feat: enhance agent management with session handling and UI improvements

backend/app/core/agent_tokens.py

@@ -0,0 +1,47 @@
+from __future__ import annotations
+
+import base64
+import hashlib
+import hmac
+import secrets
+
+ITERATIONS = 200_000
+SALT_BYTES = 16
+
+
+def generate_agent_token() -> str:
+    return secrets.token_urlsafe(32)
+
+
+def _b64encode(value: bytes) -> str:
+    return base64.urlsafe_b64encode(value).decode("utf-8").rstrip("=")
+
+
+def _b64decode(value: str) -> bytes:
+    padding = "=" * (-len(value) % 4)
+    return base64.urlsafe_b64decode(value + padding)
+
+
+def hash_agent_token(token: str) -> str:
+    salt = secrets.token_bytes(SALT_BYTES)
+    digest = hashlib.pbkdf2_hmac("sha256", token.encode("utf-8"), salt, ITERATIONS)
+    return f"pbkdf2_sha256${ITERATIONS}${_b64encode(salt)}${_b64encode(digest)}"
+
+
+def verify_agent_token(token: str, stored_hash: str) -> bool:
+    try:
+        algorithm, iterations, salt_b64, digest_b64 = stored_hash.split("$")
+    except ValueError:
+        return False
+    if algorithm != "pbkdf2_sha256":
+        return False
+    try:
+        iterations_int = int(iterations)
+    except ValueError:
+        return False
+    salt = _b64decode(salt_b64)
+    expected_digest = _b64decode(digest_b64)
+    candidate = hashlib.pbkdf2_hmac(
+        "sha256", token.encode("utf-8"), salt, iterations_int
+    )
+    return hmac.compare_digest(candidate, expected_digest)