fix: delete active session returns to dashboard, sidebar/tile delete doesn't navigate

Bug 1: killSession() now checks if _viewingSession === name and calls
closeSession() before pollSessions(). Previously the user was stuck in
the expanded terminal view for a dead session after deleting it.

Bug 2: Sidebar item click handler now ignores clicks on .sidebar-delete
buttons. Tile click handler now ignores clicks on .tile-delete buttons.
Previously stopPropagation() in the document-level delete handler fired
too late (after the sidebar-item/tile handlers had already called
openSession), causing the session to be navigated to before being killed.

Tests added:
- killSession closes active session and returns to dashboard
- sidebar click handler ignores clicks on delete button
- tile click handler ignores clicks on tile-delete button

321 JS tests pass, 760 Python tests pass.

muxplex/frontend/app.js

@@ -733,7 +733,9 @@ function renderSidebar(sessions, currentSession) {
     list.querySelectorAll('.sidebar-item').forEach((item) => {
       const name = item.dataset.session;
       const sourceUrl = item.dataset.sourceUrl || '';
-      on(item, 'click', () => {
+      on(item, 'click', (e) => {
+        // Don't navigate when clicking the delete button inside the item
+        if (e.target.closest && e.target.closest('.sidebar-delete')) return;
         if (name !== currentSession) openSession(name, { sourceUrl });
       });
     });
@@ -992,7 +994,11 @@ function renderGrid(sessions) {
 
   // Bind interaction handlers on each tile
   document.querySelectorAll('.session-tile').forEach(function(tile) {
-    on(tile, 'click', () => openSession(tile.dataset.session, { sourceUrl: tile.dataset.sourceUrl || '' }));
+    on(tile, 'click', (e) => {
+      // Don't navigate when clicking the delete button inside the tile
+      if (e.target.closest && e.target.closest('.tile-delete')) return;
+      openSession(tile.dataset.session, { sourceUrl: tile.dataset.sourceUrl || '' });
+    });
     on(tile, 'keydown', (e) => {
       if (e.key === 'Enter' || e.key === ' ') {
         openSession(tile.dataset.session, { sourceUrl: tile.dataset.sourceUrl || '' });
@@ -2237,6 +2243,10 @@ function killSession(name) {
   api('DELETE', '/api/sessions/' + name)
     .then(function() {
       showToast('Session \'' + name + '\' killed');
+      // If we deleted the session we're currently viewing, return to dashboard
+      if (_viewingSession === name) {
+        closeSession();
+      }
       pollSessions();
     })
     .catch(function(err) {

muxplex/frontend/tests/test_app.mjs

@@ -4406,3 +4406,30 @@ test('buildSidebarHTML trim happens BEFORE slice in source (structural order che
     'trailing blank trim (.pop()) must appear BEFORE .slice() in buildSidebarHTML — trim the full snapshot first, then slice the last 20 lines',
   );
 });
+
+// --- Bug fixes: delete UX ---
+
+test('killSession closes active session and returns to dashboard', () => {
+  const source = fs.readFileSync(new URL('../app.js', import.meta.url), 'utf8');
+  // Find killSession function body
+  const fnStart = source.indexOf('function killSession');
+  const fnBody = source.substring(fnStart, fnStart + 500);
+  assert.ok(fnBody.includes('_viewingSession'), 'killSession must check if deleted session is the active one');
+  assert.ok(fnBody.includes('closeSession'), 'killSession must call closeSession when deleting the active session');
+});
+
+test('sidebar click handler ignores clicks on delete button', () => {
+  const source = fs.readFileSync(new URL('../app.js', import.meta.url), 'utf8');
+  assert.ok(
+    source.includes("closest('.sidebar-delete')"),
+    "sidebar click handler must guard against clicks on .sidebar-delete button"
+  );
+});
+
+test('tile click handler ignores clicks on tile-delete button', () => {
+  const source = fs.readFileSync(new URL('../app.js', import.meta.url), 'utf8');
+  assert.ok(
+    source.includes("closest('.tile-delete')"),
+    "tile click handler must guard against clicks on .tile-delete button"
+  );
+});