herdr-throwaway-repro

A procedure for creating a temporary Herdr session, where Herdr is a runtime for terminals, panes, processes, and coding agents, to reproduce a problem safely.

In plain words
What is it for?
Reproducing issues involving Herdr servers, terminal sessions, panes, agents, APIs, or saved state.
Why use it?
It isolates experiments from the user's main session and reduces the risk of stopping or changing active work.

Skill for Claude CodeCodex

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 skills/herdrdev/herdr/herdr-throwaway-repro
Any agent
npx skills add herdrdev/herdr --skill herdr-throwaway-repro
Clone the repo
git clone --depth 1 https://github.com/herdrdev/herdr

Made for: Claude Code, Codex.

Per session 60 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,609 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 $0.00060 $0.01609
Opus 5 $0.00030 $0.00805
Sonnet 5 $0.00012 $0.00322
Haiku 4.5 $0.00006 $0.00161

Measured yesterday against content hash 4d66a4e26adb, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

herdr-throwaway-repro 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 yesterday.

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/skills/herdr-throwaway-repro/SKILL.md · 158 lines

How it starts

The opening of the file, as written. The whole thing — 158 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Herdr throwaway reproduction

Use a disposable named Herdr session when a reproduction needs a real Herdr server, panes, PTYs, agents, or socket API without risking the user's main session.

The temporary TUI only keeps the disposable session attached and supplies terminal geometry. Drive the reproduction from the parent session through Herdr's CLI/API. Do not manually operate the nested TUI unless the bug specifically requires client input.

Non-negotiable safety

  • Never run the reproduction in the default session.
  • Never stop, restart, delete, or kill the main Herdr server.
  • Never use pkill, broad process matching, or guessed PIDs for cleanup.
  • Create a unique session name. Never reuse or delete an unrelated named session.
  • Create a new outer pane and close only that pane during cleanup.
  • Read workspace, tab, pane, terminal, and agent IDs from command output. Never construct them.
  • Use /var/tmp for reproduction directories and potentially large artifacts.
  • Do not approve destructive or unnecessary agent actions.
  • Do not spend paid agent tokens without the user's approval. Use the requested low-cost model and the smallest useful prompts.

Learn the installed interface first

The installed binary is the authority. CLI syntax may have changed since this skill was written.

Confirm the caller is inside Herdr and inspect the relevant help before doing anything:

test "${HERDR_ENV:-}" = 1
herdr --version
herdr --help
herdr session
herdr pane
herdr agent

Inspect nested command help before using unfamiliar or potentially mutating commands. Do not run bare herdr for discovery because it launches or attaches the TUI.

Record which Herdr binary and version the reproduction tests. If testing a checkout build, follow the repository's instructions for running that build instead of silently substituting the installed binary.

Create the outer pane

Create a sibling shell pane in the current tab without moving focus. Use an available Herdr layout tool when the harness provides one. Otherwise use the installed pane split command after checking its help.

Read the full file on GitHub · 158 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. yesterday First seen · 158 lines · 60 tokens per session scan A 4d66a4e26adb

Subscribe to this mod's changes

herdr-throwaway-repro is a skill published in the GitHub repository herdrdev/herdr (33,954 stars, last pushed today), licensed Apache-2.0. It adds 60 tokens to every session and 1,609 once invoked, about $0.0003 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 2026-08-30.