Prepare DSPy for Python 3.15

.github/workflows/run_tests.yml

@@ -70,18 +70,31 @@ jobs:
   test:
     name: Run Tests
     runs-on: ubuntu-latest
+    # 3.15 is an allowed failure (see the matrix note). Tolerating it stops a
+    # failure from failing the workflow and, under the default fail-fast, from
+    # cancelling the 3.10-3.14 legs.
+    continue-on-error: ${{ matrix.python-version == '3.15' }}
+    env:
+      # fastuuid has no cp315 wheel and its pyo3 rejects 3.15; build it against
+      # the stable ABI on the 3.15 leg. pyo3 reads only the value "1".
+      PYO3_USE_ABI3_FORWARD_COMPATIBILITY: ${{ matrix.python-version == '3.15' && '1' || '0' }}
     permissions:
       contents: read
     strategy:
       matrix:
-        python-version: ["3.10", "3.11", "3.12", "3.13", "3.14"]
+        # 3.15 is an allowed failure (continue-on-error above) while Python 3.15
+        # is a release candidate. Its deps install from cp315 wheels except
+        # fastuuid (a litellm dep), whose pyo3 rejects a Python past 3.14; the
+        # job env builds it against the stable ABI on the 3.15 leg only.
+        python-version: ["3.10", "3.11", "3.12", "3.13", "3.14", "3.15"]
     steps:
       - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
         with:
           persist-credentials: false
       - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
         with:
           python-version: ${{ matrix.python-version }}
+          allow-prereleases: true
       - name: Install uv with caching
         uses: astral-sh/setup-uv@20cfd1bf945f4377ade1205e4dbc17946fc9a30d # v10.0.1
         with:
@@ -103,18 +116,27 @@ jobs:
   extra_test:
     name: Run Extra and Deno Tests
     runs-on: ubuntu-latest
+    # 3.15 is an allowed failure (see the note in the `test` job); tolerated so
+    # it does not fail the workflow or, under fail-fast, cancel the 3.10-3.14 legs.
+    continue-on-error: ${{ matrix.python-version == '3.15' }}
+    env:
+      # fastuuid has no cp315 wheel and its pyo3 rejects 3.15; build it against
+      # the stable ABI on the 3.15 leg. pyo3 reads only the value "1".
+      PYO3_USE_ABI3_FORWARD_COMPATIBILITY: ${{ matrix.python-version == '3.15' && '1' || '0' }}
     permissions:
       contents: read
     strategy:
       matrix:
-        python-version: ["3.10", "3.11", "3.12", "3.13", "3.14"]
+        # 3.15 is an allowed failure (see the note in the `test` job above).
+        python-version: ["3.10", "3.11", "3.12", "3.13", "3.14", "3.15"]
     steps:
       - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
         with:
           persist-credentials: false
       - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
         with:
           python-version: ${{ matrix.python-version }}
+          allow-prereleases: true
       - name: Install uv with caching
         uses: astral-sh/setup-uv@20cfd1bf945f4377ade1205e4dbc17946fc9a30d # v10.0.1
         with:
@@ -256,18 +278,27 @@ jobs:
   build_package:
     name: Build Package
     runs-on: ubuntu-latest
+    # 3.15 is an allowed failure (see the note in the `test` job); tolerated so
+    # it does not fail the workflow or, under fail-fast, cancel the 3.10-3.14 legs.
+    continue-on-error: ${{ matrix.python-version == '3.15' }}
+    env:
+      # fastuuid has no cp315 wheel and its pyo3 rejects 3.15; build it against
+      # the stable ABI on the 3.15 leg. pyo3 reads only the value "1".
+      PYO3_USE_ABI3_FORWARD_COMPATIBILITY: ${{ matrix.python-version == '3.15' && '1' || '0' }}
     permissions:
       contents: read
     strategy:
       matrix:
-        python-version: ["3.10", "3.11", "3.12", "3.13", "3.14"]
+        # 3.15 is an allowed failure (see the note in the `test` job above).
+        python-version: ["3.10", "3.11", "3.12", "3.13", "3.14", "3.15"]
     steps:
       - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
         with:
           persist-credentials: false
       - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
         with:
           python-version: ${{ matrix.python-version }}
+          allow-prereleases: true
       - name: Install uv with caching
         uses: astral-sh/setup-uv@20cfd1bf945f4377ade1205e4dbc17946fc9a30d # v10.0.1
         with:

dspy/teleprompt/__init__.py

@@ -14,7 +14,24 @@
 from dspy.teleprompt.teleprompt_optuna import BootstrapFewShotWithOptuna
 from dspy.teleprompt.vanilla import LabeledFewShot
 
