fix(js-ts): keep the export default Foo; pass linear on comment runs

scripts/engine.mjs

@@ -2492,7 +2492,7 @@ var init_js_ts = __esm({
     NAMED_DEFAULT_RE = /^\s*export\s+default\s+(?:async\s+)?(?:function|class)\s+(?!extends\b)[\w$]+/;
     EXPORT_LIST_RE = /export\s*\{([^}]*)\}\s*(from\b)?/g;
     CJS_OBJECT_RE = /module\.exports\s*=\s*\{([^}]*)\}/g;
-    DEFAULT_ID_RE = /(^|\n)\s*export(?:\s+default\s+|\s*=\s*)([A-Za-z_$][\w$]*)\s*;?\s*(?=\n|$)/g;
+    DEFAULT_ID_RE = /(^|\n)[ \t]*export(?:\s+default\s+|\s*=\s*)([A-Za-z_$][\w$]*)[ \t]*;?[ \t]*(?=\r?\n|$)/g;
     jsTs = {
       lang: "javascript/typescript",
       exts: [".ts", ".tsx", ".mts", ".cts", ".js", ".jsx", ".mjs", ".cjs"],

src/lang/js-ts.ts

@@ -80,7 +80,9 @@ function stemOf(rel: string): string {
 //   so does a declaration file's `export = Foo;`.
 const EXPORT_LIST_RE = /export\s*\{([^}]*)\}\s*(from\b)?/g;
 const CJS_OBJECT_RE = /module\.exports\s*=\s*\{([^}]*)\}/g;
-const DEFAULT_ID_RE = /(^|\n)\s*export(?:\s+default\s+|\s*=\s*)([A-Za-z_$][\w$]*)\s*;?\s*(?=\n|$)/g;
+// Horizontal whitespace only around the line: comments are blanked to spaces
+// and newlines, so a `\s*` here rescanned every blank line after each one.
+const DEFAULT_ID_RE = /(^|\n)[ \t]*export(?:\s+default\s+|\s*=\s*)([A-Za-z_$][\w$]*)[ \t]*;?[ \t]*(?=\r?\n|$)/g;
 
 function applyExportLists(content: string, symbols: CodeSymbol[]): void {
   const markExported = (name: string | undefined): void => {

tests/regex-tier.test.ts

@@ -344,6 +344,24 @@ describe("TS/JS fallback: generators, ambient declarations, Unicode names", () =
     // `export = Emitter` is how a declaration file exports its one value.
     expect(syms("d.ts", src).find((s) => s.name === "Emitter")?.exported).toBe(true);
   });
+
+  it("reads `export default Foo;` and `export = Foo` in a CRLF file", () => {
+    const exported = (src: string) => syms("d.ts", src).find((s) => s.kind === "class" && s.name === "Foo")?.exported;
+    expect(exported("class Foo {\r\n}\r\nexport default Foo;\r\n")).toBe(true);
+    expect(exported("declare class Foo {}\r\nexport = Foo  \r\n")).toBe(true);
+    expect(exported("class Foo {\r\n}\r\nexport default Foo.bar;\r\n")).toBe(false);
+  });
+
+  it("stays linear on a long run of comment lines (previously ~33 s)", () => {
+    // Comments are blanked to spaces and newlines before the export-list pass,
+    // and `export default Foo;` used to be matched with a `\s*` that crossed
+    // them: every line rescanned all the blank lines after it.
+    const comments = Array.from({ length: 50000 }, (_, i) => `// comment line ${i}`).join("\n");
+    const src = `class Foo {}\n${comments}\nconst tail = 1;\nexport default Foo;\n`;
+    const t0 = performance.now();
+    expect(syms("big.ts", src).find((s) => s.kind === "class" && s.name === "Foo")?.exported).toBe(true);
+    expect(performance.now() - t0).toBeLessThan(1500);
+  });
 });
 
 describe("doc comments and body spans on the regex tier", () => {