Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/get-bb/bb/bb-theme-authoringnpx skills add get-bb/bb --skill bb-theme-authoringgit clone --depth 1 https://github.com/get-bb/bbWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00063 | $0.01366 |
| Opus 5 | $0.00032 | $0.00683 |
| Sonnet 5 | $0.00013 | $0.00273 |
| Haiku 4.5 | $0.00006 | $0.00137 |
Grade A, and why
bb-theme-authoring scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured today.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 128 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Authoring a bb theme
A bb theme is one CSS file that overrides the app's CSS custom properties. bb discovers custom themes on disk and the Theme Preview panel shows every resolved token, its validation state, and an app mock that repaints as you edit. Work in a split: your agent thread on one side, Theme Preview on the other. Nothing needs a restart.
Theme Preview is visualization and validation only. It never creates, writes,
forks, repairs, or deletes a theme resource. Create and update theme.css from
the separate agent thread; use the existing bb theme commands to locate,
inspect, and activate themes. Validation reports inconsistent or inaccessible
results, but it never changes authored values.
Where themes live
bb theme dir # the custom-theme directory, e.g. ~/.bb/theme
One directory per theme, one file inside it:
<theme dir>/<name>/theme.css
<name> is the theme id: lowercase, letters, digits and dashes, a single path
segment. Create the directory and the file and it is listed immediately — the
Theme Preview dropdown picks it up on its next catalog refresh while the panel
is open, and bb theme list shows it at once.
File shape
Two top-level blocks. Light values in :root, .light, dark values in .dark.
Every declaration is a --token: value; custom property.
:root, .light {
--canvas: #f4f4f4; /* the app background */
--ink: #0a0a0a; /* body text */
--primary: #2e6f95; /* links, focus ring, accents */
--primary-foreground: #ffffff;
/* …more tokens… */
}
.dark {
--canvas: #1a1a1a;
--ink: #dbd8d1;
--primary: #9db6c6;
--primary-foreground: #0a0a0a;
}
You only need to declare what you change; everything else derives from bb's
base theme. The anchors that drive the most are --canvas, --ink,
--primary and --sidebar.
Tokens worth knowing
| group | tokens |
|---|---|
| Surfaces | --canvas --sidebar --card --popover --secondary --muted --surface-recessed-solid --surface-scrim |
| Ink | --ink (body) --foreground --muted-foreground --subtle-foreground --readback-foreground --sidebar-foreground |
| Accent and state | --primary --primary-foreground --file-accent --timeline-accent --surface-selected --state-hover --state-active --sidebar-accent |
| Status | --success --warning --warning-text --destructive --destructive-text --pr-merged --diff-added --diff-removed |
| Lines | --border --border-hairline --border-seam --sidebar-border --input --ring |
| Type | --font-sans --font-mono (declare once in :root) |
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- today First seen · 128 lines · 63 tokens per session scan A be1a9f98ab8a
bb-theme-authoring is a skill published in the GitHub repository get-bb/bb (2,888 stars, last pushed yesterday), licensed MIT. It adds 63 tokens to every session and 1,366 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-02.
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