-from .gepa.gepa import GEPA
+try:
+    from .gepa.gepa import GEPA
+except ModuleNotFoundError as error:
+    if error.name != "gepa":
+        raise
+
+    class GEPA(Teleprompter):
+        """Stand-in for GEPA when the gepa package is not installed.
+
+        DSPy installs gepa only on Python < 3.15, because gepa declares requires-python <3.15. The stand-in keeps
+        GEPA's Teleprompter interface, so code that inspects or wraps GEPA.__init__ and GEPA.compile still imports.
+        """
+
+        def __init__(self, *args, **kwargs):
+            raise ImportError(
+                "gepa is required to use dspy.GEPA. It is not installed by default on Python 3.15 and later "
+                "because gepa declares requires-python <3.15."
+            )
 
 __all__ = [
     "AvatarOptimizer",

pyproject.toml

@@ -13,7 +13,7 @@ description = "DSPy"
 readme = "README.md"
 authors = [{ name = "Omar Khattab", email = "okhattab@stanford.edu" }]
 license = {file = "LICENSE"}
-requires-python = ">=3.10, <3.15"
+requires-python = ">=3.10, <3.16"
 classifiers = [
     "Development Status :: 3 - Alpha",
     "Intended Audience :: Science/Research",
@@ -28,14 +28,17 @@ dependencies = [
     "requests>=2.31.0",
     "pydantic>=2.11.0",
     "pyyaml>=6.0.1",
-    "litellm>=1.65.8",
+    # litellm and gepa declare requires-python <3.15, so pip cannot install them on 3.15.
+    # The bundled lm15 engine serves LM calls without litellm; `dspy[litellm]` opts back in.
+    "litellm>=1.65.8; python_version < '3.15'",
+    "jsonschema>=4.0.0",
     "diskcache>=5.6.0",
     "json-repair>=0.54.2",
     "tenacity>=8.2.3",  # undeclared runtime dep of litellm, needed for exponential_backoff_retry
     "anyio",
     "cachetools>=5.5.0",
     "cloudpickle>=3.1.2",
-    "gepa[dspy]==0.1.4",
+    "gepa[dspy]==0.1.4; python_version < '3.15'",
 ]
 
 [project.optional-dependencies]
@@ -61,8 +64,9 @@ dev = [
     "numpy>=1.26.0",
     # LiteLLM proxy imports an internal FastAPI helper removed in 0.140.7.
     "fastapi<0.140.7; sys_platform != 'win32' and python_version < '3.14'",
-    "litellm>=1.65.8; sys_platform == 'win32' or python_version == '3.14'",
-    "litellm[proxy]>=1.65.8; sys_platform != 'win32' and python_version < '3.14'",  # Remove 3.14 condition once uvloop supports
+    "litellm>=1.65.8; sys_platform == 'win32' or python_version >= '3.14'",
+    "litellm[proxy]>=1.65.8; sys_platform != 'win32' and python_version < '3.14'",  # Remove the 3.14+ condition once uvloop supports it
+    "gepa[dspy]==0.1.4",
 ]
 test_extras = [
     "mcp; python_version >= '3.10'",

tests/test_utils/server/__init__.py

@@ -27,8 +27,8 @@ def _litellm_test_server() -> Iterator[tuple[str, str]]:
     Start one LiteLLM test server per pytest worker and tear it down when the
     session completes.
     """
-    if sys.version_info[:2] == (3, 14):
-        pytest.skip("Litellm proxy server is not supported on Python 3.14.")
+    if sys.version_info[:2] >= (3, 14):
+        pytest.skip("Litellm proxy server is not supported on Python 3.14+.")
     with tempfile.TemporaryDirectory() as server_log_dir_path:
         # Create a server log file used to store request logs
         server_log_file_path = os.path.join(server_log_dir_path, "request_logs.jsonl")