diff --git a/libs/cua-driver/rust/crates/cua-driver/tests/harness_web_test.rs b/libs/cua-driver/rust/crates/cua-driver/tests/harness_web_test.rs
index faa3ddd53e..3268c1c247 100644
--- a/libs/cua-driver/rust/crates/cua-driver/tests/harness_web_test.rs
+++ b/libs/cua-driver/rust/crates/cua-driver/tests/harness_web_test.rs
@@ -52,6 +52,23 @@ fn electron_exe() -> PathBuf {
 
 // ── shared session helper ────────────────────────────────────────────────────
 
+/// Wait (up to ~5s) for `port` to become free. These web tests use FIXED CDP
+/// ports (9222/9223) and a process-global `CUA_DRIVER_CDP_PORT`, so they must
+/// run serially (`--test-threads=1`). A previous test's host can still be
+/// releasing its port when the next launches; reusing it before then makes the
+/// daemon discover the OLD host's page (`pages[0]`), so the click lands on a
+/// stale window and the counter check fails. This guard closes that teardown
+/// overlap — belt-and-braces on top of serial execution.
+fn wait_port_free(port: u16) {
+    for _ in 0..50 {
+        if std::net::TcpStream::connect(("127.0.0.1", port)).is_err() {
+            return;
+        }
+        std::thread::sleep(Duration::from_millis(100));
+    }
+    eprintln!("warning: CDP port {port} still bound after 5s — prior host may not have released it");
+}
+
 /// Launch the harness exe + a cua-driver child with `CUA_DRIVER_CDP_PORT`
 /// pointing at the harness's CDP endpoint. Polls list_windows until the
 /// host's window appears.
@@ -63,6 +80,9 @@ where
         eprintln!("{label} host exe not found at {host_exe:?} — run test-harness/build/windows.ps1");
         return;
     }
+    // A prior test's host may still hold this fixed CDP port — wait for it to
+    // free so the daemon doesn't discover the stale host's page.
+    wait_port_free(cdp_port);
     // Set the CDP port the daemon should probe; the spawned cua-driver child
     // inherits it from this process's environment.
     std::env::set_var("CUA_DRIVER_CDP_PORT", cdp_port.to_string());
diff --git a/libs/cua-driver/rust/crates/cua-driver/tests/harness_wpf_test.rs b/libs/cua-driver/rust/crates/cua-driver/tests/harness_wpf_test.rs
index 9f5e25114d..01f11e09cc 100644
--- a/libs/cua-driver/rust/crates/cua-driver/tests/harness_wpf_test.rs
+++ b/libs/cua-driver/rust/crates/cua-driver/tests/harness_wpf_test.rs
@@ -551,16 +551,14 @@ fn harness_wpf_slider_drag() {
 
         let resp = driver.call("drag", serde_json::json!({
             "pid": pid as i64, "window_id": wid,
-            // drag screen-coords path: send_drag_synthesized takes screen
-            // coords directly. The harness window is centered at
-            // (517, 66) with the slider track at client (50-330, 275);
-            // convert to screen via ClientToScreen approximation by
-            // offsetting by window position + non-client chrome
-            // (title bar + border ~30,8). screen coords here are
-            // re-derived in window-local form by the tool's existing
-            // ClientToScreen step.
-            "from_x": 50.0, "from_y": 275.0,
-            "to_x": 330.0,  "to_y": 275.0,
+            // Window-local coords along the slider TRACK. The track row sits at
+            // window-local y≈304 (verified on the VM: y=275 landed ~29px above
+            // it, on empty GroupBox space, so the thumb never moved); the thumb
+            // rests at the left (x≈44) at value=0. Dragging left→right advances
+            // the value. (TODO: derive these from the `sld-value` element frame
+            // in get_window_state for DPI/placement independence.)
+            "from_x": 44.0, "from_y": 304.0,
+            "to_x": 330.0, "to_y": 304.0,
             "duration_ms": 700, "steps": 40,
             "dispatch": "foreground"
         }));