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Move Microsoft.Extensions.Hosting closure to Microsoft.NETCore.App#4669

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Move Microsoft.Extensions.Hosting closure to Microsoft.NETCore.App#4669
Copilot wants to merge 35 commits intomainfrom
copilot/move-hosting-extensions-down

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Copilot AI commented Feb 5, 2026

Move Microsoft.Extensions.Hosting to Base Shared Framework

This PR moves Microsoft.Extensions.Hosting and its entire package closure from the ASP.NET Core shared framework (Microsoft.AspNetCore.App) to the base shared framework (Microsoft.NETCore.App).

Changes Completed:

  • Identify the complete package closure of Microsoft.Extensions.Hosting
  • Move 35 Microsoft.Extensions packages from AspNetCoreAppLibrary to NetCoreAppLibrary in /src/runtime/src/libraries/NetCoreAppLibrary.props
  • Add source generators to NetCoreAppLibraryGenerator list (Roslyn 4.4 only)
  • Remove Microsoft.Extensions packages from ASP.NET Core SharedFramework.External.props
  • Clean up generator references in Microsoft.Internal.Runtime.AspNetCore.Transport.proj
  • Update TestData.cs to remove moved packages from ASP.NET Core lists
  • Add package version overrides to PackageOverrides.txt
  • Remove explicit package references from 333 aspnetcore project files
  • Add conditional ProjectReferences for NetCoreAppCurrent to 70 Microsoft.Extensions projects
  • Verify no BCL packages are being moved
  • Code review and security scan completed

Packages Moved (35 total):

  • Caching (2): Abstractions, Memory
  • Configuration (10): Core, Abstractions, Binder, CommandLine, EnvironmentVariables, FileExtensions, Ini, Json, UserSecrets, Xml
  • DependencyInjection (2): Core, Abstractions
  • Diagnostics (2): Core, Abstractions
  • FileProviders (3): Abstractions, Composite, Physical
  • Other (4): FileSystemGlobbing, Hosting, Hosting.Abstractions, Http
  • Logging (7): Core, Abstractions, Configuration, Console, Debug, EventLog, EventSource, TraceSource
  • Options (3): Core, ConfigurationExtensions, DataAnnotations
  • Primitives (1): Core

Source Generators Added (3):

  • Microsoft.Extensions.Configuration.Binder.SourceGeneration
  • Microsoft.Extensions.Logging.Generators.Roslyn4.4
  • Microsoft.Extensions.Options.SourceGeneration

Files Modified Summary:

  1. src/runtime/src/libraries/NetCoreAppLibrary.props - Framework definitions
  2. src/aspnetcore/eng/SharedFramework.External.props - ASP.NET external references
  3. src/runtime/src/libraries/Microsoft.Internal.Runtime.AspNetCore.Transport/src/Microsoft.Internal.Runtime.AspNetCore.Transport.proj - Transport project cleanup
  4. src/aspnetcore/src/Framework/test/TestData.cs - Test expectations
  5. src/runtime/src/installer/pkg/sfx/Microsoft.NETCore.App/PackageOverrides.txt - Package versions
  6. 333 aspnetcore .csproj/.props/.targets - Removed redundant references
  7. 70 Microsoft.Extensions src/ref projects - Added build-time dependencies for shared framework

Impact:

Microsoft.NETCore.App now provides the complete Hosting stack. All Microsoft.Extensions projects correctly declare their dependencies for shared framework builds.

Original prompt

I'd like to move Microsoft.Extensions.Hosting and it's entire package closure down from the ASP.NET shared framework into the base shared framework. @dotnet/dotnet/pull/1204 and @dotnet/dotnet/pull/2234 did this for a single assembly and show the sort of changes required. I'd like to do this for all the extensions packages in Hosting's closure. In addition to moving the libraries down, we also need to move their source generators. We do not need to add any packages used for older frameworks (like Microsoft.BCL).


💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

…mework

Co-authored-by: ericstj <8918108+ericstj@users.noreply.github.com>
@dotnet-policy-service dotnet-policy-service bot requested review from a team February 5, 2026 01:09
Copilot AI changed the title [WIP] Move Microsoft.Extensions.Hosting and its closure to base shared framework Move Microsoft.Extensions.Hosting closure to Microsoft.NETCore.App Feb 5, 2026
Copilot AI requested a review from ericstj February 5, 2026 01:14
Comment thread src/runtime/src/libraries/NetCoreAppLibrary.props Outdated
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ericstj commented Feb 5, 2026

Update https://github.com/dotnet/dotnet/blob/main/src/aspnetcore/src/Framework/test/TestData.cs
Make sure to add entries to https://github.com/dotnet/dotnet/blob/main/src/runtime/src/installer/pkg/sfx/Microsoft.NETCore.App/PackageOverrides.txt

I suspect most references in project files and targets in https://github.com/dotnet/dotnet/blob/main/src/aspnetcore can be removed as there are no special cases for things that come from the base shared framework (like System.Runtime). I reviewed everything in this search https://github.com/search?q=repo%3Adotnet%2Fdotnet%20Microsoft.Extensions.Hosting%20path%3A%2Fsrc%2Faspnetcore%2F**%2F*%20language%3Axml&type=code and it all looks to me like it can be cleaned up.

I also see many other places across repos where tools or other components are built with PackageReferences to these while targeting the latest framework -- for instance

<PackageReference Include="Microsoft.Extensions.Logging.Console" />
. Some of these we can update now -- if the repository and project is building against the "live" targeting pack. If it's not, we'll have to wait for the the build to reboostrap. In either case we should see pruning warnings that tell us to clean up the references, so we might just wait to see those and iterate on them.

@copilot please address feedback.

…nsport proj, update test data, add package overrides

Co-authored-by: ericstj <8918108+ericstj@users.noreply.github.com>
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Copilot AI commented Feb 5, 2026

Update https://github.com/dotnet/dotnet/blob/main/src/aspnetcore/src/Framework/test/TestData.cs
Make sure to add entries to https://github.com/dotnet/dotnet/blob/main/src/runtime/src/installer/pkg/sf...

All addressed in 73ab4fb:

  • Updated TestData.cs to remove moved Microsoft.Extensions packages
  • Added 35 entries to PackageOverrides.txt with ${ProductVersion}
  • Cleaned up Microsoft.Internal.Runtime.AspNetCore.Transport.proj generator references

Left Dependencies.props as is per your comment about waiting for pruning warnings to identify what needs cleanup.

Copilot AI requested a review from ericstj February 5, 2026 01:47
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ericstj commented Feb 5, 2026

@copilot -- what about all the references in aspnetcore? https://github.com/search?q=repo%3Adotnet%2Fdotnet%20Microsoft.Extensions.Hosting%20path%3A%2Fsrc%2Faspnetcore%2F**%2F*%20language%3Axml&type=code These should all be cleaned up, along with any similar references to Extensions libraries which moved down. They'll all be automatically referenced since they are part of the base shared framework.

Remove explicit package references to Microsoft.Extensions packages that have been moved to the base shared framework (Microsoft.NETCore.App). These packages are now automatically referenced from the base framework.

Cleaned up 333 files across aspnetcore including:
- eng/Dependencies.props
- All .csproj, .props, and .targets files with references to moved packages

Packages with references removed (35 total):
- Caching: Abstractions, Memory
- Configuration: Core + 9 providers (Binder, CommandLine, EnvironmentVariables, FileExtensions, Ini, Json, UserSecrets, Xml, Abstractions)
- DependencyInjection: Core, Abstractions
- Diagnostics: Core, Abstractions
- FileProviders: Abstractions, Composite, Physical
- FileSystemGlobbing
- Hosting: Core, Abstractions
- Http
- Logging: Core + 6 providers (Abstractions, Configuration, Console, Debug, EventLog, EventSource, TraceSource)
- Options: Core, ConfigurationExtensions, DataAnnotations
- Primitives

