console: allow using arrow left/right, home/end keys and history mode

[ngxson]

Fix #17828

Fix #17829

To test it, run llama-cli, write some text (without sending it) and use left/right arrows to edit them

Edit: Home/end keys and history support is allso added thanks to @ServeurpersoCom

Screen.Recording.2025-12-08.at.11.29.15.mov

Disclosure AI usage: next_utf8_char_pos is written by AI because I have no experience working with windows API. The rest is mostly written by me (minus some small auto-completion)

[ngxson]

Thanks @ServeurpersoCom for testing & adding some improvements on windows!

CC @ggerganov , this is a small feature but quite important for the UX - hope to get it merged soon!

[ngxson]

FYI, I merged some more changes from @ServeurpersoCom to include history too (using up/down keys)

[ngxson]

pinging @ggerganov in case you missed the PR. I added a video to demo how it works with the current llama-cli

in long term, I think we can remove linenoise and use the common/console.cpp system, as we probably won't use all functionalities from linenoise anyway

[ggerganov]

Tested on Mac, works as expected.

• Would be nice to add support for "Delete" if possible
• During chat, when I type a new message and hit "Up + Down" it forgets what I wrote - could be improved.

[ServeurpersoCom]

I'll add Delete/VK_DELETE support first, and test a temporary buffer for a modern bash-like history!

[ngxson]

@ServeurpersoCom do you want to add both Delete and Ctrl+Arrow support into this PR? Lmk which commit should I cherry-pick, thanks!

[ServeurpersoCom]

Bash behavior :
During navigation, you can edit as many old lines as you want, all edits persist.
When you hit Enter on any line (new or edited old one), it gets appended to permanent history -> the cool part: if you edited an old command, the original stays untouched in its position, and your edited version is added at the end.

[ServeurpersoCom]

@ServeurpersoCom do you want to add both Delete and Ctrl+Arrow support into this PR? Lmk which commit should I cherry-pick, thanks!

I put our work back in this branch (rebased)
master...ServeurpersoCom:llama.cpp:console/terminal-improvement

[ServeurpersoCom]

Done
https://github.com/user-attachments/assets/005e271e-e973-4e80-a706-e65ffd1612e7

---

console: implement bash-style history editing

- Edit any history line during UP/DOWN navigation, edits persist
- Pressing Enter appends edited version as new history entry
- Original line stay untouched in their positions

---

console: add Delete key support

- Windows: VK_DELETE detection
- Linux: ESC[3~ sequence parsing
- Forward character deletion with UTF-8 support

[ngxson]

just tested the history function on windows and mac, works fine!

[ngxson]

@ggerganov could you test again to see if the 2 problems in your last comment are all resolved? Thanks!

[ggerganov]

Yes, they are fixed.

Btw, the color of the first message is white and the next messages are green, is this expected?

This is with:

llama-cli -m ../models/gpt-oss-20b/ggml-model-mxfp4.gguf -c 0

[ggerganov]

Looks like this behaviour changed in #17827, so not related to this PR.

[ngxson]

Btw, the color of the first message is white and the next messages are green, is this expected?

Yes I discovered that in #17824 too, the problem is that the console.cpp flush the stdout immediately (including setting colors), while log.cpp queue the log message.

My quick fix on the other PR is to directly use printf in the CLI, but not quite sure if there is another solution

[bandoti]

There was a race condition on the colors I fixed when adding the reasoning to llama-cli. The problem is the tight coupling to the log routine. Please see #16603 changes to console.h/cpp