diff --git a/api/background_process.py b/api/background_process.py
index 946598c36..ab82083fa 100644
--- a/api/background_process.py
+++ b/api/background_process.py
@@ -350,7 +350,7 @@ def _truncate(text: str, limit: int) -> str:
     return s[:limit] + "\n…(truncated)"
 
 
-def format_wakeup_prompt(evt: dict) -> str | None:
+def format_wakeup_prompt(evt: object) -> str | None:
     """Build the synthetic [IMPORTANT: …] message the agent will see.
 
     Mirrors ``cli._format_process_notification`` so wakeup payloads look the
@@ -362,6 +362,10 @@ def format_wakeup_prompt(evt: dict) -> str | None:
     evt_type = evt.get("type", "completion")
     sid = str(evt.get("session_id") or "").strip()
     cmd = str(evt.get("command") or "").strip()
+    # The current server-side wakeup drain drops global watch-overflow events
+    # before this formatter because they intentionally carry no session_key.
+    # Keep this branch defensive so any future routable overflow summary is not
+    # mis-rendered as a fake process completion.
     if evt_type in {"watch_overflow_tripped", "watch_overflow_released"}:
         msg = str(evt.get("message") or "").strip()
         return f"[IMPORTANT: {msg}]" if msg else None
diff --git a/tests/test_background_process_wakeup_format.py b/tests/test_background_process_wakeup_format.py
index cb8368a1d..16e2bcf13 100644
--- a/tests/test_background_process_wakeup_format.py
+++ b/tests/test_background_process_wakeup_format.py
@@ -5,11 +5,35 @@ def test_format_wakeup_prompt_skips_empty_event():
     assert format_wakeup_prompt({}) is None
 
 
+def test_format_wakeup_prompt_skips_non_dict_event():
+    assert format_wakeup_prompt(None) is None
+    assert format_wakeup_prompt(42) is None
+
+
 def test_format_wakeup_prompt_skips_unknown_event_type():
     evt = {"type": "unknown_event", "message": "do not inject me"}
     assert format_wakeup_prompt(evt) is None
 
 
+def test_format_wakeup_prompt_handles_watch_disabled():
+    evt = {
+        "type": "watch_disabled",
+        "session_id": "proc_abc",
+        "session_key": "webui-session",
+        "command": "tail -f log",
+        "message": "Watch patterns disabled for process proc_abc.",
+    }
+    assert (
+        format_wakeup_prompt(evt)
+        == "[IMPORTANT: Watch patterns disabled for process proc_abc.]"
+    )
+
+
+def test_format_wakeup_prompt_skips_blank_watch_disabled():
+    assert format_wakeup_prompt({"type": "watch_disabled"}) is None
+    assert format_wakeup_prompt({"type": "watch_disabled", "message": ""}) is None
+
+
 def test_format_wakeup_prompt_handles_watch_overflow_tripped():
     evt = {
         "type": "watch_overflow_tripped",