data-poisoning

data-poisoning is a cursor rule for Cursor from davidmatousek/tachi. It costs 41 tokens per session (2,029 once invoked), scanned A, original, Apache-2.0.

An AI security rule for finding manipulated data used to train, fine-tune, or provide context to a language model. RAG means retrieving supporting information from a knowledge base while answering a question.

In plain words
What is it for?
Use it to assess training datasets, fine-tuning inputs, RAG indexes, vector stores, and other data sources an AI model relies on.
Why use it?
It helps detect corrupted training data, poisoned retrieval indexes, damaged knowledge bases, and hidden backdoors in fine-tuning data.

Cursor rule for Cursor

Written for Cursor: a Cursor rule (.mdc).

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is output_schema: ../../../schemas/finding.yaml.

Good fit Use it to assess training datasets, fine-tuning inputs, RAG indexes, vector stores…

Compare 6 cursor rules from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/davidmatousek/tachi
agentmods
npx agentmods add rules/davidmatousek/tachi/data-poisoning

Made for: Cursor.

Wrote 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.

agentmods badge for data-poisoning

README.md
[![agentmods](https://agentmods.dev/badge/rules/davidmatousek/tachi/data-poisoning.svg)](https://agentmods.dev/rules/davidmatousek/tachi/data-poisoning)
Your own site
<a href="https://agentmods.dev/rules/davidmatousek/tachi/data-poisoning"><img src="https://agentmods.dev/badge/rules/davidmatousek/tachi/data-poisoning.svg" alt="Measured on agentmods" height="20"></a>
Per session 41 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,029 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00041 $0.02029
Opus 5 $0.00020 $0.01014
Sonnet 5 $0.00008 $0.00406
Haiku 4.5 $0.00004 $0.00203

Measured 3d ago against content hash d9a2f4877f1e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

data-poisoning 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.

adapters/cursor/rules/data-poisoning.mdc · 168 lines

How it starts

The opening of the file, as written. The whole thing — 168 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Metadata

category: llm
threat_class: LLM
dfd_targets: [Data Store, Data Flow]
owasp_references: [OWASP LLM04:2026, OWASP LLM05:2026, OWASP LLM09:2026]
output_schema: ../../../schemas/finding.yaml

Data Poisoning Threat Agent

Purpose

Detects threats where an attacker manipulates the data that an LLM relies on for training, fine-tuning, or runtime context retrieval. Data poisoning undermines the integrity of model outputs at the source: corrupted training data produces systematically biased or unsafe model behavior, poisoned RAG knowledge bases cause the model to return attacker-controlled content as authoritative answers, and contaminated fine-tuning datasets embed persistent backdoors that activate on specific trigger inputs. This agent identifies training data manipulation, RAG index poisoning, knowledge base corruption, and fine-tuning supply chain attacks.

Detection Scope

Trigger Keywords

This agent activates when a DFD element name or description matches any of the following patterns (case-insensitive):

  • LLM
  • model
  • GPT
  • Claude
  • training
  • fine-tuning
  • fine tuning
  • RAG
  • retrieval
  • knowledge base
  • vector store
  • embedding
  • corpus

Applicable DFD Element Types

  • Data Store: Databases, vector stores, document repositories, embedding indexes, training data lakes, fine-tuning datasets, and knowledge bases that feed content into LLM pipelines.
  • Data Flow: Data pipelines that transport training data, retrieval results, embeddings, or context documents between storage and model inference processes.

Detection Patterns

  1. Training Data Manipulation: Unauthorized modification of training or fine-tuning datasets to embed biased, incorrect, or backdoored content. Look for:
    • Training datasets sourced from public or user-contributed repositories without integrity verification
    • Absence of data provenance tracking (who contributed what, when, from where)
    • No checksum or hash validation on training data files between collection and use
    • Fine-tuning pipelines that pull data from mutable shared storage without snapshot isolation

Read the full file on GitHub · 168 lines

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 · 168 lines · 41 tokens per session scan A d9a2f4877f1e

Subscribe to this mod's changes

data-poisoning is a cursor rule published in the GitHub repository davidmatousek/tachi (90 stars, last pushed 25d ago), licensed Apache-2.0. It adds 41 tokens to every session and 2,029 once invoked, about $0.0002 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 2026-09-03.