diff --git a/plugin/core/client.py b/plugin/core/client.py
index 7bade23..00bd8e8 100644
--- a/plugin/core/client.py
+++ b/plugin/core/client.py
@@ -8,6 +8,8 @@
 
 from engram import EngramClient
 
+from .client_origin import client_origin_header
+
 DEFAULT_BASE = "https://api.engram.weaviate.io"
 
 _PROFILES = (
@@ -91,7 +93,9 @@ def get_client():
     api_key = engram_api_key()
     if not api_key:
         return None
-    return EngramClient(api_key=api_key, base_url=engram_base_url())
+    return EngramClient(
+        api_key=api_key, base_url=engram_base_url(), headers=client_origin_header()
+    )
 
 
 def engram_warning():
@@ -110,7 +114,11 @@ def engram_get(path):
     whole instead of continuing with a half-resolved scope."""
     base = engram_base_url().rstrip("/")
     req = urllib.request.Request(
-        base + path, headers={"Authorization": f"Bearer {engram_api_key()}"}
+        base + path,
+        headers={
+            "Authorization": f"Bearer {engram_api_key()}",
+            **client_origin_header(),
+        },
     )
     with urllib.request.urlopen(req, timeout=5) as resp:
         return json.load(resp)
diff --git a/plugin/core/client_origin.py b/plugin/core/client_origin.py
new file mode 100644
index 0000000..cecad5f
--- /dev/null
+++ b/plugin/core/client_origin.py
@@ -0,0 +1,22 @@
+import json
+import os
+
+_MANIFEST = os.path.join(
+    os.path.dirname(__file__), "..", ".claude-plugin", "plugin.json"
+)
+
+
+def _platform():
+    return "claude"
+
+
+def _plugin_version():
+    try:
+        with open(_MANIFEST) as f:
+            return json.load(f).get("version", "unknown")
+    except Exception:
+        return "unknown"
+
+
+def client_origin_header():
+    return {"X-Engram-Client": f"{_platform()}-plugin/{_plugin_version()}"}
diff --git a/plugin/tests/test_client_origin.py b/plugin/tests/test_client_origin.py
new file mode 100644
index 0000000..06664b5
--- /dev/null
+++ b/plugin/tests/test_client_origin.py
@@ -0,0 +1,44 @@
+"""Loads the module directly by path — importing the `core` package would pull in the
+Engram SDK, which only exists in the plugin venv."""
+
+import importlib.util
+import json
+import os
+import unittest
+from unittest import mock
+
+_HERE = os.path.dirname(__file__)
+_MODULE = os.path.join(_HERE, "..", "core", "client_origin.py")
+
+spec = importlib.util.spec_from_file_location("client_origin", _MODULE)
+client_origin = importlib.util.module_from_spec(spec)
+spec.loader.exec_module(client_origin)
+
+
+class PlatformTest(unittest.TestCase):
+    def test_claude(self):
+        self.assertEqual(client_origin._platform(), "claude")
+
+
+class PluginVersionTest(unittest.TestCase):
+    def test_reads_manifest(self):
+        with open(client_origin._MANIFEST) as f:
+            expected = json.load(f)["version"]
+        self.assertEqual(client_origin._plugin_version(), expected)
+
+    def test_missing_manifest(self):
+        with mock.patch.object(client_origin, "_MANIFEST", "/nonexistent/plugin.json"):
+            self.assertEqual(client_origin._plugin_version(), "unknown")
+
+
+class HeaderTest(unittest.TestCase):
+    def test_format(self):
+        headers = client_origin.client_origin_header()
+        self.assertEqual(list(headers), ["X-Engram-Client"])
+        platform, _, version = headers["X-Engram-Client"].partition("/")
+        self.assertEqual(platform, "claude-plugin")
+        self.assertEqual(version, client_origin._plugin_version())
+
+
+if __name__ == "__main__":
+    unittest.main()