Fix TypeScript AppHost async callback deadlock by IEvangelist · Pull Request #17575 · microsoft/aspire

IEvangelist · 2026-05-28T03:02:19Z

Description

Fixes #17487.
Follow-up to #17508.

TypeScript AppHosts could still deadlock during await builder.build().run() when an async TypeScript callback was stored in lazy IOptions.Configure and invoked during BeforeStartEvent. PR #17508 fixed the dispatcher behavior for exports that already opt into RunSyncOnBackgroundThread, but the actual Aspire.Hosting/run capability was not opted in, so the real AppHost startup path could still run on StreamJsonRpc's non-concurrent synchronization context.

This changes DistributedApplication.RunAsync to export Aspire.Hosting/run with RunSyncOnBackgroundThread = true, keeping the synchronous startup portion of RunAsync off the JSON-RPC synchronization context. Existing TypeScript AppHosts can keep using:

await builder.build().run();

The PR also adds a CLI E2E regression that recreates the exact failure shape:

Creates a TypeScript empty AppHost.
Adds a local ATS extension whose exported method is marked RunSyncOnBackgroundThread = true.
Stores the TypeScript async configure callback inside lazy IOptions.Configure.
Resolves those options from BeforeStartEvent.
Verifies aspire start succeeds instead of timing out while waiting for the AppHost server.

Validation:

.\restore.cmd
dotnet build tests\Aspire.Cli.EndToEnd.Tests\Aspire.Cli.EndToEnd.Tests.csproj /p:SkipNativeBuild=true
Built a local Windows hive from this branch with .\localhive.ps1 -r win-x64 -Archive.
Manually ran the exact TypeScript lazy-options repro against that hive: aspire restore, npm run build, aspire start --format Json, and aspire stop. aspire start returned successfully in ~15s instead of timing out after 60s.

Checklist

Is this feature complete?
- Yes. Ready to ship.
- No. Follow-up changes expected.
Are you including unit tests for the changes and scenario tests if relevant?
- Yes
- No
Did you add public API?
- Yes
  - If yes, did you have an API Review for it?
    - Yes
    - No
  - Did you add <remarks /> and <code /> elements on your triple slash comments?
    - Yes
    - No
- No
Does the change make any security assumptions or guarantees?
- Yes
  - If yes, have you done a threat model and had a security review?
    - Yes
    - No
- No

Run the exported DistributedApplication.RunAsync capability on a background thread so startup callbacks invoked before the first await do not block StreamJsonRpc's non-concurrent synchronization context. Add an end-to-end TypeScript AppHost regression that recreates the lazy IOptions.Configure async callback pattern from #17487. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

github-actions · 2026-05-28T03:02:41Z

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.sh | bash -s -- 17575

Or

Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.ps1) } 17575"

Copilot

Pull request overview

This PR fixes a TypeScript AppHost startup deadlock by ensuring the exported Aspire.Hosting/run capability runs its synchronous startup path off the JSON-RPC synchronization context.

Changes:

Marks DistributedApplication.RunAsync with RunSyncOnBackgroundThread = true.
Adds a TypeScript CLI E2E regression test that reproduces lazy IOptions.Configure invoking an async ATS callback during BeforeStartEvent.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
`src/Aspire.Hosting/DistributedApplication.cs`	Opts the `run` ATS export into background-thread invocation.
`tests/Aspire.Cli.EndToEnd.Tests/TypeScriptEmptyAppHostTemplateTests.cs`	Adds regression coverage for the TypeScript lazy-options async callback deadlock scenario.

github-actions · 2026-05-28T12:04:26Z

❌ CLI E2E Tests failed — 106 passed, 2 failed, 2 unknown (commit 0bceda1)

❌ Failed Tests

Status	Test	Recording	Job	Artifacts
❌	CreateAndRunEmptyAppHostProject	Recording	#78284581886	Logs
❌	LatestCliCanStartStableChannelAppHost	Recording	#78284582589	Logs

