diff --git a/backend/tests/test_sidebar_stats.py b/backend/tests/test_sidebar_stats.py
new file mode 100644
index 00000000..dc5ec100
--- /dev/null
+++ b/backend/tests/test_sidebar_stats.py
@@ -0,0 +1,142 @@
+"""Integration tests for sidebar stats endpoint."""
+
+import pytest
+from httpx import AsyncClient
+
+
+class TestSidebarStats:
+    """Tests for GET /sessions/sidebar-stats."""
+
+    @pytest.mark.asyncio
+    async def test_sidebar_stats_no_sessions(
+        self, client: AsyncClient, auth_headers: dict
+    ):
+        """Empty stats when user has no sessions."""
+        response = await client.get(
+            "/api/v1/sessions/sidebar-stats?tz_offset=0",
+            headers=auth_headers,
+        )
+        assert response.status_code == 200
+        data = response.json()
+        assert data["resolved_today"] == 0
+        assert data["active_count"] == 0
+        assert data["total_session_minutes_today"] == 0
+        assert data["active_sessions"] == []
+        assert data["recent_completions"] == []
+        assert "tree_counts" in data
+
+    @pytest.mark.asyncio
+    async def test_sidebar_stats_with_active_session(
+        self, client: AsyncClient, auth_headers: dict, test_tree: dict
+    ):
+        """Active session appears in activity feed."""
+        create_resp = await client.post(
+            "/api/v1/sessions",
+            json={"tree_id": test_tree["id"], "ticket_number": "TK-100"},
+            headers=auth_headers,
+        )
+        assert create_resp.status_code == 201
+
+        response = await client.get(
+            "/api/v1/sessions/sidebar-stats?tz_offset=0",
+            headers=auth_headers,
+        )
+        assert response.status_code == 200
+        data = response.json()
+        assert data["active_count"] == 1
+        assert len(data["active_sessions"]) == 1
+        assert data["active_sessions"][0]["ticket_number"] == "TK-100"
+        assert data["active_sessions"][0]["tree_id"] == test_tree["id"]
+
+    @pytest.mark.asyncio
+    async def test_sidebar_stats_resolved_today(
+        self, client: AsyncClient, auth_headers: dict, test_tree: dict
+    ):
+        """Resolved session counts in resolved_today."""
+        create_resp = await client.post(
+            "/api/v1/sessions",
+            json={"tree_id": test_tree["id"]},
+            headers=auth_headers,
+        )
+        session_id = create_resp.json()["id"]
+
+        # Complete with resolved outcome
+        await client.post(
+            f"/api/v1/sessions/{session_id}/complete",
+            json={"outcome": "resolved", "outcome_notes": "Fixed it"},
+            headers=auth_headers,
+        )
+
+        response = await client.get(
+            "/api/v1/sessions/sidebar-stats?tz_offset=0",
+            headers=auth_headers,
+        )
+        assert response.status_code == 200
+        data = response.json()
+        assert data["resolved_today"] >= 1
+        assert data["active_count"] == 0
+        assert len(data["recent_completions"]) >= 1
+
+    @pytest.mark.asyncio
+    async def test_sidebar_stats_max_active_sessions(
+        self, client: AsyncClient, auth_headers: dict, test_tree: dict
+    ):
+        """Active sessions capped at 5."""
+        for i in range(7):
+            await client.post(
+                "/api/v1/sessions",
+                json={"tree_id": test_tree["id"], "ticket_number": f"TK-{i}"},
+                headers=auth_headers,
+            )
+
+        response = await client.get(
+            "/api/v1/sessions/sidebar-stats?tz_offset=0",
+            headers=auth_headers,
+        )
+        assert response.status_code == 200
+        data = response.json()
+        assert data["active_count"] == 7
+        assert len(data["active_sessions"]) == 5
+
+    @pytest.mark.asyncio
+    async def test_sidebar_stats_recent_completions_max_3(
+        self, client: AsyncClient, auth_headers: dict, test_tree: dict
+    ):
+        """Recent completions capped at 3."""
+        for i in range(5):
+            create_resp = await client.post(
+                "/api/v1/sessions",
+                json={"tree_id": test_tree["id"]},
+                headers=auth_headers,
+            )
+            session_id = create_resp.json()["id"]
+            await client.post(
+                f"/api/v1/sessions/{session_id}/complete",
+                json={"outcome": "resolved", "outcome_notes": "Done"},
+                headers=auth_headers,
+            )
+
+        response = await client.get(
+            "/api/v1/sessions/sidebar-stats?tz_offset=0",
+            headers=auth_headers,
+        )
+        assert response.status_code == 200
+        data = response.json()
+        assert len(data["recent_completions"]) == 3
+
+    @pytest.mark.asyncio
+    async def test_sidebar_stats_requires_auth(self, client: AsyncClient):
+        """Endpoint requires authentication."""
+        response = await client.get("/api/v1/sessions/sidebar-stats?tz_offset=0")
+        assert response.status_code == 401
+
+    @pytest.mark.asyncio
+    async def test_sidebar_stats_requires_tz_offset(
+        self, client: AsyncClient, auth_headers: dict
+    ):
+        """tz_offset query param is required."""
+        response = await client.get(
+            "/api/v1/sessions/sidebar-stats",
+            headers=auth_headers,
+        )
+        assert response.status_code == 422