Add custom theming

2026-07-28 20:09:40 +02:00
parent a0098a3946
commit ef32aa473e
14 changed files with 687 additions and 147 deletions
--- a/README.md
+++ b/README.md
@@ -74,7 +74,7 @@ cache directories remain fallback locations when their new `diple`
 counterparts do not yet exist.

 ```toml
-theme = "dark"                 # dark, light, high-contrast, or no-color
+theme = "dark"                 # built-in name, "custom", or an accessibility mode
 refresh_interval = "10s"
 repository = ""               # optional owner/repository default
 show_all = false              # requires repository
@@ -192,6 +192,40 @@ repeat_find = [";"]
 repeat_find_reverse = [","]
 ```

+Themes are compiled into `diple`; they do not require a separate download.
+Available names are `dark`, `light`, `catppuccin` (`catppuccin-mocha`),
+`catppuccin-latte`, `gruvbox` (`gruvbox-dark`), `gruvbox-light`,
+`one-dark-pro`, `github` (`github-dark`), `github-light`, `high-contrast`,
+and `no-color`.
+
+Set `theme = "custom"` to inherit a built-in palette and replace only the
+roles you care about:
+
+```toml
+theme = "custom"
+
+[custom_theme]
+base = "catppuccin-mocha"       # defaults to "dark"
+mode = "dark"                   # "dark" or "light"; controls Markdown rendering
+title = "#F5C2E7"
+active_foreground = "#1E1E2E"
+active_background = "#89B4FA"
+selection_background = "#313244"
+author_palette = ["#89B4FA", "#CBA6F7", "#94E2D5", "#F9E2AF"]
+syntax_theme = "catppuccin-mocha"
+```
+
+Every color override uses `#RRGGBB`. The complete set of roles is `title`,
+`dim`, `text`, `active_foreground`, `active_background`, `success`, `warning`,
+`error`, `editor_foreground`, `editor_background`, `pane_inactive`,
+`pane_active`, `quote`, `selection_background`,
+`suggestion_remove_background`, `suggestion_add_background`,
+`changed_remove_background`, and `changed_add_background`.
+`author_palette` accepts one or more colors. `syntax_theme` accepts an installed
+Chroma style name; invalid colors, bases, and syntax styles are reported as
+configuration errors at startup. The `[custom_theme]` table is ignored unless
+`theme = "custom"`.
+
 Every command binding accepts one or more Bubble Tea key names. Omitted
 settings retain their defaults, while an explicitly configured action replaces
 its default keys. Printable keys remain text in Insert mode, reply drafts, and
--- a/config.go
+++ b/config.go
@@ -36,9 +36,35 @@ type Config struct {
 	Threads         ThreadConfig      `toml:"threads"`
 	Cache           CacheConfig       `toml:"cache"`
 	Editing         EditingConfig     `toml:"editing"`
+	CustomTheme     CustomThemeConfig `toml:"custom_theme"`
 	KeyBindings     KeyBindings       `toml:"keybindings"`
 }

+type CustomThemeConfig struct {
+	Base                       string   `toml:"base"`
+	Mode                       string   `toml:"mode"`
+	Title                      string   `toml:"title"`
+	Dim                        string   `toml:"dim"`
+	Text                       string   `toml:"text"`
+	ActiveForeground           string   `toml:"active_foreground"`
+	ActiveBackground           string   `toml:"active_background"`
+	Success                    string   `toml:"success"`
+	Warning                    string   `toml:"warning"`
+	Error                      string   `toml:"error"`
+	EditorForeground           string   `toml:"editor_foreground"`
+	EditorBackground           string   `toml:"editor_background"`
+	PaneInactive               string   `toml:"pane_inactive"`
+	PaneActive                 string   `toml:"pane_active"`
+	Quote                      string   `toml:"quote"`
+	SelectionBackground        string   `toml:"selection_background"`
+	SuggestionRemoveBackground string   `toml:"suggestion_remove_background"`
+	SuggestionAddBackground    string   `toml:"suggestion_add_background"`
+	ChangedRemoveBackground    string   `toml:"changed_remove_background"`
+	ChangedAddBackground       string   `toml:"changed_add_background"`
+	AuthorPalette              []string `toml:"author_palette"`
+	SyntaxTheme                string   `toml:"syntax_theme"`
+}
+
 type DisplayConfig struct {
 	FoldResolved           bool   `toml:"fold_resolved"`
 	ThreadListWidthPercent int    `toml:"thread_list_width_percent"`
@@ -160,10 +186,8 @@ func loadConfig(path string, required bool) (Config, error) {
 }

 func validateConfig(config Config) error {
-	switch config.Theme {
-	case "dark", "light", "no-color", "high-contrast":
-	default:
-		return fmt.Errorf("theme must be dark or light")
+	if _, err := resolveThemePalette(config.Theme, config.CustomTheme); err != nil {
+		return err
 	}
 	if config.RefreshInterval.Duration < 2*time.Second {
 		return fmt.Errorf("refresh_interval must be at least 2s")
--- a/config_test.go
+++ b/config_test.go
@@ -87,6 +87,39 @@ up = ["ctrl+k"]
 	}
 }

+func TestLoadConfigParsesCustomTheme(t *testing.T) {
+	path := filepath.Join(t.TempDir(), "config.toml")
+	content := `
+theme = "custom"
+
+[custom_theme]
+base = "catppuccin-mocha"
+mode = "dark"
+title = "#112233"
+selection_background = "#223344"
+author_palette = ["#334455", "#445566"]
+syntax_theme = "gruvbox"
+`
+	if err := os.WriteFile(path, []byte(content), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	got, err := loadConfig(path, true)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := validateConfig(got); err != nil {
+		t.Fatal(err)
+	}
+	if got.Theme != "custom" ||
+		got.CustomTheme.Base != "catppuccin-mocha" ||
+		got.CustomTheme.Title != "#112233" ||
+		got.CustomTheme.SelectionBackground != "#223344" ||
+		len(got.CustomTheme.AuthorPalette) != 2 ||
+		got.CustomTheme.SyntaxTheme != "gruvbox" {
+		t.Fatalf("custom theme config = %#v", got.CustomTheme)
+	}
+}
+
 func TestValidateConfigRejectsEmptyKeyBinding(t *testing.T) {
 	config := defaultConfig()
 	config.KeyBindings.Navigation.Down = nil
--- a/highlight.go
+++ b/highlight.go
@@ -3,11 +3,11 @@ package main
 import (
 	"bytes"
 	"fmt"
-	"path/filepath"
 	"regexp"
 	"strconv"
 	"strings"

