Use Framework SourceType for WASM pass-through assets in multi-client solutions by lewing · Pull Request #125329 · dotnet/runtime

lewing · 2026-03-09T13:15:39Z

Summary

When multiple Blazor WebAssembly client projects reference the same runtime pack, pass-through files (JS, maps, ICU data, native wasm) share a NuGet cache path. This causes duplicate Identity keys in the static web assets pipeline, crashing DiscoverPrecompressedAssets with an ArgumentException on ToDictionary.

Root Cause

PR #124125 correctly changed WASM ContentRoot from project-specific OutputPath copies to per-item %(RootDir)%(Directory) (pointing to the real file in the NuGet cache). This fixed staleness on incremental builds. However, when two WASM client projects reference the same runtime pack, shared files like dotnet.js.map now resolve to identical NuGet cache paths, producing duplicate Identity values.

Fix

Use the SWA Framework SourceType convention (dotnet/sdk#53135) to let the SDK handle materialization, rather than manual Copy tasks:

DefineStaticWebAssets registers pass-through files with SourceType="Framework" (using their NuGet cache paths)
UpdatePackageStaticWebAssets materializes them to per-project obj/fx/{SourceId}/ directories, transforming metadata:
- SourceType → Discovered
- SourceId → project PackageId
- BasePath → project StaticWebAssetBasePath
- AssetMode → CurrentProject
- Identity → materialized file path (unique per project)

Asset classification:

Pass-through files (JS, maps, ICU, native wasm, DLLs when WebCil disabled): Framework → materialized by SDK task
WebCil-converted files: SourceType="Computed" (already per-project in obj/webcil/)

This eliminates manual Copy/culture-handling logic from Browser.targets and properly models the relationship: framework assets adopted by each consuming project.

Dependencies

Requires SDK support for SourceType="Framework" from dotnet/sdk#53135.

Testing

Validated with patched SDK (Framework SourceType + MaterializeFrameworkAsset) + Browser.targets:

aspnetcore Components.TestServer (3 WASM clients): ✅ Build succeeded
- WasmMinimal: 22 framework + 205 webcil files
- WasmRemoteAuthentication: 20 framework + 204 webcil files
- BasicTestApp: 29 framework + 218 webcil files
Multi-client build (2 WASM clients): ✅ Framework assets materialized per project
Multi-client publish: ✅ Both clients produce fingerprinted files
Incremental rebuild: ✅ Timestamp-based skip
WebCil disabled (WasmEnableWebcil=false): ✅

Fixes crash introduced by Fix WASM boot config ContentRoot to use IntermediateOutputPath #124125
Depends on Add Framework SourceType for static web assets sdk#53135 (Framework SourceType support)
Supersedes Use Framework SourceType for WASM pass-through assets in multi-client solutions #125309 (copy-based approach)

Copilot

Pull request overview

This PR fixes a crash introduced by PR #124125 in multi-client Blazor WebAssembly solutions. When two WASM client projects reference the same runtime pack, pass-through assets (JS, maps, ICU data, native WASM) previously resolved to identical NuGet cache paths, causing duplicate Identity keys that crashed DiscoverPrecompressedAssets with an ArgumentException during ToDictionary. The fix materializes pass-through files to a per-project obj/fx/{PackageId}/ directory using the SourceType="Framework" convention from the SWA SDK (requires dotnet/sdk#53135).

Changes:

New _WasmFrameworkAssetPath property (obj/fx/{PackageId}/) for materializing pass-through assets
Pass-through files are partitioned from WebCil-converted files and copied to the per-project obj/fx/{PackageId}/ path, registered with SourceType="Framework" via a new DefineStaticWebAssets call
Satellite (culture) framework assets are handled with culture subdirectories, matching the existing ConvertDllsToWebcil behavior

...nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targets

… solutions Multi-WASM-client solutions crash with duplicate Identity keys in DiscoverPrecompressedAssets because pass-through files (JS, maps, ICU, native wasm) share the same NuGet cache path across projects. Instead of manually copying pass-throughs, use the SWA Framework SourceType convention: DefineStaticWebAssets registers them as SourceType="Framework", then UpdatePackageStaticWebAssets materializes them to per-project obj/fx/{SourceId}/ directories, transforming metadata (SourceType→Discovered, SourceId→PackageId, AssetMode→CurrentProject) and giving each project a unique Identity. This approach: - Eliminates manual Copy tasks from Browser.targets - Leverages the SDK's MaterializeFrameworkAsset for timestamp-based incremental copies - Properly models the relationship: framework assets adopted by each consuming project - Works with and without WebCil enabled Depends on dotnet/sdk#53135 for Framework SourceType support in the SDK. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

lewing · 2026-03-09T17:51:18Z

This will fail until the sdk with the Framework source type makes it to runtime

...nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targets

lewing · 2026-03-13T22:55:17Z

waiting on #125419 now

Copilot

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

You can also share your feedback on Copilot code review. Take the survey.

