diff --git a/openspec/changes/uv-workspace-packaging/tasks.md b/openspec/changes/uv-workspace-packaging/tasks.md
index ca7d9e9..e6eb2c1 100644
--- a/openspec/changes/uv-workspace-packaging/tasks.md
+++ b/openspec/changes/uv-workspace-packaging/tasks.md
@@ -11,7 +11,7 @@
 
 - [x] 2.1 Move the existing `cloud` package under `packages/cloud-platform` while preserving every `cloud.*` import path.
 - [x] 2.2 Remove `cloud*` from the root distribution's setuptools discovery and update path-sensitive composition tests or tooling.
-- [ ] 2.3 Add packaging tests that identify the owning distribution for Runtime and cloud modules and reject reverse cloud dependencies.
+- [x] 2.3 Add packaging tests that identify the owning distribution for Runtime and cloud modules and reject reverse cloud dependencies.
 
 ## 3. Locking And Developer Commands
 
diff --git a/tests/test_workspace_packaging.py b/tests/test_workspace_packaging.py
new file mode 100644
index 0000000..2ced277
--- /dev/null
+++ b/tests/test_workspace_packaging.py
@@ -0,0 +1,68 @@
+from __future__ import annotations
+
+import ast
+import re
+import tomllib
+from importlib.metadata import packages_distributions
+from pathlib import Path
+
+
+PROJECT_ROOT = Path(__file__).resolve().parent.parent
+RUNTIME_PACKAGE_DIRS = (
+    "agents",
+    "api",
+    "core",
+    "device",
+    "driver",
+    "perception",
+    "runtime",
+    "semantic",
+    "skills_learning",
+    "storage",
+    "tools",
+    "workflow",
+    "world",
+)
+
+
+def test_workspace_distributions_own_expected_import_packages() -> None:
+    distributions = packages_distributions()
+
+    assert distributions.get("cloud") == ["device-cloud-platform"]
+    assert distributions.get("core") == ["device-agent-runtime"]
+    assert distributions.get("runtime") == ["device-agent-runtime"]
+
+
+def test_runtime_project_does_not_declare_cloud_distribution() -> None:
+    project = tomllib.loads((PROJECT_ROOT / "pyproject.toml").read_text("utf-8"))
+    dependencies = {
+        _requirement_name(requirement)
+        for requirement in project["project"].get("dependencies", [])
+    }
+    package_patterns = project["tool"]["setuptools"]["packages"]["find"]["include"]
+
+    assert "device-cloud-platform" not in dependencies
+    assert "cloud*" not in package_patterns
+
+
+def test_runtime_source_does_not_import_cloud() -> None:
+    offenders: list[str] = []
+    for package_dir in RUNTIME_PACKAGE_DIRS:
+        for path in (PROJECT_ROOT / package_dir).rglob("*.py"):
+            tree = ast.parse(path.read_text("utf-8"), filename=str(path))
+            for node in ast.walk(tree):
+                if isinstance(node, ast.Import):
+                    names = [alias.name for alias in node.names]
+                elif isinstance(node, ast.ImportFrom) and node.module:
+                    names = [node.module]
+                else:
+                    continue
+                if any(name == "cloud" or name.startswith("cloud.") for name in names):
+                    offenders.append(str(path.relative_to(PROJECT_ROOT)))
+
+    assert not offenders, f"runtime distribution imports cloud: {sorted(set(offenders))}"
+
+
+def _requirement_name(requirement: str) -> str:
+    name = re.split(r"[\s<>=!~\[]", requirement, maxsplit=1)[0]
+    return name.lower().replace("_", "-")