safety: add immutable M3 review packets

docs/CODEX_HANDOFF.md

@@ -34,6 +34,9 @@ The repository now provides:
 - a fail-closed M3 hardware-research protocol, incomplete public plan template
   and validator; validation can reach only `ready_for_review` and never
   authorizes hardware access.
+- a deterministic M3 review-packet generator that freezes only a
+  `ready_for_review` plan and creates a hash-bound, explicitly unreviewed
+  record without granting hardware access.
 
 Run the ordinary checkpoint with the bundled Codex Python or another supported
 Python interpreter and a writable `TEMP`/`TMP`:

docs/research/m3-hardware-research-protocol.md

@@ -115,6 +115,19 @@ plan bytes and SHA-256. A separate approval record must identify that hash,
 reviewer, approval time with timezone, location and exact session window. Any
 plan edit invalidates that approval.
 
+Create the frozen, non-authorizing review packet with:
+
+```powershell
+python scripts/prepare_m3_review_packet.py path/to/session-plan.json
+```
+
+The generator refuses an incomplete or invalid plan, refuses to overwrite a
+non-empty output directory, copies the exact plan bytes and hashes both the
+plan and untouched `approval-record-template.json`. A reviewer must create a
+separate approval record rather than edit the packet template. The generated
+output still states `hardware_access_authorized: false`; generating a packet is
+not approval.
+
 ## Session sequence
 
 The eventual reviewed session follows this order and stops at the first failed

docs/status/phase-0.md

@@ -96,6 +96,10 @@ evidence for:
   plan template and standard-library validator that requires exact
   evidence-backed request bytes, distinct safety roles, physical controls and
   recovery planning while always denying hardware authorization.
+- a deterministic M3 review-packet generator that accepts only a
+  `ready_for_review` plan, freezes its exact bytes and session window, records
+  SHA-256 bindings, refuses overwrite and emits an untouched, non-authorizing
+  human approval-record template.
 
 The remaining M1 gates are deliberately explicit:
 

scripts/prepare_m3_review_packet.py

@@ -0,0 +1,130 @@
+"""Freeze a review-ready M3 plan into a non-authorizing review packet."""
+
+from __future__ import annotations
+
+import argparse
+import hashlib
+import json
+import shutil
+import subprocess
+from pathlib import Path
+
+if __package__:
+    from scripts.validate_m3_hardware_protocol import validate
+else:
+    from validate_m3_hardware_protocol import validate
+
+
+ROOT = Path(__file__).resolve().parents[1]
+
+
+def _sha256(path: Path) -> str:
+    return hashlib.sha256(path.read_bytes()).hexdigest()
+
+
+def _repository_commit() -> str:
+    result = subprocess.run(
+        ["git", "rev-parse", "HEAD"],
+        cwd=ROOT,
+        check=True,
+        capture_output=True,
+        text=True,
+    )
+    return result.stdout.strip()
+
+
+def create_packet(
+    plan_path: Path,
+    output: Path,
+    repository_commit: str | None = None,
+) -> dict:
+    source = plan_path.resolve()
+    validation = validate(source)
+    if validation["status"] != "ready_for_review":
+        raise ValueError("M3 plan is not ready for review")
+
+    output = output.resolve()
+    if output.exists() and any(output.iterdir()):
+        raise ValueError(f"review-packet directory is not empty: {output}")
+    output.mkdir(parents=True, exist_ok=True)
+
+    frozen_plan = output / "plan.json"
+    shutil.copyfile(source, frozen_plan)
+    plan = json.loads(frozen_plan.read_text(encoding="utf-8-sig"))
+    commit = repository_commit or _repository_commit()
+
+    review = {
+        "schema_version": 1,
+        "review": "M3 hardware research session plan",
+        "binding": {
+            "plan_path": frozen_plan.name,
+            "plan_sha256": _sha256(frozen_plan),
+            "repository_commit": commit,
+        },
+        "session_window": {
+            "starts_at": plan["session"]["planned_at"],
+            "ends_at": plan["session"]["ends_at"],
+        },
+        "decision": "not_reviewed",
+        "reviewer": None,
+        "reviewed_at": None,
+        "notes": "",
+        "hardware_access_authorized": False,
+        "separate_human_approval_required": True,
+    }
+    review_path = output / "approval-record-template.json"
+    review_path.write_text(
+        json.dumps(review, indent=2, sort_keys=True) + "\n",
+        encoding="utf-8",
+        newline="\n",
+    )
+
+    manifest = {
+        "schema_version": 1,
+        "packet": "M3 hardware research plan review",
+        "repository_commit": commit,
+        "contains_private_evidence": False,
+        "hardware_access_authorized": False,
+        "files": [
+            {
+                "path": frozen_plan.name,
+                "bytes": frozen_plan.stat().st_size,
+                "sha256": _sha256(frozen_plan),
+            },
+            {
+                "path": review_path.name,
+                "bytes": review_path.stat().st_size,
+                "sha256": _sha256(review_path),
+            },
+        ],
+    }
+    manifest_path = output / "packet-manifest.json"
+    manifest_path.write_text(
+        json.dumps(manifest, indent=2, sort_keys=True) + "\n",
+        encoding="utf-8",
+        newline="\n",
+    )
+    return manifest
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser()
+    parser.add_argument("plan", type=Path)
+    parser.add_argument(
+        "--output",
+        type=Path,
+        default=ROOT / ".build" / "m3-review-packet",
+    )
+    args = parser.parse_args()
+    try:
+        result = create_packet(args.plan, args.output)
+    except ValueError as error:
+        parser.error(str(error))
+    print(f"packet={args.output.resolve()}")
+    print(f"plan_sha256={result['files'][0]['sha256']}")
+    print("hardware_access_authorized=false")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())

