feat(web): replace xterm.js with ghostty-web by PixPMusic · Pull Request #3820 · pingdotgg/t3code

PixPMusic · 2026-07-09T05:29:46Z

Working on #1310.

Swaps the thread terminal drawer from @xterm/xterm to ghostty-web, the libghostty-vt based drop-in mentioned in the issue. The server terminal protocol is a raw byte stream, so the change is contained to the client renderer — no server terminal changes.

Renderer swap

ghostty-web is close to API-compatible with xterm.js, but a few behaviors differ and are adapted here:

WASM init: terminal creation waits on init(); a session buffer that arrives first is replayed once the terminal mounts.
Custom key handler semantics are inverted: ghostty-web treats a true return as "consumed, skip terminal input" — the opposite of xterm.js. Without this, all typing is swallowed.
Link providers: rows/ranges are converted between the app's 1-based link helpers and ghostty-web's 0-based coordinates. The built-in OSC8/URL providers are removed since their activate() calls window.open directly, bypassing the app's preview/editor flow.
Zero-length write crash: ghostty-web 0.4.0's alloc(0) returns an out-of-bounds pointer, so write("") throws a RangeError deep in WASM. Status-only session updates produced exactly that and took the app down; writes are now guarded. (Worth an upstream report.)
viewportY semantics are inverted (0 = bottom), so the at-bottom checks used for resize scroll restoration are adapted.
Scrollbar/selection: ghostty-web renders its own canvas scrollbar and selection; the xterm-specific scrollbar theme keys and CSS import are gone, and @xterm/* dependencies are removed.

Ghostty config passthrough

Since the terminal engine is now Ghostty's, the drawer can match the user's actual Ghostty setup: the server parses ~/.config/ghostty/config (font-family, font-size, theme — including light:/dark: variants, resolved from the user themes dir or the Ghostty.app bundle) into an optional ServerConfig.terminalStyle field. The drawer overlays those colors on the app-derived theme and prepends the configured fonts. Everything is best-effort: no Ghostty config means the previous defaults exactly.

Nerd Font families are appended to the font fallback stack so powerline/devicon glyphs resolve from locally installed patched fonts (Ghostty embeds its own symbols fallback; browser canvas only walks the CSS font list), and the terminal container is painted with the theme background so partial-cell fringes match the canvas during drawer resizing.

I like this approach, but I'll remove it if asked--I could also split it out into a separate PR.

Known limitations

Runtime theme switching only updates default fg/bg/cursor — cell colors are baked in WASM at write time (ghostty-web limitation).
Ghostty config changes are picked up on client reload, not watched live.

Note

Medium Risk
Large client renderer swap with WASM/CSP changes and new server file reads; terminal I/O protocol unchanged, but regressions in input, links, scrollback, or focus are plausible in a critical UI surface.

Overview
Replaces @xterm/xterm with ghostty-web in the thread terminal drawer. The renderer waits on WASM init and bundled Symbols Nerd Font Mono before mounting; session output that arrives early is replayed once the terminal exists.

Electron CSP adds wasm-unsafe-eval and data: in connect-src for ghostty-web’s WASM and embedded payload.

The drawer adapts ghostty-web vs xterm: inverted custom key-handler semantics, 0-based link row/range conversion, clearing built-in link providers so URLs go through preview/editor, guarding zero-length writes, inverted viewportY for scroll-at-bottom, and writePreservingScrollback so scrolled-back history stays anchored on writes.

Server best-effort reads local Ghostty config (ghosttyStyle.ts) and exposes optional ServerConfig.terminalStyle (fonts, size, light/dark colors). The client overlays that on the app theme and prepends configured font families. Link detection expands to more URI schemes and git+ transport URLs; non-http(s) links open externally.

Focus on style-driven remounts uses shouldFocusTerminalAfterSetup so split views and the composer don’t lose focus.

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Note

Replace xterm.js with ghostty-web in the web terminal

Swaps the terminal renderer from xterm.js to ghostty-web, initializing a WASM module before terminal creation in ThreadTerminalDrawer.tsx.
Adds server-side Ghostty config parsing in ghosttyStyle.ts to read fonts, theme colors, and palette entries from the user's local Ghostty config; the result is forwarded to the client via a new terminalStyle field in ServerConfig.
Bundles Symbols Nerd Font Mono as a WOFF2 fallback font for icon/glyph rendering in the terminal.
Routes http(s) links through the in-app preview while delegating other schemes (e.g. git+ssh://) to the OS; strips leading git+ transport prefixes before activation.
Adds wasm-unsafe-eval to script-src and data: to connect-src in the desktop Content Security Policy to support the WASM-based renderer.
Risk: ghostty-web snaps the viewport to the bottom on every write; a writePreservingScrollback wrapper restores the previous scroll position, but this is new behavior that may surface edge cases.

