fix: open an approval window while another one has focus (closes #290)

The background centred each approval window on the last focused window,
which could be an earlier approval window still open; headless Chrome
reports one as 1280x720, the browser refused the resulting position, and
the request failed with no window. It now centres only on a browser
window, and when the browser refuses a position it asks again without one.

In the Chrome suite a test could raise its prompt while the previous
test's window was still closing. After a passed test the runner now gives
approval windows five seconds to close and fails the test if one is still
open; after a failed test it closes them.

Model: opus-5-5

src/background/index.js

@@ -437,7 +437,13 @@ async function openApprovalWindow(id) {
         width: popupWidth,
         height: popupHeight,
     };
-    if (currentWin) {
+    // Centred on a browser window only. The last focused window can be
+    // another approval window still open, and centring on one can give a
+    // position the browser refuses ("Bounds must be at least 50% within
+    // visible screen space"): headless Chrome reports this 360x600 popup as
+    // 1280x720. The request then failed with no window at all. Over a popup,
+    // the browser picks the position.
+    if (currentWin && currentWin.type === "normal") {
         opts.left = Math.round(
             currentWin.left + (currentWin.width - popupWidth) / 2,
         );
@@ -455,10 +461,23 @@ async function openApprovalWindow(id) {
         win = await windowsCreate(opts);
     } catch (e) {
         // The promise namespace reports the failure by rejecting where the
-        // callback namespace reported it by handing back no window; both land
-        // on the !win branch below, which settles the approval.
+        // callback namespace reported it by handing back no window; both
+        // leave win null.
         log.errorf("could not open the approval window:", e);
     }
+    // The browser also refuses a centred position that is too far off screen,
+    // as it is over a browser window near the screen edge. Asked again
+    // without a position, it places the window itself. If that fails too,
+    // the !win branch below settles the approval.
+    if (!win && opts.left !== undefined) {
+        delete opts.left;
+        delete opts.top;
+        try {
+            win = await windowsCreate(opts);
+        } catch (e) {
+            log.errorf("could not open the approval window:", e);
+        }
+    }
 
     const approval = pendingApprovals[id];
     if (!approval) {