View all recordings

Status	Test	Recording	Job	Artifacts
✅	AddPackageInteractiveWhileAppHostRunningDetached	Recording	#78284582335	Logs
✅	AddPackageWhileAppHostRunningDetached	Recording	#78284582335	Logs
✅	AgentCommands_AllHelpOutputs_AreCorrect	Recording	#78284582841	Logs
✅	AgentInitCommand_DefaultSelection_InstallsDefaultSkills	Recording	#78284582841	Logs
✅	AgentInitCommand_MigratesDeprecatedConfig	Recording	#78284582841	Logs
✅	AgentMcpListStructuredLogsReturnsLogsFromStarterApp	Recording	#78284583280	Logs
✅	AgentMcpListStructuredLogsReturnsLogsFromStarterApp_DevLocalhost	Recording	#78284583280	Logs
✅	AgentMcpListStructuredLogsReturnsLogsFromStarterApp_Isolated	Recording	#78284583280	Logs
✅	AllPublishMethodsBuildDockerImages	Recording	#78284582656	Logs
✅	AspireAddAndStartWorkAgainstLegacyAppHostTs	Recording	#78284583455	Logs
✅	AspireAddPackageVersionToDirectoryPackagesProps	Recording	#78284582561	Logs
✅	AspireInitSingleFileAppHostRunsViaDotnetRunAppHost	Recording	#78284582787	Logs
✅	AspireInitWithExistingAppHostDirRecreatesMissingNuGetConfigAndPreservesFiles	Recording	#78284582941	Logs
❔	AspireInitWithSolutionFileGeneratesAppHostThatBuildsAgainstChannelHive	Recording	#78284582941	Logs
✅	AspireStartUpdatesStaleTypeScriptAppHostPath	Recording	#78284583207	Logs
✅	AspireUpdateRemovesAppHostPackageVersionFromDirectoryPackagesProps	Recording	#78284582561	Logs
✅	AspireUpdateRemovesOrphanAppHostPackageVersionWhenSdkAlreadyCurrent	Recording	#78284582561	Logs
✅	Banner_DisplayedOnFirstRun	Recording	#78284583214	Logs
✅	Banner_DisplayedWithExplicitFlag	Recording	#78284583214	Logs
✅	Banner_NotDisplayedWithNoLogoFlag	Recording	#78284583214	Logs
✅	CertificatesClean_RemovesCertificates	Recording	#78284583298	Logs
✅	CertificatesTrust_WithNoCert_CreatesAndTrustsCertificate	Recording	#78284583298	Logs
✅	CertificatesTrust_WithUntrustedCert_TrustsCertificate	Recording	#78284583298	Logs
✅	ConfigSetGet_CreatesNestedJsonFormat	Recording	#78284582438	Logs
✅	CreateAndRunAspireStarterProject	Recording	#78284582589	Logs
✅	CreateAndRunAspireStarterProjectWithBundle	Recording	#78284583495	Logs
❌	CreateAndRunEmptyAppHostProject	Recording	#78284581886	Logs
✅	CreateAndRunJavaEmptyAppHostProject	Recording	#78284583068	Logs
✅	CreateAndRunJsReactProject	Recording	#78284582937	Logs
✅	CreateAndRunPythonReactProject	Recording	#78284582497	Logs
✅	CreateAndRunTypeScriptEmptyAppHostProject	Recording	#78284582111	Logs
✅	CreateAndRunTypeScriptStarterProject	Recording	#78284582664	Logs
✅	CreateJavaAppHostWithViteApp	Recording	#78284583116	Logs
✅	CreateTypeScriptAppHostWithViteApp_AllowsGuestAppPackageManagerToDiffer	Recording	#78284582050	Logs
✅	CreateTypeScriptAppHostWithViteApp_UsesConfiguredToolchain	Recording	#78284582050	Logs
✅	DashboardRunWithAgentMcpListTracesReturnsNoTraces	Recording	#78284582063	Logs
✅	DashboardRunWithAgentMcpListTracesReturnsNoTraces_DevLocalhost	Recording	#78284582063	Logs
✅	DashboardRunWithOtelTracesReturnsNoTraces	Recording	#78284582063	Logs
✅	DashboardRunWithOtelTracesReturnsNoTraces_DevLocalhost	Recording	#78284582063	Logs
✅	DeployK8sBasicApiService	Recording	#78284582400	Logs
✅	DeployK8sWithExternalHelmChart	Recording	#78284583487	Logs
✅	DeployK8sWithGarnet	Recording	#78284582341	Logs
✅	DeployK8sWithMongoDB	Recording	#78284582110	Logs
✅	DeployK8sWithMySql	Recording	#78284582520	Logs
✅	DeployK8sWithPostgres	Recording	#78284583291	Logs
✅	DeployK8sWithRabbitMQ	Recording	#78284583753	Logs
✅	DeployK8sWithRedis	Recording	#78284582579	Logs
✅	DeployK8sWithSqlServer	Recording	#78284582558	Logs
✅	DeployK8sWithValkey	Recording	#78284582986	Logs
✅	DeployTypeScriptAppToKubernetes	Recording	#78284583219	Logs
✅	DescribeCommandResolvesReplicaNames	Recording	#78284583348	Logs
✅	DescribeCommandShowsRunningResources	Recording	#78284583348	Logs
✅	DetachFormatJsonProducesValidJson	Recording	#78284583305	Logs
✅	DetachFormatJsonProducesValidJsonWhenRestartingExistingInstance	Recording	#78284583305	Logs
✅	DoPublishAndDeployListStepsWork	Recording	#78284582708	Logs
✅	DocsCommand_RendersInteractiveMarkdownFromLocalSource	Recording	#78284582397	Logs
✅	DoctorCommand_DetectsDeprecatedAgentConfig	Recording	#78284582841	Logs
