diff --git a/src/k1link/observatory/source_admission.py b/src/k1link/observatory/source_admission.py
index 166e643..e98ab09 100644
--- a/src/k1link/observatory/source_admission.py
+++ b/src/k1link/observatory/source_admission.py
@@ -684,7 +684,7 @@ class RecordedK1SourceAdmissionService:
             or manifest.session_id != media_artifact.session_id
             or manifest.artifact_id != media_artifact.artifact_id
             or manifest.public_source_id != media_artifact.public_source_id
-            or manifest.byte_length != media_artifact.byte_length
+            or not 0 < manifest.byte_length <= media_artifact.byte_length
             or len(manifest.epochs) != 1
             or manifest.synchronization != "host-arrival-best-effort"
             or not _SHA256.fullmatch(manifest.generation_sha256)
diff --git a/tests/test_observatory_source_admission.py b/tests/test_observatory_source_admission.py
index 01a9a32..068b30b 100644
--- a/tests/test_observatory_source_admission.py
+++ b/tests/test_observatory_source_admission.py
@@ -335,6 +335,75 @@ def test_portable_source_admission_is_independent_from_session_label(
     assert capability["camera_profile"]["height"] == 600
 
 
+def test_portable_source_admission_accepts_camera_archive_metadata_overhead(
+    tmp_path: Path,
+) -> None:
+    session_id = "20260828T130511Z_viewer_live"
+    manifest = _manifest(session_id, tmp_path)
+    summary_payload = b'{"schema_version":"missioncore.camera-recording/v1"}'
+    index_payload = b'{"sequence":1,"length":10}\n'
+    archive_byte_length = manifest.byte_length + len(summary_payload) + len(index_payload)
+    detail = _detail(session_id, "RAVNOVES004TREE")
+    detail = replace(
+        detail,
+        artifacts=tuple(
+            replace(artifact, byte_length=archive_byte_length)
+            if artifact.kind == "recorded-video"
+            else artifact
+            for artifact in detail.artifacts
+        ),
+    )
+    store = _Store(tmp_path, detail)
+    store.media = (
+        replace(store.media[0], byte_length=archive_byte_length),
+    )
+    service = RecordedK1SourceAdmissionService(
+        data_dir=tmp_path,
+        session_store=store,  # type: ignore[arg-type]
+        media_inspector=_Inspector(manifest),  # type: ignore[arg-type]
+        requirements=_requirements(),
+    )
+
+    admission = service.check(session_id)
+
+    assert admission.frame_count == 1
+    assert archive_byte_length > manifest.byte_length
+
+
+def test_portable_source_admission_rejects_media_payload_larger_than_catalog(
+    tmp_path: Path,
+) -> None:
+    session_id = "20260831T000000Z_viewer_live"
+    manifest = _manifest(session_id, tmp_path)
+    catalog_byte_length = manifest.byte_length - 1
+    detail = _detail(session_id, "RAVNOVES005")
+    detail = replace(
+        detail,
+        artifacts=tuple(
+            replace(artifact, byte_length=catalog_byte_length)
+            if artifact.kind == "recorded-video"
+            else artifact
+            for artifact in detail.artifacts
+        ),
+    )
+    store = _Store(tmp_path, detail)
+    store.media = (
+        replace(store.media[0], byte_length=catalog_byte_length),
+    )
+    service = RecordedK1SourceAdmissionService(
+        data_dir=tmp_path,
+        session_store=store,  # type: ignore[arg-type]
+        media_inspector=_Inspector(manifest),  # type: ignore[arg-type]
+        requirements=_requirements(),
+    )
+
+    with pytest.raises(
+        PortableSourceAdmissionIntegrityError,
+        match="epoch topology",
+    ):
+        service.check(session_id)
+
+
 def test_admission_seals_exact_catalogued_spatial_replay_metadata(
     tmp_path: Path,
 ) -> None: