diff --git a/tests/tools/test_delegate_schema_retry_context.py b/tests/tools/test_delegate_schema_retry_context.py
new file mode 100644
index 0000000000..b3b040599a
--- /dev/null
+++ b/tests/tools/test_delegate_schema_retry_context.py
@@ -0,0 +1,53 @@
+"""The schema-retry turn must run inside the delegated-child context.
+
+The main child turn is wrapped in ``delegated_child_context``; the bounded retry in
+``_validate_child_output_schema`` is a second ``run_conversation`` on the same child.
+Unwrapped, it runs with the parent worker's identity: ``HERMES_KANBAN_TASK`` is set and
+nothing marks it as a child, so the kanban stop guard nudges the child to call
+``kanban_complete``. A child owns no board task and cannot, so the nudge text displaces
+the answer the retry exists to produce and the retry fails the same schema again.
+"""
+
+from __future__ import annotations
+
+import pytest
+
+from agent.delegation_context import is_delegated_child_context
+from tools.delegate_tool_child_run import _validate_child_output_schema
+
+
+class _Child:
+    """Minimal stand-in recording the context state of each run_conversation turn."""
+
+    def __init__(self):
+        self._delegate_output_schema = {
+            "type": "object",
+            "properties": {"ok": {"type": "boolean"}},
+            "required": ["ok"],
+        }
+        self.session_id = "sess-child"
+        self.seen_in_child_context = []
+
+    def run_conversation(self, user_message=None, task_id=None, stream_callback=None):
+        self.seen_in_child_context.append(is_delegated_child_context())
+        return {"final_response": '{"ok": true}', "api_calls": 1}
+
+
+@pytest.fixture
+def kanban_env(monkeypatch):
+    monkeypatch.setenv("HERMES_KANBAN_TASK", "t_parent")
+    monkeypatch.delenv("HERMES_KANBAN_STOP_NUDGE", raising=False)
+    return monkeypatch
+
+
+def test_schema_retry_runs_in_child_context(kanban_env):
+    child = _Child()
+    result = {"final_response": "not json at all", "api_calls": 1}
+
+    assert is_delegated_child_context() is False
+    _validate_child_output_schema(child, result, 0, "child-task-0", None)
+
+    assert child.seen_in_child_context == [True], (
+        "the schema-retry turn ran outside delegated_child_context"
+    )
+    assert is_delegated_child_context() is False
diff --git a/tools/delegate_tool_child_run.py b/tools/delegate_tool_child_run.py
index 1b3a6f30f8..6766dfed21 100644
--- a/tools/delegate_tool_child_run.py
+++ b/tools/delegate_tool_child_run.py
@@ -424,9 +424,16 @@ def _validate_child_output_schema(
     # schema re-paste — the child already holds the contract in its context).
     _retry_result = None
     try:
-        _retry_result = child.run_conversation(
-            user_message=build_retry_message(_schema_errors), task_id=child_task_id, stream_callback=relay_child_text,
-        )
+        # Same identity as the main child turn (delegate_tool_child_run's worker): this runs
+        # on the parent's thread, where HERMES_KANBAN_TASK is set, so without the marker the
+        # kanban stop guard nudges the child to call kanban_complete. It owns no board task
+        # and cannot, and the nudge displaces the answer this retry exists to produce.
+        from agent.delegation_context import delegated_child_context
+        with delegated_child_context(str(getattr(child, "session_id", "") or "")):
+            _retry_result = child.run_conversation(
+                user_message=build_retry_message(_schema_errors), task_id=child_task_id,
+                stream_callback=relay_child_text,
+            )
     except Exception as _retry_exc:
         logger.warning("Subagent %d schema-retry turn failed: %s", task_index, _retry_exc)
     if isinstance(_retry_result, dict):