serena

A set of operating rules for Serena's code-navigation service, including a startup check and language-server tools. A language server helps an agent understand code symbols and their relationships.

In plain words
What is it for?
Use it when working with Serena, navigating code symbols, finding references, or renaming code through language-intelligence tools.
Why use it?
It gives the agent boundaries for using Serena and specifies that it should use the language-server backend instead of JetBrains tools.

Cursor rule for Cursor

Install

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.

agentmods
npx agentmods add rules/zzyzxlab/tao.js/serena
Clone the repo
git clone --depth 1 https://github.com/zzyzxlab/tao.js

Made for: Cursor.

Per session 174 This file is loaded in full into every session.
When invoked 174 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin unknown No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00174 $0.00174
Opus 5 $0.00087 $0.00087
Sonnet 5 $0.00035 $0.00035
Haiku 4.5 $0.00017 $0.00017

Measured 3d ago against content hash e9728499edd7, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

serena 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 3d 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.

.cursor/rules/serena.mdc · 19 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

Changes

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.

  1. 3d ago First seen · 19 lines · 174 tokens per session scan A e9728499edd7

Subscribe to this mod's changes

serena is a cursor rule published in the GitHub repository zzyzxlab/tao.js (11 stars, last pushed 13d ago), with no licence file. It adds 174 tokens to every session, about $0.0009 per session on Opus 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.