Adds tools/difftest: a Zig driver built against a copy of Ghostty
1.3.1's own src/terminal (Zig 0.15.2, set up under target/ by
tools/difftest/setup.sh) and a Rust twin on ghostty-terminal, both
printing a canonical dump of every scrollback/active row (cells,
graphemes, styles, hyperlinks, row flags), cursor, modes, regions,
tabstops and colors. A seeded generator produces escape-heavy streams
(UTF-8/wide/combining/emoji, C0, CSI with edge params, SGR, modes, ESC,
OSC, DCS, margins, insert/delete); `just difftest` runs it with Zig
assertions on (ReleaseSafe vs debug Rust) and off (ReleaseFast vs
production Rust), with minimizers and a triage script.
Divergences found and fixed in Rust (each with a regression test):
- ill-formed UTF-8 decoding follows the SIMD path a default Ghostty
build uses (not Zig's scalar fallback)
- PageList::erase_rows keeps Zig's row-flag behavior on regrow
- grapheme move on wrap with left/right margins uses the original cell
Upstream bugs found and deliberately NOT replicated (per the project
rule): a stale cell pointer after page growth in Terminal.zig:482/539
that drops a grapheme, plus several Zig assertion failures/segfaults;
documented with minimized repros in docs/rewrite/notes/difftest-DF.md.
Final run: 390k cases across many geometries, 0 divergences (Zig-abort
cases, ~0.1-0.5%, are not compared).
Test Plan:
- just difftest 20000 "1 2 3"
- cargo test -p ghostty-terminal (regression tests)
Rust's str::parse accepts and rejects different inputs than Zig's
std.fmt.parseInt/parseFloat (underscores, base prefixes, signs). The
config layer already used the Zig ports; now the protocol parsers do
too (call site -> Zig reference -> status in final-Z12.md):
- zig_fmt moves into the leaf crate ghostty-zigfmt (ghostty-vt cannot
depend on ghostty-os); ghostty-os re-exports it unchanged.
- ghostty-vt: kitty graphics keys, kitty text sizing, OSC 4/5/10-19
color indices, hex color components and intensities, OSC 9 sleep and
progress, OSC 133 exit codes, OSC 3008 fields, kitty color palette.
- ghostty-terminal: tmux layout, format variables and pane tabs.
- ghostty-os: URI ports and %XX decoding; ghostty-bench CLI arguments.
Expected values were cross-checked against the real Zig toolchain.
Test Plan:
- cargo test --workspace --no-fail-fast
- just check-macos (both), just check-windows, just check-wasm
Ports apprt/embedded.zig, main_c.zig and config/CApi.zig + c_get.zig as
crates/ghostty-lib (cdylib/staticlib/rlib `libghostty`), exporting every
function of the unchanged include/ghostty.h - the ABI Ghostty's Swift
macOS/iOS app links against. The embedded runtime implements the
runtime traits over the host's C callbacks, so the real core drives it.
- ghostty-core selects the renderer per target: Metal on Apple (surface
NSView/UIView via RtSurface::platform_view), OpenGL elsewhere.
- ghostty_config_get follows Zig's c_get rules via a CValue type (143
supported keys, checked against the Zig field types).
- The inspector C API is complete; its Metal backend replaces ImGui's
Metal renderer and has not run.
Verification: generated C ABI probe (sizeof/alignof/offsetof of every
struct/union, 755 enum values, every function linked, nm exports, headers
byte-identical to upstream); a C host on Linux covering init, CLI
actions, config, app, keys, focus and color scheme; an opt-in
test-platform feature creating real surfaces on Linux with headless EGL
and a pty (13 tests). Apple targets are clippy-clean but not run; the
Swift app has not been built against it.
Test Plan:
- cargo test -p ghostty-lib (and --features test-platform)
- cargo clippy --target aarch64-apple-darwin -p ghostty-lib (cross env
in docs/rewrite/notes/macos-M1.md)
Ports the macOS-specific Zig code behind cfg(target_os = "macos"):
- renderer: a GraphicsApi trait with generic::Renderer<G>; Metal backend
(all renderer/metal/* files, shaders.metal verbatim, runtime library
compile, IOSurface layer, CVDisplayLink), shadertoy -> MSL via naga;
OpenGL remains the backend elsewhere.
- font: CoreText face, shaper and discovery with build.rs backend
selection (coretext default; coretext-freetype / coretext-harfbuzz /
coretext-noshape features), no fontconfig/freetype/harfbuzz on Apple.
