Fix statusCode defined in base model with empty self

.chronus/changes/fix-status-code-from-base-model-2026-0-8-14-10-21.md

@@ -0,0 +1,8 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: fix
+packages:
+  - "@typespec/http"
+---
+
+Fix empty response models with `statusCode` defined in a base model

packages/http/src/http-property.ts

@@ -240,7 +240,7 @@ export function resolvePayloadProperties(
   const diagnostics = createDiagnosticCollector();
   const httpProperties = new Map<ModelProperty, HttpProperty>();
 
-  if (type.kind !== "Model" || type.properties.size === 0) {
+  if (type.kind !== "Model" || (type.properties.size === 0 && !type.baseModel)) {
     return diagnostics.wrap([]);
   }
 

packages/http/test/responses.test.ts

@@ -1,7 +1,7 @@
 import type { Model } from "@typespec/compiler";
 import { expectDiagnosticEmpty, expectDiagnostics } from "@typespec/compiler/testing";
 import { deepStrictEqual, ok, strictEqual } from "assert";
-import { describe, it } from "vitest";
+import { describe, expect, it } from "vitest";
 import { compileOperations, getOperationsWithServiceNamespace } from "./test-host.js";
 
 describe("body resolution", () => {
@@ -214,3 +214,32 @@ it("chooses correct content-type for extensible union body", async () => {
   ok(body);
   deepStrictEqual(body.contentTypes, ["text/plain"]);
 });
+
+describe("status code", () => {
+  async function getResponse(code: string) {
+    const [routes, diagnostics] = await getOperationsWithServiceNamespace(code);
+    expectDiagnosticEmpty(diagnostics);
+    expect(routes).toHaveLength(1);
+    expect(routes[0].responses).toHaveLength(1);
+    return routes[0].responses[0];
+  }
+
+  it("resolve from a property at the root", async () => {
+    const response = await getResponse(`op test1(): { @statusCode code: 201 };`);
+    expect(response.statusCodes).toEqual(201);
+  });
+
+  it("resolve from a property nested", async () => {
+    const response = await getResponse(`op test1(): { nested: { @statusCode code: 201 } };`);
+    expect(response.statusCodes).toEqual(201);
+  });
+
+  it("resolve from parent model with no local props", async () => {
+    const response = await getResponse(`
+      model Created { @statusCode code: 201 }
+      model Res extends Created {};
+      op test1(): Res;
+    `);
+    expect(response.statusCodes).toEqual(201);
+  });
+});