perf(m49): verify source payloads during assembly

tests/test_m49_portable_executor_release.py

@@ -31,6 +31,7 @@ from k1link.observatory.m49_portable_source import (
     materialize_m49_portable_source,
     read_m49_source_index,
     validate_m49_portable_source_stage,
+    validate_m49_portable_source_stage_binding,
 )
 from k1link.observatory.portable_result_contract import (
     PortableResultPackageManifest,
@@ -566,6 +567,36 @@ def test_fresh_source_stage_defers_full_validation_until_execution_boundary(
     assert validated_roots == [first_root]
 
 
+def test_bound_source_stage_rechecks_small_documents_without_rehashing_sequence(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    stage_root, _expected = _materialized_source(tmp_path, monkeypatch)
+    stage = validate_m49_portable_source_stage(stage_root)
+
+    def unexpected_sequence_rehash(*_args: object, **_kwargs: object) -> None:
+        raise AssertionError("bound-stage validation rehashed the point sequence")
+
+    monkeypatch.setattr(source_module, "_verify_sequence_files", unexpected_sequence_rehash)
+    rebound = validate_m49_portable_source_stage_binding(stage)
+
+    assert rebound == stage
+
+
+@pytest.mark.parametrize("relative_path", ["schedule.tsv", "sequence-index.ndjson"])
+def test_bound_source_stage_rejects_changed_small_documents(
+    tmp_path: Path,
+    monkeypatch: pytest.MonkeyPatch,
+    relative_path: str,
+) -> None:
+    stage_root, _expected = _materialized_source(tmp_path, monkeypatch)
+    stage = validate_m49_portable_source_stage(stage_root)
+    artifact = stage.root / relative_path
+    artifact.write_bytes(artifact.read_bytes() + b"changed")
+
+    with pytest.raises(M49PortableSourceError):
+        validate_m49_portable_source_stage_binding(stage)
+
+
 def test_source_materializer_rejects_unadmitted_adjacent_metadata(
     tmp_path: Path, monkeypatch: pytest.MonkeyPatch
 ) -> None:
@@ -756,20 +787,18 @@ def test_result_v2_assembler_and_exact_validator_round_trip(
         created_at_utc=lambda: NOW,
         invoker=fake_invoke,
     )
-    draft = runner.run(
-        PortableWorkerRuntimePlan(
-            job_id=sealed.job_id,
-            adapter_id="m49-tgs-worker006-portable-v2",
-            candidate_sha256="f" * 64,
-            setup_id=sealed.setup_id,
-            definition_sha256=sealed.definition_sha256,
-            source_bundle_sha256=sealed.source_bundle_sha256,
-            source_capability_manifest_sha256=sealed.source_capability_manifest_sha256,
-            result_contract_sha256=definition.result_contract.contract_sha256,
-            phases=M49_PORTABLE_RUNTIME_PHASES,
-        ),
-        bound_source,
+    plan = PortableWorkerRuntimePlan(
+        job_id=sealed.job_id,
+        adapter_id="m49-tgs-worker006-portable-v2",
+        candidate_sha256="f" * 64,
+        setup_id=sealed.setup_id,
+        definition_sha256=sealed.definition_sha256,
+        source_bundle_sha256=sealed.source_bundle_sha256,
+        source_capability_manifest_sha256=sealed.source_capability_manifest_sha256,
+        result_contract_sha256=definition.result_contract.contract_sha256,
+        phases=M49_PORTABLE_RUNTIME_PHASES,
     )
+    draft = runner.run(plan, bound_source)
     package = PortableResultPackageManifest.from_bytes((draft.root / "manifest.json").read_bytes())
     assert draft.root.name == package.manifest_sha256
     assert draft.result_id.startswith("m49-tgs-portable-review-")
@@ -816,6 +845,18 @@ def test_result_v2_assembler_and_exact_validator_round_trip(
             )
         )
 
+    source_rows = read_m49_source_index(
+        source_stage.root / "sequence-index.ndjson",
+        expected_frame_count=source_stage.timeline_frame_count,
+    )
+    available_row = next(row for row in source_rows if row["sample_available"] is True)
+    native_path = source_stage.root / cast(str, available_row["relative_path"])
+    native_payload = bytearray(native_path.read_bytes())
+    native_payload[-1] ^= 0x01
+    native_path.write_bytes(native_payload)
+    with pytest.raises(M49PortableResultError, match="digest changed"):
+        runner.run(plan, bound_source)
+
 
 def test_executor_release_candidate_is_deterministic_blocked_and_tamper_evident(
     tmp_path: Path,