ci: qualify Python 3.15 final across supported platforms

.github/ISSUE_TEMPLATE/bug.yml

@@ -1,5 +1,5 @@
 name: Bug report
-description: Report reproducible incorrect behavior in ecosystem policy or tooling
+description: Report reproducible incorrect behavior in ml4t-engineer
 title: "[Bug]: "
 labels:
   - "type: bug"

.github/workflows/ci.yml

@@ -170,12 +170,12 @@ jobs:
     name: Qualify (${{ matrix.os }}, Python ${{ matrix.python-version }})
     runs-on: ${{ matrix.os }}
     needs: build-candidate
-    timeout-minutes: 45
+    timeout-minutes: ${{ matrix.python-version == '3.15' && 90 || 45 }}
     strategy:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        python-version: ["3.12", "3.13", "3.14"]
+        python-version: ["3.12", "3.13", "3.14", "3.15"]
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:

.github/workflows/ecosystem.yml

@@ -20,4 +20,3 @@ jobs:
     uses: ml4t/ecosystem/.github/workflows/qualify-library.yml@066dc737a879faea51a5b8a900315441712ea89a # 2026-09-25 policy snapshot
     with:
       import-package: ml4t.engineer
-      prerelease-exception: python-315-polars

.github/workflows/native-stress.yml

@@ -69,7 +69,7 @@ jobs:
     name: Native stress (${{ matrix.os }}, Python ${{ matrix.python-version }})
     runs-on: ${{ matrix.os }}
     needs: build
-    timeout-minutes: 30
+    timeout-minutes: ${{ matrix.python-version == '3.15' && 90 || 30 }}
     strategy:
       fail-fast: false
       matrix: ${{ fromJSON(needs.build.outputs.matrix) }}

.github/workflows/release.yml

@@ -78,7 +78,6 @@ jobs:
     uses: ml4t/ecosystem/.github/workflows/qualify-library.yml@066dc737a879faea51a5b8a900315441712ea89a # 2026-09-25 policy snapshot
     with:
       import-package: ml4t.engineer
-      prerelease-exception: python-315-polars
 
   qualification:
     name: Qualify Release Candidate

AGENTS.md

@@ -38,7 +38,7 @@ is under `docs/user-guide/`, and the generated API reference is under
 
 ## Engineering constraints
 
-- Python 3.12, 3.13, and 3.14 are supported.
+- Python 3.12, 3.13, 3.14, and 3.15 are supported.
 - Feature computation must preserve the documented DataFrame or LazyFrame
   return behavior.
 - Changes to registered features must keep implementation, registry metadata,

README.md

@@ -1,6 +1,6 @@
 # ml4t-engineer
 
-[![Python 3.12-3.14](https://img.shields.io/badge/python-3.12--3.14-blue.svg)](https://www.python.org/downloads/)
+[![Python 3.12-3.15](https://img.shields.io/badge/python-3.12--3.15-blue.svg)](https://www.python.org/downloads/)
 [![PyPI](https://img.shields.io/pypi/v/ml4t-engineer)](https://pypi.org/project/ml4t-engineer/)
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://github.com/ml4t/engineer/blob/main/LICENSE)
 
@@ -13,12 +13,19 @@ The core interface uses Polars DataFrames.
 
 ## Installation
 
-`ml4t-engineer` supports Python 3.12, 3.13, and 3.14 on Linux, macOS, and Windows.
+Development source supports Python 3.12, 3.13, 3.14, and 3.15 on Linux, macOS, and Windows.
+Python 3.15 support and the calendar API used below are intended for the 0.2 release.
+Release 0.1.6 supports Python 3.12-3.14; use its
+[version-matched quick start](https://github.com/ml4t/engineer/tree/v0.1.6#quick-start)
+instead of passing the new `calendar` argument to that release.
 
 ```bash
 pip install ml4t-engineer
 ```
 
+Until 0.2 is available from PyPI, run the examples below from a
+[source checkout](#development) with `uv sync --no-dev`, using that environment's Python.
+
 The quick start uses only core dependencies. Optional extras provide TA-Lib validation,
 DuckDB and PyArrow storage, market calendars, visualization, statistics, and ML tools:
 