✅	DoctorCommand_TypeScriptAppHostReportsMissingConfiguredToolchain	Recording	#78284583202	Logs
✅	DoctorCommand_WithSslCertDir_ShowsTrusted	Recording	#78284583202	Logs
✅	DoctorCommand_WithoutSslCertDir_ShowsPartiallyTrusted	Recording	#78284583202	Logs
✅	GatewayWithoutExternalEndpoint_FailsPublishWithGuidance	Recording	#78284583490	Logs
✅	GeneratedAspireDevScript_StartsWatchMode_WithConfiguredToolchain	Recording	#78284582050	Logs
✅	GlobalMigration_HandlesCommentsAndTrailingCommas	Recording	#78284582438	Logs
✅	GlobalMigration_HandlesMalformedLegacyJson	Recording	#78284582438	Logs
✅	GlobalMigration_PreservesAllValueTypes	Recording	#78284582438	Logs
✅	GlobalMigration_SkipsWhenNewConfigExists	Recording	#78284582438	Logs
✅	GlobalSettings_MigratedFromLegacyFormat	Recording	#78284582438	Logs
✅	IngressWithoutExternalEndpoint_FailsPublishWithGuidance	Recording	#78284583490	Logs
✅	InitTypeScriptAppHost_AugmentsExistingViteRepoInWorkspaceSubdirectory	Recording	#78284582050	Logs
✅	InteractiveCSharpInitCreatesExpectedFiles	Recording	#78284583164	Logs
✅	InvalidAppHostPathWithComments_IsHealedOnRun	Recording	#78284583255	Logs
✅	JavaScriptHostingApisRunFromTypeScriptAppHost	Recording	#78284582656	Logs
❌	LatestCliCanStartStableChannelAppHost	Recording	#78284582589	Logs
✅	LatestCliCanStartStableChannelTypeScriptAppHost	Recording	#78284582589	Logs
✅	LegacySettingsMigration_AdjustsRelativeAppHostPath	Recording	#78284583207	Logs
✅	LogsCommandShowsResourceLogs	Recording	#78284583315	Logs
✅	OtelLogsReturnsStructuredLogsFromStarterApp	Recording	#78284582946	Logs
✅	OtelLogsReturnsStructuredLogsFromStarterAppIsolated	Recording	#78284582946	Logs
✅	PsCommandListsRunningAppHost	Recording	#78284583702	Logs
✅	PsFormatJsonOutputsOnlyJsonToStdout	Recording	#78284583702	Logs
✅	PublishJavaScriptPatternsGeneratesExpectedDockerComposeArtifacts	Recording	#78284583344	Logs
✅	PublishWithConfigureEnvFileUpdatesEnvOutput	Recording	#78284583344	Logs
✅	PublishWithDockerComposeServiceCallbackSucceeds	Recording	#78284583344	Logs
✅	PublishWithoutOutputPathUsesAppHostDirectoryDefault	Recording	#78284583344	Logs
✅	ResourceCommand_FailedExecution_DisplaysAppHostLogPathAndLogContainsEntries	Recording	#78284582367	Logs
✅	ResourceCommand_SetAndDeleteParameterUpdatesDescribeOutput	Recording	#78284582367	Logs
✅	RestoreGeneratesSdkFiles	Recording	#78284582209	Logs
✅	RestoreGeneratesSdkFiles_WithConfiguredToolchain	Recording	#78284581996	Logs
✅	RestoreRefreshesGeneratedSdkAfterAddingIntegration	Recording	#78284581996	Logs
✅	RestoreSupportsConfigOnlyHelperPackageAndCrossPackageTypes	Recording	#78284583300	Logs
✅	RunFromParentDirectory_UsesExistingConfigNearAppHost	Recording	#78284583573	Logs
✅	RunReportsSyntaxErrorsForDotNetAppHost	Recording	#78284583400	Logs
✅	RunReportsSyntaxErrorsForTypeScriptAppHost	Recording	#78284583400	Logs
✅	SecretCrudOnDotNetAppHost	Recording	#78284583043	Logs
✅	SecretCrudOnTypeScriptAppHost	Recording	#78284582349	Logs
✅	StagingChannel_ConfigureAndVerifySettings_ThenSwitchChannels	Recording	#78284582374	Logs
✅	StartAndWaitForTypeScriptSqlServerAppHostWithNativeAssets	Recording	#78284582462	Logs
✅	StartReportsSyntaxErrorsForDotNetAppHost	Recording	#78284583400	Logs
✅	StartReportsSyntaxErrorsForTypeScriptAppHost	Recording	#78284583400	Logs
✅	StopAllAppHostsFromAppHostDirectory	Recording	#78284582084	Logs
✅	StopJavaPolyglotAppHostUsingApphostDirectory	Recording	#78284583120	Logs
✅	StopNonInteractiveSingleAppHost	Recording	#78284582084	Logs
✅	StopTypeScriptPolyglotAppHostUsingApphostDirectory	Recording	#78284582555	Logs
✅	StopWithNoRunningAppHostExitsSuccessfully	Recording	#78284582335	Logs
✅	TypeScriptAppHostRunDoesNotDeadlockWhenLazyOptionsInvokeAsyncCallback	Recording	#78284582111	Logs
✅	UnAwaitedChainsCompileWithAutoResolvePromises	Recording	#78284581996	Logs
❔	UpdateProjectChannelToStable_CSharpEmptyAppHost_PreservesAspireConfigChannel	Recording	#78284582944	Logs
✅	UpdateProjectChannelToStable_CSharpSingleFileInit_PreservesAspireConfigChannel	Recording	#78284582944	Logs
✅	UpdateProjectChannelToStable_TypeScriptSingleFileInit_PreservesAspireConfigChannel	Recording	#78284582944	Logs
✅	UpdateProjectChannelToStable_TypeScript_PreviewsStablePackagesAndPreservesChannel	Recording	#78284582944	Logs

