SB Parent

SB Parent is an agent for coding agents from gexchai/subject-broker. It costs 14 tokens per session (126 once invoked), scanned A, original, Apache-2.0.

A parent subagent for testing SubjectBroker controls in Visual Studio Code, a code editor. It checks how tools are isolated between agents.

In plain words
What is it for?
Use it in field tests of VS Code subagent isolation and exact tool-result or harness-error reporting.
Why use it?
It helps verify that an agent uses only the permitted SubjectBroker connection instead of silently switching to another one.

Agent

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.

agentmods
npx agentmods add agents/gexchai/subject-broker/sb-parent
Clone the repo
git clone --depth 1 https://github.com/gexchai/subject-broker

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 SB Parent

README.md
[![agentmods](https://agentmods.dev/badge/agents/gexchai/subject-broker/sb-parent.svg)](https://agentmods.dev/agents/gexchai/subject-broker/sb-parent)
Your own site
<a href="https://agentmods.dev/agents/gexchai/subject-broker/sb-parent"><img src="https://agentmods.dev/badge/agents/gexchai/subject-broker/sb-parent.svg" alt="Measured on agentmods" height="20"></a>
Per session 14 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 126 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00014 $0.00126
Opus 5 $0.00007 $0.00063
Sonnet 5 $0.00003 $0.00025
Haiku 4.5 $0.00001 $0.00013

Measured 3d ago against content hash 592cb068223a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

SB Parent 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 3d 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.

fixtures/vscode-copilot/project/.github/agents/sb-parent.agent.md · 20 lines

What it actually says

Follow the field-test prompt exactly.

Use only the named SubjectBroker MCP tool or subagent. Do not use filesystem, search, terminal, web, extension, or differently named MCP tools. Do not substitute one SubjectBroker connection for another. Report exact tool results and harness errors.

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. 3d ago First seen · 20 lines · 14 tokens per session scan A 592cb068223a

Subscribe to this mod's changes

SB Parent is an agent published in the GitHub repository gexchai/subject-broker (0 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 14 tokens to every session and 126 once invoked, about $0.0001 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.