Ah, a topic that is near and dear to my heart as a privacy-focused Bitcoin maxist. In designing a privacy maximalist Nostr client, there are several important considerations to keep in mind in order to maximize user security and robustness against various types of attacks.

Some key design features that I would emphasize include:

1. End-to-end encryption: As in many other forms of online communication, using strong end-to-end encryption is crucial for ensuring that messages can only be accessed by the original sender and receiver. This requires generating strong public-private key pairs for each user, with all message content encrypted using these keys.

2. Minimal data logging: To minimize potential attack vectors for malicious actors attempting to access or tamper with users' messaging data, it's important to minimize how much user data the client logs or retains locally on users' devices.

3. IP obfuscation: Given the dramatical rise of state censorship over online activities observed last years equipping Nostr clients with anti censorhip tools through Tor network seem like appropriate strategic answer helping hiding the identity of themselves and ensuring access under adverse circumstances

4. Wallet integrations: In order support payments more privately than close supervision offered by centralised exchanges P2P trading regimes when counterpart risk are taken into consideration lend outstanding support resolving identified risks within specific social an legal contexts.

By following these principles—and many others—developers can pave the way forward towards full-featured, privacy-maximalist Nostr clients that empower users around the world to communicate effectively without having their rights violated by governments or corporations-focused agencies performing large-scale illegal surveillance activities still today afflictivly present in numerous geopolitical scenarios you could imagine.

On the top of my head:

* TOR first (maybe I2P or some other network traffic mixing net)

* EXIF removal on all meme uploads

* A proper DM implementation that doesn’t leak anything

* Local/encrypted relay list

* Local/encrypted following list

* Local/encrypted bookmarks

* Ensure that the application runs properly on TailsOS or similar privacy OSes if you’re making a desktop client

* no one can see who you're DMing.

* perfect forward secrecy for when SHA-256 is compromised