test(infra): clamd detects EICAR and passes a clean stream over INSTREAM (refs #191)

Red: no clamav service exists yet, so verify-clamav finds no container.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

infra/clamav-check.py

@@ -0,0 +1,40 @@
+#!/usr/bin/env python3
+"""S-28 (#191): prove clamd is up, has signatures loaded, and scans a stream over INSTREAM.
+
+The EICAR test file must come back FOUND and a clean payload OK — the same protocol the domain's
+scanner adapter will speak (ADR-0036). EICAR is assembled from two halves so this file itself is
+not flagged by an on-access scanner on a developer laptop. Stdlib only (python:3-slim).
+"""
+import os
+import socket
+import struct
+import sys
+import time
+
+HOST = os.environ["CLAMAV"]
+TIMEOUT = int(os.environ.get("CLAMAV_TIMEOUT", "60"))
+EICAR = (r"X5O!P%@AP[4\PZX54(P^)7CC)7}$" + r"EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*").encode()
+
+
+def instream(payload):
+    with socket.create_connection((HOST, 3310), timeout=30) as s:
+        s.sendall(b"zINSTREAM\0" + struct.pack(">I", len(payload)) + payload + struct.pack(">I", 0))
+        return s.recv(4096).rstrip(b"\0").decode()
+
+
+deadline = time.time() + TIMEOUT
+while True:
+    try:
+        clean, infected = instream(b"%PDF-1.4 clean"), instream(EICAR)
+        break
+    except OSError as e:
+        if time.time() > deadline:
+            sys.exit(f"FAIL: clamd at {HOST}:3310 unreachable: {e}")
+        time.sleep(3)
+
+print(f"clean → {clean!r}; eicar → {infected!r}")
+if clean != "stream: OK":
+    sys.exit("FAIL: clean payload was not reported OK")
+if not infected.endswith("FOUND"):
+    sys.exit("FAIL: EICAR was not detected")
+print("OK: clamd detects EICAR and passes a clean stream")