fix(adk): keep token refresh loop alive after a failed read

python/packages/kagent-adk/src/kagent/adk/_token.py

@@ -57,10 +57,15 @@ async def _read_kagent_token(self) -> str | None:
     async def _refresh_token(self):
         while True:
             await asyncio.sleep(60)  # Wait for 60 seconds before refreshing
-            token = await self._read_kagent_token()
-            if token is not None and token != self.token:
-                async with self.update_lock:
-                    self.token = token
+            try:
+                token = await self._read_kagent_token()
+                if token is not None and token != self.token:
+                    async with self.update_lock:
+                        self.token = token
+            except Exception:
+                # A single failed read must not kill the loop, or the token
+                # would never refresh again for the life of the process.
+                logger.exception("Error refreshing kagent token, will retry next cycle")
 
     async def _add_headers(self, request: httpx.Request):
         token = await self._get_token()

python/packages/kagent-adk/tests/unittests/test_token.py

@@ -0,0 +1,43 @@
+"""Tests for KAgentTokenService's background refresh loop."""
+
+import asyncio
+from unittest.mock import patch
+
+import pytest
+
+from kagent.adk._token import KAgentTokenService
+
+
+@pytest.mark.asyncio
+async def test_refresh_token_survives_unexpected_error():
+    """One failing read must not permanently stop the refresh loop.
+
+    Regression test: _refresh_token only guarded against a token read
+    returning None; any other exception from the read used to propagate out
+    of the while loop and kill the background task for the rest of the
+    process's life.
+    """
+    service = KAgentTokenService(app_name="test-agent")
+    service.token = "old-token"
+
+    read_calls = 0
+
+    async def fake_sleep(_seconds):
+        return None
+
+    async def fake_read():
+        nonlocal read_calls
+        read_calls += 1
+        if read_calls == 1:
+            raise ValueError("unexpected decode error")
+        if read_calls == 2:
+            return "new-token"
+        # Stop the loop once the point is proven.
+        raise asyncio.CancelledError
+
+    with patch("asyncio.sleep", fake_sleep), patch.object(service, "_read_kagent_token", fake_read):
+        with pytest.raises(asyncio.CancelledError):
+            await service._refresh_token()
+
+    assert read_calls == 3, "the loop must keep running after the first read raises"
+    assert service.token == "new-token", "a later successful read must still update the token"