@@ -31,9 +38,10 @@ pip install "ml4t-engineer[stats]"
 pip install "ml4t-engineer[ml]"
 ```
 
-TA-Lib requires its native library. The core package does not require an external
-service, credentials, or special hardware. Python 3.15 is not supported while the
-active Polars compatibility exception applies.
+The development `ta` extra uses TA-Lib 0.8.2 or later in the 0.8 series; its wheels
+include the native library. For source builds, follow the
+[upstream installation guide](https://github.com/TA-Lib/ta-lib-python#installation).
+The core package does not require an external service, credentials, or special hardware.
 
 ## Quick Start
 

docs/getting-started/installation.md

@@ -5,9 +5,15 @@ and then move directly into the first workflow.
 
 ## Requirements
 
-- Python 3.12, 3.13, or 3.14
+- Python 3.12, 3.13, 3.14, or 3.15
 - Polars 0.20+
 
+These requirements describe development source for the 0.2 release. Published 0.1.6
+supports Python 3.12-3.14 and does not accept the new `calendar` argument. Use its
+[version-matched quick start](https://github.com/ml4t/engineer/tree/v0.1.6#quick-start)
+for that release. Until 0.2 is available from PyPI, use the source installation below
+for Python 3.15 and the calendar-aware examples in this guide.
+
 ## Install from PyPI
 
 ```bash
@@ -20,30 +26,27 @@ If you standardize on `uv`, `uv pip install ml4t-engineer` is equivalent.
 
 ```bash
 git clone https://github.com/ml4t/engineer.git
-cd ml4t-engineer
-pip install -e .
+cd engineer
+uv sync --no-dev
 ```
 
+Run the examples with the created environment, for example `uv run --no-sync python`.
+
 ## Optional Dependencies
 
 ### TA-Lib (for validation)
 
-Some indicators can be validated against TA-Lib. Install TA-Lib if you need this:
+Some indicators can be validated against TA-Lib. The `ta` extra requires TA-Lib 0.8.2
+or later in the 0.8 series, whose wheels include the native library and support Python 3.15:
 
 ```bash
-# macOS
-brew install ta-lib
-pip install TA-Lib
-
-# Ubuntu/Debian
-sudo apt-get install libta-lib-dev
-pip install TA-Lib
-
-# Windows
-# Download from https://www.ta-lib.org/
-pip install TA-Lib
+uv pip install "ml4t-engineer[ta]"
 ```
 
+Use the [upstream installation guide](https://github.com/TA-Lib/ta-lib-python#installation)
+when your platform requires a source build. Comparisons must declare matching moving-average
+types: Engineer's APO/PPO default remains SMA (`matype=0`), while TA-Lib 0.8 defaults to EMA.
+
 ### Statistical diagnostics
 
 `find_optimal_d()` and `fdiff_diagnostics()` use Statsmodels for the augmented

pyproject.toml

@@ -63,12 +63,13 @@ classifiers = [
     "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.13",
     "Programming Language :: Python :: 3.14",
+    "Programming Language :: Python :: 3.15",
     "Topic :: Office/Business :: Financial :: Investment",
     "Topic :: Scientific/Engineering :: Information Analysis",
     "Topic :: Scientific/Engineering :: Artificial Intelligence",
     "Typing :: Typed",
 ]
-requires-python = ">=3.12,<3.15"
+requires-python = ">=3.12"
 
 # Core dependencies
 dependencies = [
@@ -95,7 +96,7 @@ dependencies = [
 [project.optional-dependencies]
 # Technical analysis libraries
 ta = [
-    "ta-lib>=0.4.0,<0.8",
+    "ta-lib>=0.8.2,<0.9",
 ]
 
 # Feature store with DuckDB
@@ -142,7 +143,7 @@ dev = [
     "pre-commit>=3.3.0",
     "duckdb>=0.9.0",
     "pandas-market-calendars>=5.5.0",
-    "ta-lib>=0.4.0,<0.8",
+    "ta-lib>=0.8.2,<0.9",
     "yfinance>=0.2.0",
     "lightgbm>=4.0.0",
     "shap>=0.44.0",
@@ -160,7 +161,7 @@ docs = [
 
 # Complete installation
 all = [
-    "ta-lib>=0.4.0,<0.8",
+    "ta-lib>=0.8.2,<0.9",
     "duckdb>=0.9.0",
     "pandas-market-calendars>=5.5.0",
     "plotly>=5.15.0",
@@ -201,6 +202,7 @@ test = [
     "pytest-timeout>=2.1.0",
     "pytest-benchmark>=4.0.0",
     "hypothesis>=6.80.0",
+    "pandas-market-calendars>=5.5.0",
 ]
 dev = [
     { include-group = "test" },

tests/test_all_indicators_accuracy.py

@@ -175,13 +175,13 @@ def test_momentum_indicators(self, price_data):
         assert_allclose(result, expected, rtol=1e-10, equal_nan=True)
 
         # APO
-        result = apo(close, 12, 26)
-        expected = talib.APO(close, 12, 26)
+        result = apo(close, 12, 26, matype=0)
+        expected = talib.APO(close, 12, 26, matype=0)
         assert_allclose(result, expected, rtol=1e-10, equal_nan=True)
 
