testing: deepen server runtime smoke coverage for audio helpers

testing/tests/server_runtime_smoke_contract.rs

@@ -7,7 +7,7 @@
 //! Why: these contracts provide broad safety coverage around startup/recovery
 //! code paths that are otherwise hard to hit from unit-only tests.
 
-use lesavka_server::audio::ClipTap;
+use lesavka_server::audio::{self, ClipTap};
 use lesavka_server::gadget::UsbGadget;
 use lesavka_server::runtime_support;
 use serial_test::serial;
@@ -61,6 +61,47 @@ fn clip_tap_writes_rotating_file_when_period_elapses() {
     }
 }
 
+#[test]
+#[serial]
+fn clip_tap_drop_flushes_pending_audio() {
+    let tag = "lesavka-cliptap-drop-contract";
+    let prefix = format!("{tag}-");
+    let before = tmp_files_with_prefix(&prefix);
+
+    let mut tap = ClipTap::new(tag, Duration::from_secs(60));
+    tap.feed(b"pending-bytes");
+    drop(tap);
+
+    let after = tmp_files_with_prefix(&prefix);
+    let created: Vec<PathBuf> = after.difference(&before).cloned().collect();
+    assert!(
+        !created.is_empty(),
+        "expected drop() to flush buffered clip bytes"
+    );
+    for path in created {
+        let _ = std::fs::remove_file(path);
+    }
+}
+
+#[test]
+#[serial]
+fn clip_tap_flush_is_noop_when_buffer_is_empty() {
+    let tag = "lesavka-cliptap-empty-contract";
+    let prefix = format!("{tag}-");
+    let before = tmp_files_with_prefix(&prefix);
+
+    let mut tap = ClipTap::new(tag, Duration::from_secs(60));
+    tap.flush();
+    drop(tap);
+
+    let after = tmp_files_with_prefix(&prefix);
+    let created: Vec<PathBuf> = after.difference(&before).cloned().collect();
+    assert!(
+        created.is_empty(),
+        "empty flush/drop should not create clip artifacts"
+    );
+}
+
 #[test]
 #[serial]
 fn gadget_queries_handle_missing_controller_paths() {
@@ -108,6 +149,25 @@ fn runtime_open_voice_with_retry_stays_bounded_for_missing_device() {
     });
 }
 
+#[test]
+#[serial]
+fn runtime_ear_handles_malformed_alsa_source_without_hanging() {
+    let rt = Runtime::new().expect("create runtime");
+    let outcome = rt.block_on(async {
+        tokio::time::timeout(
+            Duration::from_secs(3),
+            audio::ear("hw:UAC2Gadget,0\" ! malformed-pipeline", 0),
+        )
+        .await
+    });
+
+    match outcome {
+        Ok(Ok(stream)) => drop(stream),
+        Ok(Err(err)) => assert!(!err.to_string().trim().is_empty()),
+        Err(_) => panic!("audio::ear timed out for malformed ALSA source"),
+    }
+}
+
 #[test]
 #[serial]
 fn runtime_recover_hid_ignores_non_transport_errors() {