diff --git a/src/ouroboros/auto/interview_driver.py b/src/ouroboros/auto/interview_driver.py
index b188d6186..bd54b4072 100644
--- a/src/ouroboros/auto/interview_driver.py
+++ b/src/ouroboros/auto/interview_driver.py
@@ -32,6 +32,8 @@
 
 log = structlog.get_logger(__name__)
 
+INTERVIEW_SAFE_DEFAULT_SYNTHESIS_STOP_REASON_CODE = "interview_safe_default_synthesis_nonclosure"
+
 
 @dataclass(frozen=True, slots=True)
 class InterviewTurn:
@@ -431,7 +433,11 @@ async def run(self, state: AutoPipelineState, ledger: SeedDraftLedger) -> AutoIn
                         synthesis_pushed=False,
                     )
                     state.ledger = ledger.to_dict()
-                    state.mark_blocked(blocker, tool_name="interview.safe_default_synthesis")
+                    state.mark_blocked(
+                        blocker,
+                        tool_name="interview.safe_default_synthesis",
+                        error_code=INTERVIEW_SAFE_DEFAULT_SYNTHESIS_STOP_REASON_CODE,
+                    )
                     record_authoring_backend(state)
                     self._save(state)
                     return AutoInterviewResult(
@@ -446,7 +452,11 @@ async def run(self, state: AutoPipelineState, ledger: SeedDraftLedger) -> AutoIn
                         "backend_done=False, ledger defaults rolled back"
                     )
                     state.ledger = ledger.to_dict()
-                    state.mark_blocked(blocker, tool_name="interview.safe_default_synthesis")
+                    state.mark_blocked(
+                        blocker,
+                        tool_name="interview.safe_default_synthesis",
+                        error_code=INTERVIEW_SAFE_DEFAULT_SYNTHESIS_STOP_REASON_CODE,
+                    )
                     record_authoring_backend(state)
                     self._save(state)
                     return AutoInterviewResult(
diff --git a/tests/unit/auto/test_interview_pipeline.py b/tests/unit/auto/test_interview_pipeline.py
index 7031c292d..31ec1f99a 100644
--- a/tests/unit/auto/test_interview_pipeline.py
+++ b/tests/unit/auto/test_interview_pipeline.py
@@ -846,6 +846,7 @@ async def answer(
     assert result.status == "blocked"
     assert state.interview_completed is False
     assert "transcript sync failed" in (result.blocker or "")
+    assert state.last_error_code == "interview_safe_default_synthesis_nonclosure"
     assert ledger.open_gaps()
     assert not any(
         entry.key == f"{section_name}.safe_default_finalization"
@@ -881,6 +882,7 @@ async def answer(
     assert state.interview_completed is False
     assert state.pending_question == "Still need one more thing"
     assert "did not close the persisted interview" in (result.blocker or "")
+    assert state.last_error_code == "interview_safe_default_synthesis_nonclosure"
     assert ledger.open_gaps()
     assert not any(
         entry.key == f"{section_name}.safe_default_finalization"