feat: enable C# emitter in playground with backend server by JoshLove-msft · Pull Request #10346 · microsoft/typespec

JoshLove-msft · 2026-04-12T18:40:03Z

Split emitter into emit-generate.ts (Node.js) and emit-generate.browser.ts (browser stub)
Browser stub POSTs code model to playground server for generation
Created .NET playground server (ASP.NET Core) that runs the generator
Added Dockerfile for containerized deployment
Pipeline: ACR build + App Service deployment with managed identity
Bundle upload to blob storage for browser-side emitter loading
Website: added C# to playground with server URL configuration
Fix: explicit ValueExpression conversion in spread expressions to prevent SIGSEGV when ParameterProvider is spread into ValueExpression collections

- Split emitter into emit-generate.ts (Node.js) and emit-generate.browser.ts (browser stub) - Browser stub POSTs code model to playground server for generation - Created .NET playground server (ASP.NET Core) that runs the generator - Added Dockerfile for containerized deployment - Pipeline: ACR build + App Service deployment with managed identity - Bundle upload to blob storage for browser-side emitter loading - Website: added C# to playground with server URL configuration - Fix: explicit ValueExpression conversion in spread expressions to prevent SIGSEGV when ParameterProvider is spread into ValueExpression collections Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

…ployment Only add new parameters (PlaygroundBundleBuildScript, PlaygroundServerDockerfile, PlaygroundServerAppName) and server deployment section. No changes to existing publish/ESRP pipeline logic. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

pkg-pr-new · 2026-04-12T18:42:17Z

Open in StackBlitz

npm i https://pkg.pr.new/@typespec/http-client-csharp@10346

commit: cf88a0a

github-actions · 2026-04-12T18:42:47Z

No changes needing a change description found.

JoshLove-msft · 2026-04-12T18:45:25Z

Will have a follow up PR for some UX enhancements to show a compiling spinner and change highlighting.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

azure-sdk · 2026-04-12T18:53:19Z

You can try these changes here

🛝 Playground	🌐 Website	🛝 VSCode Extension

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- Simplify pipeline: remove Azure resource creation (ACR, plan, webapp, identity) since resources already exist manually; keep only ACR build and App Service container update - Move server URL default into browser stub so website doesn't need to set globalThis.__TYPESPEC_PLAYGROUND_SERVER_URL__ - Add --no-restore to Dockerfile publish step (restore already done) - Add **/artifacts/ to .dockerignore - Add azure.github.io to CORS allowed origins Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- Test default and custom server URL - Test request body contains codeModel, configuration, generatorName - Test response files are written to host - Test error handling on non-OK response - Test empty files array Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

markcowl

I think we should be able to test changes using the typespec - PR Tools ci checks, so should update that workflow to ensure proper setup

…und-server

Remove default server URL from browser stub to prevent it from leaking to third-party sites. The URL must be explicitly set via globalThis.__TYPESPEC_PLAYGROUND_SERVER_URL__ by the host site. Moved the URL configuration back to the website playground. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

The server URL is hardcoded in the browser stub with no globalThis fallback. No configuration needed from the website. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

JoshLove-msft · 2026-04-13T22:48:35Z

I think we should be able to test changes using the typespec - PR Tools ci checks, so should update that workflow to ensure proper setup

Yes, that would capture the website changes, but the emitter changes would need to be published via the emitter pipeline.

The publish stage didn't set a Node version, defaulting to Node 20 on the agent. The bundle-uploader depends on asset-emitter which requires Node >=22. Added NodeTool@0 step before the bundle upload. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

The publish stage checks out fresh source with the original package.json version (e.g. 0.1.0). The bundle uploader reads this version for latest.json. Added a step to apply the build number (e.g. 0.1.0-beta.12345) before bundling, matching Build-Packages.ps1 behavior. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

ADO template parser was failing on the inline script. Use the auto-set BUILD_BUILDNUMBER environment variable instead of the macro syntax. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

C# emitter sets BuildPrereleaseVersion=true so gets -alpha tag, matching Build-Packages.ps1 behavior. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

timotheeguerin · 2026-04-14T17:53:58Z

is there any emitter option that allow users to run a post emitting script that would allow a playground user to basically run code on the server?

No, the closest thing is there an option to configure a plugin but the plugin would need to exist on the server.

