feat(ui): sort sessions by recent activity

go/core/internal/database/client_test.go

@@ -13,6 +13,7 @@ import (
 	"github.com/pgvector/pgvector-go"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"trpc.group/trpc-go/trpc-a2a-go/protocol"
 )
 
 // TestConcurrentAgentUpserts verifies that concurrent StoreAgent calls
@@ -233,6 +234,124 @@ func TestStoreSessionIdempotence(t *testing.T) {
 	assert.Equal(t, "Updated", *retrieved.Name, "Session should have updated name")
 }
 
+func TestListSessionsOrdersByRecentActivity(t *testing.T) {
+	db := setupTestDB(t)
+	client := NewClient(db)
+	ctx := context.Background()
+
+	userID := "test-user"
+	agentID := "test-agent"
+	base := time.Date(2026, 1, 1, 12, 0, 0, 0, time.UTC)
+	sessions := []struct {
+		id        string
+		createdAt time.Time
+		updatedAt time.Time
+	}{
+		{id: "old-active", createdAt: base, updatedAt: base.Add(4 * time.Hour)},
+		{id: "new-inactive", createdAt: base.Add(3 * time.Hour), updatedAt: base.Add(3 * time.Hour)},
+		{id: "old-inactive", createdAt: base.Add(time.Hour), updatedAt: base.Add(2 * time.Hour)},
+	}
+
+	for _, s := range sessions {
+		err := client.StoreSession(ctx, &dbpkg.Session{
+			ID:      s.id,
+			UserID:  userID,
+			AgentID: &agentID,
+		})
+		require.NoError(t, err)
+		_, err = db.Exec(ctx, `
+			UPDATE session
+			SET created_at = $1, updated_at = $2
+			WHERE id = $3 AND user_id = $4
+		`, s.createdAt, s.updatedAt, s.id, userID)
+		require.NoError(t, err)
+	}
+
+	allSessions, err := client.ListSessions(ctx, userID)
+	require.NoError(t, err)
+	require.Len(t, allSessions, 3)
+	assert.Equal(t, []string{"old-active", "new-inactive", "old-inactive"}, []string{
+		allSessions[0].ID,
+		allSessions[1].ID,
+		allSessions[2].ID,
+	})
+
+	agentSessions, err := client.ListSessionsForAgent(ctx, agentID, userID)
+	require.NoError(t, err)
+	require.Len(t, agentSessions, 3)
+	assert.Equal(t, []string{"old-active", "new-inactive", "old-inactive"}, []string{
+		agentSessions[0].ID,
+		agentSessions[1].ID,
+		agentSessions[2].ID,
+	})
+}
+
+func TestStoreEventTouchesSessionActivity(t *testing.T) {
+	db := setupTestDB(t)
+	client := NewClient(db)
+	ctx := context.Background()
+
+	userID := "test-user"
+	sessionID := "active-session"
+	oldActivity := time.Date(2026, 1, 1, 12, 0, 0, 0, time.UTC)
+
+	err := client.StoreSession(ctx, &dbpkg.Session{
+		ID:     sessionID,
+		UserID: userID,
+	})
+	require.NoError(t, err)
+	_, err = db.Exec(ctx, `
+		UPDATE session
+		SET updated_at = $1
+		WHERE id = $2 AND user_id = $3
+	`, oldActivity, sessionID, userID)
+	require.NoError(t, err)
+
+	err = client.StoreEvents(ctx, &dbpkg.Event{
+		ID:        "event-1",
+		SessionID: sessionID,
+		UserID:    userID,
+		Data:      "{}",
+	})
+	require.NoError(t, err)
+
+	got, err := client.GetSession(ctx, sessionID, userID)
+	require.NoError(t, err)
+	assert.True(t, got.UpdatedAt.After(oldActivity), "session updated_at should advance after storing an event")
+}
+
+func TestStoreTaskTouchesSessionActivity(t *testing.T) {
+	db := setupTestDB(t)
+	client := NewClient(db)
+	ctx := context.Background()
+
+	userID := "test-user"
+	sessionID := "active-session"
+	oldActivity := time.Date(2026, 1, 1, 12, 0, 0, 0, time.UTC)
+
+	err := client.StoreSession(ctx, &dbpkg.Session{
+		ID:     sessionID,
+		UserID: userID,
+	})
+	require.NoError(t, err)
+	_, err = db.Exec(ctx, `
+		UPDATE session
+		SET updated_at = $1
+		WHERE id = $2 AND user_id = $3
+	`, oldActivity, sessionID, userID)
+	require.NoError(t, err)
+
+	err = client.StoreTask(ctx, &protocol.Task{
+		ID:        "task-1",
+		ContextID: sessionID,
+	})
+	require.NoError(t, err)
+
+	got, err := client.GetSession(ctx, sessionID, userID)
+	require.NoError(t, err)
+	assert.True(t, got.UpdatedAt.After(oldActivity), "session updated_at should advance after storing a task")
+}
+
 // TestStoreAgentIdempotence verifies that calling StoreAgent multiple times
 // with the same data is idempotent and doesn't error. This is critical for
 // the lock-free concurrency model where concurrent upserts must succeed.

