CC Safety Net is a pre-execution guard that analyzes coding-agent tool calls and blocks destructive commands or attempts to access sensitive files. It is for people using supported coding-agent command-line tools on Windows, macOS, or Linux. The catalogue entries provide its safety rules, instructions, hook, and plugin.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add kenryu42/cc-safety-net --skill verify-project-tighten-onlygit clone --depth 1 https://github.com/kenryu42/cc-safety-netWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/kenryu42/cc-safety-net/verify-project-tighten-only)<a href="https://agentmods.dev/skills/kenryu42/cc-safety-net/verify-project-tighten-only"><img src="https://agentmods.dev/badge/skills/kenryu42/cc-safety-net/verify-project-tighten-only/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/kenryu42/cc-safety-net/verify-project-tighten-only"><img src="https://agentmods.dev/badge/skills/kenryu42/cc-safety-net/verify-project-tighten-only.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00148 | $0.02066 |
| Opus 5.5 | $0.00059 | $0.00826 |
| Sonnet 5.5 | $0.00030 | $0.00413 |
| Haiku 4.5 | $0.00015 | $0.00207 |
Grade A, and why
verify-project-tighten-only scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Verify: a project policy cannot weaken the user policy under tighten-only
The promise
Property. With CC_SAFETY_NET_PROJECT_TIGHTEN_ONLY=1, every protection the user policy gives on its own is still given after mergeProjectPolicy merges in the project policy.
Harm if broken. A user opts into tighten-only so that a cloned repo cannot relax their guard. If the merge misses one weakening, a repo's project policy file silently turns off a destructive-command rule, a capability such as fail_closed, or secret protection for a path, and the agent runs what the user meant to block.
Run it
bun test tests/core/policy/merge-tighten-only.test.ts
It takes about 2 seconds and needs no tool beyond Bun. It also runs in bun run check (the pre-push hook and CI), so a break fails the push even if nobody runs it by hand.
What it checks
The check calls the real code, not a copy: mergeProjectPolicy(user, project, true, sessionSafetyLevel(user.safety.level, env)) exactly as loadPolicyConfig in src/core/policy/store.ts calls it. It then turns both the user policy alone and the merged policy into a set of protections with the same functions the hook uses: getCCSafetyNetEnvModes (capabilities, worktree mode), resolveEffectiveDestructiveCommandRules (which destructive rules are on), and resolveSecretDisabledRules. It fails if any protection of the user policy is missing from the merged one, and prints at most three counterexamples.
A protection is one of these strings:
| Protection | Present when |
|---|---|
fail_closed, paranoid_rm, paranoid_interpreters |
that capability is enabled |
no worktree relaxations |
worktree mode is off |
rule <id> |
that destructive rule is enabled (catastrophic rules always are) |
recursive delete checked in <path> |
destructive protection is on and <path> is not in allow_paths |
secret deny <path> |
secret protection is on and <path> is in deny_paths |
secret rule <id> in <path> |
secret protection is on, the rule is not disabled, and <path> is not in allow_paths |
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 4d ago First seen · 85 lines · 148 tokens per session scan A fadb303db5b9
verify-project-tighten-only is a skill published in the GitHub repository kenryu42/cc-safety-net (1,790 stars, last pushed 2d ago), licensed MIT. It adds 148 tokens to every session and 2,066 once invoked, about $0.0006 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-10-22.
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