diff --git a/tests/test_edge_sync_manifest.py b/tests/test_edge_sync_manifest.py
new file mode 100644
index 00000000..fcd178e0
--- /dev/null
+++ b/tests/test_edge_sync_manifest.py
@@ -0,0 +1,147 @@
+from __future__ import annotations
+
+import hashlib
+
+from core.sync.artifacts import ArtifactType
+from core.sync.manifest import validate_manifest
+
+
+def _digest(data: bytes) -> str:
+    return "sha256:" + hashlib.sha256(data).hexdigest()
+
+
+def _manifest(
+    artifact_type: str = ArtifactType.TRACE.value,
+    *,
+    signature: str | None = None,
+    content_digest: str | None = None,
+    authority: dict | None = None,
+    epistemic: dict | None = None,
+) -> dict:
+    raw: dict = {
+        "schema_version": 1,
+        "artifact_id": "artifact-1",
+        "artifact_type": artifact_type,
+        "artifact_version": "v1",
+        "content": {
+            "uri": "s3://bucket/path/object.jsonl.zst",
+        },
+        "authority": authority or {},
+        "epistemic": epistemic or {},
+        "compatibility": {
+            "min_runtime_version": "0.0.0",
+            "max_runtime_version": None,
+        },
+    }
+    if content_digest is not None:
+        raw["content"]["digest"] = content_digest
+    if signature is not None:
+        raw["signature"] = {"signature": signature, "algorithm": "test", "key_id": "test"}
+    return raw
+
+
+def test_trace_manifest_accepts_without_signature() -> None:
+    check = validate_manifest(_manifest())
+    assert check.accepted
+    assert check.reason == "accepted"
+    assert check.manifest is not None
+    assert check.manifest.artifact_type is ArtifactType.TRACE
+    assert check.manifest.default_epistemic_status == "speculative"
+    assert not check.manifest.admissible_as_evidence
+
+
+def test_runtime_affecting_manifest_requires_signature() -> None:
+    check = validate_manifest(_manifest(ArtifactType.PACK_RELEASE.value))
+    assert not check.accepted
+    assert check.reason == "missing_signature"
+
+
+def test_runtime_affecting_manifest_accepts_with_signature() -> None:
+    check = validate_manifest(
+        _manifest(ArtifactType.PACK_RELEASE.value, signature="signed-by-release-key")
+    )
+    assert check.accepted
+    assert check.manifest is not None
+    assert check.manifest.signature_present
+    assert check.manifest.artifact_type is ArtifactType.PACK_RELEASE
+
+
+def test_unknown_artifact_type_rejects() -> None:
+    check = validate_manifest(_manifest("cloud_says_true"))
+    assert not check.accepted
+    assert check.reason == "unknown_artifact_type"
+
+
+def test_unsupported_schema_version_rejects() -> None:
+    raw = _manifest()
+    raw["schema_version"] = 999
+    check = validate_manifest(raw)
+    assert not check.accepted
+    assert check.reason == "unsupported_schema_version"
+
+
+def test_hash_mismatch_rejects() -> None:
+    check = validate_manifest(
+        _manifest(content_digest=_digest(b"expected")),
+        content_bytes=b"actual",
+    )
+    assert not check.accepted
+    assert check.reason == "hash_mismatch"
+
+
+def test_hash_match_accepts() -> None:
+    payload = b"trace bytes"
+    check = validate_manifest(
+        _manifest(content_digest=_digest(payload)),
+        content_bytes=payload,
+    )
+    assert check.accepted
+
+
+def test_missing_digest_rejects_when_content_bytes_supplied() -> None:
+    check = validate_manifest(_manifest(), content_bytes=b"payload")
+    assert not check.accepted
+    assert check.reason == "missing_content_digest"
+
+
+def test_manifest_cannot_claim_hot_path_authority() -> None:
+    check = validate_manifest(_manifest(authority={"hot_path_allowed": True}))
+    assert not check.accepted
+    assert check.reason == "authority_profile_weakened"
+
+
+def test_manifest_cannot_disable_required_signature() -> None:
+    check = validate_manifest(
+        _manifest(
+            ArtifactType.PACK_RELEASE.value,
+            authority={"requires_signature": False},
+        )
+    )
+    assert not check.accepted
+    assert check.reason == "authority_profile_weakened"
+
+
+def test_manifest_cannot_make_fleet_observations_evidence() -> None:
+    check = validate_manifest(
+        _manifest(
+            ArtifactType.FLEET_OBSERVATION_BATCH.value,
+            epistemic={"admissible_as_evidence": True},
+        )
+    )
+    assert not check.accepted
+    assert check.reason == "authority_profile_weakened"
+
+
+def test_malformed_epistemic_status_defaults_speculative() -> None:
+    check = validate_manifest(_manifest(epistemic={"default_status": "institutionally_certified"}))
+    assert check.accepted
+    assert check.manifest is not None
+    assert check.manifest.default_epistemic_status == "speculative"
+
+
+def test_malformed_compatibility_rejects() -> None:
+    raw = _manifest()
+    raw["compatibility"] = {"min_runtime_version": 123}
+    check = validate_manifest(raw)
+    assert not check.accepted
+    assert check.reason == "runtime_incompatible"