fix(pilot): preserve partial results and stop on provider billing errors

tests/test_pilot_scripts.py

@@ -141,3 +141,82 @@ def test_judge_rejects_string_boolean():
     rp = load("run_pilot")
     with pytest.raises(ValueError, match="unusable judge"):
         rp.judge(ScriptedClient(['{"faithful": "false"}']), "passage", "code")
+
+
+def test_partial_resume_keeps_successful_detector_output():
+    rp = load("run_pilot")
+    row = rp.run_item(Stub(), ITEM)
+    expected_role = row["role"]
+    row.pop("judge")
+    row["errors"]["judge"] = "temporary failure"
+
+    class JudgeOnly:
+        calls = 0
+
+        def complete_json(self, messages):
+            self.calls += 1
+            assert "faithful" in messages[0]["content"]
+            return {"faithful": True}
+
+    client = JudgeOnly()
+    resumed = rp.run_item(client, ITEM, row)
+    assert client.calls == 1
+    assert resumed["role"] == expected_role
+    assert rp.complete_row(resumed)
+    assert row["errors"] == {"judge": "temporary failure"}
+
+
+def test_billing_failure_stops_before_next_detector():
+    import pytest
+
+    from leanbench.llm import LLMError
+
+    rp = load("run_pilot")
+
+    class Blocked:
+        calls = 0
+
+        def complete_json(self, messages):
+            self.calls += 1
+            raise LLMError("HTTP 400: Arrearage overdue-payment")
+
+    client = Blocked()
+    with pytest.raises(rp.ProviderBlocked) as caught:
+        rp.run_item(client, ITEM)
+    assert client.calls == 1
+    assert "role" in caught.value.row["errors"]
+    assert "judge" not in caught.value.row["errors"]
+
+
+def test_blocked_run_preserves_and_replaces_partial_row(tmp_path, monkeypatch):
+    import argparse
+    import json
+
+    from leanbench.config import Settings
+
+    rp = load("run_pilot")
+    args = argparse.Namespace(items=tmp_path / "items.jsonl", out=tmp_path / "results.jsonl",
+                              max_calls=400, dry_run=False)
+    args.items.write_text(json.dumps(ITEM) + "\n")
+    partial = {"id": "x1", "compiled": True, "role": {"flagged": False},
+               "errors": {"judge": "Arrearage"}}
+
+    def blocked(client, item, previous):
+        raise rp.ProviderBlocked(partial)
+
+    monkeypatch.setattr(rp, "run_item", blocked)
+    assert rp.execute(args, [ITEM], Settings()) == 2
+    meta = json.loads(args.out.with_suffix(".meta.json").read_text())
+    assert meta["status"] == "provider_blocked"
+    assert meta["completed_items"] == 0
+
+    def recover(client, item, previous):
+        assert previous["role"] == partial["role"]
+        return {**previous, "judge": {"faithful": True}, "errors": {}}
+
+    monkeypatch.setattr(rp, "run_item", recover)
+    assert rp.execute(args, [ITEM], Settings()) == 0
+    rows = [json.loads(line) for line in args.out.read_text().splitlines()]
+    assert len(rows) == 1 and rp.complete_row(rows[0])
+    meta = json.loads(args.out.with_suffix(".meta.json").read_text())
+    assert meta["completed_items"] == 1 and meta["status"] == "complete"