# Block Risky Characters in File and Branch Names

Block Risky Characters in File and Branch Names: what it does, its label on each agent, what it misses, and examples.

Catalog policy refname-filename-metachar, version 0.1.5, labelled blocks on Claude Code.

> Ask the user before running any command on this page: each one changes how their agent or repository behaves.

## What it does

Refuses names a shell, CI step or git can misread. Paths a change adds or renames into (commit, agent writes), and branches and tags pushed (pre-push), with command substitution, an IFS expansion, a backtick, ; & | \< \>, a double quote, a backslash, a control or bidi character, a base64-decode shape, a leading dash or trailing space or dot in a segment, or a '..' segment; a ref also with a full commit id's shape. A guard refuses git and file commands creating such names. No waiver. Friction, not a boundary.

## On each agent

| Agent | Label | What it does there |
| --- | --- | --- |
| Claude Code | Blocks | Refuses a matched shell command before it runs. Blocks on an agent's file writes and at turn end |
| Cursor | Blocks | Refuses a matched shell command before it runs. Blocks on an agent's file writes and at turn end |
| Codex | Blocks | Refuses a matched shell command before it runs. 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) |
| GitHub Copilot | Blocks | Refuses a matched shell command before it runs. 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) |
| Devin | Blocks | Refuses a matched shell command before it runs. 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) |
| Grok | Not graded | Not graded yet for Grok |
| goose | Not graded | Not graded yet for goose |
| Antigravity | Not graded | Not graded yet for Antigravity |
| OpenHands | Not graded | Not graded yet for OpenHands |
| Kimi Code | Not graded | Not graded yet for Kimi Code |
| Factory Droid | Not graded | Not graded yet for Factory Droid |

## What it misses

This policy does not state what it misses.

## Examples from its eval suite

Refused: A change adds a file whose name carries command substitution that decodes and runs a payload.

Allowed: A change adds ordinary source files.

## More

- [The policy on the catalog pages](https://chock.sh/coding/policies/refname-filename-metachar/)
- [Source at the pinned catalog commit](https://github.com/open-coder-ai/chock-catalog/tree/1e60d211c1bb767152c6ab0167932da06ab3a10f/base/refname-filename-metachar)


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