_{📹 Recordings uploaded automatically from CI run #26552008600}

IEvangelist · 2026-05-28T14:31:11Z

PR Testing Report

PR Information

PR Number: Fix TypeScript AppHost async callback deadlock #17575
Title: Fix TypeScript AppHost async callback deadlock
Head Commit: 0bceda1
Tested At: 2026-05-28T14:13:53Z
Execution Target: Container workspace at C:\Users\dapine\AppData\Local\Temp\aspire-pr-test-983352d187fe466b962bd596f5164128

CLI Version Verification

Expected Commit: 0bceda1
Installed Version: 13.5.0-pr.17575.g0bceda1c
Status: Verified - installed PR CLI version contains 0bceda1c

Changes Analyzed

Files Changed

src/Aspire.Hosting/DistributedApplication.cs - changed Aspire.Hosting/run export to RunSyncOnBackgroundThread = true
tests/Aspire.Cli.EndToEnd.Tests/TypeScriptEmptyAppHostTemplateTests.cs - added TypeScript async callback deadlock regression coverage

Change Categories

Execution Environment Notes

The PowerShell container runner script failed under PowerShell Core because $IsWindows is a built-in read-only variable; retrying through Windows PowerShell avoided that issue.
The runner then remained stuck while rebuilding the existing aspire-pr-runner image at base-image metadata resolution, so I used the already-present aspire-pr-runner:latest image directly with the same /workspace and /workspace/.aspire mounts.
The container image did not include Node.js/npm or .NET SDK. I installed Node.js/npm in each scenario container and installed .NET SDK 10.0.300 into the isolated workspace at /workspace/.dotnet.

