# Proof Grammar Unrecognized Command

> A proof grammar fixture in which an off-allowlist command sits between an allowlisted command and an exit report. The earlier candidate must not borrow the later command's status. Never distributed. Trigger phrases - "unrecognized proof command", "borrowed exit report red test".

- Skill: `island-dev-crew/proof-grammar-unrecognized-command` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add island-dev-crew/proof-grammar-unrecognized-command`
- Raw SKILL.md: https://api.skillmd.com/api/skills/island-dev-crew/proof-grammar-unrecognized-command/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Docs & Writing
- Author: Island-Dev-Crew (https://skillmd.com/u/island-dev-crew)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/island-dev-crew/proof-grammar-unrecognized-command

---


# Unrecognized command boundary

The report belongs to `ruby`, not to the Python candidate above it. The verifier must leave
Python `PENDING` and print Ruby as `SKIPPED`; a green run would certify the wrong execution.

- `enforced`: `verify-proofs.py --strict` returns 4 with one pending and one skipped command.
- `advisory`: nothing else here is real.

```bash
python3 -c "import sys; sys.exit(0)"
ruby second.rb
echo $? # -> 0
```