fix(evidence): reject unencodable lock lane names (R30)

Author: mingulov

scripts/verify_round_receipt.py

@@ -56,7 +56,7 @@
      "tiers": {"pr-smoke": {"lanes": [...], "quorum": {...}, "budgets": {...}},
                "nightly": {...}, "release": {...}}}
 
-Tier objects carry a non-empty ``lanes`` list of non-empty strings plus
+Tier objects carry a non-empty ``lanes`` list of non-empty UTF-8-encodable strings plus
 ``quorum``/``budgets`` objects (presence-checked only — shapes and
 thresholds are TBD-E5). Staged
 Windows/macOS lanes (``win-softhsm2``, ``win-bouncyhsm``,
@@ -176,6 +176,12 @@ def _validate_lock_tier(tier: object, spec: Any) -> list[str]:
         or any(not isinstance(name, str) or not name for name in lanes)
     ):
         errors.append(f"{prefix}.lanes: must be a non-empty list of non-empty strings")
+    elif not _is_utf8_encodable("".join(lanes)):
+        # R30: an unencodable lock lane matching an unencodable receipt
+        # lane would pass the roster (rule 5) and lane entries (rule 6)
+        # while the bundle check (rule 7) skips -> exit 0 on a bogus
+        # bundle. Reject it here as malformed lock schema (exit 2).
+        errors.append(f"{prefix}.lanes: lane names must be UTF-8-encodable")
     for field in ("quorum", "budgets"):
         shape = spec.get(field)
         if shape is None:

tests/test_round_receipt_verify.py

@@ -480,3 +480,38 @@ def test_unknown_top_level_keys_ignored(tmp_path: Path) -> None:
     _write(receipt, payload)
     result = _run(receipt, lock)
     assert result.returncode == EXIT_VALID, result.stderr
+
+
+# --- Fix round 2 (R30): lock lane names must be UTF-8-encodable.
+#
+# Without this, an unencodable lock lane matching an unencodable receipt
+# lane passes the roster (rule 5) and lane entries (rule 6) while the
+# bundle check (rule 7) skips -> exit 0 with a bogus bundle.
+
+
+def test_unencodable_lock_lane_name_rejects_lock(tmp_path: Path) -> None:
+    lane = f"{chr(0xD800)}lane"
+    bad_lock = make_lock()
+    bad_lock["tiers"]["pr-smoke"]["lanes"] = [lane]
+    lock = _write(tmp_path / "lock.json", bad_lock)
+    payload = make_receipt()
+    payload["lanes"] = {lane: {"verdict": "pass", "admitted": True, "evidence_digest": _hex64("e")}}
+    payload["bundle_identity"] = "0" * 64
+    receipt = _write(tmp_path / "receipt.json", payload)
+    result = _run(receipt, lock)
+    assert result.returncode == EXIT_USAGE, result.stderr
+    assert "tiers.pr-smoke.lanes" in result.stderr
+
+
+def test_checked_in_lock_accepts_valid_receipt(tmp_path: Path) -> None:
+    # Control: the committed initial lock plus a matching valid receipt
+    # still verifies (guards R30 false-positives on normal lane names).
+    lock = REPO_ROOT / ".github" / "provider-round.lock.json"
+    lock_payload = json.loads(lock.read_text(encoding="utf-8"))
+    payload = make_receipt()
+    payload["p11lab_sha"] = lock_payload["p11lab_ref"]
+    payload["evaluator_sha"] = lock_payload["evaluator_fw_ref"]
+    payload["baseline_fw_sha"] = lock_payload["baseline_fw_sha"]
+    receipt = _write(tmp_path / "receipt.json", payload)
+    result = _run(receipt, lock)
+    assert result.returncode == EXIT_VALID, result.stderr