+	"github.com/alecthomas/chroma/v2/lexers"
 	"github.com/alecthomas/chroma/v2/quick"
 )

@@ -252,9 +252,9 @@ func highlightedSource(lexer, source string) string {
 }

 func lexerForPath(path string) string {
-	ext := strings.TrimPrefix(filepath.Ext(path), ".")
-	if ext == "" {
-		return "plaintext"
+	lexer := lexers.Match(path)
+	if lexer == nil {
+		return ""
 	}
-	return ext
+	return lexer.Config().Name
 }
--- a/highlight_lexer_test.go
+++ b/highlight_lexer_test.go
@@ -0,0 +1,38 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/alecthomas/chroma/v2/lexers"
+)
+
+func TestLexerForPathUsesCompleteFilename(t *testing.T) {
+	tests := []struct {
+		path string
+		want string
+	}{
+		{"Dockerfile", "Docker"},
+		{"Makefile", "Makefile"},
+		{"src/component.tsx", "TypeScript"},
+		{"scripts/check.py", "Python"},
+		{".github/workflows/test.yml", "YAML"},
+	}
+	for _, test := range tests {
+		t.Run(test.path, func(t *testing.T) {
+			got := lexerForPath(test.path)
+			lexer := lexers.Get(got)
+			if lexer == nil {
+				t.Fatalf("lexerForPath(%q) = %q, which is not registered", test.path, got)
+			}
+			if lexer.Config().Name != test.want {
+				t.Fatalf("lexerForPath(%q) selected %q, want %q", test.path, lexer.Config().Name, test.want)
+			}
+		})
+	}
+}
+
+func TestLexerForUnknownPathAllowsContentAnalysis(t *testing.T) {
+	if got := lexerForPath("LICENSE.unknown-extension"); got != "" {
+		t.Fatalf("unknown path selected %q instead of allowing content analysis", got)
+	}
+}
--- a/main.go
+++ b/main.go
@@ -23,7 +23,7 @@ func main() {
 		showAll        = flag.Bool("all", defaults.ShowAll, "show all open PRs in --repo, not only PRs assigned to you")
 		limit          = flag.Int("limit", defaults.Limit, "maximum open PRs to load (1-1000)")
 		endpoint       = flag.String("endpoint", defaults.Endpoint, "GitHub GraphQL endpoint")
-		theme          = flag.String("theme", defaults.Theme, "color theme: dark, light, high-contrast, or no-color")
+		theme          = flag.String("theme", defaults.Theme, "color theme name (including custom, catppuccin, gruvbox, one-dark-pro, and github)")
 		foldResolved   = flag.Bool("fold-resolved", defaults.Display.FoldResolved, "start resolved threads folded")
 		listWidth      = flag.Int("thread-list-width", defaults.Display.ThreadListWidthPercent, "thread list width as terminal percentage (20-60)")
 		dashboardMode  = flag.String("dashboard-mode", defaults.Display.DashboardMode, "dashboard navigation: intermediate or hotkey")
@@ -109,7 +109,7 @@ func main() {
 		}
 		owner, name = parts[0], parts[1]
 	}
-	if err := applyTheme(config.Theme); err != nil {
+	if err := applyTheme(config.Theme, config.CustomTheme); err != nil {
 		exitf("configuration: %v", err)
 	}
 	token, err := resolveToken(config.Endpoint)
--- a/markdown.go
+++ b/markdown.go
@@ -5,6 +5,7 @@ import (
 	"sync"

 	"github.com/charmbracelet/glamour"
+	glamouransi "github.com/charmbracelet/glamour/ansi"
 	"github.com/charmbracelet/glamour/styles"
 	"github.com/charmbracelet/lipgloss"
 )
@@ -79,12 +80,7 @@ func commentMarkdownRenderer(width int) (*glamour.TermRenderer, error) {
 	if cached, ok := commentMarkdownRenderers.Load(width); ok {
 		return cached.(*glamour.TermRenderer), nil
 	}
-	style := styles.DarkStyleConfig
-	if markdownStyleName == "light" {
-		style = styles.LightStyleConfig
-	} else if markdownStyleName == "notty" {
-		style = styles.NoTTYStyleConfig
-	}
+	style := markdownStyleForTheme()
 	zero := uint(0)
 	style.Document.Margin = &zero
 	style.Code.Prefix = ""
@@ -103,6 +99,70 @@ func commentMarkdownRenderer(width int) (*glamour.TermRenderer, error) {
 	return actual.(*glamour.TermRenderer), nil
 }

