diff --git a/VERSION b/VERSION
index a8eec69..a9ad2ac 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.179
+0.5.181
diff --git a/tests/test_version_parity.py b/tests/test_version_parity.py
new file mode 100644
index 0000000..c2f6fb4
--- /dev/null
+++ b/tests/test_version_parity.py
@@ -0,0 +1,38 @@
+"""Test to strictly enforce version parity across all carriers and package code."""
+
+from __future__ import annotations
+
+import re
+from pathlib import Path
+
+import code2llm
+
+
+def test_package_version_is_valid_semver():
+    """__version__ must be a valid semver string and not 'unknown'."""
+    assert code2llm.__version__ != "unknown"
+    assert re.match(r"^\d+\.\d+\.\d+", code2llm.__version__), f"Invalid version format: {code2llm.__version__}"
+
+
+def test_version_carrier_parity():
+    """VERSION file, pyproject.toml, and code2llm.__version__ must match strictly."""
+    root = Path(__file__).resolve().parent.parent
+    version_file = root / "VERSION"
+    assert version_file.is_file(), "VERSION file is missing"
+    expected_version = version_file.read_text(encoding="utf-8").strip()
+
+    # 1. Check code2llm.__version__
+    assert code2llm.__version__ == expected_version, (
+        f"code2llm.__version__ ({code2llm.__version__}) does not match VERSION ({expected_version})"
+    )
+
+    # 2. Check pyproject.toml
+    pyproject_file = root / "pyproject.toml"
+    assert pyproject_file.is_file(), "pyproject.toml is missing"
+    pyproject_text = pyproject_file.read_text(encoding="utf-8")
+    match = re.search(r'(?m)^version\s*=\s*["\']([^"\']+)["\']', pyproject_text)
+    assert match, "version not declared in pyproject.toml"
+    pyproject_version = match.group(1)
+    assert pyproject_version == expected_version, (
+        f"pyproject.toml version ({pyproject_version}) does not match VERSION ({expected_version})"
+    )