Add expose_port previews with a Preview tab; leave setup to AGENTS.md

web/style.css

@@ -315,6 +315,7 @@ textarea {
 .changes-view,
 .files-view,
 .terminal-view,
+.preview-view,
 .inbox-view {
   flex: 1;
   min-height: 0;
@@ -1174,6 +1175,58 @@ pre.diff .meta {
   background: var(--bg);
 }
 
+.preview-header {
+  display: flex;
+  justify-content: space-between;
+  align-items: baseline;
+  gap: 12px;
+  padding: 8px 16px;
+  border-bottom: 1px solid var(--border);
+}
+
+.preview-names {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 4px;
+  min-width: 0;
+}
+
+.preview-name {
+  padding: 0 6px;
+  border: 1px solid transparent;
+  border-radius: 4px;
+  background: none;
+  color: var(--accent);
+}
+
+.preview-name.active {
+  border-color: var(--border);
+  color: var(--text);
+}
+
+.preview-port {
+  color: var(--muted);
+}
+
+.preview-open {
+  font-size: 11px;
+  white-space: nowrap;
+}
+
+.preview-body {
+  flex: 1;
+  min-height: 0;
+  display: flex;
+  flex-direction: column;
+}
+
+.preview-frame {
+  flex: 1;
+  width: 100%;
+  border: none;
+  background: var(--bg);
+}
+
 .entries {
   display: flex;
   flex-direction: column;