
+        assert response.json() == {"is_ui_ready": True, "work_statuses": {}}
 
         response = await client.post("/api/v1/state", json={"state": new_state}, headers=headers)
         assert change_state_queue._queue[1].to_dict() == {

From 4460b0be2c34776e8e971f38e60fee3776ebf573 Mon Sep 17 00:00:00 2001
From: Ethan Harris <ethanwharris@gmail.com>
Date: Mon, 19 Dec 2022 12:24:24 +0000
Subject: [PATCH 16/17] Add back assertion

---
 src/lightning_app/utilities/app_status.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/lightning_app/utilities/app_status.py b/src/lightning_app/utilities/app_status.py
index 92a474a7918eb..67a8a31f0eac8 100644
--- a/src/lightning_app/utilities/app_status.py
+++ b/src/lightning_app/utilities/app_status.py
@@ -1,3 +1,4 @@
+from datetime import datetime
 from typing import Dict, Optional
 
 from pydantic import BaseModel
@@ -12,6 +13,11 @@ class WorkStatus(BaseModel):
     message: Optional[str] = None
     count: int = 1
 
+    def __init__(self, *args, **kwargs) -> None:
+        super().__init__(*args, **kwargs)
+
+        assert self.timestamp > 0 and self.timestamp < (int(datetime.now().timestamp()) + 10)
+
 
 class AppStatus(BaseModel):
     """The ``AppStatus`` captures the current status of the app and its components."""

From 0d693eff5d1e0ecec1f1c99b430fa373c7f4c01d Mon Sep 17 00:00:00 2001
From: Ethan Harris <ethanwharris@gmail.com>
Date: Mon, 19 Dec 2022 12:42:55 +0000
Subject: [PATCH 17/17] Typing

---
 src/lightning_app/utilities/app_status.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/lightning_app/utilities/app_status.py b/src/lightning_app/utilities/app_status.py
index 67a8a31f0eac8..232c3f0b65210 100644
--- a/src/lightning_app/utilities/app_status.py
+++ b/src/lightning_app/utilities/app_status.py
@@ -1,5 +1,5 @@
 from datetime import datetime
-from typing import Dict, Optional
+from typing import Any, Dict, Optional
 
 from pydantic import BaseModel
 
@@ -13,7 +13,7 @@ class WorkStatus(BaseModel):
     message: Optional[str] = None
     count: int = 1
 
-    def __init__(self, *args, **kwargs) -> None:
+    def __init__(self, *args: Any, **kwargs: Any) -> None:
         super().__init__(*args, **kwargs)
 
         assert self.timestamp > 0 and self.timestamp < (int(datetime.now().timestamp()) + 10)