+func markdownStyleForTheme() glamouransi.StyleConfig {
+	if markdownStyleName == "notty" {
+		return styles.NoTTYStyleConfig
+	}
+	style := styles.DarkStyleConfig
+	if themeIsLight {
+		style = styles.LightStyleConfig
+	}
+	palette := editorMarkdownTheme
+	color := func(value string) *string { return &value }
+	truth := func(value bool) *bool { return &value }
+
+	style.Document.Color = color(palette.Text)
+	// Leave Text unset so inline text inherits the surrounding heading, link,
+	// quote, or paragraph color instead of flattening every Markdown token to
+	// the document foreground.
+	style.Text.Color = nil
+	style.Paragraph.Color = color(palette.Text)
+	style.Heading.Color = color(palette.Title)
+	style.H1.Color = color(palette.ActiveForeground)
+	style.H1.BackgroundColor = color(palette.ActiveBackground)
+	style.H2.Color = color(palette.Title)
+	style.H3.Color = color(palette.Title)
+	style.H4.Color = color(palette.Title)
+	style.H5.Color = color(palette.Title)
+	style.H6.Color = color(palette.Title)
+	style.HorizontalRule.Color = color(palette.Dim)
+	style.Item.Color = color(palette.Title)
+	style.Enumeration.Color = color(palette.Title)
+	style.Task.Color = color(palette.Text)
+	style.BlockQuote.Color = color(palette.Quote)
+	style.Strong.Color = color(palette.Text)
+	style.Strong.Bold = truth(true)
+	style.Emph.Color = color(palette.Text)
+	style.Link.Color = color(themeAuthorColor(palette, 0))
+	style.LinkText.Color = color(themeAuthorColor(palette, 1))
+	style.Image.Color = color(themeAuthorColor(palette, 0))
+	style.ImageText.Color = color(palette.Dim)
+	style.Code.Color = color(palette.Success)
+	style.Code.BackgroundColor = color(palette.EditorBackground)
+	style.CodeBlock.Color = color(palette.EditorForeground)
+	style.CodeBlock.BackgroundColor = color(palette.EditorBackground)
+	style.CodeBlock.Theme = palette.SyntaxTheme
+	style.CodeBlock.Chroma = nil
+	style.Table.Color = color(palette.Text)
+	style.Table.CenterSeparator = stringPointer("─")
+	style.Table.ColumnSeparator = stringPointer("│")
+	style.Table.RowSeparator = stringPointer("─")
+	style.DefinitionTerm.Color = color(palette.Title)
+	style.DefinitionDescription.Color = color(palette.Text)
+	return style
+}
+
+func themeAuthorColor(palette themePalette, index int) string {
+	if len(palette.AuthorPalette) == 0 {
+		return palette.Text
+	}
+	return palette.AuthorPalette[index%len(palette.AuthorPalette)]
+}
+
+func stringPointer(value string) *string {
+	return &value
+}
+
 func stripQuoteMarker(line string) (string, bool) {
 	trimmed := strings.TrimLeft(line, " \t")
 	if !strings.HasPrefix(trimmed, ">") {
--- a/markdown_editor_highlight.go
+++ b/markdown_editor_highlight.go
@@ -124,43 +124,30 @@ func editorMarkdownStyleStart(style editorMarkdownStyle) string {
 			return ""
 		}
 	}
-	if currentThemeName == "light" {
-		switch style {
-		case editorMarkdownHeading:
-			return "\x1b[1;38;2;154;103;0m"
-		case editorMarkdownStrong:
-			return "\x1b[1;38;2;130;80;223m"
-		case editorMarkdownEmphasis:
-			return "\x1b[3;38;2;87;96;106m"
-		case editorMarkdownCode:
-			return "\x1b[38;2;17;99;41m"
-		case editorMarkdownLink:
-			return "\x1b[4;38;2;9;105;218m"
-		case editorMarkdownDestination:
-			return "\x1b[38;2;10;112;111m"
-		case editorMarkdownQuote:
-			return "\x1b[38;2;154;103;0m"
-		case editorMarkdownComment:
-			return "\x1b[2;38;2;101;109;118m"
+	authors := editorMarkdownTheme.AuthorPalette
+	author := func(index int) string {
+		if len(authors) == 0 {
+			return editorMarkdownTheme.Text
 		}
+		return authors[index%len(authors)]
 	}
 	switch style {
 	case editorMarkdownHeading:
-		return "\x1b[1;38;2;240;183;47m"
+		return "\x1b[1m" + foregroundSequence(editorMarkdownTheme.Title)
 	case editorMarkdownStrong:
-		return "\x1b[1;38;2;198;120;221m"
+		return "\x1b[1m" + foregroundSequence(author(1))
 	case editorMarkdownEmphasis:
-		return "\x1b[3;38;2;215;218;232m"
+		return "\x1b[3m" + foregroundSequence(editorMarkdownTheme.Text)
 	case editorMarkdownCode:
-		return "\x1b[38;2;152;195;121m"
+		return foregroundSequence(editorMarkdownTheme.Success)
 	case editorMarkdownLink:
-		return "\x1b[4;38;2;97;175;239m"
+		return "\x1b[4m" + foregroundSequence(author(0))
 	case editorMarkdownDestination:
-		return "\x1b[38;2;86;182;194m"
+		return foregroundSequence(author(2))
 	case editorMarkdownQuote:
-		return "\x1b[38;2;229;192;123m"
+		return foregroundSequence(editorMarkdownTheme.Warning)
 	case editorMarkdownComment:
-		return "\x1b[2;38;2;119;119;119m"
+		return "\x1b[2m" + foregroundSequence(editorMarkdownTheme.Dim)
 	default:
 		return ""
 	}
@@ -168,15 +155,8 @@ func editorMarkdownStyleStart(style editorMarkdownStyle) string {

 func editorMarkdownStyleEnd(active bool) string {
 	foreground := "\x1b[39m"
-	if active {
-		switch currentThemeName {
-		case "dark":
-			foreground = "\x1b[38;2;215;218;232m"
-		case "light":
-			foreground = "\x1b[38;2;36;41;47m"
-		case "high-contrast":
-			foreground = "\x1b[38;2;255;255;255m"
-		}
+	if active && colorEnabled {
+		foreground = foregroundSequence(editorMarkdownTheme.EditorForeground)
 	}
 	return "\x1b[22;23;24m" + foreground
 }
--- a/markdown_test.go
+++ b/markdown_test.go
@@ -22,6 +22,10 @@ func TestCommentMarkdownDistinguishesQuoteAndReply(t *testing.T) {
 }

 func TestCommentMarkdownStylesInlineCode(t *testing.T) {
+	defer applyTheme("dark")
+	if err := applyTheme("dark"); err != nil {
+		t.Fatal(err)
+	}
 	rendered := strings.Join(renderCommentMarkdown(
 		"Use `list_comparison` for this value.", 60,
 	), "\n")
@@ -32,11 +36,30 @@ func TestCommentMarkdownStylesInlineCode(t *testing.T) {
 	if strings.Contains(plain, "Use  list_comparison  for") {
 		t.Fatalf("inline code added surrounding spaces: %q", plain)
 	}
-	if !strings.Contains(rendered, "48;5;236m") {
+	if !strings.Contains(rendered, "48;2;44;48;69m") {
 		t.Fatalf("inline code has no distinct background: %q", rendered)
 	}
 }

