Light themes for dark-painted TUIs, and color-scheme reporting

apple/GhostteaApp/Resources/Ghosttea-iOS.cdx.json

@@ -129,7 +129,7 @@
       },
       {
         "name": "ghosttea:cargo-lock:sha256",
-        "value": "6da56d16f37b315fb22ebe023528c7f4ff8b00b6674613e894838a658c2c83d3"
+        "value": "7cdc22165195a7f98749dadbf1de0801225a9a3fcac38cfc0a18b931767268e3"
       },
       {
         "name": "ghosttea:rust-target",

apple/GhostteaApp/Resources/THIRD-PARTY-NOTICES.txt

@@ -2,7 +2,7 @@ GHOSTTEA iOS THIRD-PARTY NOTICES
 ================================
 
 This file is generated from the reviewed iOS release dependency graph.
-CycloneDX SHA-256: be5713a39ecb1300ec9c5f41db8010e63fe0de4697e9c64f6e3966ac357d9b43
+CycloneDX SHA-256: 9733b5e2f5f8662b650181292deb5e5d130de982ada840cb9e53b5ffaa4f2065
 Components: 108
 Unique license documents: 97
 

apple/GhostteaKit/Compatibility/ios-release-resources.lock.json

@@ -2,15 +2,15 @@
   "schemaVersion": 1,
   "sourceBom": {
     "path": "apple/GhostteaKit/Compatibility/ios-release.cdx.json",
-    "sha256": "be5713a39ecb1300ec9c5f41db8010e63fe0de4697e9c64f6e3966ac357d9b43"
+    "sha256": "9733b5e2f5f8662b650181292deb5e5d130de982ada840cb9e53b5ffaa4f2065"
   },
   "bundledBom": {
     "path": "apple/GhostteaApp/Resources/Ghosttea-iOS.cdx.json",
-    "sha256": "be5713a39ecb1300ec9c5f41db8010e63fe0de4697e9c64f6e3966ac357d9b43"
+    "sha256": "9733b5e2f5f8662b650181292deb5e5d130de982ada840cb9e53b5ffaa4f2065"
   },
   "notices": {
     "path": "apple/GhostteaApp/Resources/THIRD-PARTY-NOTICES.txt",
-    "sha256": "ba2189bb8022dd15234bbb6438fea7905df0ae1a8f226121fd89fa501bc06aec",
+    "sha256": "584197ad95026d1abed13290bf951db8c74db0aaa46afd8f2e64db8820cb143f",
     "componentCount": 108,
     "licenseDocumentCount": 97
   }

apple/GhostteaKit/Compatibility/ios-release.cdx.json

@@ -129,7 +129,7 @@
       },
       {
         "name": "ghosttea:cargo-lock:sha256",
-        "value": "6da56d16f37b315fb22ebe023528c7f4ff8b00b6674613e894838a658c2c83d3"
+        "value": "7cdc22165195a7f98749dadbf1de0801225a9a3fcac38cfc0a18b931767268e3"
       },
       {
         "name": "ghosttea:rust-target",

apple/GhostteaKit/Compatibility/ios-rust-components.lock.json

@@ -10,7 +10,7 @@
       "pkg:cargo/ghosttea-font-fixture-ffi@0.12.0"
     ]
   },
-  "cargoLockSha256": "6da56d16f37b315fb22ebe023528c7f4ff8b00b6674613e894838a658c2c83d3",
+  "cargoLockSha256": "7cdc22165195a7f98749dadbf1de0801225a9a3fcac38cfc0a18b931767268e3",
   "components": [
     {
       "ref": "pkg:cargo/anyhow@1.0.103",

docs/webgpu-appearance-pipeline.md

@@ -46,6 +46,30 @@ A solid block cursor is inserted after selection backgrounds and before glyphs;
 the covered glyph uses `cursor-text`. Bar, underline, and hollow cursors remain
 late overlay geometry.
 
+## Light adaptation
+
+Some applications paint every cell with their own truecolor background, so a
+light theme never shows through (Grok's default theme paints `#141414`
+everywhere). With `lightAdaptation: "auto"`, the default from configuration,
+a pane is remapped when the theme background is light and at least 60% of its
+cells carry an explicit dark background. It releases below 35%, so partially
+painted scrolls do not flicker. Applications that follow the theme (Codex,
+OpenCode, Claude Code's Auto theme) never cross that threshold.
+
+The remap runs in `resolveStyle`, per style and before blending, so glyph
+coverage, color glyphs, and the shader stack are untouched. Surfaces mirror
+their OKLab-with-toe lightness around the theme background, anchored at the
+application's dominant surface. Neutral ink keeps its distance from its own
+cell background, and accents land in an APCA mid-tone band with their hue
+intact. Default foreground and background stay theme-owned. Engaging,
+re-keying, or releasing invalidates the persistent scene and geometry cache.
+
+Applications that switch themes themselves need the terminal to say which
+scheme it is. ghosttead answers `CSI ? 996 n` from the default background's
+luminance, sends `CSI ? 997 ; 1|2 n` when a theme change flips it and mode
+2031 is set, and sets `COLORFGBG` for new sessions unless the caller provides
+one.
+
 ## Catalogs and persistence
 