Test Scenarios Executed

Scenario 1: Simple TypeScript AppHost start/stop

Objective: Ensure the Aspire.Hosting/run export change does not break normal TypeScript empty AppHost startup.
Coverage Type: Happy path
Status: Passed

Steps:

Created aspire-ts-empty project SimpleTsSmoke from the PR hive.
Ran aspire restore --apphost apphost.mts.
Ran npm run build.
Ran aspire start --apphost apphost.mts --format Json.
Ran aspire stop --apphost apphost.mts.

Evidence:

Log: C:\Users\dapine\AppData\Local\Temp\aspire-pr-test-983352d187fe466b962bd596f5164128\scenario-1-simple-ts\scenario-output.txt
Start output: C:\Users\dapine\AppData\Local\Temp\aspire-pr-test-983352d187fe466b962bd596f5164128\scenario-1-simple-ts\start-output.json

Observations:

AppHost started successfully and returned dashboard metadata.
AppHost stopped successfully.

Scenario 2: TypeScript lazy-options async callback deadlock regression

Objective: Recreate the PR's deadlock shape: a TypeScript async callback stored in lazy IOptions.Configure, resolved during BeforeStartEvent, with await builder.build().run().
Coverage Type: Happy path / Regression
Status: Passed

Steps:

Created aspire-ts-empty project TsDeadlockRepro from the PR hive.
Added local DeadlockExtension C# ATS extension using [AspireExport(RunSyncOnBackgroundThread = true)].
Configured apphost.mts to set someProperty from an async TypeScript callback.
Added the local extension package to aspire.config.json.
Ran aspire restore --apphost apphost.mts.
Ran npm run build.
Ran timeout 240s aspire start --apphost apphost.mts --format Json.
Ran aspire stop --apphost apphost.mts.

Evidence:

Log: C:\Users\dapine\AppData\Local\Temp\aspire-pr-test-983352d187fe466b962bd596f5164128\scenario-2-deadlock-regression\scenario-output.txt
Start output: C:\Users\dapine\AppData\Local\Temp\aspire-pr-test-983352d187fe466b962bd596f5164128\scenario-2-deadlock-regression\start-output.json

Observations:

aspire start completed successfully instead of timing out.
The lazy options callback set the expected value and the AppHost stopped cleanly.

Scenario 3: Callback validation failure

Objective: Verify the same async callback/startup path fails safely when the callback produces invalid configuration.
Coverage Type: Unhappy path
Status: Passed

Steps:

Created aspire-ts-empty project TsDeadlockValidationFailure from the PR hive.
Added the same local DeadlockExtension validation as Scenario 2.
Configured apphost.mts to set someProperty to wrong-value.
Ran aspire restore --apphost apphost.mts.
Ran npm run build.
Ran timeout 240s aspire start --apphost apphost.mts --format Json and expected a non-zero exit.
Ran best-effort aspire stop --apphost apphost.mts.

Evidence:

Log: C:\Users\dapine\AppData\Local\Temp\aspire-pr-test-983352d187fe466b962bd596f5164128\scenario-3-validation-failure\scenario-output.txt
Start output: C:\Users\dapine\AppData\Local\Temp\aspire-pr-test-983352d187fe466b962bd596f5164128\scenario-3-validation-failure\start-output.txt

Expected Unhappy-Path Outcome: Clear startup failure/non-zero exit without hanging.

Observations:

aspire start exited with code 2, not a timeout.
Startup output included: Capability Error: Could not invoke 'run': Expected TypeScript callback to set someProperty, but got 'wrong-value'.

Summary

Scenario	Status	Notes
Version verification	Passed	Installed CLI version matched PR head `0bceda1c`
Simple TypeScript start/stop	Passed	Normal TypeScript AppHost startup still works
Deadlock regression	Passed	Async lazy-options callback path completed without timeout
Callback validation failure	Passed	Invalid callback value failed clearly with non-zero exit

Overall Result

PR VERIFIED

No issues found in the tested TypeScript AppHost async callback startup scenarios.

