From c36b5ec4ce663b79784f78e8203f575435bd88d3 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Sat, 18 Jul 2026 19:41:35 +0000
Subject: [PATCH] release: v0.13.2

---
 pyproject.toml                     |  2 +-
 python/manifoldbt/plot/backtest.py |  9 ++-
 python/tests/test_plot_charts.py   | 96 ++++++++++++++++++++++++++++++
 3 files changed, 105 insertions(+), 2 deletions(-)
 create mode 100644 python/tests/test_plot_charts.py

diff --git a/pyproject.toml b/pyproject.toml
index 0940b89..98a6803 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "manifoldbt"
-version = "0.13.1"
+version = "0.13.2"
 description = "Rust-powered backtesting engine for quantitative research"
 requires-python = ">=3.9"
 license = { file = "LICENSE" }
diff --git a/python/manifoldbt/plot/backtest.py b/python/manifoldbt/plot/backtest.py
index b5be3e6..052c55f 100644
--- a/python/manifoldbt/plot/backtest.py
+++ b/python/manifoldbt/plot/backtest.py
@@ -420,7 +420,10 @@ def monthly_returns(
             colorbar=dict(ticksuffix="%", outlinewidth=0, thickness=12),
             hoverongaps=False,
         ))
-        fig.update_yaxes(autorange="reversed")
+        # The year labels are strings, but without an explicit type plotly
+        # reads them as numbers and interpolates: a single-year backtest drew
+        # ticks at 2,022.6 / 2,022.8 / 2023 / 2,023.2 instead of one "2023" row.
+        fig.update_yaxes(type="category", autorange="reversed")
         fig.update_xaxes(side="bottom", showspikes=False)
         fig.update_yaxes(showspikes=False)
         fig.update_layout(hovermode="closest")
@@ -501,6 +504,10 @@ def returns_histogram(
             x=centers, y=counts, width=bw,
             marker_color=colors, opacity=0.7, marker_line_width=0,
             hovertemplate="%{x:.2%}: %{y}<extra></extra>",
+            # Kept out of the legend: the bars are green or red by sign, so a
+            # single swatch misrepresents them, and unnamed it showed up as
+            # "trace 0". The legend exists for the Normal overlay only.
+            showlegend=False,
         ))
         fig.add_vline(x=0, line_color=DARK_GRAY, line_width=0.8, line_dash="dash")
 
diff --git a/python/tests/test_plot_charts.py b/python/tests/test_plot_charts.py
new file mode 100644
index 0000000..92d84fb
--- /dev/null
+++ b/python/tests/test_plot_charts.py
@@ -0,0 +1,96 @@
+"""Chart-level regressions found by rendering a tearsheet and looking at it.
+
+Both defects below were invisible to file size, tag presence and trace counts.
+They only showed up on screen, so they are pinned here at the figure-spec
+level, which is cheap enough to run in CI without a browser.
+"""
+import os
+
+import pytest
+
+import manifoldbt as bt
+from manifoldbt import run_with_parquet
+
+pytest.importorskip("plotly")
+
+backtest_plots = pytest.importorskip("manifoldbt.plot.backtest")
+
+
+@pytest.fixture
+def backtest_result(golden_buy_hold_dir):
+    strategy = bt.Strategy(
+        name="chart_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_monthly_returns_year_axis_is_categorical(backtest_result):
+    """Year rows are labels, not a number line.
+
+    The labels are strings already, but with no explicit axis type plotly
+    infers a linear scale and interpolates between them: a single-year
+    backtest rendered ticks at 2,022.6 / 2,022.8 / 2023 / 2,023.2 / 2,023.4.
+    """
+    fig = backtest_plots.monthly_returns(backtest_result)
+    assert fig.layout.yaxis.type == "category"
+
+
+def test_returns_histogram_has_no_unnamed_legend_entry(monkeypatch):
+    """No trace may reach the legend without a name.
+
+    The histogram bars carried no name, so plotly labelled them "trace 0" and
+    gave them a single colour swatch even though the bars are green or red by
+    sign. The legend is there for the Normal overlay only.
+
+    Returns are injected rather than backtested: the golden fixture spans less
+    than two UTC days, so ``daily_returns_array`` comes back empty and the
+    chart short-circuits before building any trace. Asserting over that empty
+    figure passes no matter what the code does.
+    """
+    np = pytest.importorskip("numpy")
+    rng = np.random.default_rng(7)
+    monkeypatch.setattr(
+        backtest_plots, "daily_returns_array", lambda _result: rng.normal(0, 0.01, 500)
+    )
+
+    fig = backtest_plots.returns_histogram(object())
+
+    # Guard against the vacuous version of this test.
+    assert len(fig.data) >= 2, "expected the bars plus the Normal overlay"
+
+    legend_names = {
+        trace.name for trace in fig.data if trace.showlegend is not False
+    }
+    assert legend_names, "no trace reaches the legend, the check would be vacuous"
+    assert None not in legend_names, "an unnamed trace renders as 'trace 0'"
+    assert not any(
+        (name or "").startswith("trace ") for name in legend_names
+    ), f"auto-generated trace label in the legend: {legend_names}"