fix(compression): strip embedded stale todo snapshot from list message content

agent/conversation_compression.py

@@ -2428,17 +2428,25 @@ def _strip_stale_todo_snapshot(content: Any) -> Any:
             return content
         return content[:idx].rstrip()
     if isinstance(content, list):
-        return [
-            part
-            for part in content
-            if not (
-                isinstance(part, dict)
-                and part.get("type") == "text"
-                and str(part.get("text") or "")
-                .lstrip()
-                .startswith(TODO_INJECTION_HEADER)
-            )
-        ]
+        cleaned = []
+        for part in content:
+            if not isinstance(part, dict):
+                cleaned.append(part)
+                continue
+            if part.get("type") == "text":
+                text = str(part.get("text") or "")
+                idx = text.find(TODO_INJECTION_HEADER)
+                if idx != -1:
+                    stripped = text[:idx].rstrip()
+                    if stripped:
+                        p = dict(part)
+                        p["text"] = stripped
+                        cleaned.append(p)
+                else:
+                    cleaned.append(part)
+            else:
+                cleaned.append(part)
+        return cleaned
     return content
 
 

tests/agent/test_skill_todo_retention_parity.py

@@ -269,6 +269,25 @@ class TestNoticeStripLifecycle:
         assert stripped == "real user words"
         assert _PRUNED_SKILL_RELOAD_NOTICE_HEADER not in stripped
 
+    def test_strip_removes_snapshot_from_list_content(self):
+        content = [
+            {
+                "type": "text",
+                "text": (
+                    "real user words\n\n"
+                    + TODO_INJECTION_HEADER
+                    + "\n- [ ] t1. old task (pending)\n\n"
+                    + _PRUNED_SKILL_RELOAD_NOTICE_HEADER
+                    + "\nreload skill_view(name='old-skill') first."
+                ),
+            },
+            {"type": "image_url", "image_url": {"url": "data:image/png;base64,..."}},
+        ]
+        stripped = _strip_stale_todo_snapshot(content)
+        assert len(stripped) == 2
+        assert stripped[0] == {"type": "text", "text": "real user words"}
+        assert stripped[1] == {"type": "image_url", "image_url": {"url": "data:image/png;base64,..."}}
+
     def test_repeated_boundaries_keep_single_notice(self, tmp_path):
         """Second compaction with a tail already carrying snapshot+notice
         refreshes in place instead of stacking duplicates (#26981 parity)."""