Artifacts

Install log: C:\Users\dapine\AppData\Local\Temp\aspire-pr-test-983352d187fe466b962bd596f5164128\install-output.txt
Version log: C:\Users\dapine\AppData\Local\Temp\aspire-pr-test-983352d187fe466b962bd596f5164128\version.txt
Prerequisite setup log: C:\Users\dapine\AppData\Local\Temp\aspire-pr-test-983352d187fe466b962bd596f5164128\prerequisites\prerequisites-output.txt
Scenario logs: C:\Users\dapine\AppData\Local\Temp\aspire-pr-test-983352d187fe466b962bd596f5164128\scenario-*\scenario-output.txt
Captured Aspire logs: C:\Users\dapine\AppData\Local\Temp\aspire-pr-test-983352d187fe466b962bd596f5164128\captured-aspire-logs\

IEvangelist · 2026-05-29T02:18:39Z

PR Testing Report

PR Information

PR Number: Fix TypeScript AppHost async callback deadlock #17575
Title: Fix TypeScript AppHost async callback deadlock
Head Commit: 0bceda1
Tested At: 2026-05-28T13:15:56Z

CLI Version Verification

Expected Commit: 0bceda1
Installed Version: 13.5.0-pr.17575.g0bceda1c
Status: ✅ Verified

Changes Analyzed

Files Changed

src/Aspire.Hosting/DistributedApplication.cs - Modified
tests/Aspire.Cli.EndToEnd.Tests/TypeScriptEmptyAppHostTemplateTests.cs - Modified

Change Categories

Test Scenarios Executed

PR CLI install/version verification

Objective: Install dogfood CLI and verify it matches PR head commit.
Coverage Type: Setup
Status: ✅ Passed

Steps:

Installed the dogfood CLI from the PR comment
Ran /workspace/.aspire/dogfood/pr-17575/bin/aspire --version
Compared output with the PR head commit

Evidence:

Log: /workspace/artifacts/install.log
Version: /workspace/artifacts/version.txt

Observations:
Installed CLI version contains expected commit 0bceda1.

TypeScript empty AppHost smoke test

Objective: Verify a fresh TypeScript empty AppHost from the PR hive can be created, restored, built, started, and stopped.
Coverage Type: Happy path
Status: ✅ Passed

Steps:

Created aspire-empty with --language typescript
Restored packages non-interactively
Ran npm run build
Ran aspire start with an explicit AppHost path
Ran aspire stop with an explicit AppHost path

Evidence:

Log: /workspace/artifacts/typescript-smoke.log

Observations:
Fresh TypeScript empty AppHost started and stopped successfully.

Async callback deadlock regression

Objective: Verify lazy options configured through an async TypeScript callback do not deadlock during AppHost startup.
Coverage Type: Happy path / Regression
Status: ✅ Passed

Steps:

Created a fresh TypeScript empty AppHost
Added a local C# extension package with an exported options callback
Configured the option from an async TypeScript callback
Restored packages and built the TypeScript AppHost
Started and stopped the AppHost with explicit AppHost paths

Evidence:

Log: /workspace/artifacts/async-callback-deadlock-regression.log

Observations:
Async TypeScript callback completed and aspire start returned successfully.

Async callback error propagation

Objective: Verify an async TypeScript callback failure exits safely with a clear error rather than hanging.
Coverage Type: Unhappy path
Status: ✅ Passed

Steps:

Created a fresh TypeScript empty AppHost
Added the same local exported C# extension package
Configured the TypeScript callback to throw asynchronously
Restored and built the AppHost
Ran aspire start and checked for non-zero exit plus the intentional error message

Evidence:

Log: /workspace/artifacts/async-callback-error-propagation.log

Observations:
aspire start exited non-zero and surfaced the intentional callback error.
Expected Unhappy-Path Outcome: A non-zero exit with intentional callback failure, no deadlock or timeout.

Summary

Scenario	Status	Notes
PR CLI install/version verification	✅ Passed	Installed CLI version contains expected commit `0bceda1`.
TypeScript empty AppHost smoke test	✅ Passed	Fresh TypeScript empty AppHost started and stopped successfully.
Async callback deadlock regression	✅ Passed	Async TypeScript callback completed and `aspire start` returned successfully.
Async callback error propagation	✅ Passed	`aspire start` exited non-zero and surfaced the intentional callback error.

