Standalone activity prototype #1138

dandavison · 2025-10-01T18:09:40Z

To test:

In temporal checkout the WIP server branch and

make start
temporal operator namespace create -n default

Then in sdk-python, checkout this branch and

# Remove the `pytest.skip` from `tests/test_activity.py`.
git submodule update --init --recursive
uv run poe build-develop
uv run pytest -E localhost:7233 'tests/test_activity.py::test_start_activity_and_describe_activity'
uv run pytest -E localhost:7233 'tests/test_activity.py::test_manual_completion'

See

bergundy · 2025-10-01T20:58:38Z

temporalio/client.py

+        self._id_or_token = ActivityIDReference(activity_id=id, run_id=run_id)
+        self.run_id = run_id
+
+    # TODO: do we support something like `follow_runs: bool`?


No need there's no concept of an execution chain for activities.

bergundy · 2025-10-01T20:59:32Z

temporalio/client.py

+        handle = await self.start_activity(*args, **kwargs)
+        return await handle.result()
+
+    async def list_activities(


Would be interesting to see how we can model this to return both workflow and standalone "client" activities.

I've made the iterator yield Union[ActivityExecution, WorkflowActivityExecution]. Those two dataclasses share a few fields.

bergundy · 2025-10-01T21:00:12Z

temporalio/client.py


+    # - TODO: Overloads for no-param, single-param, multi-param
+    # - TODO: Support sync and async activity functions
+    async def start_activity(


Also need execute_activity but we can leave that for later.

Actually execute_activity is already present below.

bergundy · 2025-10-01T21:01:29Z

temporalio/client.py

+
+
 @dataclass(frozen=True)
 class AsyncActivityIDReference:


Consider deprecating and renaming to WorkflowActivityIDReference.

Or merging the two reference types where workflow_id becomes an optional field.

I've merged them into ActivityIDReference and retained the AsyncActivityIDReference name as an alias.

bergundy · 2025-10-01T21:38:38Z

temporalio/client.py

+    """Handle representing an activity started by a workflow."""
+
+    def __init__(
+        self, client: Client, id_or_token: Union[AsyncActivityIDReference, bytes]


This should work with any activity IMHO.

Agreed. The PR:

Makes get_async_activity_handle work for Standalone Activities and Workflow Activities. This is essentially a client appropriate for the "owner" of the activity, permitting manual completion/fail/cancellation/heartbeating

Introduces Client.get_activity_handle for SA only. This is a cliet appropriate for the caller of the activity: describe, poll, request cancellation, etc

bergundy · 2025-10-01T21:39:51Z

temporalio/client.py

+        self._id_or_token = id_or_token
+
+
+WorkflowActivityHandle = AsyncActivityHandle


This will also need pause, reset, etc...

I think we still want AsyncActivityHandle because you can obtain one with a token and can't do anything else with the token but issue completion requests.

I've added implementations of pause / unpause / reset to the new ActivityHandle for SAs.

The existing AsyncActivityHandle is unperturbed by this PR: it just gains a constructor for SAs.

bergundy · 2025-10-01T21:40:11Z

temporalio/client.py

+        """
+        raise NotImplementedError
+
+    # TODO:


Also TODO: all of the async completion methods.

You mean heartbeat, complete, fail, and report_cancellation, right? Those are all inherited from _BaseActivityHandle.

I'm on the fence whether we want to expose these methods on the activity handle as opposed to having the async completion handle as a separate concept. The use cases are different for the two.

Yes, I also changed direction here: they are now on AsyncActivityHandle, for SA as they are for WA.

bergundy · 2025-10-01T21:41:14Z

temporalio/client.py

        )


+# TODO: This name is suboptimal now. We could deprecate it and introduce WorkflowActivityHandle as a


Yeah, let's do that. Which means that you would have to accept a WorkflowActivityHandle where you accept AsyncActivityHandle.

I've renamed, and am retaining the old name as an alias to the same class object.

bergundy · 2025-10-01T21:42:26Z

temporalio/client.py


-class AsyncActivityHandle:
-    """Handle representing an external activity for completion and heartbeat."""
+class _BaseActivityHandle:


I would consider just duplicating instead of inheriting but don't have a strong opinion.

This reverts commit 7127c0fe5296d6df4c174f2792447c98934a95ce.

cretz · 2025-10-13T17:22:07Z

temporalio/activity.py

        )

+    @classmethod
+    def get_name_and_result_type(


If we're extracting this common logic out of workflow_instance.py, can we update workflow_instance.py use this too? Also, then can we get rid of must_from_callable and inline it into this method since it won't be called anywhere anymore?

cretz · 2025-10-13T17:24:10Z

temporalio/client.py

+    # - TODO: Support sync and async activity functions
+    async def start_activity(
+        self,
+        activity: Union[str, Callable[..., Awaitable[ReturnType]]],


I think when we get to the overloads, this final form may not make sense to use the generic

cretz · 2025-10-13T17:25:27Z

temporalio/common.py

    )


+class IdReusePolicy(IntEnum):


I think each top-level thing should have its own enumerate here. It doesn't make sense to have workflow ID reuse policy and not activity ID reuse policy. Same for ID conflict policy. It makes more sense from a user POV not to pretend like this is a common ID reuse policy when it is not (nor do we need it to be).