 The linked `ghostty.style` gallery seeds its built-in collection from every

native/ghosttea/crates/ghosttea-core/src/model.rs

@@ -732,6 +732,37 @@ mod tests {
         }
     }
 
+    #[test]
+    fn theme_change_reports_the_new_color_scheme_to_the_program() {
+        let runtime = Arc::new(TerminalRuntime::discover().unwrap());
+        let mut model = TerminalModel::new(
+            runtime,
+            TerminalModelOptions {
+                session_handle: 4,
+                session_epoch: 1,
+                layout_epoch: 1,
+                cols: 20,
+                rows: 4,
+                scrollback_bytes: 4096,
+            },
+        )
+        .unwrap();
+        model.feed(b"\x1b[?2031h", RenderRequest::None).unwrap();
+        let update = model
+            .set_appearance(
+                [0x4c, 0x4f, 0x69],
+                [0xef, 0xf1, 0xf5],
+                [0xdc, 0x8a, 0x78],
+                &[],
+                RenderRequest::Full,
+            )
+            .unwrap();
+        assert!(update.as_slice().iter().any(|effect| matches!(
+            effect,
+            TerminalEffect::WriteToTransport(bytes) if bytes == b"\x1b[?997;2n"
+        )));
+    }
+
     #[test]
     fn terminal_reply_precedes_semantic_and_render_effects() {
         let runtime = Arc::new(TerminalRuntime::discover().unwrap());

native/ghosttea/crates/ghosttea-vt-sys/src/ghostty_shim.c

@@ -1,4 +1,5 @@
 #include "ghostty_shim_internal.h"
+#include <math.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -9,6 +10,30 @@ struct EgTrackedSelection {
   bool rectangle;
 };
 
+static double eg_srgb_to_linear(uint8_t value) {
+  double v = value / 255.0;
+  return v <= 0.04045 ? v / 12.92 : pow((v + 0.055) / 1.055, 2.4);
+}
+
+// A background is light when dark text out-contrasts light text on it, which
+// is WCAG relative luminance above ~0.179.
+static GhosttyColorScheme eg_scheme_for_background(GhosttyColorRgb background) {
+  double luminance = 0.2126 * eg_srgb_to_linear(background.r) +
+                     0.7152 * eg_srgb_to_linear(background.g) +
+                     0.0722 * eg_srgb_to_linear(background.b);
+  return (luminance + 0.05) / 0.05 > 1.05 / (luminance + 0.05)
+             ? GHOSTTY_COLOR_SCHEME_LIGHT
+             : GHOSTTY_COLOR_SCHEME_DARK;
+}
+
+static bool eg_color_scheme(GhosttyTerminal terminal,
+                            void* userdata,
+                            GhosttyColorScheme* out_scheme) {
+  (void)terminal;
+  *out_scheme = ((EgTerminal*)userdata)->color_scheme;
+  return true;
+}
+
 int eg_terminal_set_colors(EgTerminal* state,
                            uint8_t fg_r, uint8_t fg_g, uint8_t fg_b,
                            uint8_t bg_r, uint8_t bg_g, uint8_t bg_b,
@@ -23,8 +48,27 @@ int eg_terminal_set_colors(EgTerminal* state,
   result = ghostty_terminal_set(
       state->terminal, GHOSTTY_TERMINAL_OPT_COLOR_BACKGROUND, &background);
   if (result != GHOSTTY_SUCCESS) return result;
-  return ghostty_terminal_set(
+  result = ghostty_terminal_set(
       state->terminal, GHOSTTY_TERMINAL_OPT_COLOR_CURSOR, &cursor);
+  if (result != GHOSTTY_SUCCESS) return result;
+
+  // Programs that enabled mode 2031 (Claude Code's Auto theme, Neovim) learn
+  // about a light/dark flip without re-querying. The report rides the normal
+  // PTY response buffer, so it reaches the program with the next snapshot.
+  GhosttyColorScheme scheme = eg_scheme_for_background(background);
+  if (scheme == state->color_scheme) return GHOSTTY_SUCCESS;
+  state->color_scheme = scheme;
+  bool reporting = false;
+  if (ghostty_terminal_mode_get(
+          state->terminal, GHOSTTY_MODE_COLOR_SCHEME_REPORT, &reporting) != GHOSTTY_SUCCESS ||
+      !reporting)
+    return GHOSTTY_SUCCESS;
+  char report[32];
+  size_t written = 0;
+  if (ghostty_color_scheme_report_encode(scheme, report, sizeof report, &written) ==
+      GHOSTTY_SUCCESS)
+    (void)eg_buffer_append(&state->response, (const uint8_t*)report, written);
+  return GHOSTTY_SUCCESS;
 }
 
 int eg_terminal_set_palette(EgTerminal* state,
@@ -158,6 +202,7 @@ EgTerminal* eg_terminal_new(uint16_t cols, uint16_t rows, size_t max_scrollback)
   ghostty_terminal_set(state->terminal, GHOSTTY_TERMINAL_OPT_TITLE_CHANGED, (const void*)eg_title_changed);
   ghostty_terminal_set(state->terminal, GHOSTTY_TERMINAL_OPT_PWD_CHANGED, (const void*)eg_pwd_changed);
   ghostty_terminal_set(state->terminal, GHOSTTY_TERMINAL_OPT_CLIPBOARD_WRITE, (const void*)eg_clipboard_write);
+  ghostty_terminal_set(state->terminal, GHOSTTY_TERMINAL_OPT_COLOR_SCHEME, (const void*)eg_color_scheme);
   if (eg_terminal_set_colors(
           state,
           255, 255, 255,

native/ghosttea/crates/ghosttea-vt-sys/src/ghostty_shim_internal.h

@@ -28,6 +28,9 @@ struct EgTerminal {
   EgBuffer grapheme;
   bool mouse_pressed;
   uint32_t effects;
+  // Derived from the embedder's default background; answers CSI ? 996 n and
+  // drives mode-2031 reports when a theme change flips it.
+  GhosttyColorScheme color_scheme;
 };
 
 bool eg_buffer_reserve(EgBuffer* buffer, size_t required);