Overall Result

✅ PR VERIFIED

Recommendations

No issues found in the tested scenarios.

aspire-repo-bot · 2026-05-29T19:35:35Z

✅ No documentation update needed.

docs_required → already documented by name

Triggered signal (1): pr_body_has_cli_flag_mention.

The signal fired because the PR body mentions aspire start --format Json in the manual validation section. This flag is already fully documented in the existing docs:

File: src/frontend/src/content/docs/reference/cli/commands/aspire-start.mdx
Quoted text: **\--format (Json|Table)`** — Output format for detached apphost results. Use `Json` for machine-readable output suitable for scripting and automation.(with an accompanying code example showingaspire start --format Json`)

The PR itself is a one-line bug fix (RunSyncOnBackgroundThread = true on RunAsync) plus a regression test. No new CLI flags, options, public APIs, or user-facing surface were introduced. The existing docs already describe the correct behavior for await builder.build().run() in TypeScript AppHosts.

sebastienros · 2026-05-29T21:12:55Z

/backport to release/13.4

github-actions · 2026-05-29T21:14:52Z

Started backporting to release/13.4 (link to workflow run)

Pulls in microsoft#17701 (Fix TypeScript deadlock repro E2E test) so PR GitHub Actions can complete. Main has been broken for PR events since microsoft#17575 added a test calling RunCommandFailFastAsync which microsoft#17588 renamed to RunCommandAsync. microsoft#17701 updates the call sites. No infra changes from this branch are affected by this merge. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot AI review requested due to automatic review settings May 28, 2026 03:02

IEvangelist requested review from JamesNK, danegsta, davidfowl, karolz-ms and mitchdenny as code owners May 28, 2026 03:02

Copilot started reviewing on behalf of IEvangelist May 28, 2026 03:02 View session

Copilot AI reviewed May 28, 2026

View reviewed changes

IEvangelist marked this pull request as draft May 28, 2026 11:45

github-actions Bot mentioned this pull request May 28, 2026

[repo-pulse] 📊 Repo Pulse — Daily Activity Dashboard #16404

Open

sebastienros approved these changes May 29, 2026

View reviewed changes

IEvangelist marked this pull request as ready for review May 29, 2026 14:26

IEvangelist merged commit 4cfc99d into main May 29, 2026
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IEvangelist deleted the ievangelist/dapine-test-cli-repro branch May 29, 2026 19:24

microsoft-github-policy-service Bot added this to the 13.5 milestone May 29, 2026

maddymontaquila mentioned this pull request May 29, 2026

main is red: RunCommandFailFastAsync used but undefined in TypeScriptEmptyAppHostTemplateTests (introduced by #17575) #17684

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aspire-repo-bot Bot mentioned this pull request May 29, 2026

[release/13.4] Fix TypeScript AppHost async callback deadlock #17689

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JamesNK mentioned this pull request May 29, 2026

Fix TypeScript deadlock repro E2E test #17701

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adamint mentioned this pull request May 29, 2026

Add Aspire CLI npm package release integration #17297

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Fix TypeScript AppHost async callback deadlock#17575

Fix TypeScript AppHost async callback deadlock#17575
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IEvangelist commented May 28, 2026

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IEvangelist commented May 28, 2026

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Pull request overview

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github-actions Bot commented May 28, 2026

❌ Failed Tests

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IEvangelist commented May 28, 2026

PR Testing Report

PR Information

CLI Version Verification

Changes Analyzed

Files Changed

Change Categories

Execution Environment Notes

Test Scenarios Executed

Scenario 1: Simple TypeScript AppHost start/stop

Scenario 2: TypeScript lazy-options async callback deadlock regression

Scenario 3: Callback validation failure

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IEvangelist commented May 29, 2026

PR Testing Report

PR Information

CLI Version Verification

Changes Analyzed

Files Changed

Change Categories

Test Scenarios Executed

PR CLI install/version verification

TypeScript empty AppHost smoke test

Async callback deadlock regression

Async callback error propagation

Summary

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aspire-repo-bot Bot commented May 29, 2026

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