symbi-policy

symbi-policy is a skill for Claude Code, Codex from ThirdKeyAI/symbi-gemini-cli. It costs 37 tokens per session (344 once invoked), scanned A, original, Apache-2.0.

A guide for creating, editing, and checking Cedar policies, which are text rules that decide what Symbiont agents may do.

In plain words
What is it for?
Use it to set permissions for agents, actions, and resources, including role-based, resource-scoped, time-limited, approval-required, and fully audited access.
Why use it?
It helps define access controls clearly and diagnose why a requested agent action is allowed or denied.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to set permissions for agents, actions, and resources, including role-based, resource-scoped, time-limited, approval-required, and fully audited access.

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Install with agentmods
npx agentmods add skills/thirdkeyai/symbi-gemini-cli/symbi-policy
Install

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.

Any agent
npx skills add ThirdKeyAI/symbi-gemini-cli --skill symbi-policy
Clone the repo
git clone --depth 1 https://github.com/ThirdKeyAI/symbi-gemini-cli

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for symbi-policy

README.md
[![agentmods](https://agentmods.dev/badge/skills/thirdkeyai/symbi-gemini-cli/symbi-policy/github.svg)](https://agentmods.dev/skills/thirdkeyai/symbi-gemini-cli/symbi-policy)
Your own site
<a href="https://agentmods.dev/skills/thirdkeyai/symbi-gemini-cli/symbi-policy"><img src="https://agentmods.dev/badge/skills/thirdkeyai/symbi-gemini-cli/symbi-policy/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.

agentmods 80×15 button for symbi-policy

Your own site · 80×15
<a href="https://agentmods.dev/skills/thirdkeyai/symbi-gemini-cli/symbi-policy"><img src="https://agentmods.dev/badge/skills/thirdkeyai/symbi-gemini-cli/symbi-policy.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 344 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00037 $0.00344
Opus 5 $0.00018 $0.00172
Sonnet 5 $0.00007 $0.00069
Haiku 4.5 $0.00004 $0.00034

Measured 9d ago against content hash ada80c8d52c5, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

symbi-policy 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 9d 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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

skills/symbi-policy/SKILL.md · 50 lines

What it actually says

Cedar Policy Management

Help the user create or modify Cedar policies for their Symbiont agents.

Cedar Policy Syntax Reference

Cedar policies use permit and forbid to control access:

// Allow an agent to read from a specific resource
permit(
    principal == Agent::"data-analyzer",
    action == Action::"read",
    resource in ResourceGroup::"public-datasets"
);

// Forbid writing PII unless the agent has HIPAA compliance
forbid(
    principal,
    action == Action::"write",
    resource
) when {
    resource.contains_pii == true
} unless {
    principal.compliance_level == "hipaa"
};

Common Policy Patterns

When asked to create a policy, identify the pattern:

  • Role-based: Different agent roles get different permissions
  • Resource-scoped: Permissions vary by resource type/sensitivity
  • Time-bounded: Permissions that expire or are scheduled
  • Approval-gated: Actions requiring human approval
  • Audit-all: Log everything, permit/deny selectively

Workflow

  1. Ask what the policy should govern (which agents, which actions, which resources)
  2. Identify the pattern from the list above
  3. Write the Cedar policy
  4. Save to policies/ directory
  5. If symbi is available, validate with symbi dsl parse to check syntax
Changes

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.

  1. 9d ago First seen · 50 lines · 37 tokens per session scan A ada80c8d52c5

Subscribe to this mod's changes

symbi-policy is a skill published in the GitHub repository ThirdKeyAI/symbi-gemini-cli (3 stars, last pushed 6mo ago), licensed Apache-2.0. It adds 37 tokens to every session and 344 once invoked, about $0.0002 per session on Opus 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 2026-08-31.