Fix StaticWebAssets FUTDC not tracking referenced project changes by oroztocil · Pull Request #53426 · dotnet/sdk

oroztocil · 2026-03-12T22:24:04Z

Problem

When a Blazor Web App with WebAssembly + Global interactivity has a .razor.css file modified in the Client project, the Server project's build is skipped by VS's Fast Up-to-Date Check (FUTDC). The Server's .staticwebassets.endpoints.json manifest retains stale fingerprints and ETags, causing the app to fail at runtime with "An unhandled error has occurred."

Fixes #53425
Fixes dotnet/aspnetcore#65738

Investigation

See #53425 for the analysis of the problem.

Change

`Microsoft.NET.Sdk.StaticWebAssets.Design.targets`

Added ResolveReferencedProjectsStaticWebAssetsConfiguration to CollectUpToDateCheckInputDesignTimeDependsOn. This ensures the references file is written during design-time evaluation, before CollectStaticWebAssetInputsDesignTime tries to read it.

`Microsoft.NET.Sdk.StaticWebAssets.References.targets`

Changed Overwrite="false" to Overwrite="true" on the WriteLinesToFile call. The file is fully populated from @(_ReferenceManifestPath) on each build, so there is no need to append. The existing WriteOnlyWhenDifferent="true" attribute ensures the file timestamp only changes when the content actually differs, preserving correct FUTDC behavior.

Risk

ResolveReferencedProjectsStaticWebAssetsConfiguration calls GetStaticWebAssetsProjectConfiguration on referenced projects, which is a metadata-only call (it does not resolve actual assets). The expensive ResolveReferencedProjectsStaticWebAssets target is not added to the design-time chain.

dotnet-policy-service · 2026-03-12T22:24:40Z

Thanks for your PR, @@oroztocil.
To learn about the PR process and branching schedule of this repo, please take a look at the SDK PR Guide.

Copilot

Pull request overview

This PR fixes a Visual Studio Fast Up-to-Date Check (FUTDC) design-time timing issue in Static Web Assets for Blazor solutions with referenced projects, ensuring referenced-project changes (e.g., scoped CSS outputs) are correctly tracked so stale endpoint manifests aren’t reused at runtime.

Changes:

Adds ResolveReferencedProjectsStaticWebAssetsConfiguration to the design-time FUTDC input dependency chain so the referenced-projects UTDC manifest file is generated before it is read.

Copilot · 2026-03-12T22:27:02Z

src/StaticWebAssetsSdk/Targets/Microsoft.NET.Sdk.StaticWebAssets.Design.targets

      $(CollectUpToDateCheckInputDesignTimeDependsOn);
      ResolveStaticWebAssetsConfiguration;
      ResolveProjectStaticWebAssets;
+      ResolveReferencedProjectsStaticWebAssetsConfiguration;


Adding ResolveReferencedProjectsStaticWebAssetsConfiguration to the design-time FUTDC input chain means this target will now run frequently during design-time builds. That target currently writes $(StaticWebAssetReferencesUpToDateCheckManifestPath) using WriteLinesToFile with Overwrite="false" (append) in Microsoft.NET.Sdk.StaticWebAssets.References.targets, which can cause the manifest file to grow with duplicate/stale entries across repeated evaluations and potentially degrade FUTDC performance. Consider adjusting the referenced target to overwrite (or otherwise de-dupe) the file when it is generated during design-time evaluation so the tracked inputs remain bounded and accurate.

Suggested change

ResolveReferencedProjectsStaticWebAssetsConfiguration;

I wanted to have this change as a separate PR (as it is an independent problem, only made more noticeable by the primary fix here). However, added it to this PR.

src/StaticWebAssetsSdk/Targets/Microsoft.NET.Sdk.StaticWebAssets.Design.targets

Copilot

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

test/Microsoft.NET.Sdk.StaticWebAssets.Tests/StaticWebAssetsDesignTimeTest.cs

Copilot

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

The design-time target CollectStaticWebAssetInputsDesignTime reads referenced project build manifest paths from staticwebassets.references.upToDateCheck.txt. However, this file is written by the build-time target ResolveReferencedProjectsStaticWebAssetsConfiguration, which has not run yet when VS evaluates the design-time dependency chain on initial project load. The file does not exist, the read is skipped, and VS CPS caches the empty result. Subsequent builds create the file but the design-time cache is never invalidated. This causes the Server project's FUTDC to miss changes in referenced projects' static web assets (e.g. scoped CSS bundles), skipping the Server rebuild and leaving stale fingerprints in the endpoints manifest. Fix by adding ResolveReferencedProjectsStaticWebAssetsConfiguration to CollectUpToDateCheckInputDesignTimeDependsOn so the references file is written during design-time evaluation. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

WriteLinesToFile in ResolveReferencedProjectsStaticWebAssetsConfiguration uses Overwrite=false, which appends referenced project manifest paths on every build instead of replacing the file contents. This causes the file to grow indefinitely with duplicate entries. Change to Overwrite=true. The WriteOnlyWhenDifferent=true attribute is already set, so the file timestamp will only change when the content actually differs. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Add a regression test that exercises the design-time FUTDC input collection on a clean obj folder (no prior build). This covers the scenario where VS evaluates FUTDC inputs on initial project load before any build has occurred. The existing test CollectUpToDateCheckInputOutputsDesignTime_IncludesReferencedProjectsManifests runs a full build first, so staticwebassets.references.upToDateCheck.txt already exists when the design-time targets read it. The new test skips the prior build and invokes the design-time targets directly, asserting that referenced project manifest paths are still included in UpToDateCheckInput. This would fail without the fix in Design.targets that adds ResolveReferencedProjectsStaticWebAssetsConfiguration to the design-time dependency chain. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot AI review requested due to automatic review settings March 12, 2026 22:24

github-actions bot added the Area-AspNetCore RazorSDK, BlazorWebAssemblySDK, StaticWebAssetsSDK label Mar 12, 2026

Copilot started reviewing on behalf of oroztocil March 12, 2026 22:24 View session

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oroztocil marked this pull request as draft March 12, 2026 22:31

Copilot AI mentioned this pull request Mar 12, 2026

[WIP] [WIP] Address feedback on test for StaticWebAssets FUTDC project changes #53427

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oroztocil requested a review from Copilot March 12, 2026 22:57

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oroztocil force-pushed the oroztocil/staticwebassets-futdc branch from 4a344b4 to 673b001 Compare March 12, 2026 23:09

oroztocil requested a review from Copilot March 12, 2026 23:10

Copilot started reviewing on behalf of oroztocil March 12, 2026 23:11 View session

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oroztocil and others added 3 commits March 13, 2026 01:05

oroztocil force-pushed the oroztocil/staticwebassets-futdc branch from 673b001 to 1e478f0 Compare March 13, 2026 00:13

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Fix StaticWebAssets FUTDC not tracking referenced project changes#53426

Fix StaticWebAssets FUTDC not tracking referenced project changes#53426
oroztocil wants to merge 3 commits intomainfrom
oroztocil/staticwebassets-futdc

oroztocil commented Mar 12, 2026 •

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oroztocil commented Mar 12, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Problem

Investigation

Change

Microsoft.NET.Sdk.StaticWebAssets.Design.targets

Microsoft.NET.Sdk.StaticWebAssets.References.targets

Risk

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oroztocil commented Mar 12, 2026 •

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`Microsoft.NET.Sdk.StaticWebAssets.Design.targets`

`Microsoft.NET.Sdk.StaticWebAssets.References.targets`