diff --git a/scripts/audit_no_temp_writes.py b/scripts/audit_no_temp_writes.py
new file mode 100644
index 00000000..2b367f83
--- /dev/null
+++ b/scripts/audit_no_temp_writes.py
@@ -0,0 +1,108 @@
+"""Scan ./scripts/** for any usage of the global %TEMP% directory.
+
+Used to verify the Tier 2 sandbox invariant: no production script
+under ./scripts/ may write to C:\\Users\\Ed\\AppData\\Local\\Temp\\
+(or any other platform temp dir). All scratch / intermediate files
+must live in:
+- ./tests/artifacts/  (for test artifacts)
+- C:\\Users\\Ed\\AppData\\Local\\manual_slop\\tier2\\  (for app data)
+
+This script is the canonical audit. The persistent enforcement is
+tests/test_no_temp_writes.py (a default-on pytest test that calls
+this audit's main() and asserts the return code is 0).
+
+Exit codes:
+  0  CLEAN: no script emits to %TEMP%
+  1  FOUND: at least one script uses %TEMP% (printed to stdout)
+"""
+import argparse
+import json
+import re
+import sys
+from pathlib import Path
+
+# Patterns that indicate a script is using the global temp directory.
+# The patterns cover:
+#   - Python: tempfile module, os.environ['TEMP'], etc.
+#   - PowerShell: $env:TEMP, $env:TMP
+#   - cmd: %TEMP%, %TMP%
+#   - Unix-style: /tmp/ (sometimes used in cross-platform code)
+PATTERNS = [
+    r"tempfile\.",
+    r"gettempdir",
+    r"mkstemp",
+    r"NamedTemporaryFile",
+    r"TemporaryFile",
+    r"os\.environ\[.TEMP",
+    r"os\.environ\[.TMP",
+    r"os\.environ\.get..TEMP",
+    r"os\.environ\.get..TMP",
+    r"\$env:TEMP",
+    r"\$env:TMP",
+    r"%TEMP%",
+    r"%TMP%",
+    r"/tmp/",
+    r"\bTempDir\b",
+    r"\btempfile\b",
+]
+COMPILED = re.compile("|".join(PATTERNS), re.IGNORECASE)
+
+# Throw-away scripts from prior Tier 2 tracks live here. They are
+# archived for reference but are not part of the production code.
+# The audit excludes them.
+EXCLUDE_DIRS = {"scripts/tier2/artifacts"}
+
+# This audit script itself contains the patterns it searches for.
+# Exclude it so the audit can find its own pattern definitions.
+EXCLUDE_FILES = {"scripts/audit_no_temp_writes.py"}
+
+
+def find_violations(root: str = "scripts") -> list[dict[str, object]]:
+ """Return a list of violations: each is {path, line, content}."""
+ results: list[dict[str, object]] = []
+ for f in Path(root).rglob("*"):
+  if not f.is_file():
+   continue
+  if f.suffix not in {".py", ".ps1", ".sh", ".bat", ".cmd", ".psm1"}:
+   continue
+  rel = str(f).replace("\\", "/")
+  if any(rel.startswith(d) for d in EXCLUDE_DIRS):
+   continue
+  if rel in EXCLUDE_FILES:
+   continue
+  try:
+   content = f.read_text(encoding="utf-8", errors="ignore")
+  except Exception:
+   continue
+  for i, line in enumerate(content.splitlines(), 1):
+   if COMPILED.search(line):
+    results.append({"path": rel, "line": i, "content": line.strip()})
+ return results
+
+
+def main() -> int:
+ parser = argparse.ArgumentParser(
+  description=__doc__,
+  formatter_class=argparse.RawDescriptionHelpFormatter,
+ )
+ parser.add_argument("--json", action="store_true", help="Output JSON instead of human-readable report")
+ parser.add_argument("--strict", action="store_true", help="Exit 1 if any violations are found (for CI use; the convention's CI gate)")
+ args = parser.parse_args()
+
+ violations = find_violations()
+
+ if args.json:
+  print(json.dumps({"violations": violations, "count": len(violations)}, indent=2))
+ else:
+  if not violations:
+   print("CLEAN: no script under ./scripts/ emits to %TEMP%")
+  else:
+   print(f"FOUND {len(violations)} matches:")
+   for v in violations:
+    print(f"  {v['path']}:{v['line']}: {v['content']}")
+
+ return 1 if (args.strict and violations) else 0
+
+
+if __name__ == "__main__":
+ sys.exit(main())
diff --git a/tests/test_no_temp_writes.py b/tests/test_no_temp_writes.py
new file mode 100644
index 00000000..5b62001d
--- /dev/null
+++ b/tests/test_no_temp_writes.py
@@ -0,0 +1,35 @@
+"""Default-on regression test: no script under ./scripts/ may write to
+the global %TEMP% directory (C:\\Users\\Ed\\AppData\\Local\\Temp\\).
+
+The Tier 2 sandbox is supposed to keep all scratch / intermediate
+files inside its allowlist (C:\\projects\\manual_slop_tier2 +
+C:\\Users\\Ed\\AppData\\Local\\manual_slop\\tier2 +
+C:\\Users\\Ed\\AppData\\Local\\manual_slop\\tier2_failures). Writing
+to the global Temp dir breaks that boundary: the OpenCode session
+fires the 'ask' prompt for paths outside the project root, halting
+autonomous ops.
+
+The test delegates to scripts/audit_no_temp_writes.py --strict
+which exits 1 on any violation. If this test fails, a new script
+under ./scripts/ is using %TEMP% and the Tier 2 sandbox boundary
+has been violated.
+"""
+import subprocess
+from pathlib import Path
+
+import pytest
+
+
+def test_no_script_emits_to_temp() -> None:
+ audit = Path("scripts/audit_no_temp_writes.py").resolve()
+ assert audit.exists(), f"audit script missing: {audit}"
+ result = subprocess.run(
+  ["uv", "run", "python", str(audit), "--strict"],
+  capture_output=True, text=True, timeout=60,
+ )
+ assert result.returncode == 0, (
+  f"audit found %TEMP% usage in scripts:\n{result.stdout}\n{result.stderr}\n\n"
+  f"Fix: move scratch files to tests/artifacts/ or "
+  f"C:\\Users\\Ed\\AppData\\Local\\manual_slop\\tier2\\ instead of %TEMP%."
+ )
+ assert "CLEAN" in result.stdout, f"unexpected audit output: {result.stdout}"