Pin Python SDK runtime dependency

Make the Python SDK declare its published runtime package dependency directly and resolve the runtime version from that pin instead of inferring it from the SDK package version.

Co-authored-by: Codex <noreply@openai.com>

sdk/python/_runtime_setup.py

@@ -27,16 +27,21 @@ class RuntimeSetupError(RuntimeError):
 
 
 def pinned_runtime_version() -> str:
-    source_version = _source_tree_project_version()
-    if source_version is not None:
-        return _normalized_package_version(source_version)
+    source_pin = _source_tree_runtime_dependency_version()
+    if source_pin is not None:
+        return _normalized_package_version(source_pin)
 
     try:
-        return _normalized_package_version(importlib.metadata.version(SDK_PACKAGE_NAME))
+        installed_pin = _installed_sdk_runtime_dependency_version()
     except importlib.metadata.PackageNotFoundError as exc:
         raise RuntimeSetupError(
-            f"Unable to resolve {SDK_PACKAGE_NAME} version for runtime pinning."
+            f"Unable to resolve {SDK_PACKAGE_NAME} metadata for runtime pinning."
         ) from exc
+    if installed_pin is None:
+        raise RuntimeSetupError(
+            f"Unable to resolve {PACKAGE_NAME} dependency pin from {SDK_PACKAGE_NAME}."
+        )
+    return _normalized_package_version(installed_pin)
 
 
 def ensure_runtime_package_installed(
@@ -399,20 +404,30 @@ def _release_tag(version: str) -> str:
     return f"rust-v{_codex_release_version(version)}"
 
 
-def _source_tree_project_version() -> str | None:
+def _source_tree_runtime_dependency_version() -> str | None:
     pyproject_path = Path(__file__).resolve().parent / "pyproject.toml"
     if not pyproject_path.exists():
         return None
 
-    match = re.search(
-        r'(?m)^version = "([^"]+)"$',
-        pyproject_path.read_text(encoding="utf-8"),
-    )
+    match = re.search(_runtime_dependency_pin_pattern(), pyproject_path.read_text())
     if match is None:
         return None
     return match.group(1)
 
 
+def _installed_sdk_runtime_dependency_version() -> str | None:
+    requirements = importlib.metadata.requires(SDK_PACKAGE_NAME) or []
+    for requirement in requirements:
+        match = re.search(_runtime_dependency_pin_pattern(), requirement)
+        if match is not None:
+            return match.group(1)
+    return None
+
+
+def _runtime_dependency_pin_pattern() -> str:
+    return rf'{re.escape(PACKAGE_NAME)}\s*==\s*"?([^",;\s]+)"?'
+
+
 __all__ = [
     "PACKAGE_NAME",
     "SDK_PACKAGE_NAME",