feat(compiler): add folding range kinds for comments and imports

.chronus/changes/folding-range-kinds-2026-7-23-8-51-0.md

@@ -0,0 +1,7 @@
+---
+changeKind: feature
+packages:
+  - "@typespec/compiler"
+---
+
+Language server folding ranges now report a `kind`: comments fold as `comment` and consecutive `import` statements fold together as an `imports` region. This enables editor commands such as "Fold All Block Comments" and "Fold All Imports" to work with TypeSpec files.

packages/compiler/src/server/serverlib.ts

@@ -17,6 +17,7 @@ import {
   DocumentSymbolParams,
   FileChangeType,
   FoldingRange,
+  FoldingRangeKind,
   FoldingRangeParams,
   Hover,
   HoverParams,
@@ -669,13 +670,29 @@ export function createServer(
           rangeStartSingleLines = comment.pos;
         }
       } else if (rangeStartSingleLines !== -1) {
-        addRange(rangeStartSingleLines, comment.end);
+        addRange(rangeStartSingleLines, comment.end, FoldingRangeKind.Comment);
         rangeStartSingleLines = -1;
       } else {
-        addRange(comment.pos, comment.end);
+        addRange(comment.pos, comment.end, FoldingRangeKind.Comment);
       }
     }
+    addRangesForImports();
     visitChildren(ast, addRangesForNode);
+    function addRangesForImports() {
+      const statements = ast!.statements;
+      let runStart = -1;
+      for (let i = 0; i <= statements.length; i++) {
+        const isImport = i < statements.length && statements[i].kind === SyntaxKind.ImportStatement;
+        if (isImport) {
+          if (runStart === -1) {
+            runStart = i;
+          }
+        } else if (runStart !== -1) {
+          addRange(statements[runStart].pos, statements[i - 1].end, FoldingRangeKind.Imports);
+          runStart = -1;
+        }
+      }
+    }
     function addRangesForNode(node: Node) {
       if (node.kind === SyntaxKind.Doc) {
         return; // fold doc comments as regular comments
@@ -691,16 +708,20 @@ export function createServer(
       visitChildren(node, addRangesForNode);
     }
     return ranges;
-    function addRange(startPos: number, endPos: number) {
+    function addRange(startPos: number, endPos: number, kind?: FoldingRangeKind) {
       const start = file.getLineAndCharacterOfPosition(startPos);
       const end = file.getLineAndCharacterOfPosition(endPos);
       if (start.line !== end.line) {
-        ranges.push({
+        const range: FoldingRange = {
           startLine: start.line,
           startCharacter: start.character,
           endLine: end.line,
           endCharacter: end.character,
-        });
+        };
+        if (kind !== undefined) {
+          range.kind = kind;
+        }
+        ranges.push(range);
       }
     }
   }

packages/compiler/test/server/folding.test.ts

@@ -1,6 +1,6 @@
 import { deepStrictEqual } from "assert";
 import { it } from "vitest";
-import { FoldingRange } from "vscode-languageserver";
+import { FoldingRange, FoldingRangeKind } from "vscode-languageserver";
 import { createTestServerHost } from "../../src/testing/test-server-host.js";
 
 it("includes consecutive single line comments separated by whitespaces in folding range", async () => {
@@ -9,7 +9,15 @@ it("includes consecutive single line comments separated by whitespaces in foldin
     //bar
 
     //test`);
-  deepStrictEqual(ranges, [{ endCharacter: 10, endLine: 4, startCharacter: 0, startLine: 0 }]);
+  deepStrictEqual(ranges, [
+    {
+      endCharacter: 10,
+      endLine: 4,
+      startCharacter: 0,
+      startLine: 0,
+      kind: FoldingRangeKind.Comment,
+    },
+  ]);
 });
 
 it("doesn't fold consecutive single and multi-line comment together", async () => {
@@ -21,7 +29,13 @@ it("doesn't fold consecutive single and multi-line comment together", async () =
 
     //test`);
   deepStrictEqual(ranges, [
-    { endCharacter: 10, endLine: 6, startCharacter: 4, startLine: 4 },
+    {
+      endCharacter: 10,
+      endLine: 6,
+      startCharacter: 4,
+      startLine: 4,
+      kind: FoldingRangeKind.Comment,
+    },
     { endCharacter: 6, endLine: 2, startCharacter: 0, startLine: 0 },
   ]);
 });
@@ -46,7 +60,15 @@ it("includes comments in folding range", async () => {
   const ranges = await getFoldingRanges(`/**
     description of model foo
     **/`);
-  deepStrictEqual(ranges, [{ endCharacter: 7, endLine: 2, startCharacter: 0, startLine: 0 }]);
+  deepStrictEqual(ranges, [
+    {
+      endCharacter: 7,
+      endLine: 2,
+      startCharacter: 0,
+      startLine: 0,
+      kind: FoldingRangeKind.Comment,
+    },
+  ]);
 });
 
 it("does not include one line comments in folding range", async () => {
@@ -126,6 +148,33 @@ it("folding range with one line", async () => {
   deepStrictEqual(ranges, []);
 });
 
+it("folds consecutive import statements as an imports range", async () => {
+  const ranges = await getFoldingRanges(`import "@typespec/http";
+import "@typespec/rest";
+import "@typespec/openapi";`);
+  deepStrictEqual(ranges, [
+    {
+      endCharacter: 27,
+      endLine: 2,
+      startCharacter: 0,
+      startLine: 0,
+      kind: FoldingRangeKind.Imports,
+    },
+  ]);
+});
+
+it("does not fold a single import statement", async () => {
+  const ranges = await getFoldingRanges(`import "@typespec/http";`);
+  deepStrictEqual(ranges, []);
+});
+
+it("does not fold imports separated by another statement", async () => {
+  const ranges = await getFoldingRanges(`import "@typespec/http";
+namespace Foo;
+import "@typespec/rest";`);
+  deepStrictEqual(ranges, []);
+});
+
 async function getFoldingRanges(source: string): Promise<FoldingRange[]> {
   const testHost = await createTestServerHost();
   const textDocument = testHost.addOrUpdateDocument("test/test.tsp", source);