Block Invisible Unicode
Blocks on an agent's file writes and at turn end.
Acts on
File write · Turn end
When
Before the file write · at turn end
Tested
72 of 72 pass
In a git repo
At commit
What it does
Blocks hidden Unicode in added lines: bidi, tag and plane-14 chars, word joiner, chained invisibles, zero-width/joiners/fillers by ASCII, mid-line BOM, LRM/RLM outside RTL text, selectors after ASCII, private-use runs of 16+. Allows emoji, RTL/Indic/Thai/CJK text, line-start BOM. Not caught: homoglyphs, a joiner between non-ASCII, binary files and text after U+2028 at commit. Runs: commit, agent write, turn's end. Waiver: 'pragma: allowlist invisible-unicode' same line; agent: HEAD only.
Chock adds friction. It is not a security boundary.
Its label on each agent
The catalog grades each policy on each agent. Pick an agent to build with this policy:
- Claude Code TestedBlocks Blocks on an agent's file writes and at turn endBuild →
- Cursor TestedBlocks Blocks on an agent's file writes and at turn endBuild →
- Codex TestedBlocks Blocks on an agent's file writes and at turn end. If the hook errors, the action goes through (not witnessed; the vendor's row is only partly live-run)Build →
- GitHub Copilot TestedBlocks Blocks at turn end only. It does not check a file write when it happens. If the hook errors, the action goes through (not witnessed; the vendor's row is only partly live-run)Build →
- Devin TestedBlocks Blocks at turn end only. It does not check a file write when it happens. If the hook errors, the action goes through (vendor docs only, not witnessed)Build →
- Grok Tested Not graded yet for GrokBuild →
- goose Tested Not graded yet for gooseBuild →
- Antigravity Tested Not graded yet for AntigravityBuild →
- OpenHands Untested Not graded yet for OpenHandsBuild →
- Kimi Code Untested Not graded yet for Kimi CodeBuild →
- Factory Droid Untested Not graded yet for Factory DroidBuild →
See it in action
Refused
A staged source file uses a right-to-left override to disguise code (Trojan Source).
Allowed
A staged file contains ordinary ASCII source code.
Both examples are this policy's own test cases.
What it misses
This policy does not state what it misses.
Latest change
0.1.1 · · Promoted from draft to production: every test case ran and passed, and no bug report was open. Behaviour unchanged.