diff --git a/gateway/platforms/api_server.py b/gateway/platforms/api_server.py
index 973ba5507379..e0629d270d90 100644
--- a/gateway/platforms/api_server.py
+++ b/gateway/platforms/api_server.py
@@ -96,23 +96,25 @@ logger = logging.getLogger(__name__)
 
 
 def _hermes_version() -> str:
-    """Return the hermes-agent version string, or "dev" if it can't be resolved.
+    """Return the canonical Hermes Agent version string.
 
-    Tries the installed package metadata first (authoritative for a pip/uv
-    install), then the in-tree ``hermes_cli.__version__`` (covers editable /
-    source checkouts where metadata may be stale or absent). Never raises —
-    a version probe must not be able to break the health endpoint.
+    ``hermes_cli.__version__`` is the runtime source of truth used by the CLI,
+    dashboard, portal tags, and release script. Prefer it over installed
+    distribution metadata because editable/source checkouts can retain stale
+    ``hermes_agent-*.dist-info`` after a source update until the environment is
+    reinstalled. Never raises — a version probe must not be able to break the
+    health endpoint.
     """
-    try:
-        from importlib.metadata import version
-
-        return version("hermes-agent")
-    except Exception:
-        pass
     try:
         from hermes_cli import __version__
 
         return __version__
+    except Exception:
+        pass
+    try:
+        from importlib.metadata import version
+
+        return version("hermes-agent")
     except Exception:
         return "dev"
 
diff --git a/tests/gateway/test_api_server.py b/tests/gateway/test_api_server.py
index 56734698019a..7700cec107d0 100644
--- a/tests/gateway/test_api_server.py
+++ b/tests/gateway/test_api_server.py
@@ -30,6 +30,7 @@ from gateway.platforms.api_server import (
     ResponseStore,
     _IdempotencyCache,
     _derive_chat_session_id,
+    _hermes_version,
     _redact_api_error_text,
     check_api_server_requirements,
     cors_middleware,
@@ -776,6 +777,29 @@ class TestHealthEndpoint:
             assert isinstance(data["version"], str)
             assert data["version"] != ""
 
+    def test_health_version_prefers_runtime_source_over_stale_metadata(self):
+        """Editable installs can leave importlib.metadata at an older release.
+
+        The health endpoint must report the running Hermes source version, not
+        stale ``hermes_agent-*.dist-info`` metadata from before a source update.
+        """
+        from hermes_cli import __version__
+
+        with patch("importlib.metadata.version", return_value="0.18.0"):
+            assert _hermes_version() == __version__
+
+    @pytest.mark.asyncio
+    async def test_health_endpoint_prefers_runtime_version_over_stale_metadata(self, adapter):
+        from hermes_cli import __version__
+
+        app = _create_app(adapter)
+        with patch("importlib.metadata.version", return_value="0.18.0"):
+            async with TestClient(TestServer(app)) as cli:
+                resp = await cli.get("/health")
+                assert resp.status == 200
+                data = await resp.json()
+                assert data["version"] == __version__
+
     @pytest.mark.asyncio
     async def test_v1_health_alias_returns_ok(self, adapter):
         """GET /v1/health should return the same response as /health."""