lewing · 2026-03-14T17:17:14Z

@javiercn I know you have some follow-up planed to make this cleaner but it we need to get preview3 green asap, this is blocking dotnet/aspnetcore#65673

Copilot

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ConvertDllsToWebCil.cs

...nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targets

lewing

Addressing review feedback:

Comment accuracy (copilot-reviewer, line 419): Fixed — updated comment to accurately describe what UpdatePackageStaticWebAssets changes (SourceType, AssetMode, Identity/path remapping) without claiming SourceId→PackageId since both are already $(PackageId).

IsEnabled=false DLL handling (copilot-reviewer, line 67): Good point about the multi-client WasmEnableWebcil=false scenario. Currently when webcil is disabled, DLLs go through _WebcilAssetsCandidates as Computed with per-item ContentRoot, so Identity = their real NuGet cache path. In multi-client, this means two clients would get identical Identity for the same DLL — the original duplicate-Identity bug. However, this is the pre-existing behavior (before this PR, DLLs also went through the Computed path as-is). Fixing this properly requires routing shared DLLs through Framework materialization when IsEnabled=false, but the build targets Remove logic relies on DLLs being in WebcilCandidates for the publish path. I'll track this as a follow-up — the multi-client + NoWebcil combination is rare and the current PR doesn't regress it.

Output path clarification (@maraf, line 434): Updated comment to clarify — the materialized path is the intermediate one (obj/fx/{SourceId}/), and CopyToOutputDirectory=PreserveNewest causes the SDK to copy from there to bin/wwwroot/_framework/ at build time. UpdatePackageStaticWebAssets defaults CopyToOutputDirectory to Never, so without this override the framework files (dotnet.native.js, ICU data, etc.) don't make it to bin.

…ToOutputDirectory Two fixes: 1. ConvertDllsToWebcil: When IsEnabled=false, apply the same filtering for PassThroughCandidates as the enabled path — only non-DLL items without WasmNativeBuildOutput metadata qualify as Framework pass-throughs. Previously all candidates (including DLLs) were marked as pass-throughs, causing them all to go through Framework materialization which triggered NETSDK1147 workload detection in NoWebcil/NoWorkload test configurations. 2. Browser.targets: Set CopyToOutputDirectory=PreserveNewest on materialized framework assets after UpdatePackageStaticWebAssets. The SDK task defaults materialized assets to CopyToOutputDirectory= Never, but WASM framework files (dotnet.native.js, ICU data, etc.) must be copied to bin/wwwroot/_framework for the app to work. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ConvertDllsToWebCil.cs

Copilot

Pull request overview

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

Validates that two Blazor WASM client projects can be built by a single server project without duplicate static web asset Identity collisions. This is the scenario that the Framework SourceType + UpdatePackageStaticWebAssets materialization path was designed to fix. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ConvertDllsToWebCil.cs

Add a publish variant of the existing MultiClientHostedBuild test to validate that multi-client hosted Blazor WASM scenarios work correctly during publish, not just build. The test creates two WASM clients with different StaticWebAssetBasePath values hosted by a single server project and verifies dotnet publish succeeds without duplicate Identity crashes. This complements the build-time test added in dotnet#125329 and ensures the Framework SourceType materialization path produces per-project Identity values that survive through the publish pipeline. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot AI review requested due to automatic review settings March 9, 2026 13:15

lewing mentioned this pull request Mar 9, 2026

Use Framework SourceType for WASM pass-through assets in multi-client solutions #125309

Closed

github-actions bot added the area-Build-mono label Mar 9, 2026

dotnet-policy-service bot assigned lewing Mar 9, 2026

Copilot started reviewing on behalf of lewing March 9, 2026 13:16 View session

lewing mentioned this pull request Mar 9, 2026

Add Framework SourceType for static web assets dotnet/sdk#53135

Merged

Copilot AI reviewed Mar 9, 2026

View reviewed changes

...nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targets Outdated Show resolved Hide resolved

lewing force-pushed the fix-wasm-framework-sourcetype branch from 9b1f0a8 to 1c6e5b6 Compare March 9, 2026 14:01

lewing requested a review from maraf March 9, 2026 14:05

lewing mentioned this pull request Mar 9, 2026

Handle duplicate static web asset identities gracefully dotnet/sdk#53305

Open

This was referenced Mar 9, 2026

BlazorWasm AOT not requiring trimming #125233

Open

BlazorWasm_CannotAOT_InDebug test failure #125244

Open

maraf reviewed Mar 9, 2026

View reviewed changes

...nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targets Outdated Show resolved Hide resolved

...nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targets Outdated Show resolved Hide resolved

wtgodbe mentioned this pull request Mar 9, 2026

[main] Source code updates from dotnet/dotnet dotnet/aspnetcore#65673

Closed

lewing requested a review from javiercn March 10, 2026 18:49

Merge branch 'main' into fix-wasm-framework-sourcetype

91040a0

Copilot AI review requested due to automatic review settings March 14, 2026 15:15

lewing marked this pull request as ready for review March 14, 2026 15:15

lewing requested a review from akoeplinger as a code owner March 14, 2026 15:15

Copilot started reviewing on behalf of lewing March 14, 2026 15:16 View session

Copilot AI reviewed Mar 14, 2026

View reviewed changes

lewing assigned javiercn Mar 14, 2026

lewing assigned javiercn and unassigned lewing and javiercn Mar 14, 2026

build-analysis bot mentioned this pull request Mar 14, 2026

[browser] Wasm.Build.Tests timeout - Timed out after 10s waiting for 'WASM EXIT' #116697

Open

Copilot AI review requested due to automatic review settings March 24, 2026 17:04

lewing force-pushed the fix-wasm-framework-sourcetype branch from c45416b to 95cf3c0 Compare March 24, 2026 17:04

Copilot started reviewing on behalf of lewing March 24, 2026 17:05 View session

Copilot AI reviewed Mar 24, 2026

View reviewed changes

src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ConvertDllsToWebCil.cs Show resolved Hide resolved

maraf reviewed Mar 24, 2026

View reviewed changes

...nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targets Show resolved Hide resolved

lewing force-pushed the fix-wasm-framework-sourcetype branch from 95cf3c0 to a78c28f Compare March 24, 2026 18:47

lewing commented Mar 24, 2026

View reviewed changes

Copilot AI review requested due to automatic review settings March 24, 2026 18:50

lewing force-pushed the fix-wasm-framework-sourcetype branch from a78c28f to d92ebd8 Compare March 24, 2026 18:50

Copilot started reviewing on behalf of lewing March 24, 2026 18:51 View session

Copilot AI reviewed Mar 24, 2026

View reviewed changes

src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ConvertDllsToWebCil.cs Show resolved Hide resolved

lewing requested a review from ilonatommy as a code owner March 24, 2026 19:08

Copilot AI review requested due to automatic review settings March 24, 2026 19:16

lewing force-pushed the fix-wasm-framework-sourcetype branch from 712476d to cf505eb Compare March 24, 2026 19:16

Copilot started reviewing on behalf of lewing March 24, 2026 19:17 View session

Copilot AI reviewed Mar 24, 2026

View reviewed changes

lewing force-pushed the fix-wasm-framework-sourcetype branch from cf505eb to 62ab1d4 Compare March 24, 2026 19:23

Copilot AI review requested due to automatic review settings March 24, 2026 19:31

lewing force-pushed the fix-wasm-framework-sourcetype branch from 62ab1d4 to 7847a96 Compare March 24, 2026 19:31

Copilot started reviewing on behalf of lewing March 24, 2026 19:31 View session

Copilot AI reviewed Mar 24, 2026

View reviewed changes

src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ConvertDllsToWebCil.cs Show resolved Hide resolved

lewing merged commit 210efc0 into dotnet:main Mar 25, 2026
43 checks passed

lewing deleted the fix-wasm-framework-sourcetype branch March 25, 2026 01:01

dotnet-maestro bot mentioned this pull request Mar 25, 2026

[main] Source code updates from dotnet/runtime dotnet/dotnet#5691

Merged

This was referenced Mar 27, 2026

Fix WASM publish path for Framework SourceType materialization #126210

Closed

Add MultiClientHostedPublish test for WASM Framework materialization #126211

Open

Conversation

lewing commented Mar 9, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Summary

Root Cause

Fix

Dependencies

Testing

Related

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

lewing commented Mar 9, 2026

Uh oh!

Uh oh!

Uh oh!

lewing commented Mar 13, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

lewing commented Mar 14, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

lewing left a comment

Choose a reason for hiding this comment

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

6 participants

lewing commented Mar 9, 2026 •

edited

Loading