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Azure Functions isolated worker ​

Use the isolated worker's ASP.NET Core integration with ConfigureFunctionsWebApplication(), HttpRequest, and IActionResult. Return Rivet terminals through the first-party .ToActionResult() adapter. No custom Rivet bridge or separate Functions response framework is required.

The runnable samples/FunctionsApi project targets .NET 10 and Core Tools v4. It serves two binary representations and a declared JSON error without Azure credentials or storage. From the repository root:

bash
dotnet build samples/FunctionsApi/FunctionsApi.csproj
cd samples/FunctionsApi
FUNCTIONS_WORKER_RUNTIME=dotnet-isolated func start
# GET http://localhost:7071/api/images/png
# GET http://localhost:7071/api/images/jpeg
# GET http://localhost:7071/api/images/gif -> declared 404

Routes have two representations ​

A Functions trigger route is relative, with no leading slash. The OpenAPI route is the complete public path, including the configured HTTP prefix and a leading slash. Own both constants in the contract:

csharp
public const string TriggerRoute = "images/{format}";
public const string Route = "/api/" + TriggerRoute;

Use TriggerRoute in [HttpTrigger(..., Route = ImagesContract.TriggerRoute)] and Route in Define.File<ImageInput>(Route). Do not pass the complete OpenAPI path straight into the trigger attribute. With ASP.NET integration, a leading slash can produce incorrect host routing even when spec generation succeeds.

The default prefix is api. To remove it:

json
{
  "version": "2.0",
  "extensions": { "http": { "routePrefix": "" } }
}

Then the contract path is "/" + TriggerRoute. For routePrefix: "public/v1", it is "/public/v1/" + TriggerRoute. Keep the contract and deployment configuration aligned. If Route is omitted, Functions uses the function name.

Check the implementation and the running host ​

bash
dotnet run --project Rivet.Tool/Rivet.Tool.csproj -- \
  --project samples/FunctionsApi/FunctionsApi.csproj --check

Coverage recognizes [Function] plus [HttpTrigger] methods returning a contract terminal through .ToActionResult(). It checks the HTTP method and effective route, and rejects leading slashes in trigger routes. With a project input, it reads the sibling host.json; a missing prefix uses api, while an empty prefix stays empty. The environment variable AzureFunctionsJobHost__extensions__http__routePrefix takes precedence, matching the Functions host override convention. Invalid configuration fails the check. Raw source-file analysis has no project host file and uses the default prefix unless that environment override is set.

--check without --output is the failing coverage gate. --verify checks generated-spec drift, not routing. Neither runs the host or discovers remote deployment settings. Use the same configuration when checking and deploying.

From this source checkout, run:

bash
task test:functions

This launches Core Tools against disposable sample builds and checks actual HTTP bytes, content types, a declared JSON error, and HTTP method rejection. It also checks emitted OpenAPI and coverage for default, empty and custom prefixes. The test requires .NET 10, Core Tools v4, and Python 3; missing prerequisites fail with an actionable message. It does not require Docker or an Azure subscription.

Select a declared binary representation ​

csharp
var endpoint = ImagesContract.Download.Bind(new ImageInput(format));
return endpoint.File(bytes, contentType: actualMimeType).ToActionResult();

Declare every permitted MIME type on the contract. Rivet rejects an undeclared selection, and rejects an omitted selection when more than one binary success representation exists. Selection does not inspect or convert the file bytes.

The MIME selector and configurable-prefix coverage are additions in this source checkout; use packages built from this revision until a release includes them.