Reproduction steps
Open Zed preview v1.12.0
Open a terminal pane
Run hx some_file (or any TUI that uses alternate screen: vim, htop, etc.)
Observe the top of the terminal — a ~1-line blank gap may or may not appear
Move cursor or press : → gap state may flip
Repeat opening and closing the TUI — sometimes the gap is there, sometimes not
Current vs. Expected behavior
This is a regression introduced in preview v1.12.0 . The bug is not the top gap itself (stable v1.11.3 always has it and that's consistent), but that in preview the gap appears and disappears randomly between sessions and redraw events, causing a flickering effect. It feels like a race condition in the terminal pane's dimension reporting during alternate screen transitions — LINES/COLUMNS sometimes reflect the correct renderable area and sometimes not, so the TUI computes a different layout each time. Not reproducible in Ghostty, iTerm2, or Kitty.
Expected: consistent behavior. Either always show the gap like stable, or never show it. Not randomly flip.
Zed version and system specs
Zed preview v1.12.0 , macOS 26.2 (Apple Silicon), helix 25.07.1
Attach Zed log file
Zed.log
Relevant Zed settings
settings.json
Relevant Keymap
keymap.json
(for AI issues) Model provider details
No response
If you are using WSL on Windows, what flavor of Linux are you using?
None
Reproduction steps
Open Zed preview v1.12.0
Open a terminal pane
Run hx some_file (or any TUI that uses alternate screen: vim, htop, etc.)
Observe the top of the terminal — a ~1-line blank gap may or may not appear
Move cursor or press : → gap state may flip
Repeat opening and closing the TUI — sometimes the gap is there, sometimes not
Current vs. Expected behavior
This is a regression introduced in preview v1.12.0 . The bug is not the top gap itself (stable v1.11.3 always has it and that's consistent), but that in preview the gap appears and disappears randomly between sessions and redraw events, causing a flickering effect. It feels like a race condition in the terminal pane's dimension reporting during alternate screen transitions — LINES/COLUMNS sometimes reflect the correct renderable area and sometimes not, so the TUI computes a different layout each time. Not reproducible in Ghostty, iTerm2, or Kitty.
Expected: consistent behavior. Either always show the gap like stable, or never show it. Not randomly flip.
Zed version and system specs
Zed preview v1.12.0 , macOS 26.2 (Apple Silicon), helix 25.07.1
Attach Zed log file
Zed.log
Relevant Zed settings
settings.json
Relevant Keymap
keymap.json
(for AI issues) Model provider details
No response
If you are using WSL on Windows, what flavor of Linux are you using?
None