diff --git a/decnet/web/api.py b/decnet/web/api.py
index a15c63d0..b4689f6c 100644
--- a/decnet/web/api.py
+++ b/decnet/web/api.py
@@ -1,4 +1,8 @@
 import asyncio
+# Local binding for the DB-retry sleep so tests can patch it without
+# affecting `asyncio.sleep` globally (which would otherwise starve the
+# heartbeat / worker loops that share the interpreter's asyncio module).
+from asyncio import sleep as _retry_sleep
 import os
 import traceback
 import uuid
@@ -75,7 +79,7 @@ async def lifespan(app: FastAPI) -> AsyncGenerator[None, None]:
             log.warning("DB init attempt %d/5 failed: %s", attempt, exc)
             if attempt == 5:
                 log.error("DB failed to initialize after 5 attempts — startup may be degraded")
-            await asyncio.sleep(0.5)
+            await _retry_sleep(0.5)
 
     # Conditionally enable OpenTelemetry tracing
     from decnet.telemetry import setup_tracing
diff --git a/tests/web/test_web_api.py b/tests/web/test_web_api.py
index b07a1f8d..988a9d4f 100644
--- a/tests/web/test_web_api.py
+++ b/tests/web/test_web_api.py
@@ -148,7 +148,10 @@ class TestLifespan:
         mock_repo.initialize = _failing_init
 
         with patch("decnet.web.api.repo", mock_repo):
-            with patch("decnet.web.api.asyncio.sleep", new_callable=AsyncMock):
+            # Patch only the local _retry_sleep binding — patching
+            # `asyncio.sleep` globally would starve the heartbeat loop's
+            # own sleep and leak the task past the test's lifetime.
+            with patch("decnet.web.api._retry_sleep", new_callable=AsyncMock):
                 with patch("decnet.web.api.log_ingestion_worker", return_value=asyncio.sleep(0)):
                     with patch("decnet.web.api.log_collector_worker", return_value=asyncio.sleep(0)):
                         with patch("decnet.web.api.attacker_profile_worker", return_value=asyncio.sleep(0)):