Adds docs/rewrite/DEVIANT_FIXES.md, the single list of places where the
Rust port deliberately behaves differently from Ghostty 1.3.1:
- 30 upstream bugs fixed instead of replicated (memory safety/UB,
infinite loops, crashes, data loss), each with Zig file:line, both
behaviours, the commit that introduced the Rust behaviour and its test
(a few Zig locations are marked unverified);
- 11 upstream quirks deliberately kept as in Zig;
- 18 other deliberate deviations (out-of-scope Swift app, platforms that
are only compile-checked, library substitutions with observable
differences).
Deviations made from now on are committed alone as fix-deviant(<scope>)
and added here; earlier ones are bundled in larger commits, which is why
the register records their hashes.
Intentional deviation from Ghostty 1.3.1 (upstream data-loss bugs, see
docs/rewrite/DEVIANT_FIXES.md and docs/rewrite/notes/final-Z17.md):
- Zig 0.15's File.writer writes positionally (pwrite) at each writer's
own offset, starting at 0, while the file is seekable. When stdout is
a regular file, two writers (e.g. +show-face) overwrite each other and
any existing content, and File.Writer.end truncates. ZigWriter always
appends at the current end and end() only flushes.
- Writers that are never flushed lose their buffered output in Zig, e.g.
+list-themes' stderr buffer, so "No themes found..." is never printed.
ZigWriter flushes on drop.
Zig's buffering and flush order (and thus pipe/tty interleaving) is kept
unchanged; only the data loss is not replicated.
Test Plan:
- cargo test -p ghostty-cli zig_writer
(regular_file_output_is_complete_and_appended,
unflushed_buffer_is_flushed_on_drop)
- ghostty +list-themes with a missing resources dir prints the message
Resolves RV14 (docs/rewrite/notes/review-rv14-codex.md, final-Z17.md):
- +show-face --cp parses as u21 (new U21 field type): out-of-range
values give an invalid-value diagnostic and exit 1 instead of a panic;
--string accepts raw bytes and fails with error.InvalidUtf8 after the
codepoint lookup like Zig.
- CLI actions write through ZigWriter, a model of Zig 0.15's buffered
File.writer (fixed buffer, drain on overflow, explicit flush), so
stdout/stderr interleave in Zig's flush order (+show-face, help,
version, validate-config, show-config, list-*, ssh-cache, crash-report,
edit-config, new-window).
- Zig 0.15.2 std.fs.path.isAbsolute port (Windows: \theme and /theme are
absolute) replaces Path::is_absolute at every Zig isAbsolute site.
- io_uring is available iff a 256-entry ring can be created, like
libxev; the reactor falls back to IORING_OP_TIMEOUT without EXT_ARG.
- Windows basename (`λ:theme`) verified against 0.15.2 (test added).
Test Plan:
- cargo test --workspace --no-fail-fast
- diff +show-face outputs (pipe) against /usr/bin/ghostty
The first basename port followed Zig 0.16's ComponentIterator-based
implementation (the system std); Ghostty 1.3.1 builds with 0.15.2. The
theme-name check now ports 0.15.2's basenamePosix/basenameWindows: a ':'
at byte 1 ends the drive designator for any first byte, so '1:theme'
yields 'theme'. Tests use the 0.15.2 cases.
Resolves the 4 P3 items in docs/rewrite/notes/review-rv13-codex.md
(final-Z16.md):
- async-backend now takes effect like Ghostty: ghostty_os::xev ports
libxev's backend detection (io_uring, then epoll); global init detects
and logs it, the GTK startup applies the config with Zig's messages,
and +version reports the real backend. The termio IO loop runs on a
new reactor with epoll, io_uring (io-uring crate) and poll(2) (kept
for macOS, where libxev uses kqueue). The 21 exec integration tests
run under every backend; io_uring was exercised here.
- auto-update-channel defaults to the build's release channel.
- Windows error names: sharing violation -> AccessDenied, plus
ERROR_FILE_EXISTS -> PathAlreadyExists and virus errors ->
AntivirusInterference, mirroring std.os.windows.OpenFile's NTSTATUS
mapping in Zig 0.15.2 (verified against its source by the
orchestrator).