go/core/internal/database/queries/events.sql

@@ -1,6 +1,16 @@
 -- name: InsertEvent :exec
+WITH inserted_event AS (
 INSERT INTO event (id, user_id, session_id, data, created_at, updated_at)
-VALUES ($1, $2, $3, $4, NOW(), NOW());
+VALUES ($1, $2, $3, $4, NOW(), NOW())
+RETURNING user_id, session_id
+)
+UPDATE session
+SET updated_at = NOW()
+FROM inserted_event
+WHERE inserted_event.session_id IS NOT NULL
+  AND session.id = inserted_event.session_id
+  AND session.user_id = inserted_event.user_id
+  AND session.deleted_at IS NULL;
 
 -- name: GetEvent :one
 SELECT * FROM event

go/core/internal/database/queries/sessions.sql

@@ -6,19 +6,19 @@ LIMIT 1;
 -- name: ListSessions :many
 SELECT * FROM session
 WHERE user_id = $1 AND deleted_at IS NULL
-ORDER BY created_at ASC;
+ORDER BY updated_at DESC, created_at DESC;
 
 -- name: ListSessionsForAgent :many
 SELECT * FROM session
 WHERE agent_id = $1 AND user_id = $2 AND deleted_at IS NULL
   AND (source IS NULL OR source != 'agent')
-ORDER BY created_at ASC;
+ORDER BY updated_at DESC, created_at DESC;
 
 -- name: ListSessionsForAgentAllUsers :many
 SELECT * FROM session
 WHERE agent_id = $1 AND deleted_at IS NULL
   AND (source IS NULL OR source != 'agent')
-ORDER BY created_at ASC;
+ORDER BY updated_at DESC, created_at DESC;
 
 -- name: UpsertSession :exec
 INSERT INTO session (id, user_id, name, agent_id, source, created_at, updated_at)

go/core/internal/database/queries/tasks.sql

@@ -14,12 +14,21 @@ WHERE session_id = $1 AND deleted_at IS NULL
 ORDER BY created_at ASC;
 
 -- name: UpsertTask :exec
+WITH upserted_task AS (
 INSERT INTO task (id, data, session_id, created_at, updated_at)
 VALUES ($1, $2, $3, NOW(), NOW())
 ON CONFLICT (id) DO UPDATE SET
     data       = EXCLUDED.data,
     session_id = EXCLUDED.session_id,
-    updated_at = NOW();
+    updated_at = NOW()
+RETURNING session_id
+)
+UPDATE session
+SET updated_at = NOW()
+FROM upserted_task
+WHERE upserted_task.session_id IS NOT NULL
+  AND session.id = upserted_task.session_id
+  AND session.deleted_at IS NULL;
 
 -- name: SoftDeleteTask :exec
 UPDATE task SET deleted_at = NOW() WHERE id = $1 AND deleted_at IS NULL;

go/core/internal/httpserver/handlers/sessions_test.go

@@ -79,15 +79,28 @@ func TestSessionsHandler(t *testing.T) {
 		return session
 	}
 
+	setSessionActivity := func(t *testing.T, sessionID, userID string, createdAt, updatedAt time.Time) {
+		t.Helper()
+		_, err := sharedDB.Exec(context.Background(), `
+			UPDATE session
+			SET created_at = $1, updated_at = $2
+			WHERE id = $3 AND user_id = $4
+		`, createdAt, updatedAt, sessionID, userID)
+		require.NoError(t, err)
+	}
+
 	t.Run("HandleListSessions", func(t *testing.T) {
 		t.Run("Success", func(t *testing.T) {
 			handler, dbClient, responseRecorder := setupHandler(t)
 			userID := "test-user"
+			base := time.Date(2026, 1, 1, 12, 0, 0, 0, time.UTC)
 
 			// Create test sessions
 			agentID := "1"
 			session1 := createTestSession(t, dbClient, "session-1", userID, agentID)
 			session2 := createTestSession(t, dbClient, "session-2", userID, agentID)
+			setSessionActivity(t, session1.ID, userID, base, base.Add(2*time.Hour))
+			setSessionActivity(t, session2.ID, userID, base.Add(time.Hour), base.Add(time.Hour))
 