^{Macroscope summarized c405032.}

coderabbitai · 2026-07-09T05:30:00Z

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macroscopeapp · 2026-07-09T05:41:08Z

Approvability

Verdict: Needs human review

This PR replaces the terminal emulator library (xterm.js → ghostty-web) and adds new server-side Ghostty config parsing for user terminal theming. The scope includes CSP security policy changes, new contracts, and complex WebAssembly initialization — substantial new functionality warranting human review.

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Co-authored-by: codex <codex@users.noreply.github.com>

Swap the thread terminal drawer from @xterm/xterm to ghostty-web, the libghostty-vt based drop-in. The server terminal protocol is unchanged; the swap is contained to the client renderer: - Gate terminal creation on the ghostty-web WASM init and replay the session buffer that arrives before it resolves - Invert custom key handler returns (ghostty-web treats true as "consumed", the opposite of xterm.js) - Convert link provider rows/ranges between the 1-based terminal-links helpers and ghostty-web's 0-based coordinates, and drop the built-in providers whose activate() bypasses the app's preview flow - Guard zero-length writes: ghostty-web 0.4.0 alloc(0) returns an out-of-bounds pointer and crashes on status-only session updates - Adapt at-bottom checks to ghostty-web's inverted viewportY semantics Also style the terminal from the user's local Ghostty config when one exists: the server parses font-family/font-size/theme (resolving named themes from the user themes dir or the Ghostty.app bundle) into an optional ServerConfig.terminalStyle field, and the drawer applies it over the app-derived defaults. Nerd Font fallbacks cover powerline and devicon glyphs, and the mount is painted with the theme background so partial-cell fringes match the canvas.

The desktop protocol's Content-Security-Policy blocked the ghostty-web terminal from initializing: script-src had no 'wasm-unsafe-eval', so WebAssembly compilation was rejected, and connect-src had no data:, so the library's embedded WASM payload fetch failed. Add both sources.

- Retry WASM init on a later mount instead of caching a rejected promise until page reload - Blur non-active terminals after open(): ghostty-web focuses unconditionally, letting the last-mounted split steal focus - Seed the session snapshot with version 0 and a closed status at mount so an already-exited session still surfaces its exit and closes the viewport - Keep CSS generic font keywords (monospace, system-ui, ...) unquoted when building the terminal font stack - Resolve named Ghostty themes from the Linux system dirs (/usr/share/ghostty/themes, /usr/local/share/ghostty/themes) too

- Attach a rejection handler to the terminal WASM init so a load failure logs, shows a message in the viewport, and clears on retry instead of leaving a blank pane and an unhandled rejection - Treat an empty XDG_CONFIG_HOME as unset per the XDG spec instead of resolving the Ghostty config relative to the server cwd

- Bump a terminal epoch when the deferred WASM setup finishes so the session sync effect re-runs against the live terminal even when no session field changed during the load, completing the exited-at-mount handling - Read config.ghostty as an alternate config file name and merge the XDG and macOS Application Support configs in Ghostty's load order instead of stopping at the first existing file

- Preserve a scrolled-back viewport when session output arrives: ghostty-web snaps to the bottom on every write, so re-anchor the viewport by the number of lines the write pushed into scrollback - Read both config and config.ghostty when they coexist in a Ghostty config directory instead of letting the first shadow the second - Linkify mailto/ftp/ssh/git/tel/magnet/gemini/gopher/news URLs in the terminal and open non-http schemes with the OS handler, keeping the in-app preview flow for http(s)

- Once scrollback is full its length stops growing while writes keep evicting lines, so the preserved viewport drifted toward the tail; fall back to counting written newlines at the cap - Parse config.ghostty before config so config wins conflicts, matching Ghostty's own load order

Co-authored-by: codex <codex@users.noreply.github.com>

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juliusmarminge · 2026-07-31T11:18:18Z

#4860. ghosttty-web felt kinda unmaintained and we dont "gained" anything from the added xterm compatibility.

we'll keep the bundled fonts lean and aim to add configurable fonts in a follow up

github-actions Bot added size:XL 500-999 changed lines (additions + deletions). vouch:unvouched PR author is not yet trusted in the VOUCHED list. labels Jul 9, 2026