arena SKILL.md skillA
arena from backnotprop/pstack is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add backnotprop/pstack/arena@git:20261028.23ef874Pins git:20261028.23ef874 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- backnotprop/pstack
- Path
skills/arena/SKILL.md- Versions recorded
- 15
- Latest version
- git:20261028.23ef874, committed Oct 28, 2026
- First version recorded
- May 27, 2026
- Size
- 5,797 bytes
- Repository stars
- 3,337
- License
- MIT
Spawn N parallel candidates at the same task, pick a base, graft the strongest parts of the losers into it. Use for /arena, 'arena this', 'throw it in the arena', or when one attempt at a non-trivial artifact would lock in the wrong shape.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Arena Open a todolist with one entry per phase (Frame, Fan out, Cross-judge, Pick, Graft, Verify) before launching anything. ## Phase A: Frame Every candidate gets the same prompt, so the prompt is the contract. 1. State the artifact each candidate is producing. 2. Derive the rubric, 3-6 concrete gradeable criteria for what success looks like on *this* task. It is the picker's tool in Phase D. Candidates only see the task. 3. Pick the runners. Use the `arena runners` line in the pstack settings file (`~/.cursor/rules/pstack-models.mdc` in Cursor, `~/.claude/rules/pstack-models.md` in Claude Code, `~/.agents/pstack-models.md` in other harnesses). If the file or that line is missing, default to one each on `claude-opus-5-5-xhigh` and `grok-4.7-xhigh-fast`. An `auto` or `inherit-parent` entry in this line means the parent model, so omit `model` for it. If your subagent tool rejects a configured entry, run that seat on its family's default and say so. Families go by prefix: `claude-*`, and `grok-*` with `cursor-grok-*` and `composer-*`. A refused `composer-*` entry runs on `grok-4.7-xhigh-fast`. If the family has no default, or your subagent tool rejects that default, use the… …
Read the whole file at its exact version.
How to install
mdr add backnotprop/pstack/arena@sha256:2d852994eaa2f0abThe line at the top of this page pins the label git:20261028.23ef874, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_q7hxerqwlrbimfpp)
4 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 15 versions of this file, between May 27, 2026 and Oct 28, 2026, about one every 11 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20261028.23ef874 latest | 2026-10-28 | 23ef874 | 5,797 B | A | view · diff |
| git:20261028.396c27e | 2026-10-28 | 396c27e | 5,598 B | A | view · diff |
| git:20261020.e44668c | 2026-10-20 | e44668c | 4,671 B | A | view · diff |
| git:20261015.6f131f1 | 2026-10-15 | 6f131f1 | 4,620 B | A | view · diff |
| git:20261015.df856f4 | 2026-10-15 | df856f4 | 4,511 B | A | view · diff |
| git:20261012.fce11a3 | 2026-10-12 | fce11a3 | 4,388 B | A | view · diff |
| git:20261012.f3afb70 | 2026-10-12 | f3afb70 | 4,279 B | A | view · diff |
| git:20261008.1edf0a5 | 2026-10-08 | 1edf0a5 | 5,046 B | A | view · diff |
| git:20261008.4aed5af | 2026-10-08 | 4aed5af | 4,937 B | A | view · diff |
| git:20261004.124f622 | 2026-10-04 | 124f622 | 5,082 B | A | view · diff |
| git:20261004.c0c3f13 | 2026-10-04 | c0c3f13 | 4,973 B | A | view · diff |
| git:20260914.aa2db46 | 2026-09-14 | aa2db46 | 4,666 B | A | view · diff |
| git:20260914.55bfdc2 | 2026-09-14 | 55bfdc2 | 4,591 B | A | view · diff |
| git:20260819.4b32d9d | 2026-08-19 | 4b32d9d | 5,367 B | A | view · diff |
| git:20260527.b3eabf1 | 2026-05-27 | b3eabf1 | 5,030 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (5797 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
backnotprop/pstack · 3,337 stars · license MIT · pushed 2026-10-28 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_q7hxerqwlrbimfpp GET https://markdownregistry.com/api/v1/resolve?ref=backnotprop/pstack/arena GET https://markdownregistry.com/api/v1/blob/2d852994eaa2f0abe7a9de959b21f0d5a818cc8a000acc65350d7b8fae914992
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.
More from backnotprop/pstack
Every file in backnotprop/pstack