 			req := httptest.NewRequest("GET", "/api/sessions?user_id="+userID, nil)
 			req = setUser(req, userID)
@@ -472,6 +485,9 @@ func TestSessionsHandler(t *testing.T) {
 			agent := createTestAgent(t, dbClient, agentRef)
 			session1 := createTestSession(t, dbClient, "session-1", userID, agent.ID)
 			session2 := createTestSession(t, dbClient, "session-2", userID, agent.ID)
+			base := time.Date(2026, 1, 1, 12, 0, 0, 0, time.UTC)
+			setSessionActivity(t, session1.ID, userID, base, base.Add(2*time.Hour))
+			setSessionActivity(t, session2.ID, userID, base.Add(time.Hour), base.Add(time.Hour))
 
 			req := httptest.NewRequest("GET", "/api/agents/"+namespace+"/"+agentName+"/sessions", nil)
 			req = mux.SetURLVars(req, map[string]string{"namespace": namespace, "name": agentName})

ui/src/components/sidebars/ChatItem.stories.tsx

@@ -62,7 +62,7 @@ export const ShortTitle: Story = {
     agentNamespace: "kagent",
     onDelete: async () => {},
     sessionName: "Quick question",
-    createdAt: new Date().toISOString(),
+    activityAt: new Date().toISOString(),
   },
 };
 
@@ -73,7 +73,7 @@ export const LongTitle: Story = {
     agentNamespace: "kagent",
     onDelete: async () => {},
     sessionName: "Review https://github.com/Smartest-Fly/app/pull/1234 and provide feedback on the authentication implementation",
-    createdAt: new Date().toISOString(),
+    activityAt: new Date().toISOString(),
   },
 };
 
@@ -84,7 +84,7 @@ export const LongTitleWithAgentName: Story = {
     agentNamespace: "kagent",
     onDelete: async () => {},
     sessionName: "Review https://github.com/Smartest-Fly/app/pull/1234 and provide feedback on the authentication implementation",
-    createdAt: new Date().toISOString(),
+    activityAt: new Date().toISOString(),
   },
 };
 
@@ -107,7 +107,7 @@ export const MultipleLongTitles: Story = {
           agentNamespace="kagent"
           onDelete={async () => {}}
           sessionName={title}
-          createdAt={new Date(Date.now() - i * 3600000).toISOString()}
+          activityAt={new Date(Date.now() - i * 3600000).toISOString()}
 
         />
       ))}

ui/src/components/sidebars/ChatItem.tsx

@@ -22,12 +22,12 @@ interface ChatItemProps {
   agentNamespace?: string;
   sessionName?: string;
   onDownload?: (sessionId: string) => Promise<void>;
-  createdAt?: string;
+  activityAt?: string;
   /** When true, omit delete (e.g. Sandbox single-session agents). */
   hideDelete?: boolean;
 }
 
-const ChatItem = ({ sessionId, agentName, agentNamespace, onDelete, sessionName, onDownload, createdAt, hideDelete }: ChatItemProps) => {
+const ChatItem = ({ sessionId, agentName, agentNamespace, onDelete, sessionName, onDownload, activityAt, hideDelete }: ChatItemProps) => {
   const title = sessionName || "Untitled";
 
   // Format timestamp based on how recent it is
@@ -60,7 +60,7 @@ const ChatItem = ({ sessionId, agentName, agentNamespace, onDelete, sessionName,
                 style={{
                   background: 'linear-gradient(to right, transparent, hsl(var(--sidebar-background)) 30%)',
                 }}
-              >{formatTime(createdAt)}</span>
+              >{formatTime(activityAt)}</span>
             </Link>
           </SidebarMenuButton>
           <DropdownMenu modal={false}>

ui/src/components/sidebars/GroupedChats.stories.tsx

@@ -27,13 +27,13 @@ const meta: Meta<typeof GroupedChats> = {
 export default meta;
 type Story = StoryObj<typeof GroupedChats>;
 
-const createSession = (id: string, name: string, daysAgo: number): Session => ({
+const createSession = (id: string, name: string, createdDaysAgo: number, updatedDaysAgo = createdDaysAgo): Session => ({
   id,
   name,
   agent_id: 'kgent__NS__k8s',
   user_id: "user-1",
-  created_at: new Date(Date.now() - daysAgo * 24 * 3600000).toISOString(),
-  updated_at: new Date(Date.now() - daysAgo * 24 * 3600000).toISOString(),
+  created_at: new Date(Date.now() - createdDaysAgo * 24 * 3600000).toISOString(),
+  updated_at: new Date(Date.now() - updatedDaysAgo * 24 * 3600000).toISOString(),
   deleted_at: "",
 });
 
@@ -81,3 +81,15 @@ export const ManySessions: Story = {
     ],
   },
 };
+
+export const RecentlyUpdatedOlderSession: Story = {
+  args: {
+    agentName: "k8s",
+    agentNamespace: "kagent",
+    sessions: [
+      createSession("session-old-active", "Created last week, active today", 7, 0),
+      createSession("session-new-inactive", "Created today, inactive", 0, 0.2),
+      createSession("session-yesterday", "Yesterday chat", 1),
+    ],
+  },
+};