diff --git a/apps/app/src/lib/themes/catppuccin.ts b/apps/app/src/lib/themes/catppuccin.ts
new file mode 100644
index 000000000..3de0a8596
--- /dev/null
+++ b/apps/app/src/lib/themes/catppuccin.ts
@@ -0,0 +1,101 @@
+/**
+ * Catppuccin palette (https://catppuccin.com). Light = Latte, dark = Mocha,
+ * accent = Mauve. Overrides only the two anchors (--canvas/--ink), the accent,
+ * the secondary text tiers, the semantic colors, and the ANSI palette — every
+ * neutral surface (cards, borders, sidebar, hover, selection, ring) derives
+ * from the anchors and accent in theme.css, so it follows automatically.
+ * Unlike Nord, Latte and Mocha have *different* terminal colors, so the
+ * --ansi-* (and --ansi-bg-fg-*) blocks live in BOTH selectors, not just light.
+ */
+export const catppuccinThemeCss = `
+:root, .light {
+  /* Anchors: Base / Text */
+  --canvas: #eff1f5;
+  --ink: #4c4f69;
+
+  /* Accent: Mauve */
+  --primary: #8839ef;
+  --primary-foreground: #eff1f5;
+  --file-accent: #1e66f5; /* Blue — the one path tint */
+
+  /* Text tiers: Subtext1 / Subtext0 / Overlay1 */
+  --muted-foreground: #5c5f77;
+  --readback-foreground: #6c6f85;
+  --subtle-foreground: #8c8fa1;
+
+  /* Semantic — Red / Yellow / Peach / Green / Mauve(merged) */
+  --destructive: #d20f39;
+  --destructive-foreground: #eff1f5;
+  --destructive-text: #d20f39;
+  --warning: #df8e1d;
+  --warning-text: #b8730a;
+  --attention: #fe640b;
+  --success: #40a02b;
+  --diff-added: #40a02b;
+  --diff-removed: #d20f39;
+  --pr-merged: #8839ef;
+
+  /* Terminal — official Catppuccin Latte ANSI */
+  --ansi-0:  #5c5f77;  --ansi-bg-fg-0:  #eff1f5;
+  --ansi-1:  #d20f39;  --ansi-bg-fg-1:  #eff1f5;
+  --ansi-2:  #40a02b;  --ansi-bg-fg-2:  #eff1f5;
+  --ansi-3:  #df8e1d;  --ansi-bg-fg-3:  #11111b;
+  --ansi-4:  #1e66f5;  --ansi-bg-fg-4:  #eff1f5;
+  --ansi-5:  #ea76cb;  --ansi-bg-fg-5:  #11111b;
+  --ansi-6:  #179299;  --ansi-bg-fg-6:  #eff1f5;
+  --ansi-7:  #acb0be;  --ansi-bg-fg-7:  #11111b;
+  --ansi-8:  #6c6f85;  --ansi-bg-fg-8:  #eff1f5;
+  --ansi-9:  #d20f39;  --ansi-bg-fg-9:  #eff1f5;
+  --ansi-10: #40a02b;  --ansi-bg-fg-10: #eff1f5;
+  --ansi-11: #df8e1d;  --ansi-bg-fg-11: #11111b;
+  --ansi-12: #1e66f5;  --ansi-bg-fg-12: #eff1f5;
+  --ansi-13: #ea76cb;  --ansi-bg-fg-13: #11111b;
+  --ansi-14: #179299;  --ansi-bg-fg-14: #eff1f5;
+  --ansi-15: #bcc0cc;  --ansi-bg-fg-15: #11111b;
+}
+.dark {
+  /* Anchors: Base / Text */
+  --canvas: #1e1e2e;
+  --ink: #cdd6f4;
+
+  /* Accent: Mauve */
+  --primary: #cba6f7;
+  --primary-foreground: #1e1e2e;
+  --file-accent: #89b4fa; /* Blue */
+
+  /* Text tiers: Subtext1 / Subtext0 / Overlay1 */
+  --muted-foreground: #bac2de;
+  --readback-foreground: #a6adc8;
+  --subtle-foreground: #7f849c;
+
+  /* Semantic — lighter pastels so they read on the dark base */
+  --destructive: #f38ba8;
+  --destructive-foreground: #1e1e2e;
+  --destructive-text: #f38ba8;
+  --warning: #f9e2af;
+  --warning-text: #f9e2af;
+  --attention: #fab387;
+  --success: #a6e3a1;
+  --diff-added: #a6e3a1;
+  --diff-removed: #f38ba8;
+  --pr-merged: #cba6f7;
+
+  /* Terminal — official Catppuccin Mocha ANSI */
+  --ansi-0:  #45475a;  --ansi-bg-fg-0:  #cdd6f4;
+  --ansi-1:  #f38ba8;  --ansi-bg-fg-1:  #11111b;
+  --ansi-2:  #a6e3a1;  --ansi-bg-fg-2:  #11111b;
+  --ansi-3:  #f9e2af;  --ansi-bg-fg-3:  #11111b;
+  --ansi-4:  #89b4fa;  --ansi-bg-fg-4:  #11111b;
+  --ansi-5:  #f5c2e7;  --ansi-bg-fg-5:  #11111b;
+  --ansi-6:  #94e2d5;  --ansi-bg-fg-6:  #11111b;
+  --ansi-7:  #bac2de;  --ansi-bg-fg-7:  #11111b;
+  --ansi-8:  #585b70;  --ansi-bg-fg-8:  #cdd6f4;
+  --ansi-9:  #f38ba8;  --ansi-bg-fg-9:  #11111b;
+  --ansi-10: #a6e3a1;  --ansi-bg-fg-10: #11111b;
+  --ansi-11: #f9e2af;  --ansi-bg-fg-11: #11111b;
+  --ansi-12: #89b4fa;  --ansi-bg-fg-12: #11111b;
+  --ansi-13: #f5c2e7;  --ansi-bg-fg-13: #11111b;
+  --ansi-14: #94e2d5;  --ansi-bg-fg-14: #11111b;
+  --ansi-15: #a6adc8;  --ansi-bg-fg-15: #11111b;
+}
+`;
diff --git a/apps/app/src/lib/themes/index.ts b/apps/app/src/lib/themes/index.ts
index e1afdfccc..ee3c55903 100644
--- a/apps/app/src/lib/themes/index.ts
+++ b/apps/app/src/lib/themes/index.ts
@@ -1,4 +1,5 @@
 import type { AppTheme, AppThemeId } from "@bb/domain";
+import { catppuccinThemeCss } from "./catppuccin";
 import { draculaThemeCss } from "./dracula";
 import { gruvboxThemeCss } from "./gruvbox";
 import { nordThemeCss } from "./nord";
@@ -18,6 +19,7 @@ const builtInThemeCss: Record<Exclude<AppThemeId, "custom">, string> = {
   dracula: draculaThemeCss,
   solarized: solarizedThemeCss,
   gruvbox: gruvboxThemeCss,
+  catppuccin: catppuccinThemeCss,
 };
 
