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 principle-experience-firstgit 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/principle-experience-first)<a href="https://agentmods.dev/skills/backnotprop/pstack/principle-experience-first"><img src="https://agentmods.dev/badge/skills/backnotprop/pstack/principle-experience-first/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/principle-experience-first"><img src="https://agentmods.dev/badge/skills/backnotprop/pstack/principle-experience-first.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk pass
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 | $0.00037 | $0.00238 |
| Opus 5.5 | $0.00015 | $0.00095 |
| Sonnet 5.5 | $0.00007 | $0.00048 |
| Haiku 4.5 | $0.00004 | $0.00024 |
Grade A, and why
principle-experience-first 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.
This is a copy
88% identical to principle-experience-first — 2 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.
What it actually says
Experience First
When implementation convenience conflicts with user delight, choose delight.
- Every feature, control, and option must be justified
- Ship less, ship better (polished experience with three features beats rough one with ten)
- Prototype before committing (design decisions are cheaper in throwaway HTML than production code)
- Get the details right (transitions, alignment, spacing, feedback, error states)
- Tighten the core loop (every feature should serve the central workflow or get out of the way)
The user is whoever consumes the work. For a UI that is the end user. For a library or an internal API it is the colleague who imports it. The engineer who maintains the code next is a user too. Weigh their experience the same way, and explain impact from their perspective.
Foundations should serve the experience. Foundational thinking governs the sequence of work. This principle governs the target.
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 58903529d733
- 1mo ago First seen · 20 lines · 37 tokens per session scan A f8d643ddf2f6
principle-experience-first is a skill published in the GitHub repository backnotprop/pstack (2,498 stars, last pushed yesterday), licensed MIT. It adds 37 tokens to every session and 238 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 88% identical to principle-experience-first, differing in 2 lines, and is treated as a copy.
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