Kept references for ASP.NET Core-specific packages not moved to base framework:
- Microsoft.Extensions.Diagnostics.Testing
- Microsoft.Extensions.Diagnostics.HealthChecks*
- Microsoft.Extensions.FileProviders.Embedded
- Microsoft.Extensions.Caching.Hybrid/SqlServer/StackExchangeRedis
- Microsoft.Extensions.Http.Polly
- Microsoft.Extensions.Logging.AzureAppServices
- Microsoft.Extensions.Configuration.KeyPerFile

Co-authored-by: ericstj <8918108+ericstj@users.noreply.github.com>
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Copilot AI commented Feb 5, 2026

@copilot -- what about all the references in aspnetcore? https://github.com/search?q=repo%3Adotnet%2Fdotnet%20Microsoft.Extensions.Hosting%20path%3A%2Fsrc%2Faspnetcore%2F**%2F*%20language%3Axml&type...

Fixed in 950e8af - removed explicit package references to all 35 moved Microsoft.Extensions packages from 333 aspnetcore project files. These packages are now automatically referenced from the base shared framework. Kept references only for ASP.NET Core-specific packages that weren't moved (Diagnostics.Testing, HealthChecks*, FileProviders.Embedded, Caching.Hybrid/SqlServer/StackExchangeRedis, Http.Polly, Logging.AzureAppServices, Configuration.KeyPerFile).

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wtgodbe commented Feb 5, 2026

Ooh, interesting - what was the motivation for this?

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ericstj commented Feb 5, 2026

Ooh, interesting - what was the motivation for this?

Reduce dependency bloat for libraries that rely on primitives like Microsoft.Extensions.Logging.Abstractions. This change would simplify dependency graphs, improve servicing, and reduce binary duplication in applications. I have a doc with data and measurements I'll share with you.

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ericstj commented Feb 5, 2026

@copilot -- it looks like you need to fix up all the Microsoft.Extensions projects in runtime. When a project becomes part of the shared framework it needs to declare all of its direct dependencies with ProjectReferences since it cannot rely on the pre-compiled targeting pack.

Have a look at

<ItemGroup Condition="'$(TargetFramework)' == '$(NetCoreAppCurrent)'">
<ProjectReference Include="$(LibrariesProjectRoot)System.Collections\src\System.Collections.csproj" />
<ProjectReference Include="$(LibrariesProjectRoot)System.Collections.Concurrent\src\System.Collections.Concurrent.csproj" />
<ProjectReference Include="$(LibrariesProjectRoot)System.Memory\src\System.Memory.csproj" />
<ProjectReference Include="$(LibrariesProjectRoot)System.Numerics.Vectors\src\System.Numerics.Vectors.csproj" />
<ProjectReference Include="$(LibrariesProjectRoot)System.Reflection.Emit.ILGeneration\src\System.Reflection.Emit.ILGeneration.csproj" />
<ProjectReference Include="$(LibrariesProjectRoot)System.Reflection.Emit.Lightweight\src\System.Reflection.Emit.Lightweight.csproj" />
<ProjectReference Include="$(LibrariesProjectRoot)System.Reflection.Primitives\src\System.Reflection.Primitives.csproj" />
<ProjectReference Include="$(LibrariesProjectRoot)System.Runtime\src\System.Runtime.csproj" />
<ProjectReference Include="$(LibrariesProjectRoot)System.Runtime.InteropServices\src\System.Runtime.InteropServices.csproj" />
<ProjectReference Include="$(LibrariesProjectRoot)System.Runtime.Intrinsics\src\System.Runtime.Intrinsics.csproj" />
<ProjectReference Include="$(LibrariesProjectRoot)System.Runtime.Loader\src\System.Runtime.Loader.csproj" />
<ProjectReference Include="$(LibrariesProjectRoot)System.Security.Cryptography\src\System.Security.Cryptography.csproj" />
<ProjectReference Include="$(LibrariesProjectRoot)System.Text.Encoding.Extensions\src\System.Text.Encoding.Extensions.csproj" />
<ProjectReference Include="$(LibrariesProjectRoot)System.Text.RegularExpressions\src\System.Text.RegularExpressions.csproj" />
<ProjectReference Include="$(LibrariesProjectRoot)System.Threading\src\System.Threading.csproj" />
</ItemGroup>
and
<ItemGroup Condition="'$(TargetFramework)' == '$(NetCoreAppCurrent)'">
<ProjectReference Include="$(LibrariesProjectRoot)System.Collections\ref\System.Collections.csproj" />
<ProjectReference Include="$(LibrariesProjectRoot)System.Collections.Concurrent\ref\System.Collections.Concurrent.csproj" />
<ProjectReference Include="$(LibrariesProjectRoot)System.Memory\ref\System.Memory.csproj" />
<ProjectReference Include="$(LibrariesProjectRoot)System.Runtime\ref\System.Runtime.csproj" />
</ItemGroup>
for examples.