scripts/validate_m3_hardware_protocol.py

@@ -61,14 +61,14 @@ OPERATION_KEYS = {
 }
 
 
-def _timestamp_with_timezone(value: object) -> bool:
+def _timestamp_with_timezone(value: object) -> datetime | None:
     if not isinstance(value, str):
-        return False
+        return None
     try:
         parsed = datetime.fromisoformat(value.replace("Z", "+00:00"))
     except ValueError:
-        return False
+        return None
-    return parsed.tzinfo is not None
+    return parsed if parsed.tzinfo is not None else None
 
 
 def _validate_operation(operation: dict, seen: set[str]) -> list[str]:
@@ -232,8 +232,14 @@ def validate(path: Path) -> dict:
         "machine_location", ""
     ).strip():
         incomplete.append("machine location is not recorded")
-    if not _timestamp_with_timezone(session.get("planned_at")):
+    starts_at = _timestamp_with_timezone(session.get("planned_at"))
+    ends_at = _timestamp_with_timezone(session.get("ends_at"))
+    if starts_at is None:
         incomplete.append("planned_at is not an ISO-8601 timestamp with timezone")
+    if ends_at is None:
+        incomplete.append("ends_at is not an ISO-8601 timestamp with timezone")
+    if starts_at is not None and ends_at is not None and ends_at <= starts_at:
+        errors.append("session end must be later than session start")
 
     status = "invalid" if errors else "ready_for_review" if not incomplete else "incomplete"
     return {

tests/fixtures/m3-hardware-protocol-template.json

@@ -70,6 +70,7 @@
   "session": {
     "machine_location": null,
     "planned_at": null,
+    "ends_at": null,
     "notes": ""
   }
 }

tests/test_m3_hardware_protocol.py

@@ -57,6 +57,7 @@ class M3HardwareProtocolTests(unittest.TestCase):
         plan["session"] = {
             "machine_location": "Synthetic test location",
             "planned_at": "2026-10-21T12:00:00+02:00",
+            "ends_at": "2026-10-21T12:30:00+02:00",
             "notes": "No hardware is used by this unit test.",
         }
         return plan
@@ -90,6 +91,15 @@ class M3HardwareProtocolTests(unittest.TestCase):
         )
         self.assertFalse(result["hardware_access_authorized"])
 
+    def test_session_window_must_be_bounded_and_ordered(self):
+        with tempfile.TemporaryDirectory(dir=ROOT / ".build") as directory:
+            plan = self._complete()
+            plan["session"]["ends_at"] = plan["session"]["planned_at"]
+            result = validate(self._write(Path(directory), plan))
+        self.assertEqual("invalid", result["status"])
+        self.assertIn("session end must be later than session start", result["errors"])
+        self.assertFalse(result["hardware_access_authorized"])
+
     def test_safety_boundary_cannot_be_narrowed(self):
         with tempfile.TemporaryDirectory(dir=ROOT / ".build") as directory:
             plan = self._complete()

