diff --git a/pyproject.toml b/pyproject.toml
index 27fa4e0..0940b89 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "manifoldbt"
-version = "0.13.0"
+version = "0.13.1"
 description = "Rust-powered backtesting engine for quantitative research"
 requires-python = ">=3.9"
 license = { file = "LICENSE" }
diff --git a/python/manifoldbt/plot/tearsheet.py b/python/manifoldbt/plot/tearsheet.py
index 18ec834..5128859 100644
--- a/python/manifoldbt/plot/tearsheet.py
+++ b/python/manifoldbt/plot/tearsheet.py
@@ -214,8 +214,11 @@ def tearsheet(
 
     # ── plotly.js include ─────────────────────────────────────────
     if plotlyjs == "inline":
-        import plotly.io as pio
-        plotly_js_tag = f"<script>{pio.get_plotlyjs()}</script>"
+        # get_plotlyjs lives in plotly.offline. plotly.io has never exposed it
+        # (checked on 5.24 and 6.9), so the old plotly.io lookup raised
+        # AttributeError on every inline report rather than embedding anything.
+        from plotly.offline import get_plotlyjs
+        plotly_js_tag = f"<script>{get_plotlyjs()}</script>"
     else:
         plotly_js_tag = '<script src="https://cdn.plot.ly/plotly-2.35.2.min.js" charset="utf-8"></script>'
 
diff --git a/python/tests/test_plot_tearsheet.py b/python/tests/test_plot_tearsheet.py
new file mode 100644
index 0000000..3e1a27c
--- /dev/null
+++ b/python/tests/test_plot_tearsheet.py
@@ -0,0 +1,91 @@
+"""Tearsheet rendering, in particular the offline (``plotlyjs="inline"``) report.
+
+The inline path was written against ``plotly.io.get_plotlyjs``, which does not
+exist and never has, so every offline report raised AttributeError. Nothing
+exercised it, so nothing caught it. These tests render both modes for real.
+"""
+import os
+
+import pytest
+
+import manifoldbt as bt
+from manifoldbt import run_with_parquet
+
+pytest.importorskip("plotly")
+
+tearsheet = pytest.importorskip("manifoldbt.plot.tearsheet").tearsheet
+
+# Roughly the size of the embedded plotly runtime; the point is to tell an
+# actually-embedded bundle from a one-line CDN script tag, not to pin a version.
+_RUNTIME_BYTES = 2_000_000
+_CDN_TAG = '<script src="https://cdn.plot.ly'
+
+
+@pytest.fixture
+def backtest_result(golden_buy_hold_dir):
+    strategy = bt.Strategy(
+        name="tearsheet_probe",
+        signals={"signal": bt.lit(1.0)},
+        position_sizing=bt.col("signal"),
+    )
+    config = bt.BacktestConfig(
+        universe=[1],
+        time_range_start=0,
+        time_range_end=4_000_000_000,
+        bar_interval={"Days": 1},
+        initial_capital=1000.0,
+        currency="USD",
+        execution=bt.ExecutionConfig(
+            signal_delay=1,
+            execution_price="AtClose",
+            max_position_pct=1.0,
+            allow_short=False,
+            allow_fractional=True,
+            skip_gap_bars=False,
+            position_sizing_mode="Units",
+        ),
+        fees=bt.FeeConfig(),
+        slippage={"FixedBps": {"bps": 0.0}},
+        data_version="golden_v1",
+        rng_seed=7,
+    )
+    return run_with_parquet(
+        strategy.to_json(),
+        config.to_json(),
+        os.path.join(golden_buy_hold_dir, "bars_1m.parquet"),
+        "golden_v1",
+    )
+
+
+def test_inline_report_embeds_the_runtime(backtest_result, tmp_path):
+    out = tmp_path / "inline.html"
+    tearsheet(backtest_result, save=str(out), show=False, plotlyjs="inline")
+
+    body = out.read_text(encoding="utf-8")
+    assert _CDN_TAG not in body, "inline report still loads plotly from the CDN"
+    assert out.stat().st_size > _RUNTIME_BYTES, (
+        f"inline report is only {out.stat().st_size} bytes, "
+        "the plotly runtime does not look embedded"
+    )
+
+
+def test_cdn_report_links_the_runtime_instead_of_embedding_it(
+    backtest_result, tmp_path
+):
+    out = tmp_path / "cdn.html"
+    tearsheet(backtest_result, save=str(out), show=False, plotlyjs="cdn")
+
+    body = out.read_text(encoding="utf-8")
+    assert _CDN_TAG in body
+    assert out.stat().st_size < _RUNTIME_BYTES
+
+
+def test_get_plotlyjs_comes_from_plotly_offline():
+    """Pin the import location that the inline path depends on."""
+    import plotly.io as pio
+    from plotly.offline import get_plotlyjs
+
+    assert not hasattr(pio, "get_plotlyjs"), (
+        "plotly.io grew a get_plotlyjs; the tearsheet import can be simplified"
+    )
+    assert len(get_plotlyjs()) > _RUNTIME_BYTES