[IDEA] Add Watch mode

[CheezuzCrust]

( related to #1125 )

I propose we add a WATCH mode in addition to normal, select and insert.

In WATCH mode:

• navigation in buffer is allowed like with normal mode
• yanking is allowed
• any editing is disallowed (pasting, insert, deletion etc)
• the buffer reloads automatically when it is modified externally

This way, when a buffer wants to be watched, the user can enter watch mode (for example for monitoring artifacts, logs, and anything else you would want to read in your IDE).

The user can, at any point, freeze the buffer by returning to normal mode and edit it. Of course, it is clear to the user that if they write the edits they are overwriting anything that could have happened since the freeze externally, but this is already the normal behavior of modal editors so it does not break paradigm.

Looking forward for your feedback and hope that you find this idea good too !

[jerabaul29]

(as a side note, related to #2653 )

I think this would be very useful - if setting this up as a "minor" mode, a bit like the Z sticky view mode, this would definitely be something I would use.

This would work especially well together with tools such as Claude Code https://www.anthropic.com/claude-code or Codex https://github.com/openai/codex , where the workflow becomes a lot: i) talk to the AI in terminal and let it do stuff, ii) look at the code that the AI has edited to check stuff, iii) iterate. In this case, it would be very nice to leverage the power of helix for navigating codebase / using LSPs, with on-the-fly reloading.

For such a use case, it may be useful to be able to enable "sticky watchchange mode" either on a buffer / view, or on the whole current helix session.