You can determine which references to add by looking either looking at the assembly references present in the built binaries, or just iterate on adding to fix the build errors (might take a while). Try not to add any unnecessary dependencies.

You can do a lightweight build of these projects using /src/runtime/dotnet.sh build on individual projects. Once you're all done you can give your work a test using /src/runtime/build.sh libs to build all of the libraries.

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Copilot AI commented Feb 5, 2026

@copilot -- it looks like you need to fix up all the Microsoft.Extensions projects in runtime. When a project becomes part of the shared framework it needs to declare all of its direct dependencies w...

I understand the requirement. Adding conditional ProjectReferences for NetCoreAppCurrent to ~60 src/ref projects across 35 packages is a large task. Given the scope, would you prefer:

  1. I systematically add them project-by-project (will take time but ensures accuracy)
  2. An automated script approach (faster but needs careful validation)
  3. Start with a subset (e.g., the dependency tree roots like Primitives, then work up)

I can determine dependencies by analyzing existing PackageReferences and ProjectReferences in each project file. Should I proceed with option 1 or 3?

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ericstj commented Feb 5, 2026

@copilot If I were doing the task, I'd just write a script to dump simple name references of the file. For each simple name reference I'd ensure the project had a ProjectReference to represent that. After building one project you can actually find previously compiled versions of these files in the sdk that is downloaded.

Reference assemblies are in:
src/runtime/.dotnet/packs/Microsoft.AspNetCore.App.Ref/11.0.0-/ref/net11.0
src/runtime/.dotnet/shared/Microsoft.AspNetCore.App/11.0.0-

Just go at it to fix all of them at once.

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ericstj commented Feb 24, 2026

Testing this out with the changes to unblock roslyn.

@dotnet-policy-service dotnet-policy-service bot requested review from a team February 24, 2026 00:33
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ericstj commented Feb 26, 2026

Microsoft.Extensions.Logging.Debug namespace causing name resolution issues.

Between System.Diagnostics.Debug and Microsoft.Extensions.Logging.Debug
@dotnet-policy-service dotnet-policy-service bot requested a review from a team February 26, 2026 19:43
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ericstj commented Feb 26, 2026

Woohoo! Made it through product build + phase1 source build!

The next set of failures are phase2 pruning errors. We could remove those package references for source-build but it will break non-source build which still uses the older targeting packs.

@ViktorHofer -- what do you think about disabling pruning warnings in phase 2 and deferring those fixes for backflow/rebootstrapping when they can be done without a sourcebuild-only condition?

Additionally -- for other reasons I'm planning to change the scope of this PR to only a few assemblies. I wanted to take this one as far as I could, but I think now is a good point to switch to the smaller assembly set.

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agocke commented Feb 27, 2026

Isn't this going to increase the size of netcoreapp?

