pstack is a collection of plain Agent Skills and engineering principles that guide AI-assisted software development across coding agents such as Claude Code, Codex, Pi, Cursor, and OpenCode. It is for developers who want reusable practices for tasks including testing, technical writing, debugging, review, and coordinating agent work. The catalogue entries are the project's skills, agents, and plugin.
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.
npx skills add backnotprop/pstack --skill ketchupgit clone --depth 1 https://github.com/backnotprop/pstackWrote 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/skills/backnotprop/pstack/ketchup)<a href="https://agentmods.dev/skills/backnotprop/pstack/ketchup"><img src="https://agentmods.dev/badge/skills/backnotprop/pstack/ketchup/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/skills/backnotprop/pstack/ketchup"><img src="https://agentmods.dev/badge/skills/backnotprop/pstack/ketchup.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk warn
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 | $0.00045 | $0.01186 |
| Opus 5.5 | $0.00018 | $0.00474 |
| Sonnet 5.5 | $0.00009 | $0.00237 |
| Haiku 4.5 | $0.00005 | $0.00119 |
Grade A, and why
ketchup 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 today.
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.
This is a copy
98% identical to ketchup — 5 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 38 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Ketchup
Catch the user up on what changed in this chat since the last message they wrote before /ketchup, and help them understand each change, not only where it stands. Notifications and subagent results are not their messages. Assume the user remembers their last message and nothing after it.
Use /bro's voice, not its task: plain words, short sentences, no jargon, like one person catching up another. Say what changed for the user, not how you did it. Say "the tests pass", not "CI is green". Leave out hashes, file paths, commands, build numbers, and test counts unless the user needs one to act. Call each PR, branch, or agent by a name the user would know, not by a label you invented. If a fact needs context to make sense, give the context or leave the fact out.
Gather what changed
Keep this turn read-only. Make visuals only from what you already have: do not change code, start an app or a job, or post anything. Collect your own work since that message, reports from subagents, and messages from anyone else in this chat. Check the current state of each PR, CI run, or agent this chat touched. Check each number you will show against the facts it comes from, and say so when you correct one.
An action item is a decision or step only the user can take, such as a product choice, an approval, an irreversible action, or access you lack. Include any still waiting on the user, even one raised before their last message. Work you can still do yourself is not an action item. Never make up a call to fill the reply. A step the user did not ask for and the work does not need is not an action item, unless it is irreversible and waiting on the user: give it one action line, no visual, and skip what happens if the user does not answer.
Write the reply
Keep the whole reply well under 150 words, not counting visuals. When something is easier to grasp as a picture than as sentences, draw it: how a design or system works, a PR stack or dependency chain with each PR's state, a before and after of a fix, or options side by side. Never draw a status list or boxes with nothing connecting them. Never give a fact twice, in text or across visuals. Leave out work that changed nothing for the user. When words run short, cut from what happened before you cut from the action items.
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.
- today Changed b5aa507627d2
- yesterday Changed · +10 lines · +3 tokens per session 05a25e69c716
- 3d ago First seen · 28 lines · 42 tokens per session scan A 3b00c552fdb2
ketchup is a skill published in the GitHub repository backnotprop/pstack (1,942 stars, last pushed today), licensed MIT. It adds 45 tokens to every session and 1,186 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 98% identical to ketchup, differing in 5 lines, and is treated as a copy.
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