Allow original-uri final state for POST operations and warn on missing GET

.chronus/changes/allow-original-uri-post-operations-2026-04-17-02-40-00.md

@@ -0,0 +1,7 @@
+---
+changeKind: feature
+packages:
+  - "@azure-tools/typespec-azure-core"
+---
+
+Allow `original-uri` final state via for POST operations in addition to PUT and PATCH. When `@useFinalStateVia("original-uri")` is specified and there is no GET operation at the original URI, a `no-operation-at-original-uri` warning diagnostic is emitted and the final result is treated as `void`.

packages/typespec-azure-core/src/decorators/use-final-state-via.test.ts

@@ -47,17 +47,18 @@ it("emits error for missing header", async () => {
     message: `There was no header corresponding to the desired final-state-via value 'location'.`,
   });
 });
-it("emits error for original-uri on non-PUT request", async () => {
+it("emits error for original-uri on non-PUT/PATCH/POST request", async () => {
   const diagnostics = await Tester.diagnose(`
     @pollingOperation(bar)
     @useFinalStateVia("original-uri")
-    @post op foo(): {};
+    @delete op foo(): {};
 
     @route("/polling")
     @get op bar(): {status: "Succeeded" | "Failed" | "Cancelled"};
   `);
   expectDiagnostics(diagnostics, {
     code: "@azure-tools/typespec-azure-core/invalid-final-state",
-    message: "The final state value 'original-uri' can only be used in http PUT operations",
+    message:
+      "The final state value 'original-uri' can only be used in http PUT, PATCH, or POST operations",
   });
 });

packages/typespec-azure-core/src/lib.ts

@@ -43,10 +43,18 @@ export const $lib = createTypeSpecLibrary({
       severity: "warning",
       messages: {
         badValue: paramMessage`Specified final state value '${"finalStateValue"}' is not valid. It must be one of ("operation-location", "original-uri", "location", "azure-async-operation")`,
-        notPut: "The final state value 'original-uri' can only be used in http PUT operations",
+        notPut:
+          "The final state value 'original-uri' can only be used in http PUT, PATCH, or POST operations",
         noHeader: paramMessage`There was no header corresponding to the desired final-state-via value '${"finalStateValue"}'.`,
       },
     },
+    "no-operation-at-original-uri": {
+      severity: "warning",
+      messages: {
+        default:
+          "The 'original-uri' final state is specified, but there is no GET operation at the original URI. The final result will be treated as 'void'.",
+      },
+    },
     "bad-record-type": {
       severity: "warning",
       messages: {

packages/typespec-azure-core/src/lro-helpers.ts

@@ -24,6 +24,7 @@ import {
 } from "@typespec/compiler";
 import { $ } from "@typespec/compiler/typekit";
 import {
+  getAllHttpServices,
   getHeaderFieldName,
   getHttpOperation,
   getOperationVerb,
@@ -61,6 +62,7 @@ import {
   type StatusMonitorMetadata,
 } from "./decorators/polling-location.js";
 import { PollingOperationKey } from "./decorators/polling-operation.js";
+import { reportDiagnostic } from "./lib.js";
 import type { PropertyMap } from "./lro-info.js";
 import { FinalStateValue, getFinalStateOverride } from "./state/final-state.js";
 
@@ -404,24 +406,46 @@ function createLroMetadata(
   context: LroContext,
 ): LroMetadata | undefined {
   const [finalState, model] = getFinalStateVia(program, operation, context);
-  if (finalState === undefined || model === undefined || context.pollingStep === undefined)
-    return undefined;
+  if (finalState === undefined || context.pollingStep === undefined) return undefined;
+
+  // If original-uri is explicitly specified via @useFinalStateVia and there's no GET
+  // operation at the same path, emit a warning and treat the final result as void.
+  // We check both finalState and finalStateOverride to only emit the diagnostic when
+  // the user explicitly opted into original-uri (via @useFinalStateVia), not when
+  // original-uri is the natural computed state (e.g., for standard resource create operations).
+  let resolvedModel = model;
+  const finalStateOverride = getFinalStateOverride(program, operation);
+  if (
+    finalState === FinalStateValue.originalUri &&
+    finalStateOverride === FinalStateValue.originalUri
+  ) {
+    if (!hasGetOperationAtSamePath(program, context.httpOperation)) {
+      reportDiagnostic(program, {
+        code: "no-operation-at-original-uri",
+        target: operation,
+      });
+      // When there's no GET at the original URI, treat the final result as void
+      resolvedModel = $(program).intrinsic.void;
+    }
+  }
+
+  if (resolvedModel === undefined) return undefined;
   const logicalPathName =
     context.finalStep?.kind === "pollingSuccessProperty"
       ? context.finalStep.target.name
       : undefined;
 
   let finalResult: Model | Scalar | UnknownType | "void" =
-    model.kind === "Model" ||
-    model.kind === "Scalar" ||
-    (model.kind === "Intrinsic" && !isVoidType(model))
-      ? model
+    resolvedModel.kind === "Model" ||
+    resolvedModel.kind === "Scalar" ||
+    (resolvedModel.kind === "Intrinsic" && !isVoidType(resolvedModel))
+      ? resolvedModel
       : "void";
   let finalEnvelopeResult: Model | Scalar | UnknownType | "void" =
-    model.kind === "Model" ||
-    model.kind === "Scalar" ||
-    (model.kind === "Intrinsic" && !isVoidType(model))
-      ? model
+    resolvedModel.kind === "Model" ||
+    resolvedModel.kind === "Scalar" ||
+    (resolvedModel.kind === "Intrinsic" && !isVoidType(resolvedModel))
+      ? resolvedModel
       : "void";
   if (context.finalStep && context.finalStep.kind === "pollingSuccessProperty") {
     finalEnvelopeResult = context.pollingStep.responseModel;
@@ -432,9 +456,9 @@ function createLroMetadata(
   return {
     operation: operation,
     logicalResult:
-      model.kind === "Intrinsic" || model.kind === "Scalar"
+      resolvedModel.kind === "Intrinsic" || resolvedModel.kind === "Scalar"
         ? context.pollingStep.responseModel
-        : model,
+        : resolvedModel,
     finalStateVia: finalState,
     statusMonitorStep: context.statusMonitorStep,
     pollingInfo: context.pollingStep,
@@ -954,6 +978,22 @@ function isMatchingGetOperation(
   return sourceHttp.path === targetHttp.path && targetHttp.verb === "get";
 }
 
+/**
+ * Checks if there is a GET operation at the same path as the given operation
+ * in the program's HTTP services.
+ */
+function hasGetOperationAtSamePath(program: Program, httpOperation: HttpOperation): boolean {
+  const [services] = getAllHttpServices(program);
+  for (const service of services) {
+    for (const op of service.operations) {
+      if (op.verb === "get" && op.path === httpOperation.path) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
 function processFinalLink(
   program: Program,
   modelOrOperation: Model | Operation,

packages/typespec-azure-core/src/state/final-state.ts

@@ -39,7 +39,7 @@ export function validateFinalState(
   finalState: FinalStateValue,
 ): FinalStateValue | undefined {
   if (finalState === FinalStateValue.originalUri) {
-    if (operation.verb !== "put" && operation.verb !== "patch") {
+    if (operation.verb !== "put" && operation.verb !== "patch" && operation.verb !== "post") {
       reportDiagnostic(program, {
         code: "invalid-final-state",
         target: operation.operation,