diff --git a/.gitignore b/.gitignore
index 73edcbb..e387de6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -16,3 +16,7 @@ htmlcov/
 .coverage.*
 coverage.xml
 *.cover
+
+# Runtime artifacts
+*.db
+audit.db
diff --git a/src/cmcp_runtime/mcp/server.py b/src/cmcp_runtime/mcp/server.py
index febeb5e..3035f83 100644
--- a/src/cmcp_runtime/mcp/server.py
+++ b/src/cmcp_runtime/mcp/server.py
@@ -206,15 +206,20 @@ async def _handle_mcp(self, request: Request) -> Response:
         """Handle MCP JSON-RPC 2.0 calls."""
         # DOS-001: reject oversized requests before parsing to prevent OOM
         content_length = request.headers.get("content-length")
-        if content_length and int(content_length) > self._max_request_bytes:
-            return JSONResponse(
-                {
-                    "jsonrpc": "2.0",
-                    "error": {"code": -32600, "message": "Request body too large"},
-                    "id": None,
-                },
-                status_code=413,
-            )
+        if content_length:
+            try:
+                cl = int(content_length)
+            except ValueError:
+                return JSONResponse({"error": "invalid Content-Length"}, status_code=400)
+            if cl > self._max_request_bytes:
+                return JSONResponse(
+                    {
+                        "jsonrpc": "2.0",
+                        "error": {"code": -32600, "message": "Request body too large"},
+                        "id": None,
+                    },
+                    status_code=413,
+                )
         try:
             body = await request.body()
             if len(body) > self._max_request_bytes:
diff --git a/src/cmcp_verify/opaque.py b/src/cmcp_verify/opaque.py
index b7ae245..2fe1da4 100644
--- a/src/cmcp_verify/opaque.py
+++ b/src/cmcp_verify/opaque.py
@@ -71,6 +71,12 @@ def verify_opaque_measurement(
         result.details["hint"] = "raw_evidence not provided; cannot verify with Opaque"
         return result
 
+    if not endpoint or not endpoint.startswith("https://"):
+        raise ValueError(
+            f"Opaque attestation endpoint must use https://. Got: {endpoint!r}. "
+            "Set CMCP_OPAQUE_ATTESTATION_ENDPOINT to a valid https:// URL."
+        )
+
     # POST raw_evidence (base64-encoded) to the Opaque attestation endpoint
     payload = json.dumps({
         "measurement": measurement,
diff --git a/tests/unit/test_low_batch_186_187_191_194.py b/tests/unit/test_low_batch_186_187_191_194.py
index 1f1235f..b382320 100644
--- a/tests/unit/test_low_batch_186_187_191_194.py
+++ b/tests/unit/test_low_batch_186_187_191_194.py
@@ -184,7 +184,7 @@ def test_redact_auth_headers_no_auth_unchanged():
 
 def test_opaque_api_key_not_logged_on_failure(monkeypatch, caplog):
     """HW-008: OPAQUE_API_KEY value must not appear in log output on failure."""
-    monkeypatch.setenv("CMCP_OPAQUE_ATTESTATION_ENDPOINT", "https://attest.opaque.co/v1/verify")
+    monkeypatch.setenv("CMCP_OPAQUE_ATTESTATION_ENDPOINT", "https://attest.example.com/v1/verify")
     monkeypatch.setenv("OPAQUE_API_KEY", "sk-supersecret-key-do-not-log")
     import cmcp_verify.opaque as opaque_mod
     importlib.reload(opaque_mod)
@@ -211,7 +211,7 @@ def mock_urlopen(req, timeout=None):
         opaque_mod.verify_opaque_measurement(
             "sha384:" + "a" * 96,
             b"\x00" * 64,
-            opaque_endpoint="https://attest.opaque.co/v1/verify",
+            opaque_endpoint="https://attest.example.com/v1/verify",
         )
     auth = captured.get("headers", {}).get("authorization")
     assert auth == "Bearer test-api-key-12345"
diff --git a/tests/unit/test_tdx_opaque_verify.py b/tests/unit/test_tdx_opaque_verify.py
index c197e28..fb27551 100644
--- a/tests/unit/test_tdx_opaque_verify.py
+++ b/tests/unit/test_tdx_opaque_verify.py
@@ -102,7 +102,7 @@ def test_opaque_no_endpoint_configured(monkeypatch):
 
 
 def test_opaque_no_raw_evidence_fails_closed(monkeypatch):
-    monkeypatch.setenv("CMCP_OPAQUE_ATTESTATION_ENDPOINT", "https://attest.opaque.co/v1/verify")
+    monkeypatch.setenv("CMCP_OPAQUE_ATTESTATION_ENDPOINT", "https://attest.example.com/v1/verify")
     result = verify_opaque_measurement("sha384:" + "a" * 96, None)
     assert result.verified is False
     assert result.failure_reason == "no_raw_evidence"
@@ -121,7 +121,7 @@ def test_opaque_endpoint_returns_verified(monkeypatch):
         result = verify_opaque_measurement(
             "sha384:" + "a" * 96,
             b"\x00" * 64,
-            opaque_endpoint="https://attest.opaque.co/v1/verify",
+            opaque_endpoint="https://attest.example.com/v1/verify",
         )
 
     assert result.verified
@@ -140,7 +140,7 @@ def test_opaque_endpoint_returns_unverified(monkeypatch):
         result = verify_opaque_measurement(
             "sha384:" + "a" * 96,
             b"\x00" * 64,
-            opaque_endpoint="https://attest.opaque.co/v1/verify",
+            opaque_endpoint="https://attest.example.com/v1/verify",
         )
 
     assert not result.verified
@@ -154,7 +154,7 @@ def test_opaque_network_error(monkeypatch):
         result = verify_opaque_measurement(
             "sha384:" + "a" * 96,
             b"\x00" * 64,
-            opaque_endpoint="https://attest.opaque.co/v1/verify",
+            opaque_endpoint="https://attest.example.com/v1/verify",
         )
 
     assert result.verified