Nexus CHASM async completion (1/2) by stephanos · Pull Request #9951 · temporalio/temporal

stephanos · 2026-04-14T20:33:08Z

What changed?

Support Nexus async completion in CHASM.

PS: completion-before-start will be handled in a follow-up PR.

How did you test it?

Potential risks

Is behind feature flag.

stephanos · 2026-04-15T19:11:51Z

 	"time"

 	"github.com/gorilla/mux"
 	"github.com/nexus-rpc/sdk-go/nexus"


Moved here from components; adjusted some of the names to fit into new package better.

stephanos · 2026-04-15T23:29:14Z

 	// When the request has nil headers, it should fall back to the local client.
+	var gotPath string
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		assert.Equal(t, commonnexus.PathCompletionCallbackNoIdentifier, r.URL.Path)


addressed linter error

stephanos · 2026-04-15T23:29:46Z

-				result:      result,
-				retryPolicy: h.config.RetryPolicy(),
-			})
-			return err


addressed linter error by moving out

stephanos · 2026-04-16T00:02:37Z

-	// user-agent header contains Nexus SDK client info in the form <sdk-name>/v<sdk-version>
-	headerUserAgent        = "user-agent"
-	clientNameVersionDelim = "/v"
-)


^ these already exist in temporal/service/frontend/nexus_handler.go

One step closer to eliminating the tech debt we created with the duplication of interceptors here.

stephanos · 2026-04-16T00:16:24Z

 }

-func (h *NexusHTTPHandler) parseTlsAndAuthInfo(r *http.Request, nc *nexusContext) (*http.Request, error) {
+func (h *NexusOperationHTTPHandler) parseTLSAndAuthInfo(r *http.Request, nc *nexusContext) (*http.Request, error) {


address linter error

stephanos · 2026-04-16T00:24:05Z

+			// The update may legitimately delete the addressed component, in which case
+			// there is no new ref to return even though the transition succeeded.
+			return nil, nil
+		}


I had to add this stopgap to make tests pass.

cc @yycptt if you have thoughts on this issue

LGTM, I think we just need to document chasm.UpdateComponent to mention that the returned ref could be nil if the component is not the root and it was deleted in the transaction.

ah make sense! Thanks!

bergundy

Overall this looks great.

JFYI (not blocking this PR), you're also missing the fallback to the "current" run. That's only relevant for workflow operations though. I think we'll need some special handling for the token for workflow. I think the archetype should be on the token and we can change the behavior based on that.

bergundy · 2026-04-16T20:36:46Z

-	fx.Invoke(EndpointRegistryLifetimeHooks),
 	fx.Provide(schedulerpb.NewSchedulerServiceLayeredClient),
-	nexusfrontend.Module,
+	chasmnexus.Module,


Isn't this supposed to be FrontendModule?

see https://github.com/temporalio/temporal/pull/9951/changes#r3089760669

Yes, on the feature branch we have FrontendModule and I'll change it there; didn't want to pull that change in here.

bergundy · 2026-04-16T20:38:31Z

-	// user-agent header contains Nexus SDK client info in the form <sdk-name>/v<sdk-version>
-	headerUserAgent        = "user-agent"
-	clientNameVersionDelim = "/v"
-)


One step closer to eliminating the tech debt we created with the duplication of interceptors here.

bergundy · 2026-04-16T20:40:50Z

 // CompleteOperation implements nexus.CompletionHandler.
 // nolint:revive // (cyclomatic complexity) This function is long but the complexity is justified.
-func (h *completionHandler) CompleteOperation(ctx context.Context, r *nexusrpc.CompletionRequest) (retErr error) {
+func (h *NexusCompletionHandler) CompleteOperation(ctx context.Context, r *nexusrpc.CompletionRequest) (retErr error) {


Does this struct need to be exported? I thought we only reference it from within the frontend package. (Same for the constructor, etc...)

