fix(settings): reconcile secret status and model drafts

server/src/app/core/secret_box.py

@@ -26,7 +26,7 @@ def get_or_create_secret_key() -> bytes:
     if SECRET_KEY_FILE.exists():
         encoded = SECRET_KEY_FILE.read_text(encoding="utf-8").strip()
         if encoded:
-            return base64.urlsafe_b64decode(encoded.encode("ascii"))
+            return read_secret_key()
 
     secret_key = secrets.token_bytes(KEY_BYTES)
     encoded = base64.urlsafe_b64encode(secret_key).decode("ascii")
@@ -34,6 +34,23 @@ def get_or_create_secret_key() -> bytes:
     return secret_key
 
 
+def read_secret_key() -> bytes:
+    """只读取现有主密钥，解密路径不得因缺失密钥而生成新文件。"""
+
+    if not SECRET_KEY_FILE.exists():
+        raise ValueError("Secret key file is missing")
+
+    try:
+        encoded = SECRET_KEY_FILE.read_text(encoding="utf-8").strip()
+        secret_key = base64.urlsafe_b64decode(encoded.encode("ascii"))
+    except (OSError, UnicodeError, ValueError) as exc:
+        raise ValueError("Secret key file is invalid") from exc
+
+    if len(secret_key) != KEY_BYTES:
+        raise ValueError("Secret key length is invalid")
+    return secret_key
+
+
 def _keystream(secret_key: bytes, nonce: bytes, length: int) -> bytes:
     chunks: list[bytes] = []
     counter = 0
@@ -57,7 +74,14 @@ def encrypt_secret(value: str) -> str:
     secret_key = get_or_create_secret_key()
     nonce = secrets.token_bytes(NONCE_BYTES)
     plaintext = value.encode("utf-8")
-    ciphertext = bytes(a ^ b for a, b in zip(plaintext, _keystream(secret_key, nonce, len(plaintext)), strict=False))
+    ciphertext = bytes(
+        a ^ b
+        for a, b in zip(
+            plaintext,
+            _keystream(secret_key, nonce, len(plaintext)),
+            strict=False,
+        )
+    )
     mac = hmac.new(secret_key, b"mac:" + nonce + ciphertext, hashlib.sha256).digest()
 
     encoded_nonce = base64.urlsafe_b64encode(nonce).decode("ascii")
@@ -78,7 +102,7 @@ def decrypt_secret(value: str) -> str:
     if version != SECRET_BOX_VERSION:
         raise ValueError("Unsupported secret payload version")
 
-    secret_key = get_or_create_secret_key()
+    secret_key = read_secret_key()
     nonce = base64.urlsafe_b64decode(encoded_nonce.encode("ascii"))
     ciphertext = base64.urlsafe_b64decode(encoded_ciphertext.encode("ascii"))
     expected_mac = base64.urlsafe_b64decode(encoded_mac.encode("ascii"))
@@ -87,5 +111,12 @@ def decrypt_secret(value: str) -> str:
     if not hmac.compare_digest(actual_mac, expected_mac):
         raise ValueError("Secret payload integrity check failed")
 
-    plaintext = bytes(a ^ b for a, b in zip(ciphertext, _keystream(secret_key, nonce, len(ciphertext)), strict=False))
+    plaintext = bytes(
+        a ^ b
+        for a, b in zip(
+            ciphertext,
+            _keystream(secret_key, nonce, len(ciphertext)),
+            strict=False,
+        )
+    )
     return plaintext.decode("utf-8")