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Will we have an announcement about this? It's a significant change.

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@ViktorHofer -- what do you think about disabling pruning warnings in phase 2 and deferring those fixes for backflow/rebootstrapping when they can be done without a sourcebuild-only condition?

Whatever we do here, let's find a solution that works in the future as well when additional assemblies get absorbed into the shared framework. There are three layers in play here for which I have different perspectives:

Shared framework repositories

These should use have a live PackageOverrides.txt file available at restore time and hand to that the sdk via the PrunePackageTargetingPackRoots property that Daniel exposed for us. For aspnetcore these means producing the PackageOverrides.txt file in their GenerateFiles step that runs before restore. For runtime, I would avoid such an approach as it creates an up-front dependency (which is fine for aspnetcore as they already require that but for runtime which is finally able to restore and build without any upfront steps, that would be unfortunate). Honestly, I would just check the PackageOverrides.txt file into the source tree and automatically keep it up-to-date via the already existing build task.

This will ensure that in both stage1 and stage2, packages that get absorbed into the shared framework can be removed.

Btw, shared framework repos should now also opt into LoadPrunePackageDataFromNearestFramework for a smoother migration to the next TFM.

Downstream repositories (which depend on runtime assets)

With your other change, all downstream repositories that depend on runtime assets now use the live targeting pack and with that receive the live PackageOverrides.txt file. So, in both stage1 and stage2 the packages can be removed when targeting the latest TFM.

Repositories that build before runtime (and depend on runtime assets)

That's the layer that is currently failing in this PR. There's not a good for answer for those, IMO. Conditionally referencing the packages based on stage1 vs stage2 creates a rift that the source-build team always tries to avoid. To be clear, the repositories affected are the VMR orchestrator and (transitive) runtime repo dependencies: SBRP, Arcade, command-line-api and cecil.

Disabling package pruning in stage2 and then later after a re-bootstrap re-enabling it is an option. That's quite manual though. We could also add NU1510 to WarningsNotAsErrors in these few repos as there doesn't seem to be any impact. IIRC NuGet already marks these as PrivateAssets and ExcludeAssets. Showing a warning is sufficient. That setting could be conditionally applied on building inside the VMR even.

Hope that helps...

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ericstj commented Mar 3, 2026

Isn't this going to increase the size of netcoreapp?

Yes for the runtimepacks - however corresponding aspnet packs will shrink by the same amount. The total size of CLI install will decrease due to removal of duplicate assemblies in the SDK and tools. No change for folks who enable linker and don't use anything in these packages. Still it's a growth for some who don't use the linker nor use these packages today. A tradeoff. The same folks see growth for every feature we add to the framework. As I mentioned I'm adjusting the scope - I kept this PR going to get to the end of onion peeling and understand the changes needed to make these types of breaks in the VMR.

Will we have an announcement about this? It's a significant change.

Of course. I've been talking about this change in our internal backlog reviews for nearly 6 months now.

These should use have a live PackageOverrides.txt file available at restore time and hand to that the sdk via the PrunePackageTargetingPackRoots property that Daniel exposed for us.
So, in both stage1 and stage2 the packages can be removed when targeting the latest TFM.

I'm not sure they do. I think they only have those after restore since the SDK will go down the PackageDownload route for acquiring the targeting packs. The only reason we see this in early repos in phase2 is that those are the very first repos that build with the new targeting pack before restore (and thus with pruning data).

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ViktorHofer commented Mar 3, 2026

The total size of CLI install will decrease due to removal of duplicate assemblies in the SDK and tools

The sdk is now constructed via symlinks. @MichaelSimons can provide more details

I'm not sure they do. I think they only have those after restore

That comment was for shared framework repos. They construct a live PackageOverrides.txt file and it would be ideal of that would already be available at repo restore time.

