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/drill/assertions.py

@@ -0,0 +1,89 @@
+"""Post-session deterministic assertions for drill scenarios."""
+
+from __future__ import annotations
+
+import os
+import subprocess
+from dataclasses import dataclass
+from pathlib import Path
+
+from drill.verifier import CriterionResult
+
+
+@dataclass
+class AssertionResult:
+    command: str
+    passed: bool
+    exit_code: int
+    stdout: str
+    stderr: str
+
+    def to_criterion_result(self) -> CriterionResult:
+        evidence = f"exit code {self.exit_code}"
+        if self.stdout:
+            evidence += f"\nstdout: {self.stdout}"
+        if self.stderr:
+            evidence += f"\nstderr: {self.stderr}"
+        return CriterionResult(
+            criterion=f"[assertion] {self.command}",
+            verdict="pass" if self.passed else "fail",
+            evidence=evidence,
+            rationale="Deterministic assertion " + ("passed" if self.passed else "failed"),
+            source="assertion",
+        )
+
+
+def run_verify_assertions(
+    assertions: list[str],
+    results_dir: Path,
+    workdir: Path,
+    *,
+    timeout_seconds: int = 10,
+) -> list[AssertionResult]:
+    bin_dir = Path(__file__).parent.parent / "bin"
+    env = {
+        **os.environ,
+        "DRILL_WORKDIR": str(workdir),
+        "PATH": f"{bin_dir}:{os.environ.get('PATH', '')}",
+    }
+    results: list[AssertionResult] = []
+    for cmd in assertions:
+        try:
+            proc = subprocess.run(
+                ["bash", "-c", cmd],
+                cwd=results_dir,
+                capture_output=True,
+                text=True,
+                env=env,
+                timeout=timeout_seconds,
+            )
+            results.append(
+                AssertionResult(
+                    command=cmd,
+                    passed=proc.returncode == 0,
+                    exit_code=proc.returncode,
+                    stdout=proc.stdout.strip(),
+                    stderr=proc.stderr.strip(),
+                )
+            )
+        except subprocess.TimeoutExpired:
+            results.append(
+                AssertionResult(
+                    command=cmd,
+                    passed=False,
+                    exit_code=124,
+                    stdout="",
+                    stderr=f"Timed out after {timeout_seconds}s",
+                )
+            )
+        except Exception as e:
+            results.append(
+                AssertionResult(
+                    command=cmd,
+                    passed=False,
+                    exit_code=-1,
+                    stdout="",
+                    stderr=str(e),
+                )
+            )
+    return results