Starting Claude with CLAUDE_CODE_NO_FLICKER=1 results in rendering defect

[aaronjensen]

At least for me, when I open a new ghostel in zsh, then start claude with CLAUDE_CODE_NO_FLICKER=1 claude, I get the line where I should be able to type visually collapsed. If I resize the window, it renders fine. Interestingly enough, if I start claude directly with the claude-code package, it renders fine.

[emil-e]

Which verison is this?

[dakra]

And I assume this doesn't happen with ghostty proper?

Asking because I can't seem to reproduce it on my system and claude-code is well known for being very buggy,
and the bugs change day to day.

Another note is that with ghostel, the default claude-code renderer is completely useable.
alt-screen apps (what /tui fullscreen is) have different drawbacks but you kinda have to use them in vterm for example.

[emil-e]

I also cannot reproduce this. I will note that I'm working on an improvement to rendering correctness and performance, so it's possible that it also solves this just virtue of being more correct.

[aaronjensen]

@emil-e @dakra could you try with tab-bar-mode enabled?

And correct, this does not happen with ghostty.

Are you saying that vterm is better for alt-screen apps that ghostel?

[dakra]

@emil-e @dakra could you try with tab-bar-mode enabled?

works for me with and without tab-bar-mode. Does it work for you when you have tab-bar-mode disabled?

I added a few more infos to ghostel-debug-info.
Could update ghostel and then reproduce the broken state and before resizing call M-x ghostel-debug-info and
paste that output here.
Maybe claude --version would also be good to know so we're comparing the same claude.

Are you saying that vterm is better for alt-screen apps that ghostel?

Oh no, not at all. I was just saying that normal claude-code in vterm is so bad that you have to use some hacks or the /tui fullscreen version to have it halfway usable. ghostel has all features vterm has and I couldn't think of anything where vterm would be preferred.

[aaronjensen]

It looks a little different now and it does reproduce with tab bar off. It didn't seem to at first, but it does now.

❯ claude --version                                    
2.1.119 (Claude Code)

ghostel-debug-info

=== ghostel-debug-info ===

--- System ---
Emacs version:       31.0.50
System type:         darwin
System config:       aarch64-apple-darwin25.4.0
Window system:       ns
Display pixel size:  1663x1080
Char size:           13x27 px
Native comp:         yes

--- Ghostel ---
Package version:     0.18.1
Min module version:  0.18.1
Library path:        /Users/myuser/.emacs.d/elpaca/builds/ghostel/ghostel.elc
Resource root:       /Users/myuser/.emacs.d/elpaca/builds/ghostel/
Module loaded:       yes
Module version:      0.18.1
Module file:         /Users/myuser/.emacs.d/elpaca/builds/ghostel/ghostel-module.dylib
Module size:         1381000 bytes
Module modified:     2026-04-27 00:46:51

--- Frame ---
Frame size:          125x37 (cols x rows)
Frame pixel size:    1663x1044
Tab-bar lines:       1 (tab-bar-mode on)
Tool-bar lines:      0
Menu-bar lines:      0
Internal border:     0 px
Background mode:     light
Enabled themes:      (modern-tab-bar nano-light)

