fix(adapters): validate iat before it reaches the record, not after

src/agentrust_trace/adapters/agt.py

@@ -13,6 +13,7 @@
 
 import rfc8785
 from agentrust_trace.models import (
+    JCS_SAFE_INTEGER,
     Appraisal,
     BuildProvenance,
     ModelInfo,
@@ -57,7 +58,17 @@ class AGTSessionResult:
 
     iat: int = field(default_factory=lambda: int(time.time()))
     """Issuance timestamp. Defaults to now."""
-
+    def __post_init__(self) -> None:
+        if (
+            not isinstance(self.iat, int)
+            or isinstance(self.iat, bool)
+            or self.iat < 0
+            or self.iat > JCS_SAFE_INTEGER
+        ):
+            raise ValueError(
+                f"iat must be a non-negative integer Unix timestamp within the JCS "
+                f"safe-integer range, got {self.iat!r}"
+            )
 
 class TraceAGTAdapter:
     """Build Level 0 TRACE Trust Records from AGT govern() session output.

src/agentrust_trace/adapters/sandbox.py

@@ -80,6 +80,7 @@
 import rfc8785
 
 from agentrust_trace.models import (
+    JCS_SAFE_INTEGER,
     Appraisal,
     BuildProvenance,
     ModelInfo,
@@ -227,9 +228,20 @@ def __post_init__(self) -> None:
         if not _DIGEST_RE.match(self.image_digest):
             raise ValueError(
                 f"image_digest {self.image_digest!r} must be a sha256: or sha384: digest."
+               )
+        if (
+            not isinstance(self.iat, int)
+            or isinstance(self.iat, bool)
+            or self.iat < 0
+            or self.iat > JCS_SAFE_INTEGER
+        ):
+            raise ValueError(
+                f"iat must be a non-negative integer Unix timestamp within the JCS "
+                f"safe-integer range, got {self.iat!r}"
             )
 
 
+
 class TraceSandboxAdapter:
     """Build Trust Records from a sandboxed agent runtime's session output.
 

tests/test_agt_adapter.py

@@ -286,3 +286,27 @@ def test_an_unappraised_record_still_signs_and_verifies() -> None:
     signed = sign_record(record, key)
     assert verify_record(signed, public_key_or_jwk=key_to_jwk(key)) is not None
     assert signed["appraisal"]["status"] == "none"
+
+
+# ---------------------------------------------------------------------------
+# iat reaches the record untouched (same failure mode as #320)
+# ---------------------------------------------------------------------------
+
+@pytest.mark.parametrize("iat", ["1800000000", True, False, -5, 1.5, 2**60])
+def test_iat_must_be_a_bounded_non_negative_integer(iat) -> None:
+    """Every other field here reaches the record through a models.py pydantic
+    constructor, which coerces or refuses a bad type before it is dumped. `iat`
+    used to reach build_trust_record's top-level "iat" key untouched, with
+    AGTSessionResult performing no validation of any field at all: a numeric
+    string or a bool survived to the signed wire form, and TrustRecord.model_validate()
+    reported it valid (pydantic's lax mode coerces on the way in) while the wire
+    bytes stayed the original, schema-invalid type. Same failure mode as
+    provenance.build_record's pre-#320 issued_at coercion."""
+    with pytest.raises(ValueError, match="iat must be a non-negative integer"):
+        _make_session(iat=iat)
+
+
+def test_valid_iat_round_trips_as_an_int_on_the_wire() -> None:
+    record = _make_adapter().build_trust_record(_make_session(iat=1800000000))
+    assert record["iat"] == 1800000000
+    assert isinstance(record["iat"], int)

tests/test_sandbox_adapter.py

@@ -319,6 +319,25 @@ def test_a_bad_sandbox_id_fails_at_the_adapter_not_at_model_validate() -> None:
         _make_session(sandbox_id="build-7f2a")
 
 
+@pytest.mark.parametrize("iat", ["1800000000", True, False, -5, 1.5, 2**60])
+def test_iat_must_be_a_bounded_non_negative_integer(iat) -> None:
+    """Every other field here reaches the record through a models.py pydantic
+    constructor, which coerces or refuses a bad type before it is dumped. `iat`
+    used to reach build_trust_record's top-level "iat" key untouched, so a
+    numeric string or a bool survived to the signed wire form: model_validate()
+    reported it valid (pydantic's lax mode coerces on the way in) while the wire
+    bytes stayed the original, schema-invalid type. Same failure mode as
+    provenance.build_record's pre-#320 issued_at coercion."""
+    with pytest.raises(ValueError, match="iat must be a non-negative integer"):
+        _make_session(iat=iat)
+
+
+def test_valid_iat_round_trips_as_an_int_on_the_wire() -> None:
+    record = _make_adapter().build_trust_record(_make_session(iat=1800000000))
+    assert record["iat"] == 1800000000
+    assert isinstance(record["iat"], int)
+
+
 # ---------------------------------------------------------------------------
 # 6. Transcript hashing uses JCS
 # ---------------------------------------------------------------------------