+func TestCommentMarkdownUsesActiveThemePalette(t *testing.T) {
+	defer applyTheme("dark")
+	if err := applyTheme("catppuccin-mocha"); err != nil {
+		t.Fatal(err)
+	}
+	rendered := strings.Join(renderCommentMarkdown(
+		"## Heading\n\nUse `value` and [link](https://example.com).\n\n```python\nif ready:\n    return 1\n```",
+		80,
+	), "\n")
+	for _, sequence := range []string{
+		"38;2;203;166;247", // Catppuccin mauve heading/link.
+		"38;2;166;227;161", // Catppuccin green inline code/string.
+	} {
+		if !strings.Contains(rendered, sequence) {
+			t.Fatalf("Markdown did not use active palette color %q:\n%q", sequence, rendered)
+		}
+	}
+}
+
 func TestWrappedQuoteKeepsRailOnEveryLine(t *testing.T) {
 	const width = 28
 	lines := renderCommentMarkdown(
--- a/suggestions_test.go
+++ b/suggestions_test.go
@@ -88,8 +88,8 @@ func TestDetailRendersSuggestionAsRemovalAndAddition(t *testing.T) {
 func TestSuggestionBackgroundIsDirectionalWithoutTextUnderline(t *testing.T) {
 	removed := suggestionHighlight("  - ", "old", 12, '-')
 	added := suggestionHighlight("  + ", "new", 12, '+')
-	if !strings.Contains(removed, "\x1b[48;5;52m") ||
-		!strings.Contains(added, "\x1b[48;5;22m") {
+	if !strings.Contains(removed, suggestionRemoveBackground) ||
+		!strings.Contains(added, suggestionAddBackground) {
 		t.Fatalf("suggestion decorations missing: removed=%q added=%q", removed, added)
 	}
 	if strings.Contains(removed, "\x1b[4m") || strings.Contains(added, "\x1b[4m") ||
@@ -100,8 +100,8 @@ func TestSuggestionBackgroundIsDirectionalWithoutTextUnderline(t *testing.T) {
 	if ansi.StringWidth(removed) != 12 || ansi.StringWidth(added) != 12 {
 		t.Fatal("suggestion backgrounds do not fill the row")
 	}
-	if !strings.Contains(removed, "\x1b[0m\x1b[48;5;52m     ") ||
-		!strings.Contains(added, "\x1b[0m\x1b[48;5;22m     ") {
+	if !strings.Contains(removed, "\x1b[0m"+suggestionRemoveBackground+"     ") ||
+		!strings.Contains(added, "\x1b[0m"+suggestionAddBackground+"     ") {
 		t.Fatal("padded row remainder is still underlined")
 	}
 }
--- a/theme.go
+++ b/theme.go
@@ -2,97 +2,329 @@ package main

 import (
 	"fmt"
+	"strconv"
+	"strings"

+	"github.com/alecthomas/chroma/v2/styles"
 	"github.com/charmbracelet/lipgloss"
 )

-var currentThemeName = "dark"
+type themePalette struct {
+	Mode                       string
+	Title, Dim, Text           string
+	ActiveForeground           string
+	ActiveBackground           string
+	Success, Warning, Error    string
+	EditorForeground           string
+	EditorBackground           string
+	PaneInactive, PaneActive   string
+	Quote                      string
+	SelectionBackground        string
+	SuggestionRemoveBackground string
+	SuggestionAddBackground    string
+	ChangedRemoveBackground    string
+	ChangedAddBackground       string
+	AuthorPalette              []string
+	SyntaxTheme                string
+	NoColor                    bool
+	HighContrast               bool
+}