We should not eschew consistency just because we may have a NexusOperationIdReusePolicy one day (and we'll be happy we kept them separate if they diverge). This is no different than cancellation type or any of these others.

cretz · 2025-10-13T17:27:06Z

temporalio/client.py

+        retry_policy: Optional[temporalio.common.RetryPolicy] = None,
+        search_attributes: Optional[
+            Union[
+                temporalio.common.SearchAttributes,


IMO we don't need to accept this deprecated form of search attributes for newer API, but it's not harmful

Thanks, I meant to remove that. Removed.

cretz · 2025-10-13T17:31:11Z

temporalio/client.py

+
+    def list_activities(
+        self,
+        query: Optional[str] = None,


Can you confirm whether we expect a query specifically saying activity kind is "standalone" at this time so that when we add non-standalone one day it doesn't surprise users?

cretz · 2025-10-13T18:30:09Z

temporalio/common.py

+    TIMED_OUT = 6  # ACTIVITY_EXECUTION_STATUS_TIMED_OUT
+
+
+class PendingActivityState(IntEnum):


I think this also may make sense in the client module

cretz · 2025-10-13T19:11:02Z

temporalio/activity.py

I think we should go ahead and put here the expected changes to activity runtime. Specifically I assume all workflow_-prefixed fields of Info will become optional. I would also recommend either a "kind" enumerate for activities, or add an is_standalone akin to is_local so users can know it's not the traditional activity.

cretz · 2025-10-13T19:11:34Z

temporalio/converter.py

+    namespace: str
+    """Namespace."""
+
+    workflow_id: Optional[str]


What situations would workflow ID be optional here?

cretz · 2025-10-13T19:21:04Z

temporalio/exceptions.py

+# TODO: This error class has required history event fields. I propose we retain it as
+# workflow-specific and introduce client.ActivityFailureError for an error in a standalone activity.
+# We could deprecate this name and introduce WorkflowActivityError as a preferred-going-forwards
+# alias.


I agree with behavior, but disagree with the aliasing. This specifically maps to ActivityFailureInfo in our API, I think we should keep that naming correlation (same for all failure errors). I expect similar for standalone Nexus operation failures (they don't use the named-in-proto failure messages, so they don't affect failure error things).

cretz · 2025-10-13T19:51:02Z

temporalio/converter.py

+    activity_id: Optional[str]
+    """Activity ID. Optional if this is an activity started from a workflow."""


In what situations is this optional? To confirm, is this not the activity ID for regular activities? We have to make sure that every value that is present on the deserialization side is present on the serialization side. So a workflow should always set this (right now it's defaulted in the constructor of the activity handle, but we can move it out if needed).

dandavison force-pushed the standalone-activity branch from a1d3efe to 23df3f8 Compare October 1, 2025 18:13

bergundy reviewed Oct 1, 2025

View reviewed changes

dandavison force-pushed the standalone-activity branch 3 times, most recently from e53a5c2 to 0a21bf7 Compare October 8, 2025 21:47

dandavison changed the title ~~Standalone activity API sketches~~ Standalone activity prototype Oct 8, 2025

dandavison force-pushed the standalone-activity branch from 07c6917 to 49ae6c3 Compare October 9, 2025 15:39

dandavison mentioned this pull request Oct 9, 2025

Standalone activity prototype temporalio/sdk-core#1031

Draft

dandavison force-pushed the standalone-activity branch from 49ae6c3 to 818c417 Compare October 9, 2025 15:51

dandavison added 4 commits October 10, 2025 02:43

Sketch standalone activity client APIs

7666cdc

Partial revert

c725d71

Update core: temporalio/api#640

b5d2d2f

Test standalone activity

896fc87

dandavison force-pushed the standalone-activity branch from 818c417 to 375a6e9 Compare October 10, 2025 06:43

dandavison added 4 commits October 10, 2025 02:48

poe gen-protos-docker

32ff692

Implement list/count activities

c78fee7

alphabetical order

e6f6ca2

ActivityHandle.result

51f7da8

dandavison force-pushed the standalone-activity branch 2 times, most recently from 2ca269e to c681c13 Compare October 10, 2025 08:43

dandavison added 2 commits October 10, 2025 05:42

Implement start_activity

7781c2a

Update sdk-core

ecbaed9

dandavison added 3 commits October 10, 2025 05:42

Server isn't returning RunID yet

4a4a731

Add activity IDs to test since they are now set in context

32f5abb

Eliminate base serialization context class

d28ae5b

dandavison force-pushed the standalone-activity branch from c681c13 to ace675c Compare October 10, 2025 09:42

Extend tests

741603f

dandavison force-pushed the standalone-activity branch from ace675c to 741603f Compare October 10, 2025 09:47

dandavison added 11 commits October 10, 2025 09:17

Don't hardcode workflow IDs

1e75e38

Fix AsyncActivityHandle

e069732

TEMP: Alter manual activity tests to not require worker

e37c625

Skip tests globally

269d532

Revert "TEMP: Alter manual activity tests to not require worker"

4d355d1

This reverts commit 7127c0fe5296d6df4c174f2792447c98934a95ce.

Assert describe returns new state after transition

976532d

Fix cancellation and failure tests

92faa7f

Cleanup

ea402d9

Add experimental notices

af9f80a

Workaround mypy bug

48d5ddc

Skip Standalone Activity tests in CI

d71fe31

cretz reviewed Oct 13, 2025

View reviewed changes

		self._id_or_token = id_or_token


		WorkflowActivityHandle = AsyncActivityHandle

		)


		# TODO: This name is suboptimal now. We could deprecate it and introduce WorkflowActivityHandle as a

		TIMED_OUT = 6 # ACTIVITY_EXECUTION_STATUS_TIMED_OUT


		class PendingActivityState(IntEnum):

		activity_id: Optional[str]
		"""Activity ID. Optional if this is an activity started from a workflow."""

Standalone activity prototype #1138

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Standalone activity prototype #1138

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