hrdx: Instructions file for Codex

AGENTS.md

hrdx AGENTS.md is an instructions file for Codex, OpenCode from patriceckhart/hrdx. It costs 2,474 tokens per session, scanned A, original, MIT.

Repository instructions for coding agents working on hrdx, a lightweight terminal multiplexer written in Go. A terminal multiplexer lets one terminal run multiple persistent panes or workspaces.

In plain words
What is it for?
Use it to understand the repository's working agreement, inspect relevant code and tests, and follow its correctness requirements before editing.
Why use it?
It helps agents make changes that preserve hrdx's intended behavior, portability, and small design.

Instructions file for CodexOpenCode

Written for Codex and OpenCode: the file is AGENTS.md. Also seen: mentions AGENTS.md.

This is patriceckhart/hrdx's own configuration. It tells Codex and OpenCode how to work on hrdx itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything hrdx configures →

Reuse

Borrowing it

Nothing to install: this file belongs to patriceckhart/hrdx. 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/patriceckhart/hrdx/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/patriceckhart/hrdx

Made for: Codex, OpenCode.

Wrote this? Show the measurements

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Per session 2,474 This file is loaded in full into every session.
When invoked 2,474 The same file — it is already loaded in full.
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 $0.02474 $0.02474
Opus 5 $0.01237 $0.01237
Sonnet 5 $0.00495 $0.00495
Haiku 4.5 $0.00247 $0.00247

Measured 5d ago against content hash c2187cf7b988, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

hrdx 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 5d 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.

AGENTS.md · 228 lines

How it starts

The opening of the file, as written. The whole thing — 228 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Working Agreement for hrdx

This file defines how automated coding assistants should work in this repository. Treat it as a practical operating manual, not a substitute for reading the code.

Product intent

hrdx is an experimental, minimal, lightweight terminal multiplexer for coding agents and shells. Changes should preserve its defining properties:

  • one portable Go binary
  • every pane backed by a real PTY
  • projects represented as workspaces with tabs and split layouts
  • terminal behavior compatible with ordinary agent TUIs and shells
  • persistent sessions through a lightweight holder process
  • predictable behavior on macOS, Linux, and Windows
  • a small dependency and operational footprint

Prefer a narrow, explicit implementation over a generalized subsystem. New abstractions must earn their cost through a real ownership boundary or repeated use.

Starting a task

Build context before editing:

  1. Inspect git status --short --branch. Existing modifications may belong to the user or another agent.
  2. Locate and read every AGENTS.md that governs the target path.
  3. Read the owning implementation, nearby tests, and user-facing documentation for the behavior.
  4. Reproduce reported failures when feasible. Keep expected behavior distinct from observed behavior.
  5. For GitHub work, inspect the issue, discussion, or pull request before implementing it. Do not change branches merely to review a pull request.

Do not use one search result or one function as a complete model of a feature. Follow the path through UI state, terminal or holder behavior, persistence, API representations, tests, and platform-specific files where relevant.

Code ownership map

Put behavior in the package that owns the concern:

Area Responsibility
cmd/hrdx CLI flags, configuration assembly, startup, process modes, and platform wiring
internal/api Socket server, newline-delimited JSON protocol, public request and response types, subscriptions
internal/holder Persistent PTY ownership, attach and detach, replay ring, holder protocol
internal/state Serializable workspaces, tabs, panes, layouts, and preferences
internal/term PTY pane lifecycle, input encoding, resize, scrollback, selection, terminal-facing helpers
internal/ui Bubble Tea model, rendering, layout, input, menus, settings, persistence coordination, API handling
internal/vt Escape parsing, terminal state, glyphs, colors, history, and screen model
internal/update Update checks and self-update
internal/winproc Windows foreground-process and process-tree behavior

Read the full file on GitHub · 228 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.

  1. 5d ago First seen · 228 lines · 2,474 tokens per session scan A c2187cf7b988

Subscribe to this mod's changes

hrdx AGENTS.md is an instructions file published in the GitHub repository patriceckhart/hrdx (48 stars, last pushed 4d ago), licensed MIT. It adds 2,474 tokens to every session, about $0.0124 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 2026-09-03.

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