-func applyTheme(name string) error {
-	colorEnabled = true
-	switch name {
-	case "dark":
-		titleStyle = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("#F0B72F"))
-		dimStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#777777"))
-		activeStyle = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("#FFFFFF")).Background(lipgloss.Color("#3B4261"))
-		okStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#67C587"))
-		warnStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#E5C07B"))
-		badStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#E06C75"))
-		editorLineStyle = lipgloss.NewStyle().
-			Foreground(lipgloss.Color("#D7DAE8")).
-			Background(lipgloss.Color("#2C3045"))
-		paneInactiveColor = lipgloss.Color("#50566F")
-		paneActiveColor = lipgloss.Color("#F0B72F")
-		authorPalette = []lipgloss.Color{
-			"#61AFEF", "#C678DD", "#56B6C2", "#E5C07B",
-			"#E06C75", "#98C379", "#D19A66", "#7FC8FF",
+var (
+	currentThemeName    = "dark"
+	themeIsLight        bool
+	editorMarkdownTheme themePalette
+)
+
+func applyTheme(name string, custom ...CustomThemeConfig) error {
+	var configured CustomThemeConfig
+	if len(custom) > 0 {
+		configured = custom[0]
 	}
-		codeHighlightTheme = "github-dark"
-		markdownStyleName = "dark"
-		quoteRailStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#777777"))
-		selectedLineBackground = "\x1b[48;5;24m"
-		suggestionRemoveBackground = "\x1b[48;5;52m"
-		suggestionAddBackground = "\x1b[48;5;22m"
-		changedRemoveBackground = "\x1b[48;2;55;0;0m"
-		changedAddBackground = "\x1b[48;2;0;55;0m"
-	case "light":
-		titleStyle = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("#9A6700"))
-		dimStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#656D76"))
-		activeStyle = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("#FFFFFF")).Background(lipgloss.Color("#0969DA"))
-		okStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#1A7F37"))
-		warnStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#9A6700"))
-		badStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#CF222E"))
-		editorLineStyle = lipgloss.NewStyle().
-			Foreground(lipgloss.Color("#24292F")).
-			Background(lipgloss.Color("#DDE8FF"))
-		paneInactiveColor = lipgloss.Color("#8C959F")
-		paneActiveColor = lipgloss.Color("#0969DA")
-		authorPalette = []lipgloss.Color{
-			"#0550AE", "#8250DF", "#0A706F", "#9A6700",
-			"#CF222E", "#116329", "#953800", "#0969DA",
+	palette, err := resolveThemePalette(name, configured)
+	if err != nil {
+		return err
 	}
-		codeHighlightTheme = "github"
-		markdownStyleName = "light"
-		quoteRailStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#656D76"))
-		selectedLineBackground = "\x1b[48;5;153m"
-		suggestionRemoveBackground = "\x1b[48;5;224m"
-		suggestionAddBackground = "\x1b[48;5;194m"
-		changedRemoveBackground = "\x1b[48;2;255;170;170m"
-		changedAddBackground = "\x1b[48;2;170;230;170m"
-	case "high-contrast":
-		titleStyle = lipgloss.NewStyle().Bold(true).Underline(true).Foreground(lipgloss.Color("#FFFF00"))
-		dimStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#FFFFFF"))
-		activeStyle = lipgloss.NewStyle().Bold(true).Reverse(true)
-		okStyle = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("#00FF00"))
-		warnStyle = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("#FFFF00"))
-		badStyle = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("#FF5555"))
-		editorLineStyle = lipgloss.NewStyle().
-			Foreground(lipgloss.Color("#FFFFFF")).
-			Reverse(true)
-		paneInactiveColor, paneActiveColor = lipgloss.Color("#FFFFFF"), lipgloss.Color("#FFFF00")
-		authorPalette = []lipgloss.Color{"#00FFFF", "#FF55FF", "#FFFF00", "#00FF00", "#FFFFFF"}
-		codeHighlightTheme, markdownStyleName = "github-dark", "dark"
-		quoteRailStyle = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("#FFFFFF"))
-		selectedLineBackground = "\x1b[7m"
-		suggestionRemoveBackground, suggestionAddBackground = "\x1b[48;5;88m", "\x1b[48;5;28m"
-		changedRemoveBackground, changedAddBackground = "\x1b[48;5;88m", "\x1b[48;5;28m"
-	case "no-color":
-		colorEnabled = false
-		titleStyle = lipgloss.NewStyle()
-		dimStyle = lipgloss.NewStyle()
+	colorEnabled = !palette.NoColor
+	themeIsLight = palette.Mode == "light"
+	editorMarkdownTheme = palette
+
+	if palette.NoColor {
+		titleStyle, dimStyle = lipgloss.NewStyle(), lipgloss.NewStyle()
 		activeStyle = lipgloss.NewStyle().Reverse(true)
 		okStyle, warnStyle, badStyle = lipgloss.NewStyle(), lipgloss.NewStyle(), lipgloss.NewStyle()
 		editorLineStyle = lipgloss.NewStyle().Reverse(true)
 		paneInactiveColor, paneActiveColor = "", ""
 		authorPalette = []lipgloss.Color{""}
-		codeHighlightTheme, markdownStyleName = "github", "notty"
 		quoteRailStyle = lipgloss.NewStyle()
 		selectedLineBackground, suggestionRemoveBackground, suggestionAddBackground = "", "", ""
 		changedRemoveBackground, changedAddBackground = "", ""
-	default:
-		return fmt.Errorf("unknown theme %q", name)
+		codeHighlightTheme, markdownStyleName = "github", "notty"
+	} else {
+		titleStyle = lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color(palette.Title))
+		dimStyle = lipgloss.NewStyle().Foreground(lipgloss.Color(palette.Dim))
+		activeStyle = lipgloss.NewStyle().Bold(true).
+			Foreground(lipgloss.Color(palette.ActiveForeground)).
+			Background(lipgloss.Color(palette.ActiveBackground))
+		okStyle = lipgloss.NewStyle().Foreground(lipgloss.Color(palette.Success))
