fix: isolate path-backed python source modules

tests/wf_sources_python/test_loader.py

@@ -86,6 +86,152 @@ registry = [echo]
     assert set(source.capabilities.node_specs) == {"local.ops.echo"}
 
 
+def test_load_python_source_isolates_same_module_name_across_roots(
+    tmp_path: Path,
+) -> None:
+    left_root = tmp_path / "left"
+    right_root = tmp_path / "right"
+    left_root.mkdir()
+    right_root.mkdir()
+    source_template = """
+from __future__ import annotations
+
+from pydantic import BaseModel
+from wf_authoring import node
+
+class Input(BaseModel):
+    text: str
+
+class Output(BaseModel):
+    value: str
+
+@node(name="{name}")
+def operation(payload: Input) -> Output:
+    return Output(value=payload.text)
+
+registry = [operation]
+"""
+    (left_root / "ops.py").write_text(
+        source_template.format(name="left"), encoding="utf-8"
+    )
+    (right_root / "ops.py").write_text(
+        source_template.format(name="right"), encoding="utf-8"
+    )
+
+    left = load_python_source(
+        source_id="local.left",
+        path=left_root,
+        module="ops",
+        registry="registry",
+    )
+    right = load_python_source(
+        source_id="local.right",
+        path=right_root,
+        module="ops",
+        registry="registry",
+    )
+
+    assert set(left.capabilities.node_specs) == {"local.left.left"}
+    assert set(right.capabilities.node_specs) == {"local.right.right"}
+
+
+def test_load_python_source_supports_relative_imports_under_source_root(
+    tmp_path: Path,
+) -> None:
+    source_root = tmp_path / "relative_source"
+    package_root = source_root / "pkg"
+    package_root.mkdir(parents=True)
+    (package_root / "__init__.py").write_text("", encoding="utf-8")
+    (package_root / "labels.py").write_text(
+        'LABEL = "relative"\n',
+        encoding="utf-8",
+    )
+    (package_root / "ops.py").write_text(
+        """
+from __future__ import annotations
+
+from pydantic import BaseModel
+from wf_authoring import node
+
+from .labels import LABEL
+
+class Input(BaseModel):
+    text: str
+
+class Output(BaseModel):
+    value: str
+
+@node(name=LABEL)
+def operation(payload: Input) -> Output:
+    return Output(value=payload.text)
+
+registry = [operation]
+""",
+        encoding="utf-8",
+    )
+
+    source = load_python_source(
+        source_id="local.relative",
+        path=source_root,
+        module="pkg.ops",
+        registry="registry",
+    )
+
+    assert set(source.capabilities.node_specs) == {"local.relative.relative"}
+
+
+def test_load_python_source_supports_delayed_relative_imports(
+    tmp_path: Path,
+) -> None:
+    source_root = tmp_path / "delayed_relative_source"
+    package_root = source_root / "pkg"
+    package_root.mkdir(parents=True)
+    (package_root / "__init__.py").write_text("", encoding="utf-8")
+    (package_root / "labels.py").write_text(
+        'LABEL = "delayed"\n',
+        encoding="utf-8",
+    )
+    (package_root / "registry.py").write_text(
+        """
+def build_registry():
+    from .ops import operation
+
+    return [operation]
+""",
+        encoding="utf-8",
+    )
+    (package_root / "ops.py").write_text(
+        """
+from __future__ import annotations
+
+from pydantic import BaseModel
+from wf_authoring import node
+
+from .labels import LABEL
+
+class Input(BaseModel):
+    text: str
+
+class Output(BaseModel):
+    value: str
+
+@node(name=LABEL)
+def operation(payload: Input) -> Output:
+    return Output(value=payload.text)
+""",
+        encoding="utf-8",
+    )
+
+    source = load_python_source(
+        source_id="local.delayed",
+        path=source_root,
+        module="pkg.registry",
+        registry="build_registry",
+    )
+
+    assert set(source.capabilities.node_specs) == {"local.delayed.delayed"}
+
+
 def test_load_python_source_propagates_enabled_flag() -> None:
     source = load_python_source(
         source_id="local.ops",