fix(oci): resolve mypy type errors and add type-checking test gate

The OCI client code introduced several mypy errors that went unnoticed
because mypy was configured but never enforced in tests or CI.

Type fixes:
- lazy_oci_deps.py: suppress import-untyped for oci SDK (no type stubs)
- oci_client.py: cast response.stream to Iterator[bytes] (httpx types it
  as SyncByteStream | AsyncByteStream but it's iterable at runtime)
- oci_client.py: use .get("model", "") to satisfy str expectation
- test_oci_client.py: suppress attr-defined on dynamic module stubs

New test gate (tests/test_oci_mypy.py):
- Runs mypy on OCI source and test files as part of pytest
- Uses --follow-imports=silent to isolate from pre-existing AWS errors
- Skips gracefully if mypy is not on PATH
- Ensures future type regressions fail the test suite immediately

Author: fede-kamel

poetry.lock

@@ -52,6 +52,7 @@ oci = { version = "^2.165.0", optional = true }
 
 [tool.poetry.extras]
 oci = ["oci"]
+aiohttp=["aiohttp", "httpx-aiohttp"]
 
 [tool.poetry.group.dev.dependencies]
 mypy = "==1.13.0"
@@ -99,6 +100,3 @@ section-order = ["future", "standard-library", "third-party", "first-party"]
 [build-system]
 requires = ["poetry-core"]
 build-backend = "poetry.core.masonry.api"
-
-[tool.poetry.extras]
-aiohttp=["aiohttp", "httpx-aiohttp"]

pyproject.toml

@@ -24,7 +24,7 @@ def lazy_oci() -> Any:
         ImportError: If the OCI SDK is not installed
     """
     try:
-        import oci
+        import oci  # type: ignore[import-untyped]
         return oci
     except ImportError:
         raise ImportError(OCI_INSTALLATION_MESSAGE)

src/cohere/manually_maintained/lazy_oci_deps.py

@@ -530,7 +530,7 @@ def _hook(response: httpx.Response) -> None:
 
         # For streaming responses, wrap the stream with a transformer
         if is_stream:
-            original_stream = response.stream
+            original_stream = typing.cast(typing.Iterator[bytes], response.stream)
             transformed_stream = transform_oci_stream_wrapper(original_stream, endpoint, is_v2)
             response.stream = Streamer(transformed_stream)
             # Reset consumption flags
@@ -640,7 +640,7 @@ def transform_request_to_oci(
     Returns:
         Transformed request body in OCI format
     """
-    model = normalize_model_for_oci(cohere_body.get("model"))
+    model = normalize_model_for_oci(cohere_body.get("model", ""))
 
     if endpoint == "embed":
         if "texts" in cohere_body:

src/cohere/oci_client.py

@@ -55,19 +55,19 @@
 
 if "tokenizers" not in sys.modules:
     tokenizers_stub = types.ModuleType("tokenizers")
-    tokenizers_stub.Tokenizer = object
+    tokenizers_stub.Tokenizer = object  # type: ignore[attr-defined]
     sys.modules["tokenizers"] = tokenizers_stub
 
 if "fastavro" not in sys.modules:
     fastavro_stub = types.ModuleType("fastavro")
-    fastavro_stub.parse_schema = lambda schema: schema
-    fastavro_stub.reader = lambda *args, **kwargs: iter(())
-    fastavro_stub.writer = lambda *args, **kwargs: None
+    fastavro_stub.parse_schema = lambda schema: schema  # type: ignore[attr-defined]
+    fastavro_stub.reader = lambda *args, **kwargs: iter(())  # type: ignore[attr-defined]
+    fastavro_stub.writer = lambda *args, **kwargs: None  # type: ignore[attr-defined]
     sys.modules["fastavro"] = fastavro_stub
 
 if "httpx_sse" not in sys.modules:
     httpx_sse_stub = types.ModuleType("httpx_sse")
-    httpx_sse_stub.connect_sse = lambda *args, **kwargs: None
+    httpx_sse_stub.connect_sse = lambda *args, **kwargs: None  # type: ignore[attr-defined]
     sys.modules["httpx_sse"] = httpx_sse_stub
 
 

tests/test_oci_client.py

@@ -0,0 +1,65 @@
+"""Mypy type-checking gate for OCI client code.
+
+Runs mypy on OCI source and test files and fails if any type errors are found.
+This prevents type regressions from being introduced silently.
+
+Run with:
+    pytest tests/test_oci_mypy.py
+"""
+
+import os
+import shutil
+import subprocess
+import unittest
+
+MYPY_BIN = shutil.which("mypy")
+
+# Files that must stay mypy-clean
+OCI_SOURCE_FILES = [
+    "src/cohere/oci_client.py",
+    "src/cohere/manually_maintained/lazy_oci_deps.py",
+]
+
+OCI_TEST_FILES = [
+    "tests/test_oci_client.py",
+]
+
+# --follow-imports=silent prevents mypy from crawling into transitive
+# dependencies (e.g. the AWS client) that have pre-existing errors.
+_MYPY_BASE = [
+    "--config-file", "mypy.ini",
+    "--follow-imports=silent",
+]
+
+
+def _run_mypy(files: list[str], extra_env: dict[str, str] | None = None) -> tuple[int, str]:
+    """Run mypy on the given files and return (exit_code, output)."""
+    assert MYPY_BIN is not None
+    env = {**os.environ, **(extra_env or {})}
+    result = subprocess.run(
+        [MYPY_BIN, *_MYPY_BASE, *files],
+        capture_output=True,
+        text=True,
+        env=env,
+    )
+    return result.returncode, (result.stdout + result.stderr).strip()
+
+
+@unittest.skipIf(MYPY_BIN is None, "mypy not found on PATH")
+class TestOciMypy(unittest.TestCase):
+    """Ensure OCI files pass mypy with no new errors."""
+
+    def test_oci_source_types(self):
+        """OCI source files must be free of mypy errors."""
+        code, output = _run_mypy(OCI_SOURCE_FILES)
+        self.assertEqual(code, 0, f"mypy found type errors in OCI source:\n{output}")
+
+    def test_oci_test_types(self):
+        """OCI test files must be free of mypy errors."""
+        # PYTHONPATH=src so mypy can resolve `import cohere`
+        code, output = _run_mypy(OCI_TEST_FILES, extra_env={"PYTHONPATH": "src"})
+        self.assertEqual(code, 0, f"mypy found type errors in OCI tests:\n{output}")
+
+
+if __name__ == "__main__":
+    unittest.main()