+		warnStyle = lipgloss.NewStyle().Foreground(lipgloss.Color(palette.Warning))
+		badStyle = lipgloss.NewStyle().Foreground(lipgloss.Color(palette.Error))
+		editorLineStyle = lipgloss.NewStyle().
+			Foreground(lipgloss.Color(palette.EditorForeground)).
+			Background(lipgloss.Color(palette.EditorBackground))
+		paneInactiveColor = lipgloss.Color(palette.PaneInactive)
+		paneActiveColor = lipgloss.Color(palette.PaneActive)
+		quoteRailStyle = lipgloss.NewStyle().Foreground(lipgloss.Color(palette.Quote))
+		authorPalette = make([]lipgloss.Color, len(palette.AuthorPalette))
+		for index, color := range palette.AuthorPalette {
+			authorPalette[index] = lipgloss.Color(color)
+		}
+		selectedLineBackground = backgroundSequence(palette.SelectionBackground)
+		suggestionRemoveBackground = backgroundSequence(palette.SuggestionRemoveBackground)
+		suggestionAddBackground = backgroundSequence(palette.SuggestionAddBackground)
+		changedRemoveBackground = backgroundSequence(palette.ChangedRemoveBackground)
+		changedAddBackground = backgroundSequence(palette.ChangedAddBackground)
+		codeHighlightTheme = palette.SyntaxTheme
+		markdownStyleName = "dark"
+		if themeIsLight {
+			markdownStyleName = "light"
+		}
+		if palette.HighContrast {
+			titleStyle = titleStyle.Underline(true)
+			activeStyle = lipgloss.NewStyle().Bold(true).Reverse(true)
+			okStyle, warnStyle, badStyle = okStyle.Bold(true), warnStyle.Bold(true), badStyle.Bold(true)
+			editorLineStyle = lipgloss.NewStyle().
+				Foreground(lipgloss.Color(palette.EditorForeground)).Reverse(true)
+			quoteRailStyle = quoteRailStyle.Bold(true)
+			selectedLineBackground = "\x1b[7m"
+		}
 	}
 	currentThemeName = name
 	commentMarkdownRenderers.Clear()
 	return nil
 }
+
+func resolveThemePalette(name string, custom CustomThemeConfig) (themePalette, error) {
+	if name == "custom" {
+		base := custom.Base
+		if base == "" {
+			base = "dark"
+		}
+		if base == "custom" {
+			return themePalette{}, fmt.Errorf("custom_theme.base cannot be custom")
+		}
+		palette, err := resolveThemePalette(base, CustomThemeConfig{})
+		if err != nil {
+			return themePalette{}, fmt.Errorf("custom_theme.base: %w", err)
+		}
+		applyCustomTheme(&palette, custom)
+		if err := validateThemePalette(palette); err != nil {
+			return themePalette{}, fmt.Errorf("custom_theme: %w", err)
+		}
+		return palette, nil
+	}
+	palette, ok := builtinThemePalettes()[name]
+	if !ok {
+		return themePalette{}, fmt.Errorf(
+			"unknown theme %q; use dark, light, catppuccin, catppuccin-latte, "+
+				"gruvbox, gruvbox-light, one-dark-pro, github, github-light, "+
+				"high-contrast, no-color, or custom", name,
+		)
+	}
+	return palette, nil
+}
+
+func applyCustomTheme(palette *themePalette, custom CustomThemeConfig) {
+	set := func(target *string, value string) {
+		if value != "" {
+			*target = value
+		}
+	}
+	set(&palette.Mode, custom.Mode)
+	set(&palette.Title, custom.Title)
+	set(&palette.Dim, custom.Dim)
+	set(&palette.Text, custom.Text)
+	set(&palette.ActiveForeground, custom.ActiveForeground)
+	set(&palette.ActiveBackground, custom.ActiveBackground)
+	set(&palette.Success, custom.Success)
+	set(&palette.Warning, custom.Warning)
+	set(&palette.Error, custom.Error)
+	set(&palette.EditorForeground, custom.EditorForeground)
+	set(&palette.EditorBackground, custom.EditorBackground)
+	set(&palette.PaneInactive, custom.PaneInactive)
+	set(&palette.PaneActive, custom.PaneActive)
+	set(&palette.Quote, custom.Quote)
+	set(&palette.SelectionBackground, custom.SelectionBackground)
+	set(&palette.SuggestionRemoveBackground, custom.SuggestionRemoveBackground)
+	set(&palette.SuggestionAddBackground, custom.SuggestionAddBackground)
+	set(&palette.ChangedRemoveBackground, custom.ChangedRemoveBackground)
+	set(&palette.ChangedAddBackground, custom.ChangedAddBackground)
+	set(&palette.SyntaxTheme, custom.SyntaxTheme)
+	if len(custom.AuthorPalette) > 0 {
+		palette.AuthorPalette = append([]string(nil), custom.AuthorPalette...)
+	}
+	palette.NoColor, palette.HighContrast = false, false
+}
+
+func validateThemePalette(palette themePalette) error {
+	if palette.Mode != "dark" && palette.Mode != "light" {
+		return fmt.Errorf("mode must be dark or light")
+	}
+	colors := map[string]string{
+		"title": palette.Title, "dim": palette.Dim, "text": palette.Text,
+		"active_foreground": palette.ActiveForeground,
+		"active_background": palette.ActiveBackground,
+		"success":           palette.Success, "warning": palette.Warning, "error": palette.Error,
+		"editor_foreground": palette.EditorForeground,
+		"editor_background": palette.EditorBackground,
+		"pane_inactive":     palette.PaneInactive, "pane_active": palette.PaneActive,
+		"quote": palette.Quote, "selection_background": palette.SelectionBackground,
+		"suggestion_remove_background": palette.SuggestionRemoveBackground,
+		"suggestion_add_background":    palette.SuggestionAddBackground,
+		"changed_remove_background":    palette.ChangedRemoveBackground,
+		"changed_add_background":       palette.ChangedAddBackground,
+	}
+	for name, value := range colors {
+		if !validHexColor(value) {
+			return fmt.Errorf("%s must be a #RRGGBB color", name)
+		}
+	}
+	if len(palette.AuthorPalette) == 0 {
+		return fmt.Errorf("author_palette must contain at least one color")
+	}
+	for _, color := range palette.AuthorPalette {
+		if !validHexColor(color) {
+			return fmt.Errorf("author_palette contains invalid color %q", color)
+		}
+	}
+	if _, ok := styles.Registry[palette.SyntaxTheme]; !ok {
