What is UltraCode-Shim AGENTS.md?

A setup runbook for UltraCode-Shim, a small Python proxy that lets Claude Code use models the user already has access to. A proxy is an intermediary that receives requests and forwards them to another service.

It helps set up the proxy, verify Python and Claude Code, choose orchestrator and worker models, and launch the configured UltraCode mode.

It gives assistants a checked sequence for prerequisites, installation, model selection, and troubleshooting without adding Python packages.

How OnlyTerp/UltraCode-Shim configures Codex and OpenCode

Reuse

Borrowing it

Nothing to install: this file belongs to OnlyTerp/UltraCode-Shim. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/OnlyTerp/UltraCode-Shim/main/AGENTS.md

Clone the repo

git clone --depth 1 https://github.com/OnlyTerp/UltraCode-Shim

Made for: Codex, OpenCode.

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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/onlyterp/ultracode-shim/agents-md/github.svg)](https://agentmods.dev/instructions/onlyterp/ultracode-shim/agents-md)

Your own site

<a href="https://agentmods.dev/instructions/onlyterp/ultracode-shim/agents-md"><img src="https://agentmods.dev/badge/instructions/onlyterp/ultracode-shim/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.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/onlyterp/ultracode-shim/agents-md"><img src="https://agentmods.dev/badge/instructions/onlyterp/ultracode-shim/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 2,489 This file is loaded in full into every session.

When invoked 2,489 The same file — it is already loaded in full.

Security scan C 2 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.

Model	Per session	Once invoked
Fable 5.1	$0.02489	$0.02489
Opus 5.5	$0.00996	$0.00996
Sonnet 5.5	$0.00498	$0.00498
Haiku 4.5	$0.00249	$0.00249

Measured 2mo ago against content hash 64fa3a2b67ea, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade C, and why

UltraCode-Shim AGENTS.md scanned grade C with 2 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 2mo 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.

Downloads and executes remote codehighSupply chain

curl | sh runs whatever the server returns today, which is not necessarily what it returned when this was reviewed.

curl -fsSL https://raw.githubusercontent.com/OnlyTerp/UltraCode-Shim/main/install.sh | bash

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl -fsSL https://raw.githubusercontent.com/OnlyTerp/UltraCode-Shim/main/install.sh | bash

AGENTS.md · 190 lines

How it starts

The opening of the file, as written. The whole thing — 190 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Runbook for AI assistants

You are helping a user set up UltraCode-Shim: it lets Claude Code's UltraCode mode run on any model the user already pays for, chosen from the pre-launch orchestrator/worker selector or from the /model menu.

Follow these phases in order. Do not skip the doctor. Everything here is pure Python standard library — do not pip install anything. Prefer the commands exactly as written; they are cross-platform-aware.

Phase 0 — Understand the goal (read once)

The end state: the user double-clicks "UltraCode (All Models)", picks an orchestrator + worker in the selector, and Claude Code opens already pointed at that choice. They can still type /model later and pick any backend they configured. The mechanism (no magic): a tiny loopback proxy (proxy.py) sits at ANTHROPIC_BASE_URL, advertises the user's models plus synthesized Worker → X entries on GET /v1/models, adds the UltraCode envelope to every request, and routes each pick to its real backend. See docs/HOW_IT_WORKS.md.

Phase 1 — Prerequisites

Run and confirm each:

python3 --version (or python --version) → must be ≥ 3.8.
claude --version → Claude Code CLI must be installed. If missing: npm i -g @anthropic-ai/claude-code.
Confirm the user has UltraCode access in their Claude plan (they'd have used /effort ultracode before). If not, this project can't grant it.

Phase 2 — Get the code + baseline check

Fastest path — the one-command installer (clones if needed, runs the offline self-test, creates config.json, and installs a ultracode launcher on PATH):

# mac/linux/WSL
curl -fsSL https://raw.githubusercontent.com/OnlyTerp/UltraCode-Shim/main/install.sh | bash
# windows (PowerShell)
irm https://raw.githubusercontent.com/OnlyTerp/UltraCode-Shim/main/install.ps1 | iex

If you already have a checkout, run ./install.sh (or .\install.ps1) from inside it. Either way, the installer runs the offline self-test for you.

If you'd rather do it by hand (or the installer can't run):

Read the full file on GitHub · 190 lines

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.

2mo ago First seen · 190 lines · 2,489 tokens per session scan C 64fa3a2b67ea

Subscribe to this mod's changes

UltraCode-Shim AGENTS.md is an instructions file published in the GitHub repository OnlyTerp/UltraCode-Shim (442 stars, last pushed 2mo ago), licensed MIT. It adds 2,489 tokens to every session, about $0.0100 per session on Opus 5.5. A static security scan graded it C with 2 findings (downloads and executes remote code, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Backend and APIs

UltraCode-Shim AGENTS.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
UltraCode-Shim AGENTS.mdOnlyTerp/UltraCode-Shim	Instructions file	442	2mo ago	MIT	C	2,489	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

UltraCode-Shim: Instructions file for Codex