diff --git a/skillopt_sleep/backend.py b/skillopt_sleep/backend.py
index 95b44b23..c331a721 100644
--- a/skillopt_sleep/backend.py
+++ b/skillopt_sleep/backend.py
@@ -1570,6 +1570,24 @@ def _call(self, prompt: str, *, max_tokens: int = 1024) -> str:
 
     @staticmethod
     def _parse_jsonl_response(raw: str) -> str:
+        """Concatenate assistant text from a Copilot JSONL event stream.
+
+        Behaviourally identical to ``skillopt.model.copilot_backend``'s
+        ``parse_copilot_jsonl``; vendored because this package keeps ZERO
+        dependency on the research package (see the module docstring of
+        ``skillopt_sleep.gate`` for the same arrangement). Keep the two in sync.
+
+        A malformed event must never take down the whole stream: the CLI emits
+        one JSON object per line, so a single bad line loses at most that line's
+        text while the surrounding ``assistant.message`` events still parse.
+        ``data`` is therefore type-checked rather than assumed to be an object.
+        A truthy non-dict (``"text"``, ``5``, a non-empty list) would otherwise
+        raise ``AttributeError`` from the field access, which no caller catches.
+
+        The exception list is deliberately wider than the research-package copy:
+        ``json.loads`` raises ``RecursionError`` rather than ``JSONDecodeError``
+        on a deeply nested payload.
+        """
         parts: List[str] = []
         for line in raw.splitlines():
             line = line.strip()
@@ -1579,8 +1597,13 @@ def _parse_jsonl_response(raw: str) -> str:
                 obj = json.loads(line)
             except (ValueError, RecursionError, TypeError):
                 continue
+            if not isinstance(obj, dict):
+                continue
             if obj.get("type") == "assistant.message":
-                content = (obj.get("data") or {}).get("content")
+                data = obj.get("data")
+                if not isinstance(data, dict):
+                    continue
+                content = data.get("content")
                 if isinstance(content, str) and content:
                     parts.append(content)
         return "\n".join(parts).strip()
diff --git a/tests/test_sleep_engine.py b/tests/test_sleep_engine.py
index cfd05162..d3113865 100644
--- a/tests/test_sleep_engine.py
+++ b/tests/test_sleep_engine.py
@@ -1435,6 +1435,26 @@ def test_parse_jsonl_ignores_oversized_integer(self):
         raw = '{"type":"assistant.message","data":' + "9" * 5000 + "}"
         self.assertEqual(CopilotCliBackend._parse_jsonl_response(raw), "")
 
+    def test_parse_jsonl_skips_non_dict_data_without_losing_stream(self):
+        # A malformed event must cost only its own line: the surrounding
+        # assistant.message events still have to reach the caller. Mirrors
+        # tests/test_copilot_exec_backend.py for the research-package copy.
+        from skillopt_sleep.backend import CopilotCliBackend
+        for bad in ('"text"', "5", "[1,2]", "true"):
+            raw = "\n".join([
+                '{"type":"assistant.message","data":{"content":"first"}}',
+                '{"type":"assistant.message","data":' + bad + "}",
+                '{"type":"assistant.message","data":{"content":"second"}}',
+            ])
+            with self.subTest(data=bad):
+                self.assertEqual(
+                    CopilotCliBackend._parse_jsonl_response(raw), "first\nsecond"
+                )
+
+    def test_parse_jsonl_ignores_non_object_top_level(self):
+        from skillopt_sleep.backend import CopilotCliBackend
+        self.assertEqual(CopilotCliBackend._parse_jsonl_response("[]\nnull\n"), "")
+
     def test_isolated_home_by_default(self):
         from skillopt_sleep.backend import CopilotCliBackend
         be = CopilotCliBackend()