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Themes

Themes restyle everything — the presence orb, the thought bubble, every card, and every surface BOR generates. A theme is a complete identity: a palette, fonts, border style, wallpaper, and a handbook that tells the AI how to design within it. You change themes just by asking.

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Changing the theme

“Make it feel like a glossy 2000s aqua desktop.”

BOR sets the matching theme (y2k-frutiger), optionally generates a matching wallpaper, may set fonts, and restyles the presence and all surfaces. Tools:

• set_theme — set the theme, and optionally a wallpaper and fonts.
• reset_theme — return to the default.

set_theme can carry:

• a <wallpaper> — either from_prompt="…" (BOR generates an image), a literal url="…", or a CSS background string.
• <fonts display="…" system="…" mono="…"> — typography overrides.
• <atmosphere> — ambient styling.

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The v2 presence themes

The v2 presence ships ten full themes, each with its own token set (palette, accent, fonts, border/radius style): The presence reads data-theme from config and applies the right token block. These same themes drive the look of the MCP marketplace window, which mirrors whichever theme you’re on.

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Theme handbooks (design guidelines)

A theme isn’t just CSS — it’s a handbook the AI must read before generating a surface for that theme. The handbooks live in design-guideline/<theme>.md (and the classic shell has many more theme handbooks under shell/themes/). The handbook is the canonical contract: palette, type scale, spacing, components, motion, and the dos/don’ts that keep a generated surface on-brand. This is enforced by the design gate: before the first create_app/create_shortcut/update_* in a turn, BOR must call get_ux_ui_strict_guidelines, which returns:

• the strict shortcut-card spec (design-guideline/shortcut-card.md),
• the app icon kit (UX_app_icons_and_thumbnails.html),
• the active theme’s handbook.

Only after seeing those may BOR generate a surface. This is why every surface looks intentional rather than generic.

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The default aesthetic

BOR’s default aesthetic is strict, Apple-grade black & white — no emojis, no gradients, no color in core UI. The named themes above are deliberate, opinionated departures from that default; within a theme, BOR follows that theme’s identity (which may be very colorful). The design skill is run before any UI redesign.

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Wallpapers

When a theme calls for it, BOR generates a wallpaper with the image tool and applies it as the macOS desktop wallpaper (best-effort, via the host). Generated wallpapers are saved under os-data/.../images/ and the applied one under os-data/v2-wallpaper/.

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Per-theme user extras

Each theme has a user-extras.css (one of the few files in the source tree BOR is allowed to write). It’s the AI’s canvas for “I want a sticker on the homepage” or “a clock in the corner” — small decorative additions that persist for that theme without touching the OS source.

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Tools

See Adding a theme to build your own.