What is Assistantd and why he needs Keychain. Assistantd Wants to use the “login” then the yych, popup of the sistet pempor.
When Macos come alerts containing “keychain“, most users think if it is not a malware virus or application that wants access to the Keychain Access passwords present on Mac.
A popup that requires access to “login” In Keychain it can also be worrying and stressful for the user.

What is assistantd and why the message appears “assistantd wants to use the “login” keychain”?
Assistantd is one daemon introduced by Apple on macos and iOS that provides support for services such as dictation and Siri voice commands. Specifically, assist the process by which the user's voice message is transformed into text into office applications or even in TextEdit.
Framework for Assistantd can be found in:
/System/Library/PrivateFrameworks/AssistantServices.framework/
In order to improve the performance and accurate, it is possible that at times this Assantd will ask for access to Keychain. Most likely to Contacts.
Siri uses access to contacts, and the reason is very simple. “Hi, Siri … Call Mama”. Previously Daemon must know what contact is in the agenda with the name “Mama”, to execute the action requested by the user.
In conclusion, if Assantd asks for login access to Keychain, all you have to do is enter the password, and the stressful popup will disappear.