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/rules/study8677/repobrain/windsurfrules)<a href="https://agentmods.dev/rules/study8677/repobrain/windsurfrules"><img src="https://agentmods.dev/badge/rules/study8677/repobrain/windsurfrules/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/rules/study8677/repobrain/windsurfrules"><img src="https://agentmods.dev/badge/rules/study8677/repobrain/windsurfrules.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 | $0.00227 | $0.00227 |
| Opus 5.5 | $0.00091 | $0.00091 |
| Sonnet 5.5 | $0.00045 | $0.00045 |
| Haiku 4.5 | $0.00023 | $0.00023 |
Grade A, and why
windsurfrules 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.
What it actually says
Windsurf bootstrap rules
Authoritative behavior rules live in AGENTS.md.
Before acting:
- Read
AGENTS.md. - Load dynamic context from
.repobrain/(conventions.md,structure.md, decisions, memory).
Hard rule — query the RepoBrain hub first
When .repobrain/ exists, any broad codebase question (architecture, "where
is X implemented", "how does X work", "what calls X", dependency/impact
analysis, data flow, onboarding) MUST go through rb-ask first:
rb-ask "<question>" --workspace .
Do NOT manually grep, rg, find, or fan out file reads to answer a
broad question before you have run rb-ask for it. Manual search is allowed
only to verify exact lines after rb-ask points at a file, for narrow
single-symbol lookups, or when rb-ask is genuinely unavailable. See
AGENTS.md for the full policy.
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 First seen · 24 lines · 227 tokens per session scan A eb2fec3fe550
windsurfrules is a cursor rule published in the GitHub repository study8677/repobrain (1,327 stars, last pushed yesterday), licensed MIT. It adds 227 tokens to every session, about $0.0009 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 2026-09-08.
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ponytail
Ponytail, lazy senior dev mode. Always pick the simplest solution that works.
angular-20
This rule provides comprehensive best practices and coding standards for Angular development, focusing on modern TypeScript, standalone components, signals, and performance optimizations.
dev-standard
Apache Superset development standards and guidelines for Cursor IDE.
prefer-assertions-over-defensive-checks
Prefer assertions over defensive checks when data is guaranteed to be valid.
prefer-direct-imports-over-module-mocks
Prefer extracting a testable core over vi.mock / vi.resetModules when unit tests need to reach production logic entangled with config, env, or singletons.