+		return fmt.Errorf("unknown Chroma syntax_theme %q", palette.SyntaxTheme)
+	}
+	return nil
+}
+
+func validHexColor(value string) bool {
+	if len(value) != 7 || value[0] != '#' {
+		return false
+	}
+	_, err := strconv.ParseUint(value[1:], 16, 24)
+	return err == nil
+}
+
+func backgroundSequence(color string) string {
+	value, err := strconv.ParseUint(strings.TrimPrefix(color, "#"), 16, 24)
+	if err != nil {
+		return ""
+	}
+	return fmt.Sprintf(
+		"\x1b[48;2;%d;%d;%dm", (value>>16)&0xff, (value>>8)&0xff, value&0xff,
+	)
+}
+
+func foregroundSequence(color string) string {
+	value, err := strconv.ParseUint(strings.TrimPrefix(color, "#"), 16, 24)
+	if err != nil {
+		return ""
+	}
+	return fmt.Sprintf(
+		"\x1b[38;2;%d;%d;%dm", (value>>16)&0xff, (value>>8)&0xff, value&0xff,
+	)
+}
+
+func builtinThemePalettes() map[string]themePalette {
+	dark := palette(
+		"dark", "#F0B72F", "#777777", "#D7DAE8", "#FFFFFF", "#3B4261",
+		"#67C587", "#E5C07B", "#E06C75", "#D7DAE8", "#2C3045",
+		"#50566F", "#F0B72F", "#777777", "#18344F", "#370000", "#003700",
+		"#370000", "#003700", "onedark",
+		"#61AFEF", "#C678DD", "#56B6C2", "#E5C07B", "#E06C75", "#98C379", "#D19A66", "#7FC8FF",
+	)
+	light := palette(
+		"light", "#9A6700", "#656D76", "#24292F", "#FFFFFF", "#0969DA",
+		"#1A7F37", "#9A6700", "#CF222E", "#24292F", "#DDE8FF",
+		"#8C959F", "#0969DA", "#656D76", "#ADD6FF", "#FFD7D5", "#CCFFD8",
+		"#FFAAAA", "#AAE6AA", "github",
+		"#0550AE", "#8250DF", "#0A706F", "#9A6700", "#CF222E", "#116329", "#953800", "#0969DA",
+	)
+	catMocha := palette(
+		"dark", "#CBA6F7", "#6C7086", "#CDD6F4", "#1E1E2E", "#CBA6F7",
+		"#A6E3A1", "#F9E2AF", "#F38BA8", "#CDD6F4", "#313244",
+		"#45475A", "#CBA6F7", "#6C7086", "#313244", "#452B36", "#23402E",
+		"#512B3A", "#254936", "catppuccin-mocha",
+		"#89B4FA", "#CBA6F7", "#94E2D5", "#F9E2AF", "#F38BA8", "#A6E3A1", "#FAB387",
+	)
+	catLatte := palette(
+		"light", "#8839EF", "#8C8FA1", "#4C4F69", "#EFF1F5", "#8839EF",
+		"#40A02B", "#DF8E1D", "#D20F39", "#4C4F69", "#DCE0E8",
+		"#9CA0B0", "#8839EF", "#8C8FA1", "#CCD0DA", "#F2CDCD", "#C9E7CA",
+		"#EFB8C0", "#B8DDB5", "catppuccin-latte",
+		"#1E66F5", "#8839EF", "#179299", "#DF8E1D", "#D20F39", "#40A02B", "#FE640B",
+	)
+	gruvbox := palette(
+		"dark", "#FABD2F", "#928374", "#EBDBB2", "#282828", "#458588",
+		"#B8BB26", "#FABD2F", "#FB4934", "#EBDBB2", "#3C3836",
+		"#665C54", "#D3869B", "#928374", "#3C3836", "#4C2828", "#324028",
+		"#5A2929", "#354929", "gruvbox",
+		"#83A598", "#D3869B", "#8EC07C", "#FABD2F", "#FB4934", "#B8BB26", "#FE8019",
+	)
+	gruvboxLight := palette(
+		"light", "#D79921", "#928374", "#3C3836", "#FBF1C7", "#458588",
+		"#98971A", "#D79921", "#CC241D", "#3C3836", "#EBDBB2",
+		"#A89984", "#B16286", "#928374", "#D5C4A1", "#F2C8C5", "#D8E0B0",
+		"#E9B9B3", "#C9D59A", "gruvbox-light",
+		"#458588", "#B16286", "#689D6A", "#D79921", "#CC241D", "#98971A", "#D65D0E",
+	)
+	oneDark := palette(
+		"dark", "#E5C07B", "#5C6370", "#ABB2BF", "#FFFFFF", "#3E4451",
+		"#98C379", "#E5C07B", "#E06C75", "#ABB2BF", "#2C313C",
+		"#4B5263", "#61AFEF", "#5C6370", "#2C313C", "#4B2B31", "#2D4032",
+		"#562D35", "#314A35", "onedark",
+		"#61AFEF", "#C678DD", "#56B6C2", "#E5C07B", "#E06C75", "#98C379", "#D19A66",
+	)
+	githubDark := palette(
+		"dark", "#D29922", "#8B949E", "#E6EDF3", "#FFFFFF", "#1F6FEB",
+		"#3FB950", "#D29922", "#F85149", "#E6EDF3", "#161B22",
+		"#30363D", "#58A6FF", "#8B949E", "#1F2937", "#4A2028", "#183D2A",
+		"#5A222C", "#1C4A30", "github-dark",
+		"#58A6FF", "#BC8CFF", "#39C5CF", "#D29922", "#F85149", "#3FB950", "#DB6D28",
+	)
+	highContrast := palette(
+		"dark", "#FFFF00", "#FFFFFF", "#FFFFFF", "#FFFFFF", "#000000",
+		"#00FF00", "#FFFF00", "#FF5555", "#FFFFFF", "#000000",
+		"#FFFFFF", "#FFFF00", "#FFFFFF", "#000080", "#5F0000", "#005F00",
+		"#5F0000", "#005F00", "github-dark",
+		"#00FFFF", "#FF55FF", "#FFFF00", "#00FF00", "#FFFFFF",
+	)
+	highContrast.HighContrast = true
+	noColor := dark
+	noColor.NoColor = true
+	return map[string]themePalette{
+		"dark": dark, "light": light,
+		"catppuccin": catMocha, "catppuccin-mocha": catMocha,
+		"catppuccin-latte": catLatte,
+		"gruvbox":          gruvbox, "gruvbox-dark": gruvbox, "gruvbox-light": gruvboxLight,
+		"one-dark-pro": oneDark, "onedark": oneDark,
+		"github": githubDark, "github-dark": githubDark, "github-light": light,
+		"high-contrast": highContrast, "no-color": noColor,
+	}
+}
+
+func palette(
+	mode, title, dim, text, activeFG, activeBG, success, warning, failure,
+	editorFG, editorBG, paneInactive, paneActive, quote, selection,
+	suggestionRemove, suggestionAdd, changedRemove, changedAdd, syntax string,
+	authors ...string,
+) themePalette {
+	return themePalette{
+		Mode: mode, Title: title, Dim: dim, Text: text,
+		ActiveForeground: activeFG, ActiveBackground: activeBG,
+		Success: success, Warning: warning, Error: failure,
+		EditorForeground: editorFG, EditorBackground: editorBG,
+		PaneInactive: paneInactive, PaneActive: paneActive, Quote: quote,
+		SelectionBackground:        selection,
+		SuggestionRemoveBackground: suggestionRemove,
+		SuggestionAddBackground:    suggestionAdd,
+		ChangedRemoveBackground:    changedRemove, ChangedAddBackground: changedAdd,
+		AuthorPalette: append([]string(nil), authors...), SyntaxTheme: syntax,
+	}
+}
--- a/theme_test.go
+++ b/theme_test.go
@@ -3,6 +3,8 @@ package main
 import (
 	"strings"
 	"testing"
+
+	"github.com/charmbracelet/lipgloss"
 )