I saw that NexusOperationHTTPHandler and OpenAPIHTTPHandler are exported, too, and matched that here for consistency. It can be unexported. I'll make the change.

bergundy · 2026-04-16T20:41:49Z


 	completion, err := h.CallbackTokenGenerator.DecodeCompletion(token)
-	if err != nil {
+	if err != nil || completion == nil {


Why would the completion be nil and the error not be nil? That seems unexpected behavior to me.

bergundy · 2026-04-16T22:49:35Z

+			}
+			namespaceID = ref.GetNamespaceId()
+			businessID = ref.GetBusinessId()
+		}


System isn't relevant here, it follows a separate path.

bergundy · 2026-04-16T22:51:23Z

+
+		namespaceID := completion.GetNamespaceId()
+		businessID := completion.GetWorkflowId()
+		if namespaceID == "" && len(completion.GetComponentRef()) > 0 {


I would put validation in DecodeCompletion to ensure that either the HSM fields are all present of component ref is not empty. We should never have both variations populated.

bergundy · 2026-04-16T22:52:13Z

+			namespaceID = ref.GetNamespaceId()
+			businessID = ref.GetBusinessId()


Let's verify that these aren't empty here.

bergundy · 2026-04-16T23:36:28Z

 	return TransitionTimedOut.Apply(o, ctx, EventTimedOut{})
 }

+func (o *Operation) HandleNexusCompletion(


Maybe put this next to saveInvocationResult because functionally there is a lot of overlap? And I would add a comment mentioning why these two separate methods exist. Ideally we'd have only one but I'd rather not spend time refactoring that right now. We can live with a bit of duplication here.

bergundy · 2026-04-16T23:49:12Z

+			// The update may legitimately delete the addressed component, in which case
+			// there is no new ref to return even though the transition succeeded.
+			return nil, nil
+		}


LGTM, I think we just need to document chasm.UpdateComponent to mention that the returned ref could be nil if the component is not the root and it was deleted in the transaction.

bergundy · 2026-04-16T23:51:18Z

-	callbackToken, err = gen.Tokenize(workflowNotFoundToken)
-	s.NoError(err)
-	completion.Header = nexus.Header{commonnexus.CallbackTokenHeader: callbackToken}
+	if !chasmEnabled {


You can have an equivalent token mutation test for the CHASM implementation though.

…-async-compl-1

stephanos force-pushed the stephanos/nexus-chasm-async-compl-1 branch 7 times, most recently from 8f06aca to de6a5b0 Compare April 15, 2026 04:20

stephanos changed the title ~~Nexus CHASM async completion~~ Nexus CHASM async completion (1/2) Apr 15, 2026

stephanos force-pushed the stephanos/nexus-chasm-async-compl-1 branch 2 times, most recently from af87649 to 34b5d4f Compare April 15, 2026 17:05

stephanos changed the base branch from main to stephanos/nexus-completion-refactor April 15, 2026 17:14

stephanos force-pushed the stephanos/nexus-chasm-async-compl-1 branch 6 times, most recently from 3a01f82 to 8254f69 Compare April 15, 2026 18:27

stephanos changed the base branch from stephanos/nexus-completion-refactor to main April 15, 2026 18:28

stephanos force-pushed the stephanos/nexus-chasm-async-compl-1 branch 10 times, most recently from ef6a516 to 597e8d2 Compare April 15, 2026 18:59

stephanos commented Apr 15, 2026

View reviewed changes

stephanos force-pushed the stephanos/nexus-chasm-async-compl-1 branch from 597e8d2 to 35c28a9 Compare April 15, 2026 19:17

stephanos commented Apr 15, 2026

View reviewed changes

stephanos force-pushed the stephanos/nexus-chasm-async-compl-1 branch 15 times, most recently from 1c5d51f to b6ee1e8 Compare April 15, 2026 23:58

stephanos commented Apr 16, 2026

View reviewed changes

Nexus CHASM async completion

22b3af4

stephanos commented Apr 16, 2026

View reviewed changes

yycptt approved these changes Apr 16, 2026

View reviewed changes

bergundy reviewed Apr 16, 2026

View reviewed changes

stephanos added 7 commits April 17, 2026 10:00

document UpdateComponent nil

be3b43a

don't export handler

ee60e7c

drop from if

ac7cc48

validateCompletion

049ba69

add chasm token mutation tests

8b063ff

move HandleNexusCompletion

0b08368

Merge remote-tracking branch 'origin/main' into stephanos/nexus-chasm…

a035aad

…-async-compl-1

		namespaceID = ref.GetNamespaceId()
		businessID = ref.GetBusinessId()

Conversation

stephanos commented Apr 14, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

What changed?

How did you test it?

Potential risks

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

stephanos Apr 16, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

bergundy left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

stephanos commented Apr 14, 2026 •

edited

Loading

stephanos Apr 16, 2026 •

edited

Loading