fix: locate bundled lame binary in flattened dist builds

Author: jankarres

src/internal/binary/resolve-binary.ts

@@ -1,5 +1,5 @@
 import { existsSync } from "node:fs";
-import { join } from "node:path";
+import { dirname, join } from "node:path";
 import { fileURLToPath, pathToFileURL } from "node:url";
 
 declare const __dirname: string | undefined;
@@ -36,10 +36,41 @@ const moduleUrl = (() => {
     return deriveModuleUrl(meta, resolvedFilename);
 })();
 
+function findPackageRootFrom(startDir: string): string | null {
+    let current = startDir;
+
+    while (true) {
+        const packageJsonPath = join(current, "package.json");
+        if (existsSync(packageJsonPath)) {
+            return current;
+        }
+
+        const parent = dirname(current);
+        if (parent === current) {
+            return null;
+        }
+
+        current = parent;
+    }
+}
+
 function resolvePackageRoot(
     moduleHref: string | undefined,
     dirname: string | undefined,
 ): string {
+    const normalizedDir =
+        dirname ??
+        (moduleHref != null
+            ? fileURLToPath(new URL(".", moduleHref))
+            : undefined);
+
+    if (normalizedDir) {
+        const detectedRoot = findPackageRootFrom(normalizedDir);
+        if (detectedRoot) {
+            return detectedRoot;
+        }
+    }
+
     if (dirname) {
         return join(dirname, "..", "..", "..");
     }

tests/unit/resolve-binary.test.ts

@@ -105,4 +105,20 @@ describe("resolve-binary", () => {
         const derivedFromCwd = resolvePackageRoot(undefined, undefined);
         expect(derivedFromCwd).toBe(process.cwd());
     });
+
+    it("detects package root when compiled assets live directly inside dist", async () => {
+        const projectRoot = join(sharedTempDir, "pkg-flat");
+        const distDir = join(projectRoot, "dist");
+
+        await mkdir(distDir, { recursive: true });
+        await writeFile(join(projectRoot, "package.json"), "{}");
+
+        const { resolvePackageRoot } = await importResolver();
+        const derived = resolvePackageRoot(
+            pathToFileURL(join(distDir, "index.cjs")).href,
+            distDir,
+        );
+
+        expect(derived).toBe(projectRoot);
+    });
 });