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.
npx skills add study8677/repobrain --skill knowledge-layergit 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/skills/study8677/repobrain/knowledge-layer)<a href="https://agentmods.dev/skills/study8677/repobrain/knowledge-layer"><img src="https://agentmods.dev/badge/skills/study8677/repobrain/knowledge-layer/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/study8677/repobrain/knowledge-layer"><img src="https://agentmods.dev/badge/skills/study8677/repobrain/knowledge-layer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00042 | $0.00379 |
| Opus 5.5 | $0.00017 | $0.00152 |
| Sonnet 5.5 | $0.00008 | $0.00076 |
| Haiku 4.5 | $0.00004 | $0.00038 |
Grade A, and why
knowledge-layer 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 9d 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
Knowledge Layer Skill
Purpose
Provide a high-level deployment wrapper over RepoBrain core, with graph-first knowledge injection and all-file support (code, docs, data, media metadata).
Inputs
refresh_filesystem(workspace=".", full=False)ask_filesystem(question, workspace=".")
Refresh automatically chooses a first complete build, matching interrupted-task
resume, committed-diff update, or no-op. full=True always starts a new complete
build. The workspace defaults to the current directory and must be a clean Git
worktree. Ask stays read-only and only suggests rb-refresh when knowledge is
stale. Both refresh surfaces report failures without replacing usable knowledge.
Outputs
- Refresh writes graph-first artifacts under
.repobrain/:knowledge_graph.jsonknowledge_graph.mdknowledge_graph.mmddocument_index.mddata_overview.mdmedia_manifest.md- plus existing
conventions.mdandstructure.md
- Ask returns a grounded answer with source paths.
Boundaries
- Skill is a wrapper layer only; no standalone runtime.
- Core Hub/Agent/Pipeline architecture remains the source of truth.
Compatibility
- Existing commands (
rb-refresh,rb-ask,rb-mcp) remain valid. - High-level aliases can be disabled with
RB_ENABLE_LAYER_ALIASES=0.
Degrade Strategy
- If graph artifacts are unavailable, ask falls back to
structure.mdandconventions.mdcontext.
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 9d ago Changed · +6 lines 8314db5595e8
- 1mo ago First seen · 38 lines · 42 tokens per session scan A 50de21c42cdb
knowledge-layer is a skill published in the GitHub repository study8677/repobrain (1,346 stars, last pushed 3d ago), licensed MIT. It adds 42 tokens to every session and 379 once invoked, about $0.0002 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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