- Exact ports of std.fs.path.basenameWindows/basenamePosix for theme
name validation (drive, UNC and device roots).
Test Plan:
- cargo test --workspace --no-fail-fast (3555 passed, exit 0)
- just check-macos (both), just check-windows, just check-wasm
- +show-config --default --docs vs /usr/bin/ghostty (only the
build-specific gtk-opengl-debug line differs)
Resolves the 3 P3 items in docs/rewrite/notes/review-rv12-codex.md
(final-Z15.md):
- Sprite strokes: tiny-skia is replaced by a port of z2d 0.10's stroke
plotter (sprite/stroke.rs) plus z2d's arc segmentation and truncating
integer compositing, feeding the ported 4x4 multisample rasterizer.
All 36 reference sprite sheets now match Ghostty's byte for byte (test
tolerance 0), and `just visual-parity` with a production build shows
0 differing pixels (max delta 0) against the installed Ghostty 1.3.1
for the test page (block and bar cursor) and the tabs+splits scenario,
terminal area and chrome alike. tiny-skia dependency removed.
- zig_error maps errno values per target via libc (Linux, Darwin/BSD)
and Win32 codes the way Zig std does on Windows.
- theme=. / theme=.. report "it is a directory" via a port of
std.fs.path.basename, matching Ghostty.
Test Plan:
- cargo test --workspace --no-fail-fast (3498 passed, exit 0)
- cargo build --profile production && just visual-parity
- just check-macos (both), just check-windows, just check-wasm
Resolves the 3 remaining gaps in docs/rewrite/notes/review-rv11-codex.md
(final-Z14.md):
- ghostty-bench validates every occurrence of enum options in order
(Args::take_enum; empty value resets) like cli/args.zig, so
`--mode=bad --mode=noop` fails as in Zig.
- Theme paths with an interior NUL open the prefix like Zig's C-string
path handling (verified against /usr/bin/ghostty).
- Filesystem diagnostics print Zig's error names (error.FileNotFound,
NotDir, AccessDenied, IsDir, NameTooLong, SymLinkLoop, ...) via a
shared ghostty_os::zig_error mapping used by theme/path/config-file/
file_load/edit-config/list-themes; messages match the oracle.
Test Plan:
- cargo test --workspace --no-fail-fast
- just check-macos (both), just check-windows, just check-wasm
Adds scripts/visual-parity.sh (`just visual-parity`): launches the
installed Ghostty 1.3.1 and the Rust build in an isolated headless
nested weston (GL renderer, Mesa forced, weston-screenshooter via
--debug), with identical isolated config, a deterministic test page
(ASCII, ligatures, all SGR styles and underline kinds, 16/256/truecolor,
box/block/braille/powerline/nerd icons, CJK, emoji, wide chars,
cursor) and a tabs+splits scenario driven through Xwayland, then diffs
the captures (terminal area and chrome separately, heatmaps).
Fixes found by comparing against the original:
- A pane stayed blank after a nested split: the GTK render path called
draw_frame(false) where Ghostty uses drawFrame(true) (a re-realized
GLArea has a new swap chain that nothing else redraws).
- Sprite glyph antialiasing now ports z2d's default 4x4 multisample
rasterizer instead of tiny-skia's analytic coverage (pixels differing
from Ghostty's reference sprite sheets: 5.76% -> 1.20%, none off by
more than 96 levels); the sheet test tolerance is tightened to 0.1%.
Result vs Ghostty 1.3.1: test page 0.020% of pixels differ (196 px at
curly-underline ends and diagonal box strokes, max delta 86 levels);
tabs+splits and headerbar/tab bar are bit-identical. Details in
docs/rewrite/notes/visual-parity-VP.md.
Test Plan:
- just visual-parity (needs weston, weston-screenshooter, xdotool)
- cargo test -p ghostty-font (sprite sheet comparison)
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)
Resolves the 8 gaps in docs/rewrite/notes/review-rv10-codex.md
(final-Z13.md):
- P1 memory safety: the C key-table action (and hovered-link/open-URL
payloads) could advertise a length larger than the NUL-truncated
allocation. A counted_bytes helper now passes the full bytes plus a
trailing NUL with len == byte count, like Zig's backing slices; all
C pointer+len structs were audited and tested to read exactly len.
