---
title: "block-invisible-unicode"
description: "The mechanizable slice of prompt-injection defense, enforced at two points: at commit (the git hook, over staged changes) and at agent tool-use (over a tool call's arguments, as the agent writes), invisible and direction"
canonical: https://agentpluginsdirectory.com/plugins/block-invisible-unicode
last-updated: 2026-10-02
---

# block-invisible-unicode
The mechanizable slice of prompt-injection defense, enforced at two points: at commit (the git hook, over staged changes) and at agent tool-use (over a tool call's arguments, as the agent writes), invisible and direction-override Unicode. Bidi controls make code read differently than it parses (Trojan Source, CVE-2021-42574); Unicode tag-block characters smuggle instructions that are invisible to a human reviewer but fully legible to the agent reading the file. Zero-width joiners and bidi marks (ZWJ/ZWNJ/LRM/RLM) are deliberately NOT matched, they are legitimate in emoji sequences and in Persian, Arabic and Indic text, so ordinary internationalised content passes; only the override/embed/isolate controls and the tag block, which have no honest use in a source tree, are blocked. Escape: 'pragma: allowlist invisible-unicode' on the same line.
- Slug: block-invisible-unicode
- Publisher: chock-core
- Repository: https://github.com/open-coder-ai/chock
- Manifest: .agents/policies/block-invisible-unicode/plugin.json
- Version: 0.0.4
- License: Apache-2.0
- Category (editorial): security
- Skills: 1 (block-invisible-unicode)
- MCP servers: 0
- Stars: 8
- Repository created: 2026-08-17
- Repository last pushed: 2026-10-02
- Publisher type: Organization
- Listing: https://agentpluginsdirectory.com/plugins/block-invisible-unicode
- Schema: https://agent-plugins.org/schemas/1.0.0/plugin.schema.json

## Skills

- block-invisible-unicode: Pre-commit gate for the mechanizable slice of prompt-injection defense: invisible and direction-override Unicode in staged changes. Bidi controls make code read differently than it parses (Trojan Source, CVE-2021-42574); Unicode tag-block characters smuggle instructions that are invisible to a huma…

Descriptions come from the frontmatter of each SKILL.md, punctuation lightly normalized.