fix: modernize dependency recovery guidance (#5282)

nanobot/channels/weixin/runtime.py

@@ -1683,7 +1683,10 @@ def _encrypt_aes_ecb(data: bytes, aes_key_b64: str) -> bytes:
         encryptor = cipher_obj.encryptor()
         return encryptor.update(padded) + encryptor.finalize()
     except ImportError:
-        logger.warning("Cannot encrypt media: install 'pycryptodome' or 'cryptography'")
+        logger.warning(
+            "Cannot encrypt media. Run `nanobot plugins enable weixin` "
+            "to install WeChat support."
+        )
         return data
 
 
@@ -1715,7 +1718,10 @@ def _decrypt_aes_ecb(data: bytes, aes_key_b64: str) -> bytes:
             decryptor = cipher_obj.decryptor()
             decrypted = decryptor.update(data) + decryptor.finalize()
         except ImportError:
-            logger.warning("Cannot decrypt media: install 'pycryptodome' or 'cryptography'")
+            logger.warning(
+                "Cannot decrypt media. Run `nanobot plugins enable weixin` "
+                "to install WeChat support."
+            )
             return data
 
     return _pkcs7_unpad_safe(decrypted)

nanobot/channels/weixin/tests/test_weixin_channel.py

@@ -1080,6 +1080,32 @@ def test_decrypt_aes_ecb_strips_valid_pkcs7_padding() -> None:
     assert decrypted == plaintext
 
 
+def test_missing_aes_dependency_recommends_weixin_plugin(monkeypatch) -> None:
+    real_import = __import__
+
+    def fake_import(name, *args, **kwargs):
+        if name.startswith(("Crypto", "cryptography")):
+            raise ImportError("missing AES dependency")
+        return real_import(name, *args, **kwargs)
+
+    warnings: list[str] = []
+    monkeypatch.setattr("builtins.__import__", fake_import)
+    monkeypatch.setattr(
+        weixin_mod.logger,
+        "warning",
+        lambda message, *args: warnings.append(message.format(*args)),
+    )
+    key_b64 = "MDEyMzQ1Njc4OWFiY2RlZg=="
+    data = b"unencrypted media"
+
+    assert _encrypt_aes_ecb(data, key_b64) == data
+    assert _decrypt_aes_ecb(data, key_b64) == data
+    assert warnings == [
+        "Cannot encrypt media. Run `nanobot plugins enable weixin` to install WeChat support.",
+        "Cannot decrypt media. Run `nanobot plugins enable weixin` to install WeChat support.",
+    ]
+
+
 class _DummyDownloadResponse:
     def __init__(self, content: bytes, status_code: int = 200) -> None:
         self.content = content