ghostty-rs/docs/rewrite/notes/final-Z11.md

Z11: RV9 gap groups (Ghostty 1.3.1 parity)

Fixes for the six gap groups in review-rv9-codex.md. No version change, no commit.

Fixes

1. Interior NUL in font names. fontconfig::Pattern::add_string_bytes ends the value at the first NUL (the C-string handoff Zig does) instead of failing, so font-family, font-style and codepoint-map families no longer hit the assert! in discovery::to_fc_pattern. Test: discovery::tests::interior_nul_in_font_names_ends_the_c_string.
2. Numeric grammars. New ghostty_os::zig_fmt: exact ports of std.fmt.parseInt/parseUnsigned (underscores, 0b/0o/0x in both cases, sign rules, len > 2 prefix gate, Overflow vs InvalidCharacter) and std.fmt.parseFloat (grammar of parse.zig incl. validUnderscores, hex floats via a port of convertHex incl. the many-digits path, inf/ infinity/nan). Decimal values are rounded by Rust's correctly rounded FromStr once the Zig grammar accepted the text. Ported all std tests. Used by: primitive int/float fields (base 0), palette key (u8, base 0, Zig error names), variation values, mouse-scroll bare float, quick-terminal px/%, window-padding (u32, base 10), duration (parseUnsigned u64), background-blur radius, codepoint/clipboard map hex (base 16), metric modifiers, keybind numeric parameters (base 10 / float), ssh-cache entry timestamp, GIO_LAUNCHED_DESKTOP_FILE_PID. Also found by differential runs: Zig {d} prints nan (Rust NaN); finalize clamps use Zig @min/@max/clamp NaN and +-0 semantics (cli_args::zig_min/zig_max/zig_clamp); a failed background-blur radius parse leaves radius (0 or the previous radius) like Zig's in-place union initialisation.
3. C strings. config_capi getters, C action titles/strings (action_c::Keep) and the embedded clipboard write callback now end the C string at the first NUL instead of deleting NUL bytes.
4. GTK new-window args. --working-directory=/--title= trim only std.ascii.whitespace (space, \t, \n, \r, VT, FF); U+00A0 etc. survive.
5. Shell tokenizer. New ghostty_os::arg_iterator::ArgIteratorGeneral (port of std.process.ArgIteratorGeneral, including comments/ single_quotes options, skip, NUL terminates). Command::arg_iterator (and so shell-integration detection) use it: space, tab, CR and LF split. Ported the std "response file arg parsing" test plus separator/quote/NUL tests; termio test detect_shell_splits_on_all_zig_separators.
6. Parser diagnostics. UTF-8 validation moved to where Zig would notice it: metric modifiers (InvalidFormat), quick-terminal size (MissingUnit/ InvalidValue), link (NotImplemented), colors/palette (InvalidCharacter), background-blur, keybind trigger (parsed after the action, like Parser.init) and action parameters (known action with bad bytes is InvalidFormat, unknown name InvalidAction). Other differences found: config-file open errors are printed as error.FileNotFound etc.; paths with interior NUL resolve/open as the C string prefix (EncodedOs::to_syscall_path) for relative path expansion, config-file, custom shaders, background image, gtk css.

Differential harness

Script (not committed): for each of the 202 Config.zig fields x ~220 hostile and valid values, run /usr/bin/ghostty +validate-config --config-file=F and +show-config (value in $XDG_CONFIG_HOME/ghostty/config) against the Rust binary and compare exit code, stdout and stderr. Final state: zero mismatches except theme (resources path differs by install location), auto-update-channel default (tip vs stable, build channel) and gtk-opengl-debug (debug build).

Regression tests: crates/ghostty-config/tests/zig_parity.rs, ghostty_os::zig_fmt::tests, ghostty_os::arg_iterator::tests, ghostty-config command tests, lib/gtk tests listed above.

Not covered / notes

• ghostty-terminal OSC/tmux/kitty parsers also call parseInt (terminal/osc/parsers/*.zig, tmux/*.zig, kitty/*.zig); they are outside the config/input scope of this task and still use Rust str::parse/ from_str_radix. zig_fmt is available for a follow-up.
• Windows/macOS behaviour is covered by cross-checks only.