Server-side (Program.cs): - Request size limit: 10 MB max body via Kestrel - Content-Type validation: must be application/json - JSON parse error handling: returns 400 on invalid JSON - Subprocess timeout: 5 minutes, kills process tree on timeout (504) - Security headers: X-Content-Type-Options, X-Frame-Options, Referrer-Policy Client-side (emit-generate.browser.ts): - Validate response content-type is application/json - Validate response shape: { files: Array<{ path, content }> } - Validate each file entry has string path and content Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Mock responses now include Headers with content-type to match the response validation added in the browser stub. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

markcowl · 2026-04-17T01:26:10Z

  }

-  const result: { files: Array<{ path: string; content: string }> } = await response.json();
+  const contentType = response.headers.get("content-type");


I'm wondering about a limit on response size? content-length is not a great way to police this, but not sure what size quotas are available to use

Added a Content-Length check against a 10 MB limit before parsing the response JSON. As you noted, Content-Length isn't always reliable, but it provides a reasonable guard against obviously oversized responses without buffering the entire body.

-- Generated by Copilot

Checks Content-Length header against a 10 MB limit before parsing the response JSON to protect against unexpectedly large responses. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

JoshLove-msft and others added 2 commits April 12, 2026 11:36

JoshLove-msft requested review from AlitzelMendez, ShivangiReja, bterlson, chrisradek, christothes, iscai-msft, jorgerangel-msft, joseharriaga, jsquire, m-nash, markcowl, srnagar, timotheeguerin and witemple-msft as code owners April 12, 2026 18:40

microsoft-github-policy-service bot added meta:website TypeSpec.io updates emitter:client:csharp Issue for the C# client emitter: @typespec/http-client-csharp eng labels Apr 12, 2026

JoshLove-msft commented Apr 12, 2026

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Comment thread ...erator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ScmMethodProviderCollection.cs

fix: restore plugin path resolution in emitter.ts

da56524

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

fix: prettier formatting, cspell words, lint cleanup

b07b370

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

fix: clarify browser stub comment

a6006ff

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

JoshLove-msft commented Apr 13, 2026

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Comment thread packages/http-client-csharp/playground-server/Program.cs

timotheeguerin reviewed Apr 13, 2026

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Comment thread eng/emitters/pipelines/templates/stages/emitter-stages.yml

Comment thread eng/emitters/pipelines/templates/stages/emitter-stages.yml Outdated

Comment thread website/src/components/playground-component/playground.tsx Outdated

jorgerangel-msft reviewed Apr 13, 2026

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Comment thread packages/http-client-csharp/playground-server/Dockerfile Outdated

Comment thread packages/http-client-csharp/.dockerignore

weshaggard reviewed Apr 13, 2026

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Comment thread eng/emitters/pipelines/templates/stages/emitter-stages.yml

JoshLove-msft and others added 3 commits April 13, 2026 10:00

style: format emit-generate.browser.ts

ef6e306

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

fix: add missing GenerateOptions properties in browser test

a7c273b

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

markcowl reviewed Apr 13, 2026

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Comment thread packages/http-client-csharp/emitter/src/emit-generate.browser.ts Outdated

JoshLove-msft and others added 3 commits April 13, 2026 15:39

Merge remote-tracking branch 'upstream/main' into feat/csharp-playgro…

01c4644

…und-server

fix: hardcode server URL in emitter, remove configurability

fadf720

The server URL is hardcoded in the browser stub with no globalThis fallback. No configuration needed from the website. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

JoshLove-msft and others added 5 commits April 13, 2026 15:52

fix: use BUILD_BUILDNUMBER env var in version stamp script

ed629d0

ADO template parser was failing on the inline script. Use the auto-set BUILD_BUILDNUMBER environment variable instead of the macro syntax. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

fix: use alpha/beta version tag based on BuildPrereleaseVersion

b4d53db

C# emitter sets BuildPrereleaseVersion=true so gets -alpha tag, matching Build-Packages.ps1 behavior. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

style: format emitter-stages.yml

700d1b1

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

timotheeguerin reviewed Apr 14, 2026

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JoshLove-msft force-pushed the feat/csharp-playground-server branch from c36f99a to 5cb4659 Compare April 15, 2026 02:37

fix: add headers to mock responses in browser stub tests

bd34a3c

Mock responses now include Headers with content-type to match the response validation added in the browser stub. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

markcowl reviewed Apr 17, 2026

View reviewed changes

feat: add response size limit check in browser emitter

cf88a0a

Checks Content-Length header against a 10 MB limit before parsing the response JSON to protect against unexpectedly large responses. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

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