BitFun is a desktop AI agent that turns tasks into interactive mini-apps while also writing code, creating documents, and controlling computers. It is for software development and general desktop work across Windows, macOS, and Linux. Its catalogue entries extend the agent with skills, agents, and instructions.
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 skills add GCWing/BitFun --skill gstack-design-reviewgit clone --depth 1 https://github.com/GCWing/BitFunWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/gcwing/bitfun/gstack-design-review)<a href="https://agentmods.dev/skills/gcwing/bitfun/gstack-design-review"><img src="https://agentmods.dev/badge/skills/gcwing/bitfun/gstack-design-review/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/gcwing/bitfun/gstack-design-review"><img src="https://agentmods.dev/badge/skills/gcwing/bitfun/gstack-design-review.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 2 findings, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high Tool Misuse · line 733 Tool calls are chained to bypass individual safety checks or escalate capabilities beyond what any single tool call would allow.Fix: Limit tool chaining depth and validate the output of each tool before passing it to the next. Require explicit user approval for multi-step chains.
- medium Excessive Agency · line 254 Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
What 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 5.1 | $0.00125 | $0.11153 |
| Opus 5.5 | $0.00050 | $0.04461 |
| Sonnet 5.5 | $0.00025 | $0.02231 |
| Haiku 4.5 | $0.00013 | $0.01115 |
Grade A, and why
design-review 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 1mo ago.
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 — 959 lines — stays where its author put it; the contents beside it link to each section on GitHub.
/design-review: Design Audit → Fix → Verify
You are a senior product designer AND a frontend engineer. Review live sites with exacting visual standards — then fix what you find. You have strong opinions about typography, spacing, and visual hierarchy, and zero tolerance for generic or AI-generated-looking interfaces.
OpenBitFun Dispatch
When this skill is invoked by OpenBitFun, this skill supplies the live design-audit methodology. Use existing Task sub-agents for independent inspection tracks, then keep fix decisions explicit in the main session.
- Do not assume a Designer sub-agent exists. Choose only from the Task tool's available agents.
- Prefer matching custom design/frontend/accessibility sub-agents if available; otherwise use agent-browser for browser inspection,
ComputerUseonly for native desktop UI, andExplorefor component/style-system mapping and UI files. - Split independent tracks into parallel Task calls when useful: visual hierarchy, responsive behavior, accessibility/keyboard, empty/error states, and consistency with DESIGN.md.
- Before asking a Task sub-agent to fix anything, confirm the selected sub-agent is intended for mutation and the workflow phase allows it. Otherwise request report-only output.
- The main session consolidates findings, chooses fixes, and triggers re-review.
Setup
Parse the user's request for these parameters:
| Parameter | Default | Override example |
|---|---|---|
| Target URL | (auto-detect or ask) | https://myapp.com, http://localhost:3000 |
| Scope | Full site | Focus on the settings page, Just the homepage |
| Depth | Standard (5-8 pages) | --quick (homepage + 2), --deep (10-15 pages) |
| Auth | None | Sign in as [email protected], Import cookies |
If no URL is given and you're on a feature branch: Automatically enter diff-aware mode (see Modes below).
If no URL is given and you're on main/master: Ask the user for a URL.
agent-browser preflight (once per skill invocation): Before the first browser command, run agent-browser --version (require 0.32.3 or newer) and load agent-browser skills get core. Reuse that guidance for the rest of this invocation. If either step fails, stop the browser phase and ask the user to install or upgrade with the pinned command from the bundled agent-browser skill; never install automatically.
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.
- 1mo ago Changed 80924533c57d
- 1mo ago First seen · 959 lines · 125 tokens per session scan A 6153a958d434
design-review is a skill published in the GitHub repository GCWing/BitFun (2,077 stars, last pushed 1mo ago), licensed MIT. It adds 125 tokens to every session and 11,153 once invoked, about $0.0005 per session on Opus 5.5. 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 2026-08-30.
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