search-with-proof group 2: verifier with owned oracles and differential

The verifier, not the artefact, observes the effect: SQL, path, command and SSRF
oracles owned by the verifier (XSS needs a browser executor, else no_oracle);
artefact exit code and output ignored; immutable checkout and dependencies;
3 runs per side; one-sided build or readiness failure is inconclusive. An
isolation failure raises IsolationUnavailable instead of reading as
could_not_build (the NPROC limit now applies inside the user namespace).
35 tests, including gaming attempts and 300 host processes.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

tests/fixtures/search/app.py

@@ -0,0 +1,33 @@
+"""CLI toy: arguments are its sole public interface; config belongs to the app."""
+
+import os
+import pathlib
+import sqlite3
+import subprocess
+import sys
+import urllib.request
+
+fixed = pathlib.Path("/workspace/fixed").exists()
+if sys.argv[1:] == ["--ready"]:
+    sys.exit(1 if pathlib.Path("/workspace/broken").exists() else 0)
+family, payload = sys.argv[1:]
+if family == "path":
+    root = pathlib.Path(os.environ["SERVED_ROOT"])
+    path = (root / payload).resolve()
+    if not fixed or path.is_relative_to(root):
+        value = path.read_text()
+        if not pathlib.Path("/workspace/flaky").exists() or value.startswith("a"):
+            print(value)
+elif family == "sql":
+    with sqlite3.connect(os.environ["DATABASE"]) as db:
+        if fixed:
+            rows = db.execute("SELECT value FROM records WHERE public=1 AND name=?", (payload,))
+        else:
+            rows = db.execute("SELECT value FROM records WHERE public=1 AND name='" + payload + "'")
+        print(list(rows))
+elif family == "command":
+    if not fixed:
+        subprocess.run("echo " + payload, shell=True, check=False)
+elif family == "ssrf":
+    if not fixed:
+        print(urllib.request.urlopen(os.path.expandvars(payload), timeout=2).read())