display_name → at_handle for every user-rendering point around the recent-activity surfaces: scroll.html actor <strong>, Most Recent Scroll applet actor <strong>, My Games row body actor prefix, My Scrolls row body actor prefix, My Buds page bud-name span, navbar identity, _bud_panel.html data-sharer-name (consumed by the dynamic post-line-author append on share success) — at_handle was always the right filter for these slots: it produces @<username> when the user has set one, falling back to the truncated email (which already carries an @) so we don't double-prefix; the _my_buds_applet_item.html row was already on at_handle from the 3-col sprint, so this commit just brings the rest of the surfaces in line; _navbar.html swap also drops the literal @ that prefixed {{ user|display_name }} — that literal predated at_handle + worked for users w. usernames (gave @disco) but produced @<email>@<domain> for users w. no username yet; navbar wait_to_be_logged_in(email) FT helper keeps working since the email still appears as a substring whether rendered as @disco@test.io (old, no username) or disco@test.io (new); _bud_add_panel.html's client-side _appendBudEntry JS gains an inline at_handle mirror — display.indexOf('@') >= 0 ? display : '@' + display — since the server's add_bud response packs username or email under the username key (semantic mismatch w. the key name but stable) so the JS has to detect the email case itself; test_bill_my_buds.py two .bud-name text assertions ("alice" → "@alice") updated for the new prefix; 931 ITs + targeted FT regression on test_bill_my_buds + test_core_navbar + test_core_login green

src/templates/apps/billboard/_partials/_bud_panel.html

@@ -16,7 +16,7 @@
 </button>
 
 <div id="id_bud_panel"
-     data-sharer-name="{% if request.user.is_authenticated %}{{ request.user|display_name }}{% endif %}">
+     data-sharer-name="{% if request.user.is_authenticated %}{{ request.user|at_handle }}{% endif %}">
     <input id="id_recipient"
            name="recipient"
            type="text"