Ask HN: Any AI model chat interfaces for power users?

I feel chronically disappointed in the experience of using the chat interface for ChatGPT, Gemini, and other SOTA models. They all bring with them their own underwhelming UX.

For example, some features I would want:

* "fork" a convo into a different thread (like Slack threads) so it doesn't clutter the context.

* "merge" (reference) existing threads into a convo.

* Remove parts of a convo because they mess up the context and are influencing the model too much.

* Tag convos or categorize them under multiple directories. Or create shortcuts, like they're documents. (i.e. not just one directory)

* A search that isn't a basic text search from 2022 but an actual LLM searching over past convos.

* Use "incognito mode" and then if I like the convo, move it out of incognito mode (most of my prompts start off in incognito mode).

There's so many more ways I can see the chat experience being better. It seems like it should be its own product (ideally open source and lets me choose my own models, maybe multiple at the same time for a given prompt). CLIs and coding agents are kind of like this, but don't really have all these features, and are more code-oriented than I want. Are there any "power user" chat interfaces out there?