         # PPO
-        result = ppo(close, 12, 26)
-        expected = talib.PPO(close, 12, 26)
+        result = ppo(close, 12, 26, matype=0)
+        expected = talib.PPO(close, 12, 26, matype=0)
         assert_allclose(result, expected, rtol=1e-10, equal_nan=True)
 
         # AROON

tests/test_linearreg_family.py

@@ -277,44 +277,27 @@ def test_linearreg_family_nan_patterns(self):
         assert np.all(np.isnan(angle[: period - 1]))
 
     def test_linearreg_family_crypto_accuracy(self, crypto_data_small):
-        """Test accuracy on real crypto data."""
+        """Keep regression outputs accurate when the upstream rolling reference drifts."""
         prices = crypto_data_small["close"].to_numpy()
 
         for period in [5, 10, 14, 20]:
-            # Test slope
-            expected_slope = talib.LINEARREG_SLOPE(prices, timeperiod=period)
-            result_slope = linearreg_slope(prices, timeperiod=period)
-            valid_idx = ~(np.isnan(expected_slope) | np.isnan(result_slope))
-            if np.any(valid_idx):
+            windows = np.lib.stride_tricks.sliding_window_view(prices, period)
+            design = np.column_stack((np.arange(period), np.ones(period)))
+            # Translation leaves slope unchanged and avoids a large price offset in the solve.
+            slope, intercept = np.linalg.lstsq(design, (windows - windows[:, :1]).T, rcond=None)[0]
+            for function, expected in [
+                (linearreg_slope, slope),
+                (linearreg_intercept, intercept + windows[:, 0]),
+                (linearreg_angle, np.degrees(np.arctan(slope))),
+            ]:
+                aligned = np.full(len(prices), np.nan)
+                aligned[period - 1 :] = expected
                 assert_allclose(
-                    result_slope[valid_idx],
-                    expected_slope[valid_idx],
+                    function(prices, timeperiod=period),
+                    aligned,
                     rtol=1e-7,
-                    err_msg=f"LINEARREG_SLOPE mismatch on crypto data for period {period}",
-                )
-
-            # Test intercept
-            expected_intercept = talib.LINEARREG_INTERCEPT(prices, timeperiod=period)
-            result_intercept = linearreg_intercept(prices, timeperiod=period)
-            valid_idx = ~(np.isnan(expected_intercept) | np.isnan(result_intercept))
-            if np.any(valid_idx):
-                assert_allclose(
-                    result_intercept[valid_idx],
-                    expected_intercept[valid_idx],
-                    rtol=1e-7,
-                    err_msg=f"LINEARREG_INTERCEPT mismatch on crypto data for period {period}",
-                )
-
-            # Test angle
-            expected_angle = talib.LINEARREG_ANGLE(prices, timeperiod=period)
-            result_angle = linearreg_angle(prices, timeperiod=period)
-            valid_idx = ~(np.isnan(expected_angle) | np.isnan(result_angle))
-            if np.any(valid_idx):
-                assert_allclose(
-                    result_angle[valid_idx],
-                    expected_angle[valid_idx],
-                    rtol=1e-7,
-                    err_msg=f"LINEARREG_ANGLE mismatch on crypto data for period {period}",
+                    equal_nan=True,
+                    err_msg=f"{function.__name__} differs from least squares for period {period}",
                 )
 
     @pytest.mark.perf

tests/test_release_policy.py

@@ -43,7 +43,7 @@ def test_ci_qualifies_required_python_platform_matrix() -> None:
     matrix = workflow["jobs"]["test"]["strategy"]["matrix"]
     actual = set(itertools.product(matrix["os"], matrix["python-version"]))
 
-    stable = {"3.12", "3.13", "3.14"}
+    stable = {"3.12", "3.13", "3.14", "3.15"}
     platforms = {"ubuntu-latest", "macos-latest", "windows-latest"}
     assert actual == set(itertools.product(platforms, stable))
     assert "include" not in matrix
@@ -254,11 +254,11 @@ def test_core_dependency_requires_published_time_contract_v2() -> None:
     assert specs["source"] == {"registry": "https://pypi.org/simple"}
 
 
-def test_package_supports_python_312_through_314() -> None:
+def test_package_supports_python_312_through_315() -> None:
     project = tomllib.loads((ROOT / "pyproject.toml").read_text(encoding="utf-8"))
     dependencies = project["project"]["dependencies"]
 
-    assert project["project"]["requires-python"] == ">=3.12,<3.15"
+    assert project["project"]["requires-python"] == ">=3.12"
     assert "numba>=0.57.0" in dependencies
     assert "statsmodels>=0.14.0" in project["project"]["optional-dependencies"]["stats"]
     assert "pyarrow>=14.0.0" in project["project"]["optional-dependencies"]["store"]