--- Buffer ---
Buffer name:         *ghostel: ✳ Claude Code*
Major mode:          ghostel-mode
Default directory:   /Users/myuser/.emacs.d/
Remote:              no
Active minor modes:  +popup-buffer-mode +popup-mode anzu-mode auto-composition-mode auto-compression-mode auto-encryption-mode better-jumper-local-mode better-jumper-mode consult-notes-denote-mode corfu-history-mode delete-selection-mode denote-menu-bar-mode denote-rename-buffer-mode eldoc-mode electric-indent-mode elpaca-use-package-mode eros-mode eval-sexp-fu-flash-mode evil-ghostel-mode evil-local-mode evil-mc-mode evil-mode evil-surround-mode file-name-shadow-mode flycheck-mode gcmh-mode global-anzu-mode global-auto-revert-mode global-display-line-numbers-mode global-eldoc-mode global-evil-mc-mode global-evil-surround-mode global-flycheck-mode global-font-lock-mode global-git-commit-mode global-leader-key-leader-override-mode hide-mode-line-mode leader-key-leader-override-mode line-number-mode magit-prime-mode mini-frame-mode minibuffer-nonselected-mode minibuffer-regexp-mode modern-tab-bar-mode monet-mode mouse-wheel-mode ns-auto-titlebar-mode override-global-mode pdf-occur-global-minor-mode recentf-mode repeat-mode save-place-mode savehist-mode server-mode show-paren-mode speed-of-thought-mode tab-bar-history-mode tab-bar-mode tab-line-mode tabspaces-mode transient-mark-mode treemacs-filewatch-mode treemacs-follow-mode treemacs-fringe-indicator-mode treemacs-git-mode undo-fu-session-global-mode undo-fu-session-mode vertico-mode vertico-mouse-mode which-key-mode which-key-posframe-mode windmove-mode window-divider-mode ws-butler-global-mode ws-butler-mode yas-global-mode yas-minor-mode

--- Process ---
PID:                 39454
Status:              run
Command:             /bin/sh -c stty erase '^?' iutf8 -ixon rows 34 columns 87 2>/dev/null; printf '\033[H\033[2J'; exec /opt/homebrew/bin/zsh
TTY:                 /dev/ttys002
Configured shell:    /opt/homebrew/bin/zsh
Detected shell type: zsh
Shell integration:   t

--- Window ---
Window body:         87x34 (cols x rows)
Max chars per line:  87
Window start:        1
Window end:          393
Fringes:             left=16px right=16px outside-margins=nil
Margins:             left=0 right=0
Line numbers:        off
Buffer windows:      1

--- Terminal ---
Term size:           87x32 (cols x rows)
Buffer size:         392 chars, 32 lines
Point:               304
DEC 2026 (sync):     off
Alt screen:          yes
Force next redraw:   nil
Pending output:      0 chunks
Redraw timer:        none
Copy mode:           off

--- Non-default ghostel settings ---
ghostel-keymap-exceptions: ("C-c" "C-x" "C-u" "C-h" "C-g" "M-x" "M-o" "M-:" "C-\\" "C-o")
  default: ("C-c" "C-x" "C-u" "C-h" "M-x" "M-o" "M-:" "C-\\")
ghostel-max-scrollback: 100000
  default: 5242880

[emil-e]

@aaronjensen Did you say that it resolves on resizing? I have also seen this in my personal setup that starts Ghostel in a similar way - the initial term size is wrong.

@dakra I wonder if there's something with ghostel-exec that doesn't give the process a correct initial terminal size?

[dakra]

@aaronjensen I just pushed a potential fix on main can you try again.

@emil-e was right that we had a sizing problem between ghostel--start-process and ghostel--init-buffer.
They were using different sizing info, this is fixed with 23cdc7c

But the problem could still persist if the popup display get's a size change between --init-buffer and us showing the buffer,
so I just added a one-shot timer that triggers after initialization that checks if the Emacs windows was resized in between us creating the libghostty view and then actual displaying (like some popup mode or display rule).
This fix is in 387c275

Hopefully now everything works 🤞

[emil-e]

@dakra Shouldn't we be reacting to some callback instead of using a short timer? I don't have enough context of the problem.

[aaronjensen]

That seems to have fixed it for me. Thank you!

[dakra]

@dakra Shouldn't we be reacting to some callback instead of using a short timer? I don't have enough context of the problem.

Ha, I already wanted to answer that there is no hook/callback that fires for our problem.
But that was for the first commit only, thinking about the second commit with the timer, I think I was too fast
and agree that it's better to not use the timer.

I should have done all in a feature branch and PR but since this is already on master I pushed the new non-timer version directly there as well.

[dakra]

That seems to have fixed it for me. Thank you!

@aaronjensen nice. I added one more commit (see comment above), can you try with that change as well please?

[emil-e]

I should have done all in a feature branch and PR but since this is already on master I pushed the new non-timer version directly there as well.

Fixed is better than not fixed!