Im trying to make a list of each time Bitcoin Core has updated the wallet format. I did this with the help of AI so I would like if someone can confirm this list is correct:

2009 - Non-HD Wallet

    Version: Bitcoin 0.1.0
    Format: The original wallet.dat format.
    Description: This format stored private keys and transaction data in a single file without any hierarchical structure. Users had to manage their keys manually, and there was no support for key derivation.

2012 - Non-HD Wallet (Updated)

    Version: Bitcoin 0.7.0
    Format: Continued use of the non-HD wallet format.
    Description: While the core structure remained the same, improvements were made in terms of security and performance. However, it still lacked the features of hierarchical deterministic (HD) wallets.

2014 - Introduction of HD Wallets

    Version: Bitcoin 0.9.0
    Format: HD Wallet (BIP32).
    Description: Bitcoin Core introduced support for HD wallets, allowing users to generate a tree of keys from a single seed. This format improved privacy and key management, as users could create new addresses for each transaction without needing to manage multiple private keys manually.

2016 - Enhanced HD Wallet Features

    Version: Bitcoin 0.13.0
    Format: HD Wallet with BIP44 support.
    Description: This version added support for BIP44, which defined a standard for multi-account hierarchical deterministic wallets. Users could now manage multiple accounts within a single wallet, further enhancing organization and privacy.

2018 - HD Descriptor Wallets

    Version: Bitcoin 0.16.0
    Format: HD Descriptor Wallets (BIP39 and BIP32).
    Description: Bitcoin Core introduced descriptor wallets, which allow users to define how addresses are generated using descriptors. This format provides more flexibility and transparency in wallet management, enabling users to specify the derivation paths and types of addresses (e.g., P2PKH, P2SH, P2WPKH).

2020 - Continued Improvements

    Version: Bitcoin 0.21.0
    Format: Enhanced HD Descriptor Wallets.
    Description: Further refinements were made to the descriptor wallet format, improving usability and security. This included better integration with external tools and libraries, making it easier for developers to work with Bitcoin wallets.

Another very important piece of information I would like to know is: Has Bitcoin Core software ever automatically upgraded the wallet.dat files as you updated the versions, or if you started with a 2013 wallet for example, the file stays in non-HD format? Im asking because core wants to deprecated older wallet files in (I think) the next 30 version. As of now im using Knots and im interested to know what they will do there. I think updating should be prompted to the user and optional.