fix(compression): ignore background process notifications

agent/context_compressor.py

@@ -177,6 +177,7 @@ MAX_ITERATIONS_SUMMARY_REQUEST = (
     "Please provide a final response summarizing what you've found and accomplished so far, "
     "without calling any more tools."
 )
+_BACKGROUND_PROCESS_NOTIFICATION_PREFIX = "[IMPORTANT: Background process "
 
 
 def _fresh_compaction_message_copy(msg: Dict[str, Any]) -> Dict[str, Any]:
@@ -4582,7 +4583,8 @@ This compaction should PRIORITISE preserving all information related to the focu
         """Recognize internal user-role rows after SessionDB projection.
 
         SessionDB preserves role/content but not underscore-prefixed metadata,
-        so the stable todo and continuation content markers are authoritative.
+        so stable runtime-notification, todo, and continuation content markers
+        are authoritative.
         """
         if not isinstance(message, dict) or message.get("role") != "user":
             return False
@@ -4618,6 +4620,8 @@ This compaction should PRIORITISE preserving all information related to the focu
             _LENGTH_CONTINUATION_NETWORK_STUB,
             _LENGTH_CONTINUATION_OUTPUT_LIMIT,
         } or text.startswith(
+            _BACKGROUND_PROCESS_NOTIFICATION_PREFIX
+        ) or text.startswith(
             TODO_INJECTION_HEADER + "\n"
         ) or text.startswith(
             _LENGTH_CONTINUATION_DROPPED_TOOLS_PREFIX

tests/agent/test_context_compressor_zero_user_provenance.py

@@ -21,6 +21,7 @@ from agent.conversation_compression import (
     compress_context,
 )
 from hermes_state import SessionDB
+from tools.process_registry import format_process_notification
 from tools.todo_tool import TODO_INJECTION_HEADER
 
 
@@ -237,6 +238,52 @@ def test_real_task_wins_over_trailing_max_iterations_nudge(compressor):
     assert messages[idx]["content"] == human["content"]
 
 
+@pytest.mark.parametrize(
+    "event",
+    [
+        pytest.param(
+            {
+                "type": "completion",
+                "session_id": "proc_build",
+                "command": "scripts/run_tests.sh tests/agent/",
+                "exit_code": 0,
+                "output": "42 passed",
+            },
+            id="completion",
+        ),
+        pytest.param(
+            {
+                "type": "watch_match",
+                "session_id": "proc_server",
+                "command": "python server.py",
+                "pattern": "Application startup complete",
+                "output": "Application startup complete",
+            },
+            id="watch_match",
+        ),
+    ],
+)
+def test_background_process_notifications_do_not_become_compaction_anchors(
+    compressor, event
+):
+    notification = format_process_notification(event)
+    assert notification is not None
+    process_turn = {"role": "user", "content": notification}
+    human = {"role": "user", "content": "Refactor the auth module and add tests."}
+    messages = [
+        human,
+        {"role": "assistant", "content": "Working on it."},
+        process_turn,
+    ]
+
+    assert ContextCompressor._is_synthetic_compression_user_turn(process_turn) is True
+    assert ContextCompressor._transcript_has_real_user_turn([process_turn]) is False
+    assert compressor._derive_auto_focus_topic(messages) == (
+        "Recent user focus:\n- Refactor the auth module and add tests."
+    )
+    assert compressor._find_last_user_message_idx(messages, head_end=0) == 0
+
+
 @pytest.mark.parametrize(
     "content",
     [