- input: KeymapDarwin via UCKeyTranslate, option-as-alt, mac keycodes.
- os: macos, mach, cf_release_thread, NSProcessInfo args and macOS
branches; config: macOS defaults, keybinds, Application Support paths.
- termio/core: login(1) wrapping, openpty/execvpe, Darwin child exit
handling, os_log logging.
Compile-checked for aarch64/x86_64-apple-darwin (clippy -D warnings
clean) using the cross setup in docs/rewrite/notes/macos-M1.md; cannot
run here. The embedded runtime/C API (embedded.zig) is the next step.
Also includes the cross-platform integration edits shared by the crash,
verification, Windows and macOS work (Cargo target-gating, thread
crash-context hooks, apprt-gtk surface/IME refactor, termio/os cfg
gates), a cfg fix so ghostty-config builds on wasm32, and an allow for
the intentional recursion in the crash overflow test.
Test Plan:
- cargo test --workspace (3224 passed)
- cargo clippy --workspace --all-targets -- -D warnings
- cargo check --target aarch64-apple-darwin -p ghostty-renderer (with
the documented cross env)
Addresses the partial ports listed in
docs/rewrite/notes/review-completeness-codex.md (details in
docs/rewrite/notes/gaps-X2.md):
- Flatpak: the exit watcher no longer consumes the host command; a
shared FlatpakSignalHandle lets closing a surface still SIGHUP the
host process group.
- Child environment is byte-preserving end to end (ghostty_os::EnvMap
of OsStrings) and Snap paths are filtered like filterSnapPaths.
- argv handling no longer panics on non-UTF-8 arguments.
- URI percent-decoding keeps raw bytes; OSC 7 pwd is passed through
without lossy conversion.
- Keybinding comparison/hashing uses full Unicode case folding from a
table generated from CaseFolding.txt (Unicode 17.0.0).
- Link regexes set Oniguruma's whole-search retry limit through the new
minimal ghostty-onig crate (one SAFETY-commented FFI call).
- OSC 9 NUL-capacity check ordering matches Zig.
- Wayland registry binds/clears globals advertised after startup.
- Custom shaders may pass sampler2D to helper functions (naga adapter).
- +list-themes preview renders OSC 8 links, styled underlines and
follows color-scheme reports.
Also includes the inspector's integration edits in shared files
(renderer state hook, termio VT recording, core/apprt-gtk wiring), X1's
config/input/cli additions for completion generation, and a fix for a
race in the termio backpressure test (it wrote before `stty raw`
applied, so the cooked line discipline dropped bytes past MAX_CANON).
Test Plan:
- cargo test --workspace
- cargo clippy --workspace --all-targets -- -D warnings
Adds crates/ghostty-bench, a port of ZIG/src/benchmark and src/synthetic:
the ghostty-bench binary (terminal-stream, terminal-parser,
codepoint-width, grapheme-break, is-symbol, osc-parser, screen-clone
with Zig's CLI) and ghostty-synthetic data generators (+ascii, +utf8,
+osc, plus a Rust-only +sgr mode).
Measured against Ghostty's own ghostty-bench built with Zig 0.15.2
(ReleaseFast) vs --profile production, the hot paths were optimized
without behaviour changes:
- Terminal::print single-lookup fast path for width-1 chars mid-line
- page grapheme allocator: bitmap first-fit instead of a linear scan
(was 38% of utf8 stream time; randomized equivalence test added)
- plain cells skip per-cell work in clear_cells and row cloning
- ASCII fast path + strict hand-written UTF-8 decoder (exhaustive
equivalence test against std)
- parser/OSC parser split into inlined fast and state-change paths
- RenderState allocates grapheme vectors only for grapheme rows
- Page::assert_integrity no-op stub so the production profile builds
terminal-stream is now at parity (ascii 1.08x, utf8 0.97x, SGR 1.04x of
Zig's time). Still slower: screen-clone (~2.6x, zero-filling fresh
cell Vecs vs Zig's lazily-zeroed mmap), osc-parser (1.9x), and the raw
parser on SGR data (1.5x). Full table in docs/rewrite/notes/perf-P1.md.
