Fix FastLanes runner dependency isolation

.github/workflows/benchmark-fastlanes.yml

@@ -314,7 +314,13 @@ jobs:
           from pathlib import Path
 
           results = json.loads(Path(sys.argv[1]).read_text())
-          evidence = results.get("evidence", {})
+          evidence = results.get("evidence")
+          if evidence is None:
+              raise SystemExit(
+                  "FastLanes claim "
+                  f"{results.get('status', 'UNKNOWN')}: "
+                  f"{results.get('failure_reason', 'no failure reason recorded')}"
+              )
           if evidence.get("status") != "MEASURED":
               raise SystemExit(f"FastLanes claim status: {evidence.get('status')}")
           mixed = evidence.get("mixed", {})

src/format_bench/claims/__init__.py

@@ -1,5 +1,23 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
 from .fastlanes import run_fastlanes_claim
-from .tsfile import run_tsfile_claim
-from .vortex import run_vortex_stress
+
+if TYPE_CHECKING:
+    from .tsfile import run_tsfile_claim
+    from .vortex import run_vortex_stress
 
 __all__ = ["run_fastlanes_claim", "run_tsfile_claim", "run_vortex_stress"]
+
+
+def __getattr__(name: str):
+    if name == "run_tsfile_claim":
+        from .tsfile import run_tsfile_claim
+
+        return run_tsfile_claim
+    if name == "run_vortex_stress":
+        from .vortex import run_vortex_stress
+
+        return run_vortex_stress
+    raise AttributeError(f"module {__name__!r} has no attribute {name!r}")

tests/test_claims_import.py

@@ -0,0 +1,18 @@
+import subprocess
+import sys
+
+
+def test_fastlanes_claim_import_does_not_require_tsfile_dependencies() -> None:
+    code = """
+import sys
+sys.modules["pyarrow"] = None
+from format_bench.claims.fastlanes import run_fastlanes_claim
+assert callable(run_fastlanes_claim)
+"""
+    completed = subprocess.run(
+        [sys.executable, "-c", code],
+        check=False,
+        capture_output=True,
+        text=True,
+    )
+    assert completed.returncode == 0, completed.stderr

tests/test_fastlanes_workflow.py

@@ -37,4 +37,5 @@ def test_fastlanes_retry_workflow_preserves_build_and_measurement_logs() -> None
     assert '"status": "UNSUPPORTED" if not available else "FAILED"' in workflow
     assert "case_hash_algorithm" in workflow
     assert "input/data.csv" in workflow
+    assert "no failure reason recorded" in workflow
     assert "if: always()" in workflow