[browser] Apply COOP/COEP headers only when threads are enabled#118767
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maraf merged 1 commit intodotnet:mainfrom Aug 15, 2025
Merged
[browser] Apply COOP/COEP headers only when threads are enabled#118767maraf merged 1 commit intodotnet:mainfrom
maraf merged 1 commit intodotnet:mainfrom
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Pull Request Overview
This PR conditionally applies Cross-Origin Opener Policy (COOP) and Cross-Origin Embedder Policy (COEP) headers in WebAssembly applications based on the WasmEnableThreads setting. The changes ensure that these security headers, which are required for SharedArrayBuffer support in multi-threaded applications, are only applied when threading is actually enabled.
Key changes:
- Added a new command-line flag
--apply-cop-headersto control COOP/COEP header application - Modified build targets to conditionally pass the flag when
WasmEnableThreads=true - Updated host configuration to respect the new setting when configuring web server options
Reviewed Changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| src/mono/wasm/host/CommonConfiguration.cs | Adds ApplyCopHeaders property and --apply-cop-headers command-line option |
| src/mono/wasm/host/BrowserHost.cs | Updates web server configuration methods to use the new COOP/COEP setting conditionally |
| src/mono/wasm/build/WasmApp.Common.targets | Conditionally adds --apply-cop-headers argument when WasmEnableThreads=true |
| src/mono/nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targets | Same conditional logic for WebAssembly SDK projects |
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Tagging subscribers to 'arch-wasm': @lewing |
javiercn
approved these changes
Aug 15, 2025
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Apply COOP/COEP headers only when
WasmEnableThreads=truethe same as Blazor's DevServer does.Originally it was partially blocked by dotnet/sdk#32551, but that is resolved as well.
Fixes #109937