Test Plan:
- cargo test --workspace (no failures)
- cargo run --profile production -p ghostty-bench -- +terminal-stream
--data=<file> and compare with Zig's ghostty-bench
This is the integration step that turns the ported crates into a working
terminal: `cargo run` now opens a GTK window running the user's shell.
ghostty-core ports App.zig, Surface.zig (split into keyboard, mouse,
binding, clipboard and config submodules), surface_mouse.zig and
global.zig, and implements the runtime traits. perform_binding_action
handles every binding action.
Cross-crate integration:
- The core<->runtime traits (CoreApp, CoreSurface, RtApp, RtSurface,
Waker) move from apprt-gtk into ghostty_apprt::runtime_api so the core
stays runtime-agnostic; Scrollbar/RendererHealth stand-ins are replaced
by the real terminal/renderer types.
- termio now uses ghostty_renderer::state::{State, SharedState}; the
renderer calls kitty_update; image-storage-limit is applied at init
and on config change.
- The search thread locks the terminal through a TerminalLock trait so
it can share the render state mutex; termio's Wakeup gained a hook to
wake the renderer thread.
- apprt-gtk: GL proc addresses are resolved through libepoxy's
epoxy_glFoo pointer variables (plain glFoo symbols resolved to null),
default DPI fixed to 96, libadwaita version read without GTK init so
--version works headless.
The root binary dispatches +actions to ghostty-cli (list-fonts,
show-face and new-window are now wired) and otherwise runs the GTK app
with the real core.
Verified at runtime on Wayland and X11: shell prompt and colored output
render, child exit closes the window cleanly. Not yet verified: keyboard
and mouse input, clipboard, IME, tabs and splits (no key injection was
possible in this environment). GHOSTTY_DEBUG_SCREENSHOT=<png> dumps the
renderer's last frame for headless checks.
Test Plan:
- cargo test --workspace (2890 passed)
- cargo clippy --workspace --all-targets -- -D warnings
- GSETTINGS_BACKEND=memory GHOSTTY_RESOURCES_DIR=/usr/share/ghostty \
cargo run
Ports ZIG/src/apprt/gtk into ghostty-apprt-gtk: every GObject class
(application, window, tab, split tree, surface + scrolled window,
child-exited banner, search/key-state/resize overlays, command palette,
global shortcuts, all dialogs, config wrapper) as glib subclasses with
the same GType names, properties, signals and template children; GDK
key translation; X11 and Wayland window-protocol helpers (blur, CSD,
quick terminal via gtk4-layer-shell); single-instance D-Bus IPC;
gsettings; cgroup scope creation.
build.rs compiles Ghostty's blueprints with blueprint-compiler and
bundles UI, CSS and icons into a gresource, as Ghostty's build does.
The core is not ported yet, so the crate defines the boundary it needs
in src/core.rs (CoreApp, CoreSurface, RtApp, RtSurface, Waker); the
spec is in docs/rewrite/notes/ghostty-apprt-gtk.md. ghostty-core will
implement these traits (the crate no longer depends on core to avoid a
cycle). examples/demo.rs runs the app with a dummy core that clears the
GLArea; it launches on Wayland without GTK criticals.
Stubs/open items: toggle_visibility, float_window, secure_input and
close_all_windows return false; inspector is a no-op; X11/Wayland
protocol code is untested against real compositors; gtk4-rs doesn't
expose the GLArea framebuffer id, so the renderer must query it.
Also registers ghostty-apprt and ghostty-cli in workspace.dependencies.
Test Plan:
- cargo test -p ghostty-apprt-gtk (36 tests)
- DEMO_QUIT_AFTER_MS=3000 cargo run -p ghostty-apprt-gtk --example demo
Start of the full Rust rewrite of Ghostty 1.3.1 (reference source in
../ghostty). Sets up a workspace whose crates mirror Ghostty's Zig modules
(vt, unicode, datastruct, os, input, config, terminal, font, renderer,
termio, core, apprt-gtk) so porting work can proceed in parallel per crate.
Also adds:
- docs/rewrite/{ARCHITECTURE,PLAN,STATUS,AGENT_GUIDE}.md: crate map, core
design decisions (safe Rust, slab-based PageList, logical capacity
accounting), phased plan, progress tracker, and porting rules.
- Workspace clippy config relaxing pedantic lints that are pure noise for
low-level terminal code (casts, long functions).
- Shared vt types needed by several work packages up front: kitty
keyboard flags (kitty/key.rs) and the CSI separator bitset (SepList).
Test Plan:
- cargo test -p ghostty-vt (3 tests pass)
- cargo clippy -p ghostty-vt --all-targets -- -D warnings
ddidderr