tests/test_m3_review_packet.py

@@ -0,0 +1,113 @@
+import copy
+import hashlib
+import json
+import tempfile
+import unittest
+from pathlib import Path
+
+from scripts.prepare_m3_review_packet import ROOT, create_packet
+
+
+TEMPLATE = ROOT / "tests" / "fixtures" / "m3-hardware-protocol-template.json"
+
+
+class M3ReviewPacketTests(unittest.TestCase):
+    def _ready_plan(self, root: Path) -> Path:
+        plan = copy.deepcopy(json.loads(TEMPLATE.read_text(encoding="utf-8")))
+        plan["roles"] = {
+            "operator": "Synthetic Operator",
+            "safety_observer": "Synthetic Observer",
+            "protocol_reviewer": "Synthetic Reviewer",
+        }
+        for key in plan["physical_controls"]:
+            plan["physical_controls"][key] = True
+        plan["physical_controls"]["emission_inhibition_method"] = "Synthetic method"
+        plan["software_controls"]["operation_allowlist_enforced"] = True
+        plan["software_controls"]["reversible_driver_plan_reviewed"] = True
+        plan["allowed_operations"] = [{
+            "operation_id": "synthetic-read-identity",
+            "purpose": "Synthetic packet test only",
+            "evidence_artifact_id": "sha256-0123456789abcdef0123",
+            "evidence_level": "independently-implemented",
+            "safety_class": "read-only-no-motion-no-emission",
+            "direction": "host-to-controller-request-response",
+            "request_hex": "0102",
+            "expected_response": "Synthetic fixed response contract",
+            "timeout_ms": 1000,
+            "maximum_attempts": 1,
+            "state_change_expected": False,
+        }]
+        plan["recovery"].update({
+            "power_down_procedure_reviewed": True,
+            "driver_rollback_procedure_reviewed": True,
+            "incident_record_destination_prepared": True,
+        })
+        plan["session"] = {
+            "machine_location": "Synthetic location",
+            "planned_at": "2026-10-21T12:00:00+02:00",
+            "ends_at": "2026-10-21T12:30:00+02:00",
+            "notes": "Synthetic unit test only",
+        }
+        path = root / "source-plan.json"
+        path.write_text(json.dumps(plan), encoding="utf-8")
+        return path
+
+    def test_packet_freezes_exact_plan_and_stays_non_authorizing(self):
+        with tempfile.TemporaryDirectory(dir=ROOT / ".build") as directory:
+            root = Path(directory)
+            source = self._ready_plan(root)
+            source_bytes = source.read_bytes()
+            output = root / "packet"
+            manifest = create_packet(source, output, repository_commit="a" * 40)
+            review = json.loads((output / "approval-record-template.json").read_text())
+            frozen_bytes = (output / "plan.json").read_bytes()
+        self.assertEqual(source_bytes, frozen_bytes)
+        self.assertEqual(hashlib.sha256(source_bytes).hexdigest(), review["binding"]["plan_sha256"])
+        self.assertEqual("not_reviewed", review["decision"])
+        self.assertFalse(review["hardware_access_authorized"])
+        self.assertFalse(manifest["hardware_access_authorized"])
+        self.assertEqual("a" * 40, manifest["repository_commit"])
+
+    def test_incomplete_public_template_is_rejected(self):
+        with tempfile.TemporaryDirectory(dir=ROOT / ".build") as directory:
+            with self.assertRaisesRegex(ValueError, "not ready for review"):
+                create_packet(TEMPLATE, Path(directory) / "packet", "b" * 40)
+
+    def test_changed_plan_changes_binding(self):
+        with tempfile.TemporaryDirectory(dir=ROOT / ".build") as directory:
+            root = Path(directory)
+            source = self._ready_plan(root)
+            create_packet(source, root / "one", "c" * 40)
+            one = json.loads((root / "one" / "approval-record-template.json").read_text())
+            plan = json.loads(source.read_text())
+            plan["session"]["notes"] = "Changed synthetic note"
+            source.write_text(json.dumps(plan), encoding="utf-8")
+            create_packet(source, root / "two", "c" * 40)
+            two = json.loads((root / "two" / "approval-record-template.json").read_text())
+        self.assertNotEqual(one["binding"]["plan_sha256"], two["binding"]["plan_sha256"])
+
+    def test_nonempty_output_is_not_overwritten(self):
+        with tempfile.TemporaryDirectory(dir=ROOT / ".build") as directory:
+            root = Path(directory)
+            source = self._ready_plan(root)
+            output = root / "packet"
+            output.mkdir()
+            sentinel = output / "keep.txt"
+            sentinel.write_text("keep", encoding="utf-8")
+            with self.assertRaisesRegex(ValueError, "not empty"):
+                create_packet(source, output, "d" * 40)
+            self.assertEqual("keep", sentinel.read_text(encoding="utf-8"))
+
+    def test_manifest_hashes_every_packet_file(self):
+        with tempfile.TemporaryDirectory(dir=ROOT / ".build") as directory:
+            root = Path(directory)
+            output = root / "packet"
+            manifest = create_packet(self._ready_plan(root), output, "e" * 40)
+            for record in manifest["files"]:
+                path = output / record["path"]
+                self.assertEqual(path.stat().st_size, record["bytes"])
+                self.assertEqual(hashlib.sha256(path.read_bytes()).hexdigest(), record["sha256"])
+
+
+if __name__ == "__main__":
+    unittest.main()