 export function resolveAppThemeCss(appearance: AppTheme): string {
diff --git a/apps/server/src/services/skills/builtin-skills/bb-cli/SKILL.md b/apps/server/src/services/skills/builtin-skills/bb-cli/SKILL.md
index 13d440d35..e24828c92 100644
--- a/apps/server/src/services/skills/builtin-skills/bb-cli/SKILL.md
+++ b/apps/server/src/services/skills/builtin-skills/bb-cli/SKILL.md
@@ -148,7 +148,7 @@ For review or fix pipelines, get the environment ID from
 - Commands:
   - `bb theme list` — built-in themes and which palette is active.
   - `bb theme set <id>` — switch to a built-in: `default`, `nord`, `dracula`,
-    `solarized`, `gruvbox`.
+    `solarized`, `gruvbox`, `catppuccin`.
   - `bb theme set-custom --file <path.css>` — load a custom stylesheet and
     activate it. This is the only way to set custom CSS (Settings only switches
     between built-ins).
diff --git a/apps/server/src/services/skills/builtin-skills/bb-cli/references/theming.md b/apps/server/src/services/skills/builtin-skills/bb-cli/references/theming.md
index 4ed7aff20..0b9c9733f 100644
--- a/apps/server/src/services/skills/builtin-skills/bb-cli/references/theming.md
+++ b/apps/server/src/services/skills/builtin-skills/bb-cli/references/theming.md
@@ -230,7 +230,7 @@ and semantics:
 - `bb theme set-custom --file ./my-theme.css` — load and activate a custom
   stylesheet (the only way to set custom CSS).
 - `bb theme set <id>` — switch to a built-in (`default`, `nord`, `dracula`,
-  `solarized`, `gruvbox`).
+  `solarized`, `gruvbox`, `catppuccin`).
 - `bb theme show --css` — dump the active custom CSS; `bb theme list` shows the
   active palette; `bb theme reset` returns to `default`.
 
diff --git a/packages/domain/src/app-theme.ts b/packages/domain/src/app-theme.ts
index 4c28d4464..a4df63a85 100644
--- a/packages/domain/src/app-theme.ts
+++ b/packages/domain/src/app-theme.ts
@@ -15,6 +15,7 @@ export const appThemeIdSchema = z.enum([
   "dracula",
   "solarized",
   "gruvbox",
+  "catppuccin",
   "custom",
 ]);
 export type AppThemeId = z.infer<typeof appThemeIdSchema>;
@@ -44,6 +45,11 @@ export const builtInThemes: readonly BuiltInThemeMeta[] = [
     description: "Balanced light and dark (Schoonover palette)",
   },
   { id: "gruvbox", name: "Gruvbox", description: "Warm retro earth tones" },
+  {
+    id: "catppuccin",
+    name: "Catppuccin",
+    description: "Soothing pastel — Latte light, Mocha dark",
+  },
 ];
 
 /** Built-in palette ids (everything except "custom"). */