- ghostty-bench args follow cli/args.zig (ordered duplicates, empty
value resets, first bad value errors, parseBool spellings); the C
benchmark tokenizer uses the ArgIteratorGeneral port.
- OSC 7 derived titles, desktop notifications and OSC 8 hover links
forward raw bytes to the runtime; GTK converts only for display.
- C diagnostic getter exports original bytes; escaped surrogates report
Utf8CannotEncodeSurrogateHalf; config float formatters print `nan`.
- Config::finalize_for(AppRuntime): GTK-only finalization (gtk-single-
instance=detect) and termio's cgroup hooks apply only to the GTK
runtime, so libghostty keeps `detect` like Zig.
Test Plan:
- cargo test --workspace --no-fail-fast (exit 0)
- cargo test -p ghostty-lib --features test-platform
- just check-wasm (macOS/Windows clippy re-run after the concurrent
terminal changes land)
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
Resolves the 6 differential gap groups in docs/rewrite/notes/review-
rv9-codex.md (details in final-Z11.md):
- ghostty_os::zig_fmt ports std.fmt.parseInt/parseUnsigned/parseFloat
(underscores, 0x/0o/0b prefixes, hex floats, inf/nan) with the Zig std
tests and replaces every int/float parse in config, keybind
parameters, ssh-cache and desktop detection.
- Interior NUL no longer panics in font names and ends C strings like
Zig's backing bytes (fontconfig, C config getters, title actions,
clipboard callback, relative paths, config-file, shaders, background
image, GTK CSS).
- GTK new-window arguments are trimmed of ASCII whitespace only.
- Command tokenization uses a port of std.process.ArgIteratorGeneral
(incl. CR/LF separators) with its std tests.
- UTF-8 validation happens where Zig's field parsers do it, so error
kinds match (metric modifiers, quick-terminal size, link, ...).
A scripted differential run of 202 fields x ~220 hostile/valid values
against /usr/bin/ghostty (+validate-config and +show-config: exit code,
stdout, stderr) now has zero mismatches besides build-specific defaults
(theme resources path, auto-update-channel, gtk-opengl-debug); it also
surfaced and fixed background-blur failure state, NaN formatting and
NaN/-0 finalize clamps. Regression tests: ghostty-config/tests/
zig_parity.rs.
Test Plan:
- cargo test --workspace --no-fail-fast (3456 passed, exit 0)
- just check-macos (both), just check-windows, just check-wasm
Zig parses config values (cli/args.zig, Config.zig field parsers,
config/string.zig) from raw byte slices, and each field type decides
whether it requires UTF-8 (InvalidValue otherwise) or stores bytes. The
port escape-encoded raw bytes into Strings at the line reader and let
fields parse the escaped text, so fields could observe encoding
artifacts; successive audits kept finding such leaks (RV5-RV8).
Field parsers now receive the original bytes: text fields validate UTF-8
where Zig does, byte/path fields store bytes (EncodedOs/OsString). This
resolves all 9 RV8 findings (docs/rewrite/notes/review-rv8-codex.md),
each with a regression test: Windows path conversion fails with
BadPathName instead of substituting U+FFFD; Windows process launch uses
strict UTF-8 like Zig's Command; the WTF-8 decoder accepts paired-
surrogate encodings like Zig; literal U+FDD0 Unicode key triggers;
selection-word-chars and clipboard-codepoint-map reject invalid UTF-8;
font style / codepoint-map family names use original bytes; C title
actions forward bytes; D-Bus new-window/Flatpak conversions match Zig.
Design, sweep and validation: docs/rewrite/notes/final-bytes-refactor.md.
Also moves the bundled iTerm2-Color-Schemes license out of
resources/themes/ so +list-themes no longer lists it as a theme
(output is now byte-identical to Ghostty 1.3.1).
Done by Codex (gpt-6-astra), reviewed and verified by the orchestrator.
