Sibyl-Research-Team
diff --git a/‎sibyl/gpu_scheduler.py‎
Lines changed: 8 additions & 0 deletions b/‎sibyl/gpu_scheduler.py‎
Lines changed: 8 additions & 0 deletions
diff --git a/‎tests/test_gpu_scheduler.py‎
Lines changed: 33 additions & 0 deletions b/‎tests/test_gpu_scheduler.py‎
Lines changed: 33 additions & 0 deletions
@@ -24,6 +24,7 @@
 """
 import fcntl
 import json
+import logging
 import re
 import shlex
 import time
@@ -33,6 +34,8 @@
 
 from sibyl._paths import get_system_state_dir
 
+_log = logging.getLogger(__name__)
+
 
 @contextmanager
 def _progress_lock(workspace_root: Path, timeout_sec: float = 30.0):
@@ -296,6 +299,11 @@ def topo_sort_layers(tasks: list[dict]) -> list[list[dict]]:
             if dep in task_map:
                 in_degree[t["id"]] += 1
                 children[dep].append(t["id"])
+            else:
+                _log.warning(
+                    "Task %s depends on non-existent task %s — treating as satisfied",
+                    t["id"], dep,
+                )
 
     layers = []
     queue = deque([tid for tid, deg in in_degree.items() if deg == 0])
 
@@ -1183,6 +1183,39 @@ def test_script_includes_dispatch_logic(self):
         assert "DISPATCH" in script
 
 
+# ══════════════════════════════════════════════
+# Warn on missing dependencies
+# ══════════════════════════════════════════════
+
+def test_topo_sort_warns_on_missing_dependency(caplog):
+    """Should log a warning when a task depends on a non-existent task."""
+    import logging
+    tasks = [
+        {"id": "a", "depends_on": ["ghost"]},
+        {"id": "b", "depends_on": []},
+    ]
+    with caplog.at_level(logging.WARNING):
+        layers = topo_sort_layers(tasks)
+    assert any("ghost" in r.message for r in caplog.records)
+    # 'a' should still be included (treat missing dep as satisfied)
+    all_ids = {t["id"] for layer in layers for t in layer}
+    assert "a" in all_ids
+    assert "b" in all_ids
+
+
+def test_topo_sort_no_warning_for_valid_deps(caplog):
+    """Should not warn when all dependencies exist."""
+    import logging
+    tasks = [
+        {"id": "a", "depends_on": []},
+        {"id": "b", "depends_on": ["a"]},
+    ]
+    with caplog.at_level(logging.WARNING):
+        layers = topo_sort_layers(tasks)
+    assert not any("non-existent" in r.message for r in caplog.records)
+    assert len(layers) == 2
+
+
 # ══════════════════════════════════════════════
 # TTL-based stale lease cleanup
 # ══════════════════════════════════════════════