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The total size of CLI install will decrease due to removal of duplicate assemblies in the SDK and tools

The sdk is now constructed via symlinks. @MichaelSimons can provide more details

See the deduplication one pager for details. FYI, the implementation is currently scoped to content within the sdk folder.

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agocke commented Mar 3, 2026

I don’t understand: what is the plan for users of self-contained apps with no ASP reference? How can they avoid a regression?

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ericstj commented Mar 3, 2026

Symlinks won't accomplish the same things since the SDK will not symlink to the ASP.NET shared framework (binaries might even differ due to crossgen differences). It'd still carry copies of things app-local. Also those can't be represented in the Zip, nor in MSIs (unless we're talking about adding custom actions here). I see @MichaelSimons paper calls this out. Net-net even in light of deduplication efforts (which are great!) moving these down will still reduce the size of the SDK -- just as it will reduce the size of folks building non-ASP.NET fx-dependent applications using ME, Aspire, MEAI, etc.

That comment was for shared framework repos. They construct a live PackageOverrides.txt file and it would be ideal of that would already be available at repo restore time.

I see - so consumption of the same shared framework built in that repo. I'm not worried about that for this change since we already handle minimizing references to things in runtime built against shared framework. I don't expect many hits on those.

You also mentioned downstream repos -- I don't see a way to have them pick up live pruning data unless we do a "pre-restore" of the targeting packs, or explicitly stage those into the SDK's packs folder. This feels like too much complexity for something that we can just "no-warn" and peel off into follow up PR.

I'll see how much of a problem this actually is after reducing the set as I've already mentioned.

I don’t understand: what is the plan for users of self-contained apps with no ASP reference? How can they avoid a regression?

@agocke as I've mentioned it's a tradeoff. Any feature addition to the framework grows the size of the framework for people not using that feature. Where does the line get drawn? For folks who really care about size we have the linker. Everything moved here would be linked out if not used. We don't have promises around the size of self-contained apps that don't use the linker between major versions of a release. They see growth (regression) with pretty much every release.

Size of self-contained hello-world across different framework versions

Target Framework linux-x64 win-x64
netcoreapp2.1 70.7 MB (184 files) 65.34 MB (217 files)
netcoreapp3.1 74.89 MB (191 files) 65.75 MB (225 files)
net5.0 72.11 MB (186 files) 65.11 MB (225 files)
net6.0 69.04 MB (184 files) 68.72 MB (227 files)
net7.0 71.49 MB (187 files) 69.61 MB (187 files)
net8.0 70.56 MB (187 files) 70.56 MB (187 files)
net9.0 75.97 MB (189 files) 74.38 MB (189 files)
net10.0 78.76 MB (192 files) 76.99 MB (192 files)

Reducing the size/technology-count/build-reference-count growth was one of the reasons I mentioned above that I'm dialing this back since I don't think all the side-effects outweighed the benefits. I've been more concerned with the build perf and technology prolifieration since folks can mitigate runtime pack size growth with linker -- but you are right to raise it as it does impact some. The size of the a few of the options being considered is as follows - measuring cross-gened size for RIDs, app-local files for IL, counts are runtime files but are mostly of the same order as reference files.

Size of proposed assembly set moves

Group linux-x64 win-x64 IL size
Hosting-closure (30 references) 2.3 MB (31 files) 3.7 MB (32 files) 2.3 MB (33 files)
Abstractions (9 references) 698 KB (9 files) 793 KB (9 files) 412 KB (9 files)
DI/Logging/Options Abstractions (4 references) 468 KB (4 files) 509 KB (4 files) 239 KB (4 files)
DI/Logging Abstractions (2 references) 269 KB (2 files) 289 KB (2 files) 131 KB (2 files)

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ericstj commented Mar 3, 2026

I'm going to close this PR and move discussion to the issue on this. dotnet/runtime#67487

@ericstj ericstj closed this Mar 3, 2026
@akoeplinger akoeplinger deleted the copilot/move-hosting-extensions-down branch March 17, 2026 17:20
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