diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index cbacd3b..ca63f3d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -37,3 +37,5 @@ jobs:
         run: make test-quiet PYTHON=python
         env:
           MPLBACKEND: Agg
+          # Optional repo secret; live-brain tests skip when it is empty.
+          NEUPRINT_APPLICATION_CREDENTIALS: ${{ secrets.NEUPRINT_TOKEN }}
diff --git a/Makefile b/Makefile
index 47f245b..0187d40 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,7 @@
        examples example-basic example-connectome example-navigation example-gui \
        example-gui-smoke figures \
        cli-list cli-simulate cli-simulate-offline cli-train cli-train-offline \
-       test-neuprint test-all
+       test-neuprint test-live test-all
 
 PYTHON   := .venv/bin/python
 PIP      := .venv/bin/pip
@@ -118,6 +118,9 @@ cli-train-offline: ## Train with synthetic brain (no token needed)
 
 # ── neuPrint (requires token) ─────────────────────────────────────────────
 
+test-live: ## End-to-end pytest against the real brain (needs token)
+	$(PYTEST) tests/test_live_brain.py -q
+
 test-neuprint: ## Test real neuPrint mini brain fetch + simulate
 ifndef NEUPRINT_APPLICATION_CREDENTIALS
 	$(error NEUPRINT_APPLICATION_CREDENTIALS not set. Create .env or export it)
diff --git a/src/flynet/jax_trainer.py b/src/flynet/jax_trainer.py
index a1972e8..1707345 100644
--- a/src/flynet/jax_trainer.py
+++ b/src/flynet/jax_trainer.py
@@ -613,7 +613,7 @@ def train_navigation(
         total = time.time() - t0
         print(
             f"\nTraining complete: {episodes} episodes in {total:.1f}s "
-            f"({total / episodes:.2f}s/ep)"
+            f"({total / max(episodes, 1):.2f}s/ep)"
         )
         final_sr = log.episode_success_rate[-1] if log.episode_success_rate else 0.0
         print(f"Final success rate (10-ep window): {final_sr:.0%}")
@@ -1259,7 +1259,7 @@ def train_navigation(
         total = time.time() - t0
         print(
             f"\nTraining complete: {episodes} episodes in {total:.1f}s "
-            f"({total / episodes:.2f}s/ep)"
+            f"({total / max(episodes, 1):.2f}s/ep)"
         )
         final_sr = log.episode_success_rate[-1] if log.episode_success_rate else 0.0
         print(f"Final success rate (10-ep window): {final_sr:.0%}")
diff --git a/tests/test_live_brain.py b/tests/test_live_brain.py
new file mode 100644
index 0000000..3f6839d
--- /dev/null
+++ b/tests/test_live_brain.py
@@ -0,0 +1,37 @@
+"""End-to-end check against the real neuPrint hemibrain/CNS data.
+
+Skipped unless NEUPRINT_APPLICATION_CREDENTIALS is set, so offline CI stays
+hermetic. Run with ``make test-live``.
+"""
+
+import os
+
+import numpy as np
+import pytest
+
+from flynet import ConnectomeLoader, SpikingNetwork
+
+pytestmark = pytest.mark.skipif(
+    not os.environ.get("NEUPRINT_APPLICATION_CREDENTIALS"),
+    reason="needs a neuPrint token",
+)
+
+
+@pytest.fixture(scope="module")
+def real_net(tmp_path_factory):
+    # Fresh cache dir so this really hits the server rather than a stale file.
+    loader = ConnectomeLoader(cache_dir=str(tmp_path_factory.mktemp("cache")))
+    ids, edges, motors = loader.load_or_fetch_mini(neuron_type="DNge104")
+    assert loader.last_source == "neuprint"
+    return SpikingNetwork(ids, edges, motor_ids=motors)
+
+
+def test_real_brain_loads(real_net):
+    assert len(real_net.ids) > 10
+    assert len(real_net.motors) == 2
+
+
+def test_real_brain_settles_to_finite_motor_output(real_net):
+    real_net.settle(z_right=2.0, z_left=0.5)
+    drv, _ = real_net.turn(rho_right=2.0, rho_left=0.5)
+    assert np.all(np.isfinite(drv))