Fix x-ms-paths sorting for query-only paths

.chronus/changes/fix-xms-paths-sorting-2026-03-23-18-18-00.md

@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@azure-tools/typespec-autorest"
+---
+
+Fix sorting of x-ms-paths entries that start with `?` (query-only paths). Previously these paths were not sorted alphabetically.

packages/typespec-autorest/src/json-schema-sorter/sorter.ts

@@ -107,8 +107,17 @@ function defaultCompare(a: number | string, b: number | string) {
 
 /** Sort urls in a specific way so path with field show up before a fixed segment. */
 function compareUrl(leftPath: string, rightPath: string) {
-  const leftParts = leftPath.split("/").slice(1);
-  const rightParts = rightPath.split("/").slice(1);
+  // Separate path and query string portions to handle x-ms-paths entries starting with "?"
+  const leftQueryIndex = leftPath.indexOf("?");
+  const rightQueryIndex = rightPath.indexOf("?");
+  const leftPathPortion = leftQueryIndex >= 0 ? leftPath.substring(0, leftQueryIndex) : leftPath;
+  const rightPathPortion =
+    rightQueryIndex >= 0 ? rightPath.substring(0, rightQueryIndex) : rightPath;
+  const leftQuery = leftQueryIndex >= 0 ? leftPath.substring(leftQueryIndex) : "";
+  const rightQuery = rightQueryIndex >= 0 ? rightPath.substring(rightQueryIndex) : "";
+
+  const leftParts = leftPathPortion ? leftPathPortion.split("/").slice(1) : [];
+  const rightParts = rightPathPortion ? rightPathPortion.split("/").slice(1) : [];
 
   for (let i = 0; i < Math.max(leftParts.length, rightParts.length); i++) {
     // Have we exhausted the path parts of one of them?
@@ -137,8 +146,8 @@ function compareUrl(leftPath: string, rightPath: string) {
     }
   }
 
-  // Must be the same
-  return 0;
+  // Path portions are the same, compare query strings
+  return defaultCompare(leftQuery, rightQuery);
 }
 
 function resolveSchema(schema: JsonSchemaType, reader: JsonSchemaReader): ResolvedJsonSchemaType {

packages/typespec-autorest/test/sorting.test.ts

@@ -80,6 +80,42 @@ describe("typespec-autorest: OpenAPI output should be determinstic", () => {
     ]);
   });
 
+  it("sorts x-ms-paths with query-only paths", () => {
+    const sorted = sortOpenAPIDocument({
+      swagger: "2.0",
+      info: {} as any,
+      paths: {},
+      "x-ms-paths": {
+        "?b=1": {},
+        "?a=1": {},
+        "?c=1": {},
+      },
+    });
+
+    deepStrictEqual(Object.keys(sorted["x-ms-paths"]!), ["?a=1", "?b=1", "?c=1"]);
+  });
+
+  it("sorts x-ms-paths with mixed path and query-only entries", () => {
+    const sorted = sortOpenAPIDocument({
+      swagger: "2.0",
+      info: {} as any,
+      paths: {},
+      "x-ms-paths": {
+        "/b?_overload=op1": {},
+        "?b=1": {},
+        "/a?_overload=op2": {},
+        "?a=1": {},
+      },
+    });
+
+    deepStrictEqual(Object.keys(sorted["x-ms-paths"]!), [
+      "?a=1",
+      "?b=1",
+      "/a?_overload=op2",
+      "/b?_overload=op1",
+    ]);
+  });
+
   it("header already in lexical order", async () => {
     const res = await openApiFor(
       `