Lift drill into evals/ at 013fcb8b7dbefd6d3fa4653493e5d2ec8e7f985b

rsync of obra/drill@013fcb8b7d into superpowers/evals/, excluding
.git/, .venv/, results/, .env/, __pycache__/, *.egg-info/,
.private-journal/.

The drill repo is unaffected by this commit; archival is a separate
manual step after this PR merges.

Source SHA recorded at evals/.drill-source-sha for divergence
detection.

evals/tests/test_engine.py

@@ -0,0 +1,173 @@
+from __future__ import annotations
+
+import json
+import subprocess
+from pathlib import Path
+
+from drill.engine import RunResult, ScenarioConfig, VerifyConfig, snapshot_filesystem
+
+
+class TestVerifyConfig:
+    def test_defaults(self):
+        vc = VerifyConfig()
+        assert vc.criteria == []
+        assert vc.assertions == []
+        assert vc.observe is False
+
+    def test_from_dict(self):
+        vc = VerifyConfig(
+            criteria=["test criterion"],
+            assertions=["tool-called Read"],
+            observe=True,
+        )
+        assert len(vc.criteria) == 1
+        assert len(vc.assertions) == 1
+        assert vc.observe is True
+
+
+class TestScenarioConfig:
+    def test_loads_from_yaml(self, tmp_path):
+        scenario_file = tmp_path / "test.yaml"
+        scenario_file.write_text("""
+scenario: test-scenario
+description: "A test"
+user_posture: naive
+setup:
+  helpers:
+    - create_base_repo
+  assertions:
+    - "git rev-parse --is-inside-work-tree"
+turns:
+  - intent: "Do the thing"
+limits:
+  max_turns: 10
+  turn_timeout: 60
+verify:
+  criteria:
+    - "Thing was done"
+  assertions:
+    - "tool-called Bash"
+  observe: true
+""")
+        config = ScenarioConfig.from_yaml(scenario_file)
+        assert config.scenario == "test-scenario"
+        assert config.user_posture == "naive"
+        assert config.limits["max_turns"] == 10
+        assert len(config.turns) == 1
+        assert len(config.verify.criteria) == 1
+        assert len(config.verify.assertions) == 1
+        assert config.verify.observe is True
+
+    def test_loads_without_assertions(self, tmp_path):
+        scenario_file = tmp_path / "test.yaml"
+        scenario_file.write_text("""
+scenario: minimal
+verify:
+  criteria:
+    - "Something happened"
+""")
+        config = ScenarioConfig.from_yaml(scenario_file)
+        assert config.verify.assertions == []
+        assert config.verify.observe is False
+
+    def test_loads_without_verify(self, tmp_path):
+        scenario_file = tmp_path / "test.yaml"
+        scenario_file.write_text("""
+scenario: bare-minimum
+""")
+        config = ScenarioConfig.from_yaml(scenario_file)
+        assert config.verify.criteria == []
+        assert config.verify.assertions == []
+
+
+class TestSnapshotFilesystem:
+    def test_captures_git_state(self, tmp_path):
+        subprocess.run(["git", "init", "-b", "main"], cwd=tmp_path, capture_output=True)
+        subprocess.run(
+            ["git", "commit", "--allow-empty", "-m", "init"], cwd=tmp_path, capture_output=True
+        )
+        snapshot = snapshot_filesystem(tmp_path)
+        data = json.loads(snapshot)
+        assert "git_status" in data
+        assert "branch" in data
+        assert "worktree_list" in data
+        assert "files" in data
+
+
+class TestRunResult:
+    def test_serializes_to_dir(self, tmp_path):
+        result = RunResult(
+            scenario="test",
+            backend="claude",
+            timestamp="2026-04-07T14-30-00",
+            session_log="session output here",
+            filesystem_json='{"files": []}',
+            tool_calls_jsonl='{"tool": "Bash"}\n',
+            verdict_json='{"criteria": [], "observations": [], "summary": "ok"}',
+            meta={"backend": "claude", "duration_seconds": 42, "actor_turns": 5},
+        )
+        result.save(tmp_path)
+        assert (tmp_path / "session.log").read_text() == "session output here"
+        assert (tmp_path / "filesystem.json").exists()
+        assert (tmp_path / "tool_calls.jsonl").exists()
+        assert (tmp_path / "verdict.json").exists()
+        assert (tmp_path / "meta.json").exists()
+
+
+class TestEngineAssertionIntegration:
+    def test_run_result_save_splits_artifacts_and_verdict(self, tmp_path):
+        result = RunResult(
+            scenario="test",
+            backend="claude",
+            timestamp="2026-04-20T10-00-00",
+            session_log="log here",
+            filesystem_json='{"files": []}',
+            tool_calls_jsonl='{"tool": "Bash"}\n',
+            verdict_json='{"criteria": [], "observations": [], "summary": "ok"}',
+            meta={"backend": "claude"},
+        )
+        result.save_artifacts(tmp_path)
+        assert (tmp_path / "session.log").exists()
+        assert (tmp_path / "filesystem.json").exists()
+        assert (tmp_path / "tool_calls.jsonl").exists()
+        assert not (tmp_path / "verdict.json").exists()
+        assert not (tmp_path / "meta.json").exists()
+
+        result.save_verdict(tmp_path)
+        assert (tmp_path / "verdict.json").exists()
+        assert (tmp_path / "meta.json").exists()
+
+
+class TestEngineRunParams:
+    def test_run_result_uses_custom_output_dir(self, tmp_path: Path) -> None:
+        custom_dir = tmp_path / "custom" / "run-00"
+        result = RunResult(
+            scenario="test",
+            backend="claude",
+            timestamp="2026-04-20T10-00-00",
+            session_log="log",
+            filesystem_json='{"files": []}',
+            tool_calls_jsonl='{"tool": "Bash"}\n',
+            verdict_json='{"criteria": [], "observations": [], "summary": "ok"}',
+            meta={"backend": "claude"},
+        )
+        result.save(custom_dir)
+        assert (custom_dir / "session.log").read_text() == "log"
+        assert (custom_dir / "verdict.json").exists()
+        assert (custom_dir / "meta.json").exists()
+
+    def test_run_result_nested_dir_created(self, tmp_path: Path) -> None:
+        deep_dir = tmp_path / "a" / "b" / "c" / "run-05"
+        result = RunResult(
+            scenario="test",
+            backend="claude",
+            timestamp="2026-04-20T10-00-00",
+            session_log="log",
+            filesystem_json='{"files": []}',
+            tool_calls_jsonl='{"tool": "Bash"}\n',
+            verdict_json='{"criteria": [], "observations": [], "summary": "ok"}',
+            meta={"backend": "claude"},
+        )
+        result.save(deep_dir)
+        assert deep_dir.exists()
+        assert (deep_dir / "session.log").exists()