RepoBrain is a repository knowledge engine that lets coding agents ask grounded questions about a codebase and receive answers linked to source files and lines. It is for developers using Claude Code, Cursor, Codex, Windsurf, and other AI coding tools. Catalogue add-ons extend its commands, instructions, skills, rules, plugin, and hook workflows.
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.
git clone --depth 1 https://github.com/study8677/repobrainWrote 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/commands/study8677/repobrain/rb-ask)<a href="https://agentmods.dev/commands/study8677/repobrain/rb-ask"><img src="https://agentmods.dev/badge/commands/study8677/repobrain/rb-ask/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/commands/study8677/repobrain/rb-ask"><img src="https://agentmods.dev/badge/commands/study8677/repobrain/rb-ask.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00033 | $0.00605 |
| Opus 5.5 | $0.00013 | $0.00242 |
| Sonnet 5.5 | $0.00007 | $0.00121 |
| Haiku 4.5 | $0.00003 | $0.00060 |
Grade A, and why
rb-ask 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 2d 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.
What it actually says
Run the RepoBrain CLI for the current workspace:
通过 RepoBrain CLI 询问当前工作区：
The engine prefers knowledge for HEAD, otherwise a compatible ancestor on the
current history. Uncommitted edits are allowed: use knowledge as background,
inspect current source for changed behavior, and keep freshness notices. Never
use unrelated sibling knowledge or automatically start a refresh. If no usable
knowledge exists on current history, report the rb-refresh hint.
允许边改边问。引擎优先读当前提交的知识，没有时读当前分支祖先版本；旧知识作为背景，
修改处以当前源码为准，保留时效提示。不要借用其他分支独有的知识，也不要自动刷新。
当前历史上没有可用知识时，再提示先运行 rb-refresh。
$ARGUMENTS
Use Bash:
RB_ASK_TIMEOUT_SECONDS="${RB_ASK_TIMEOUT_SECONDS:-120}" rb-ask "$ARGUMENTS" --workspace "$PWD"
If .env sets RB_HOST_RUNNER (codex or generic), the same command drives
the user's local logged-in CLI (Codex / Trae / Claude / …) for rb-ask instead
of an API key. The same host-runner backend also powers rb-refresh (tool-free
stages run through the CLI; conventions and git insights degrade to
deterministic output).
如果 .env 设置了 RB_HOST_RUNNER（codex 或 generic），同一个命令会通过
用户本机已登录的 CLI（Codex / Trae / Claude / …）运行 rb-ask，不走 API key。
同一套 host-runner 后端也支撑 rb-refresh（无工具阶段走 CLI，conventions 与
git insights 降级为确定性产物）。
使用 Bash：
RB_ASK_TIMEOUT_SECONDS="${RB_ASK_TIMEOUT_SECONDS:-120}" rb-ask "$ARGUMENTS" --workspace "$PWD"
If rb-ask is not found, tell the user the engine CLI is not installed and suggest:
如果找不到 rb-ask，说明 engine CLI 尚未安装，建议用户运行：
pipx install "git+https://github.com/study8677/repobrain.git#subdirectory=engine"
Prefer rb-ask over manual file search. If the answer returns insufficient detail, follow up with targeted Read/Grep.
优先使用 rb-ask，不要先手动搜索文件。如果返回的信息不够，再用有目标的 Read/Grep 补充。
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.
- 2d ago Changed · +10 lines a611b5a8e368
- 1mo ago First seen · 46 lines · 33 tokens per session scan A 971b9ef387d2
rb-ask is a command published in the GitHub repository study8677/repobrain (1,346 stars, last pushed 2d ago), licensed MIT. It adds 33 tokens to every session and 605 once invoked, about $0.0001 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 commands, from other repositories
create-skill
Create a new skill via GitHub search, LLM generation, or both.
sync-all
Sync skills, commands, MCP servers, and preferences between Claude, Codex, Copilot, and Cursor in one operation.
sync-to-cursor
Sync skills, commands, agents, hooks, rules, and MCP from Claude, Codex, or Copilot to Cursor IDE.
search-skills
Fuzzy search installed skills by name or description.
skill-trace-enable
Enable skill tracing to track which skills are loaded and invoked.
suggest-skills
Identify gaps in your skill library and suggest new skills to create based on project context.