feat: add safe distributed checkpoint intake and preflight

tests/test_checkpoint_errors.py

@@ -0,0 +1,38 @@
+"""Stable runtime failures remain aligned with the accepted error registry."""
+
+from __future__ import annotations
+
+import json
+from pathlib import Path
+
+from obliteratus.checkpoint_errors import CheckpointContractError
+
+
+ROOT = Path(__file__).resolve().parents[1]
+
+
+def test_runtime_error_contract_covers_every_registered_code_exactly():
+    registry = json.loads(
+        (
+            ROOT / "docs/checkpoints/schemas/checkpoint-error-codes-v1.json"
+        ).read_text()
+    )
+
+    for entry in registry["entries"]:
+        error = CheckpointContractError(
+            entry["code"],
+            detail="bounded_detail",
+            affected_refs=("b", "a", "a"),
+        )
+        assert error.code == entry["code"]
+        assert error.category == entry["category"]
+        assert error.phase == entry["phase"]
+        assert error.affected_refs == ("a", "b")
+        assert set(error.to_blocker()) == {
+            "code",
+            "category",
+            "phase",
+            "affected_refs",
+            "retryable",
+            "next_action",
+        }