 func TestApplyThemeChangesAllRenderingThemes(t *testing.T) {
@@ -11,6 +13,12 @@ func TestApplyThemeChangesAllRenderingThemes(t *testing.T) {
 			t.Fatal(err)
 		}
 	}()
+	if err := applyTheme("dark"); err != nil {
+		t.Fatal(err)
+	}
+	if codeHighlightTheme != "onedark" {
+		t.Fatalf("dark syntax theme = %q, want onedark", codeHighlightTheme)
+	}
 	if err := applyTheme("light"); err != nil {
 		t.Fatal(err)
 	}
@@ -32,3 +40,110 @@ func TestNoColorThemeDisablesSyntaxColors(t *testing.T) {
 		t.Fatalf("no-color source contains terminal colors: %q", rendered)
 	}
 }
+
+func TestBuiltinThemesApply(t *testing.T) {
+	defer applyTheme("dark")
+	names := []string{
+		"dark", "light",
+		"catppuccin", "catppuccin-mocha", "catppuccin-latte",
+		"gruvbox", "gruvbox-dark", "gruvbox-light",
+		"one-dark-pro", "github", "github-dark", "github-light",
+		"high-contrast", "no-color",
+	}
+	for _, name := range names {
+		t.Run(name, func(t *testing.T) {
+			if err := applyTheme(name); err != nil {
+				t.Fatal(err)
+			}
+			if len(authorPalette) == 0 {
+				t.Fatal("theme has no author colors")
+			}
+		})
+	}
+}
+
+func TestLightBuiltinThemesSelectLightRendering(t *testing.T) {
+	defer applyTheme("dark")
+	for _, name := range []string{"light", "catppuccin-latte", "gruvbox-light", "github-light"} {
+		if err := applyTheme(name); err != nil {
+			t.Fatal(err)
+		}
+		if !themeIsLight || markdownStyleName != "light" {
+			t.Fatalf("%s was not treated as a light theme", name)
+		}
+	}
+}
+
+func TestCustomThemeOverlaysBuiltinBase(t *testing.T) {
+	defer applyTheme("dark")
+	custom := CustomThemeConfig{
+		Base:          "catppuccin-mocha",
+		Title:         "#010203",
+		AuthorPalette: []string{"#112233", "#445566"},
+		SyntaxTheme:   "gruvbox",
+	}
+	if err := applyTheme("custom", custom); err != nil {
+		t.Fatal(err)
+	}
+	if currentThemeName != "custom" ||
+		titleStyle.GetForeground() != lipgloss.Color("#010203") ||
+		codeHighlightTheme != "gruvbox" {
+		t.Fatalf(
+			"custom theme was not applied: name=%q title=%q syntax=%q",
+			currentThemeName, titleStyle.GetForeground(), codeHighlightTheme,
+		)
+	}
+	if len(authorPalette) != 2 ||
+		authorPalette[0] != lipgloss.Color("#112233") ||
+		authorPalette[1] != lipgloss.Color("#445566") {
+		t.Fatalf("custom author palette = %#v", authorPalette)
+	}
+	if selectedLineBackground == "" {
+		t.Fatal("custom theme did not inherit unspecified base colors")
+	}
+}
+
+func TestCustomThemeValidation(t *testing.T) {
+	tests := []struct {
+		name   string
+		custom CustomThemeConfig
+		want   string
+	}{
+		{
+			name:   "invalid color",
+			custom: CustomThemeConfig{Title: "red"},
+			want:   "title must be a #RRGGBB color",
+		},
+		{
+			name:   "invalid syntax theme",
+			custom: CustomThemeConfig{SyntaxTheme: "not-a-chroma-theme"},
+			want:   "unknown Chroma syntax_theme",
+		},
+		{
+			name:   "recursive base",
+			custom: CustomThemeConfig{Base: "custom"},
+			want:   "custom_theme.base cannot be custom",
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			_, err := resolveThemePalette("custom", test.custom)
+			if err == nil || !strings.Contains(err.Error(), test.want) {
+				t.Fatalf("error = %v, want it to contain %q", err, test.want)
+			}
+		})
+	}
+}
+
+func TestCatppuccinUsesCanonicalMauveAccent(t *testing.T) {
+	palette, err := resolveThemePalette("catppuccin-mocha", CustomThemeConfig{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if palette.Title != "#CBA6F7" || palette.ActiveBackground != "#CBA6F7" {
+		t.Fatalf(
+			"Catppuccin accent is title=%q active=%q, want mauve",
+			palette.Title, palette.ActiveBackground,
+		)
+	}
+}
--- a/tui.go
+++ b/tui.go
@@ -2314,6 +2314,7 @@ func (m App) healthLines() []string {
 	components = append(components, refresh)
 	components = append(components, HealthComponent{
 		Name: "configuration", Level: healthOK, Summary: "configuration loaded and validated",
+		Detail: "theme " + currentThemeName,
 	})
 	if m.readState != nil {
 		component := HealthComponent{
--- a/tui_test.go
+++ b/tui_test.go
@@ -1704,7 +1704,7 @@ func TestTabHidesListAndHRestoresIt(t *testing.T) {

 func TestSelectedBackgroundFillsLine(t *testing.T) {
 	rendered := selectedBackground("code", 12)
-	if !strings.Contains(rendered, "\x1b[48;5;24m") || ansi.StringWidth(rendered) != 12 {
+	if !strings.Contains(rendered, selectedLineBackground) || ansi.StringWidth(rendered) != 12 {
 		t.Fatalf("selected background was not full width: %q", rendered)
 	}
 }