fix(client): let Copy buttons write the clipboard in the desktop app

Only fullscreen was granted, so navigator.clipboard.writeText was
refused and every Copy button did nothing. Grant clipboard-sanitized-write;
reading stays refused.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2 files changed, 18 insertions, 3 deletions

diff --git a/packages/meshbay-client/src/main.js b/packages/meshbay-client/src/main.js
index 794477b..c263d2c 100644
--- a/packages/meshbay-client/src/main.js
+++ b/packages/meshbay-client/src/main.js
@@ -499,9 +499,13 @@ function publicKeyB64(privateKey) {
   return der.subarray(der.length - 32).toString('base64');
 }
 
-// Everything the interface is allowed to ask Chromium for. Watching a film
-// full-screen is the whole list.
-const GRANTED_PERMISSIONS = new Set(['fullscreen']);
+// Everything the interface is allowed to ask Chromium for: watching a film
+// full-screen, and putting text on the clipboard. The second is what every Copy
+// button needs (an invitation link, the recovery key, the node key, a cast
+// URL); refused, `navigator.clipboard.writeText` rejects and each button
+// quietly did nothing. Write only, and sanitized — reading the clipboard stays
+// refused, because that is someone else's text.
+const GRANTED_PERMISSIONS = new Set(['fullscreen', 'clipboard-sanitized-write']);
 
 // No hub call is still going to be answered after this. The hub's longest is
 // signaling a WebRTC offer, which gives up at fifteen seconds of its own.
diff --git a/packages/meshbay-hub/tests/test_desktop_shell.py b/packages/meshbay-hub/tests/test_desktop_shell.py
index fcf6c4d..e6eefc2 100644
--- a/packages/meshbay-hub/tests/test_desktop_shell.py
+++ b/packages/meshbay-hub/tests/test_desktop_shell.py
@@ -96,6 +96,17 @@ def test_video_may_go_fullscreen():
     assert "fullscreen" in _granted_permissions()
 
 
+def test_copy_buttons_may_write_the_clipboard_and_nothing_may_read_it():
+    """
+    Every Copy button calls `navigator.clipboard.writeText`, which Chromium
+    gates on `clipboard-sanitized-write`. With only `fullscreen` granted it was
+    refused, and each button did nothing — reported on the invitation link's.
+    """
+    granted = _granted_permissions()
+    assert "clipboard-sanitized-write" in granted
+    assert "clipboard-read" not in granted
+
+
 def test_both_permission_handlers_answer_from_the_same_list():
     """`Permissions.query` takes the check handler and a request takes the
     other; two lists would eventually disagree about what the page may do."""