fix: detect installed ALSA runtime library

src/manifest.test.ts

@@ -156,6 +156,21 @@ describe("the manifest itself", () => {
     expect(installState(missing!)).toBe("absent");
   });
 
+  test("libasound2 is detected through its multiarch shared library", () => {
+    // libasound2t64 installs no command called `libasound2`. Without an
+    // explicit file probe, doctor reports a missing package immediately
+    // after apt successfully installed it.
+    const tool = TOOLS.find((candidate) => candidate.name === "libasound2");
+    expect(tool?.file).toEndWith("-linux-gnu/libasound.so.2");
+    expect(tool?.cmd).toBeUndefined();
+
+    const seen = { ...tool!, file: import.meta.path } as typeof tool;
+    expect(installState(seen!)).toBe("ok");
+
+    const missing = { ...tool!, file: "/nonexistent/libasound.so.2" } as typeof tool;
+    expect(installState(missing!)).toBe("absent");
+  });
+
   test("what init.sh sources, the manifest installs", () => {
     // The gap this closes: init.sh sourced bash_completion from the
     // first version and nothing ever declared the package. On a desktop

src/manifest.ts

@@ -1005,6 +1005,14 @@ export const TOOLS: Tool[] = [
     name: "libasound2",
     about: "the ALSA library dit links against",
     scope: "desktop",
+    // This package exposes a shared library, not a command named
+    // `libasound2`. Probing PATH therefore reports it missing even after apt
+    // installed it successfully. Ubuntu uses its Debian multiarch directory
+    // for the runtime library on both architectures red-dev supports.
+    file:
+      process.arch === "arm64"
+        ? "/usr/lib/aarch64-linux-gnu/libasound.so.2"
+        : "/usr/lib/x86_64-linux-gnu/libasound.so.2",
     u24: apt("libasound2t64"),
     win: skip(NO_GUI),
   },