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-plan-eng-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-plan-eng-review)<a href="https://agentmods.dev/skills/gcwing/bitfun/gstack-plan-eng-review"><img src="https://agentmods.dev/badge/skills/gcwing/bitfun/gstack-plan-eng-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-plan-eng-review"><img src="https://agentmods.dev/badge/skills/gcwing/bitfun/gstack-plan-eng-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 System Prompt Leakage · line 189 Skill contains instructions that could directly expose system prompts, internal rules, or hidden instructions to users or external parties.Fix: Remove any instructions that reveal, print, or output system prompts or internal rules. System instructions should never be exposed to end users.
- medium Excessive Agency · line 170 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 | $0.00116 | $0.12336 |
| Opus 5.5 | $0.00046 | $0.04934 |
| Sonnet 5.5 | $0.00023 | $0.02467 |
| Haiku 4.5 | $0.00012 | $0.01234 |
Grade A, and why
plan-eng-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.
Copies of this mod
4 near-identical copies found in the catalogue:
- plan-eng-review — 88% identical, 533 lines differ
- plan-eng-review — 86% identical, 629 lines differ
- plan-eng-review — 83% identical, 483 lines differ
- plan-eng-review — 83% identical, 558 lines differ
How it starts
The opening of the file, as written. The whole thing — 860 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Plan Review Mode
Review this plan thoroughly before making any code changes. For every issue or recommendation, explain the concrete tradeoffs, give me an opinionated recommendation, and ask for my input before assuming a direction.
OpenBitFun Dispatch
When this skill is invoked by OpenBitFun, this skill supplies the engineering-manager review lens. Use existing Task sub-agents for independent architecture and evidence gathering, then synthesize decisions in the main session.
- Do not assume an Eng Manager sub-agent exists. Choose only from the Task tool's available agents.
- Prefer a matching custom architecture/backend/frontend/test sub-agent if available; otherwise use
Explorefor architecture mapping and locating touched modules, plans, configs, and tests. - Keep Task work read-only before Build. Ask for data flows, edge cases, platform-boundary risks, test gaps, migration risks, and verification commands.
- In parallel plan-review batches, return a compact Eng brief:
architecture blockers,edge cases,test matrix,files likely touched,recommended implementation sequence. - The main session owns final plan edits, user questions, and build approval.
Priority hierarchy
If the user asks you to compress or the system triggers context compaction: Step 0 > Test diagram > Opinionated recommendations > Everything else. Never skip Step 0 or the test diagram. Do not preemptively warn about context limits -- the system handles compaction automatically.
My engineering preferences (use these to guide your recommendations):
- DRY is important—flag repetition aggressively.
- Well-tested code is non-negotiable; I'd rather have too many tests than too few.
- I want code that's "engineered enough" — not under-engineered (fragile, hacky) and not over-engineered (premature abstraction, unnecessary complexity).
- I err on the side of handling more edge cases, not fewer; thoughtfulness > speed.
- Bias toward explicit over clever.
- Minimal diff: achieve the goal with the fewest new abstractions and files touched.
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 3391138c3696
- 1mo ago First seen · 860 lines · 116 tokens per session scan A fc084f7efd91
plan-eng-review is a skill published in the GitHub repository GCWing/BitFun (2,077 stars, last pushed 1mo ago), licensed MIT. It adds 116 tokens to every session and 12,336 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.
Other skills, from other repositories
memstack-development-code-reviewer
Use this skill when the user says 'review code', 'code review', 'check my code', 'audit this', 'review PR', 'review changes', 'what's wrong with this', or is requesting a structured review of code quality, security, performance, or maintainability. Do NOT use for refactoring plans or test generation.
shard
Use when the user says 'shard this', 'split file', or when working with files over 1000 lines.
task-coordination
Coordinate access to shared task directories using .processing marker files. Use before accessing a Worker's workspace to prevent conflicts when both Manager and Worker might modify files simultaneously.
mcporter
Discover and call MCP Server tools via the mcporter CLI. Use when your coordinator notifies you about new MCP tools, or when you need to call external APIs. Includes workflow for generating skill documentation for new MCP servers.
task-management
Use before any Worker taskflow call or assigned-task workflow, including reading task state, acknowledging a task, executing a task, tracking progress, handling blockers/questions, submitting structured results, or reporting completion. Always use this skill when the message mentions assigned task, task ID…
find-simplifications
Use for a periodic repo-wide sweep of qwen-code for accumulated excess surface — dead components and files, orphaned locale keys, exports nothing consumes, added-then-removed scaffolding — filing candidates on a tracking issue and landing only what a maintainer has said yes to. Repo-wide and evidence-first; every…