Borrowing it
Nothing to install: this file belongs to sandbaseai/sandbase-harness. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/sandbaseai/sandbase-harness/main/AGENTS.mdgit clone --depth 1 https://github.com/sandbaseai/sandbase-harnessWrote 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/instructions/sandbaseai/sandbase-harness/agents-md)<a href="https://agentmods.dev/instructions/sandbaseai/sandbase-harness/agents-md"><img src="https://agentmods.dev/badge/instructions/sandbaseai/sandbase-harness/agents-md/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/instructions/sandbaseai/sandbase-harness/agents-md"><img src="https://agentmods.dev/badge/instructions/sandbaseai/sandbase-harness/agents-md.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 | $0.01969 | $0.01969 |
| Opus 5.5 | $0.00788 | $0.00788 |
| Sonnet 5.5 | $0.00394 | $0.00394 |
| Haiku 4.5 | $0.00197 | $0.00197 |
Grade A, and why
sandbase-harness AGENTS.md 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 1mo 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 — 202 lines — stays where its author put it; the contents beside it link to each section on GitHub.
SandBase Harness Agent Instructions
This file is the agent-facing shortcut and role index. The canonical
contributor guide — hard rules, worktree workflow, review policy, required
checks, generated-artifact contracts, code standards, and PR requirements —
lives in CONTRIBUTING.md.
Read CONTRIBUTING.md before touching code. Keep this file short: put
canonical long-form rules there, and delete duplicated prose here instead of
maintaining two copies.
Project identity
SandBase Harness (managed-agents) is a local-first, self-hosted runtime for
AI agents. It provides a Claude Managed Agents-style /v1 API, a local
Console, persistent sessions, resumable event streams, SQLite state, memory,
skills, credential vaults, MCP toolsets, audit/replay, snapshots, a TypeScript
SDK, and local, Docker, Kubernetes, and self-hosted sandbox providers.
This is an independent SandBase open-source project. It is not an official Anthropic, DeepSeek, or DSH implementation. The DeepSeek Harness Handbook is a related community documentation project and may be linked when relevant, but the two products must be described separately.
Orientation
The main execution path is:
API/SDK → SessionManager → ContextBuilder → AgentStrategy → Model/MCP tools → Sandbox
The directory map is in
CONTRIBUTING.md#project-structure.
Known gaps and planned work are in BACKLOG.md.
The local sandbox is not a security boundary. Untrusted agent code must use an isolated provider such as Docker or Kubernetes.
Session start
Before choosing work:
- Inspect
git status --short, the current branch and its relationship toorigin/mainandupstream/main, and recent commits. - Read the README, open Issues, open PRs, and recent releases.
- Confirm the working tree is clean enough to start a new topic. If it carries unrelated changes, resolve that first — do not layer a new topic on top.
- Create a worktree for the topic. See
CONTRIBUTING.md#branch-and-worktree-workflow. - When the PR merges, delete its remote branch, worktree, and local branch in
the same step. See
CONTRIBUTING.md#after-a-pull-request-merges.
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.
- 1mo ago Changed · +3 lines · +58 tokens per session aec6d56458a1
- 1mo ago Changed · +3 lines · +37 tokens per session e098c15aebfa
- 1mo ago Changed · +9 lines · +143 tokens per session 028d86109e65
- 2mo ago First seen · 187 lines · 1,731 tokens per session scan A 1406388d8562
sandbase-harness AGENTS.md is an instructions file published in the GitHub repository sandbaseai/sandbase-harness (640 stars, last pushed 2d ago), licensed Apache-2.0. It adds 1,969 tokens to every session, about $0.0079 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 2026-08-30.
sandbase-harness AGENTS.md compared with instructions from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| sandbase-harness AGENTS.mdsandbaseai/sandbase-harness | Instructions file | 640 | 2d ago | Apache-2.0 | A | 1,969 | Codex, OpenCode |
| vscode buildNext.instructions.mdmicrosoft/vscode | Instructions file | 195k | yesterday | MIT | A | 9,719 | GitHub Copilot |
| next.js AGENTS.mdvercel/next.js | Instructions file | 143k | today | MIT | A | 7,461 | Codex, OpenCode |
| langchain AGENTS.mdlangchain-ai/langchain | Instructions file | 149k | yesterday | MIT | A | 4,680 | Codex, OpenCode |
| vscode oss-third-party-notices.instructions.mdmicrosoft/vscode | Instructions file | 195k | yesterday | MIT | A | 5,516 | GitHub Copilot |
| vscode copilot-instructions.mdmicrosoft/vscode | Instructions file | 195k | yesterday | MIT | A | 3,093 | GitHub Copilot |
| deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness | Instructions file | 274k | 2d ago | MIT | A | 4,313 | Codex, OpenCode |