The VT formatter was treating cells without text as blank and emitting
them as plain spaces, losing any background color styling. This caused
TUIs like htop to lose their background colors when rehydrating terminal
state (e.g., after detach/reattach in zmx).
For styled formats (VT/HTML), cells with background colors or style_id
are now emitted with proper SGR sequences and a space character instead
of being accumulated as unstyled blanks.
Adds handling for bg_color_palette and bg_color_rgb content tags which
were previously unreachable.
Reference: https://ampcode.com/threads/T-019b7a35-c3f3-73fc-adfa-00bbe9dbda3c
The issue is in ghostty_src/src/terminal/formatter.zig#L1117-L1129:
- Cells without text are treated as "blank" (line 1117-1119) - this includes cells that only have background colors
- When blank cells are emitted, they're plain spaces (line 1129) - writer.splatByteAll(' ', blank_cells) outputs spaces without any SGR styling
- Background-only cells (bg_color_palette, bg_color_rgb) are marked unreachable (lines 1233-1235) because the code assumes hasText() already filtered them
This means when htop draws a row like:
`[green bg]CPU: 45%[red bg] [default]`
The trailing cells with red background but no text get accumulated as blanks and emitted as plain spaces - losing the background color.
Fixes#9426
Since we can't set the meta charset tag since we emit partial HTML, we
use codepoint entities like `{` for non-ASCII characters to
ensure proper rendering.
This adds HTML formatting capabilities to the formatter package. HTML is
emitted as inline styles. For palette indexes, direct RGB is emitted if
we have access to a palette; otherwise, we fall back to CSS variables.
This isn't exposed to end users yet, but will enable copy as html
features. This is available in libghostty.
Fixes#9395
**AI disclosure:** I used AI (Amp) to help me write tests, but the
implementation was done manually. I reviewed everything.
This replaces the logic of Screen.selectionString with calls to
ScreenFormatter.
This means that all our various selection-based features like copying to
clipboards now uses the new formatter. The formatter code is now
user-facing.
This forced us to pass all selectionString tests which revealed some
edge cases that were not handled correctly before in the formatter! The
formatter now handles:
- Plain text now emits `\n` instead of `\r\n`. VT emits `\r\n`
- Rectangular selections
- Various wide character edge cases
- Selection is now inclusive on the end, not exclusive
This adds the option `pin_map` or `point_map` (for pages) to formatter,
allowing callers to get a byte-by-byte mapping for where on the screen
each encoding maps to. This is used by search internals and hyperlinks.
I haven't hooked that all up yet. This diff was big enough I wanted this
as one.
Tests significantly cover the new feature.
Next up, we'll rip out `selectionString` and replace it with formatters!
This adds a new formatter that can be used with standard Zig `{f}`
formatting that emits any portion of the terminal screen as VT
sequences. In addition to simply styling, this can emit the entire
terminal/screen state such as cursor positions, active style, terminal
modes, etc.
To do this, I've extracted all formatting to a dedicated `formatter`
package within `terminal`. This handles all formatting types (currently
plaintext and VT formatting, but can imagine things like HTML in the
future). Presently, we have "formatting" split out across a variety of
places in Terminal, Screen, PageList, and Page. I didn't remove this
code yet but I intend to unify it all on formatter in the future.
This also doesn't expose this functionality in any user-facing way yet.
This PR just adds it to the ghostty-vt Zig module and unit tests it.
Ghostty app changes will come later.
**This also improves the readonly stream** to handle OSC color
operations for _setting_ but it doesn't emit any responses of course,
since its readonly.