Test Plan:
- cargo test --workspace --no-fail-fast (3428 passed, exit 0)
- just check-macos (both), just check-windows, just check-wasm
- +show-config --default --docs, +list-keybinds, +list-actions --docs,
+list-themes --plain compared with /usr/bin/ghostty
Zig's KeyEvent.utf8 and the embedded API's key/preedit text are byte
slices passed through to key encoding and the pty; the port converted
them lossily to UTF-8.
- KeyEvent.utf8 is &[u8] end to end (ghostty-input encoder, core,
ghostty-lib C API, libghostty-vt key events, GTK callers). Where Zig
validates with Utf8View (alternates, modify-other-keys, ctrl CSI-u,
associated text, binding unicode lookup) invalid text takes the same
"no UTF-8" fallback.
- Invalid preedit UTF-8 behaves like Zig's `try Utf8View.init`: the
prior preedit is cleared and marked dirty, the callback returns an
error (logged by the C API) and no preedit is set.
- The inspector key widget shows invalid key text lossily, display only.
Test Plan:
- cargo test --workspace --no-fail-fast (3407 passed)
- cargo test -p ghostty-lib --features test-platform (C-API key text
0xff 0xfe reaches the pty unchanged)
- just check-macos (both), just check-windows, just check-wasm
screen_file_contents_and_write occasionally failed with NotFound when
run in parallel with screen_temp_file_keeps_non_utf8_path_bytes: that
test sets TMPDIR to a short-lived directory via temp_env, and
std::env::temp_dir() evaluated outside temp_env's lock could resolve
into it. The temp-file section now runs under temp_env's lock with
TMPDIR unset. 25 consecutive runs of the core lib tests pass.
Resolves the 9 gap groups in docs/rewrite/notes/review-rv7-codex.md and
audits every string-typed config field against its consumers
(field -> consumers -> decode status table in final-Z9.md):
- Windows EnvMap keys use a port of Zig's nls.zig uppercase table
(upcaseW); Windows locale init follows Zig's chain (setlocale +
_putenv_s); malformed WTF-8 now fails process launch conversions like
Zig instead of substituting U+FFFD; kitty file paths convert WTF-8.
- bash --rcfile/--init-file, configured TERM and inherited GTK LANG
keep their original bytes.
- C API clipboard completion and ghostty_surface_binding_action take
bytes; complete_clipboard_request is byte-typed through the core.
- text:/csi:/esc: bindings, enquiry-response, input = path:, embedded
initial_input, search needles, titles, link regexes, clipboard
codepoint map, command palette text and GTK font/namespace values
decode the escape encoding before use.
Remaining by design: D-Bus a{ss} values and +new-window arguments are
UTF-8 by D-Bus type. C API key/preedit text follows separately.
Test Plan:
- cargo test --workspace
- just check-macos (both), just check-windows, just check-wasm
Resolves the 7 gap groups in docs/rewrite/notes/review-rv6-codex.md
(final-Z8.md):
- crash (macOS): request_abort_dump returns false on mach_msg receive
timeout/error so the signal-path fallback runs; EXC_SOFT_SIGNAL keeps
the signal number in the minidump exception info.
- Default SHELL read as an OS string and stored in encoded command form.
- macOS executable search works on raw PATH bytes; the default path is
used only when PATH is unset.
- Windows: config env overrides are decoded; EnvMap compares keys as
WTF-16 units with per-unit Unicode simple uppercasing (no lossy
conversion, distinct lone-surrogate keys stay distinct).
- +show-config writes original bytes for encoded OS data, so export +
reload round-trips; UTF-8 configs are byte-identical as before.
- Zig's ensureLocale chain lives in ghostty-os for all Unix targets and
is used by both the GTK app and the C API init.
Also makes the quick-terminal GTK replay test independent of compositor
focus: GTK's is-active is read-only, so when niri actually focuses the
layer surface the simulated focus-out cannot drive autohide and that
assertion is skipped (the production logic is unchanged and matches Zig).
Test Plan:
- cargo test --workspace (3390 passed, incl. tests/gtk_replay.rs)
- just check-macos (both), just check-windows, just check-wasm
ddidderr