tui: detect terminal light/dark background and adapt the palette#402
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The Matrix palette was a single dark-tuned set of foreground colors drawn on the terminal's own background, so on a light terminal the light-green text was hard to read. Now the TUI ships the palette in two variants (Theme::dark / Theme::light) and resolves which to use at startup. theme.toml gains `mode = "auto" | "light" | "dark"` (default auto). In auto, the TUI queries the terminal background via OSC 11 (\x1b]11;?\x07), parses the RGB reply into luminance, and picks light (>0.5) or dark; a terminal that doesn't answer falls back to dark. `[colors]` overrides apply on top of the active variant. The query runs once right after enable_raw_mode (before the event loop consumes stdin), with a ~120ms timed poll/read on the tty fd (Unix; non-unix → dark). - theme.rs: ThemeMode, Theme::light(), ThemeConfig (load + resolve), detect_terminal_is_light + OSC 11 luminance parsing. - cli Cargo.toml: libc (Unix) for the timed read. - app.rs: load config at startup, re-resolve the palette after raw mode. - docs/configuration.md + spec 0027. Tests: mode parsing, forced-vs-auto resolution + dark fallback, OSC 11 luminance (light/dark, 8- and 16-bit channels). 7 theme tests pass.
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Problem. The Matrix palette was a single dark-tuned set of foreground colors drawn on the terminal's own background (
Color::Reset, nobgof its own). On a light terminal the light-green text is low-contrast and hard to read.Approach (option A from the discussion): be terminal-theme-aware via OSC 11.
Theme::dark()(unchanged) andTheme::light()(dark-green functional text, darker rain heads so they read on white, pale tails).theme.tomlgainsmode = "auto" | "light" | "dark"(defaultauto).auto, at startup the TUI queries the terminal background with OSC 11 (\x1b]11;?\x07), parses the RGB reply into perceived luminance, and picks light (>0.5) or dark. A terminal that doesn't answer falls back to dark.[colors]overrides apply on top of whichever variant is active.Mechanics. The query runs once, right after
enable_raw_modeand before the event loop consumes stdin, with a ~120 ms timedpoll/readon the tty fd (Unix; non-Unix → dark). One new dep:libc(Unix only).Changes
theme.rs:ThemeMode,Theme::light(),ThemeConfig(load+resolve),detect_terminal_is_light+ OSC 11 luminance parsing;parse_theme→parse_theme_onto(base, …).crates/cli/Cargo.toml:[target.'cfg(unix)'.dependencies] libc.app.rs: parse config at startup, re-resolve the palette after raw mode (before the first render).docs/configuration.md+ spec0027.Tests
modeparsing; forced-vs-auto resolution + dark fallback when unanswered; OSC 11 luminance (white→light, black→dark, 8- and 16-bit channels, garbage→None). 7 theme tests pass; full build clean.Verification note
The unit tests cover parsing/resolution, but the live query needs a real terminal (the test harness's stdin isn't a tty). Best confirmed by running the
constructbinary on a light vs dark terminal and watching the palette switch.mode = "dark"/"light"forces it if your terminal doesn't answer OSC 11.Non-goals
Doesn't paint its own background (still relies on the terminal's); no live re-detection on theme change (resolved once at startup); no Windows OSC (→ dark).