block-invisible-unicode

{
  "name": "block-invisible-unicode",
  "version": "0.0.4",
  "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-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. [Session-enforced via PreToolUse and Stop hooks; needs git and a Python 3.11+. PreToolUse judges the file a tool call would write; Stop re-reads what the turn actually left on disk, so a file written through a shell heredoc is judged too. With no working Python the hook exits 2; without git, fail-open clients allow silently. A gate that cannot reach a decision refuses rather than allowing one it never judged. Enforcement at every commit and in CI still needs chock installed in the repo. Codex requires a one-time trust review per hook -- the plugin is ADVISORY until you approve its hook, and a plugin update voids that trust until re-approved.]",
  "author": {
    "name": "chock-core"
  },
  "repository": "https://github.com/open-coder-ai/chock-catalog",
  "license": "Apache-2.0",
  "keywords": [
    "chock",
    "policy-as-code",
    "hook",
    "block",
    "{'control': 'asi01', 'coverage': 'partial', 'note': 'blocks the hidden-character slice of goal-hijack payloads a diff can show; semantic injection defense remains advisory (injection-defense, owasp-asi01-agent-goal-hijack)'}"
  ],
  "interface": {
    "displayName": "Block Invisible Unicode",
    "shortDescription": "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.",
    "composerIcon": "./assets/icon.svg"
  },
  "skills": "./skills",
  "hooks": "./hooks/hooks.json"
}