feat(frontend): rename group (reassign members via setSessionGroup)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/shell/AppShell.tsx

@@ -9,6 +9,7 @@ import { RenameDialog } from "./RenameDialog";
 import { DeleteConfirmDialog } from "./DeleteConfirmDialog";
 import { SteerInput, ComposerFooter } from "./SteerInput";
 import { WorkflowBar } from "./WorkflowBar";
+import { Pencil } from "lucide-react";
 import { Button } from "../components/ui/button";
 import { Toaster } from "../components/ui/sonner";
 import { toast } from "sonner";
@@ -40,6 +41,7 @@ export function AppShell() {
   const [renameTarget, setRenameTarget] = useState<SessionSummary | null>(null);
   const [deleteTarget, setDeleteTarget] = useState<SessionSummary | null>(null);
   const [collapsedGroups, setCollapsedGroups] = useState<Record<string, boolean>>({});
+  const [renameGroupTarget, setRenameGroupTarget] = useState<string | null>(null);
 
   const groups = useMemo(
     () => [...new Set(sessions.map((s) => s.group).filter((g): g is string => !!g))].sort(),
@@ -79,6 +81,18 @@ export function AppShell() {
       }
     }
   }
+  async function renameGroup(oldName: string, newName: string) {
+    const trimmed = newName.trim();
+    if (!trimmed || trimmed === oldName) return;
+    try {
+      for (const s of sessions.filter((x) => x.group === oldName)) {
+        await setSessionGroup(s.id, trimmed);
+      }
+      refresh();
+    } catch {
+      toast.error("Failed to rename group.");
+    }
+  }
   async function toggleArchive(s: SessionSummary) {
     try {
       await (s.archived ? unarchiveSession(s.id) : archiveSession(s.id));
@@ -225,15 +239,25 @@ export function AppShell() {
             <div className="flex flex-col gap-3 pb-2">
               {groups.map((g) => (
                 <div key={g}>
-                  <button
-                    type="button"
-                    onClick={() => setCollapsedGroups((c) => ({ ...c, [g]: !c[g] }))}
-                    aria-expanded={!collapsedGroups[g]}
-                    className="flex w-full items-center gap-1 px-1 pb-1 text-left text-[0.7rem] font-semibold uppercase tracking-wide text-muted-foreground hover:text-foreground"
-                  >
-                    <span className="select-none">{collapsedGroups[g] ? "▸" : "▾"}</span>
-                    <span className="truncate">{g}</span>
-                  </button>
+                  <div className="group/gh flex items-center gap-1">
+                    <button
+                      type="button"
+                      onClick={() => setCollapsedGroups((c) => ({ ...c, [g]: !c[g] }))}
+                      aria-expanded={!collapsedGroups[g]}
+                      className="flex min-w-0 flex-1 items-center gap-1 px-1 pb-1 text-left text-[0.7rem] font-semibold uppercase tracking-wide text-muted-foreground hover:text-foreground"
+                    >
+                      <span className="select-none">{collapsedGroups[g] ? "▸" : "▾"}</span>
+                      <span className="truncate">{g}</span>
+                    </button>
+                    <button
+                      type="button"
+                      aria-label={`Rename group ${g}`}
+                      onClick={() => setRenameGroupTarget(g)}
+                      className="rounded p-0.5 text-muted-foreground opacity-0 transition-opacity hover:bg-accent group-hover/gh:opacity-100"
+                    >
+                      <Pencil className="size-3" />
+                    </button>
+                  </div>
                   {!collapsedGroups[g] && (
                     <NavSessions
                       sessions={activeList.filter((s) => s.group === g)}
@@ -291,6 +315,14 @@ export function AppShell() {
           }}
         />
       )}
+      {renameGroupTarget && (
+        <RenameDialog
+          open
+          initial={renameGroupTarget}
+          onOpenChange={(o) => { if (!o) setRenameGroupTarget(null); }}
+          onSubmit={async (name) => { await renameGroup(renameGroupTarget, name); setRenameGroupTarget(null); }}
+        />
+      )}
       {deleteTarget && (
         <DeleteConfirmDialog
           open