existing-code

A project rule saying that existing code should not be changed unless the user asks for that change.

In plain words
What is it for?
It is for setting a boundary around changes during coding work.
Why use it?
It helps prevent unrelated edits to code that is already in the project.

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/matipojo/cursor-rules/existing-code
Clone the repo
git clone --depth 1 https://github.com/matipojo/cursor-rules

Made for: Cursor.

Per session 25 This file is loaded in full into every session.
When invoked 25 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin original 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 $0.00025 $0.00025
Opus 5 $0.00013 $0.00013
Sonnet 5 $0.00005 $0.00005
Haiku 4.5 $0.00003 $0.00003

Measured 2d ago against content hash 0df041ac94dc, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

existing-code 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.

.cursor/rules/existing-code.mdc · 6 lines

What it actually says

Never touch existing code unless it's part of a user request

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. 2d ago First seen · 6 lines · 25 tokens per session scan A 0df041ac94dc

Subscribe to this mod's changes

existing-code is a cursor rule published in the GitHub repository matipojo/cursor-rules (31 stars, last pushed 1y ago), licensed MIT. It adds 25 tokens to every session, about $0.0001 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.