opensession: Skill for Claude Code

.agents/skills/pstack-suite/skills/principle-experience-first/SKILL.md

principle-experience-first is a skill for Claude Code from tellahq/opensession. It costs 37 tokens per session (268 once invoked), scanned A, original, MIT.

A product-design principle for making technical choices based on how the result feels and works for its users, including developers who maintain it.

In plain words
What is it for?
Use it when deciding which features to build, refining interfaces, planning feedback and error states, or weighing usability against engineering convenience.
Why use it?
It helps prevent crowded, rough products and keeps implementation choices from taking priority over user experience.

Skill for Claude Code

Written for Claude Code: disable-model-invocation in frontmatter. Also seen: installed under .agents/ (shared by several agents).

This is tellahq/opensession's own configuration. It tells Claude Code how to work on opensession 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 opensession configures →

Reuse

Borrowing it

Nothing to install: this file belongs to tellahq/opensession. 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/tellahq/opensession/main/.agents/skills/pstack-suite/skills/principle-experience-first/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/tellahq/opensession

Made for: Claude Code.

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.

agentmods badge for principle-experience-first

README.md
[![agentmods](https://agentmods.dev/badge/skills/tellahq/opensession/principle-experience-first.svg)](https://agentmods.dev/skills/tellahq/opensession/principle-experience-first)
Your own site
<a href="https://agentmods.dev/skills/tellahq/opensession/principle-experience-first"><img src="https://agentmods.dev/badge/skills/tellahq/opensession/principle-experience-first.svg" alt="Measured on agentmods" height="20"></a>
Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 268 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 5.1 $0.00037 $0.00268
Opus 5 $0.00018 $0.00134
Sonnet 5 $0.00007 $0.00054
Haiku 4.5 $0.00004 $0.00027

Measured 2d ago against content hash f8d643ddf2f6, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

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 2d 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.

Origin

Copies of this mod

6 near-identical copies found in the catalogue:

.agents/skills/pstack-suite/skills/principle-experience-first/SKILL.md · 20 lines

What it actually says

Experience First

The product is the experience. Every technical decision either helps or hurts it. When implementation convenience conflicts with user delight, choose delight.

  • Say no to 1,000 things (every feature, control, and option must earn its place)
  • 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)
  • Sweat the details (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 seat.

Foundations should serve the experience, not the other way around. Foundational thinking governs the sequence of work; this principle governs the target.

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. 2d ago First seen · 20 lines · 37 tokens per session scan A f8d643ddf2f6

Subscribe to this mod's changes

principle-experience-first is a skill published in the GitHub repository tellahq/opensession (355 stars, last pushed yesterday), licensed MIT. It adds 37 tokens to every session and 268 once invoked, about $0.0002 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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