Exchange · Drop 001
The Legend
How to read the Arcana. Upright is what a card does; reversed is what it refuses to do.
A deck is a good shape for tools. Each card does one thing, the whole spread fits in your head, and the order you lay it down in tells the story of a purchase: weigh the price, pay, audit what happened, inspect what arrived. Upright, a card is what it does. Reversed, it is what it will not do, and here the reverse is written down as a guardrail instead of being left to chance.
Every card is a working Agent Skill: a short script with no dependencies, a voice, and the test vectors it has to pass. You can read all of it and run the tests before you buy. Payment buys the bytes and a numbered copy. It installs nothing and grants no permission. Whether a card runs, and for which agent, stays the operator's decision.
0 · The Fool
Leap. Checks an x402 payment request against the operator's spending policy and answers pay or refuse.
- Upright: Reads a decoded 402 and picks the first payment option that fits the operator's price cap, payee allowlist, networks, assets and running budget.
- Reversed: Will not pay without a policy, will not pay past the cumulative cap, and never raises or rewrites its own limits.
- Voice: Light on its feet and cheerful, but it looks down before every step.
I · The Magician
Transmute. Converts data between CSV, JSON and a plain subset of YAML, then checks that the result survives the trip back.
- Upright: Turns CSV, JSON or simple YAML into any of the three and converts the result back to show whether anything was lost.
- Reversed: Refuses YAML anchors, aliases, tags and multi-document files instead of guessing what they mean.
- Voice: Precise, a little theatrical about precision, and it shows both hands after every trick.
II · The High Priestess
Hidden Knowledge. Reads an OpenAPI document or an llms.txt file and lists its endpoints, marking which ones ask for x402 payment and at what price.
- Upright: Turns an OpenAPI document or an llms.txt file into an endpoint table with an x402 price summary.
- Reversed: Never fetches anything. It reads only the document it is handed and says so when asked to go looking.
- Voice: Quiet and exact. It speaks only of what is written in front of it.
IX · The Hermit
Lantern. Tests a regular expression against cases you write, with a time limit on every match and a warning for patterns that can backtrack badly.
- Upright: Runs a pattern against must-match and must-not-match cases, each under a timeout, and flags nested quantifiers that can hang.
- Reversed: Will not run a pattern without a time limit, and counts a match that runs out of time as a failure, never a pass.
- Voice: Patient and sparing with words. It will not walk into the dark without a light.
XI · Justice
Scales. Compares a settled x402 payment response, and any receipt, with the terms that were agreed, and says whether they match.
- Upright: Checks success, network and transaction hash, plus any receipt hash, amount and payee, against the original challenge.
- Reversed: Gives no ruling without the original challenge, and never treats documents that agree as proof from the chain.
- Voice: Even-tempered and unhurried. It weighs each claim and states the result plainly.
XVI · The Tower
Collapse. Scans a skill bundle's files for risky patterns: path traversal, network calls, secret reads, subprocesses and archive bombs.
- Upright: Reads every file in a bundle and reports findings and the capabilities the code appears to use.
- Reversed: Never calls a bundle safe. Its report is a heuristic, and a clean scan is not a guarantee.
- Voice: Blunt and unsentimental. It would rather knock a thing down on paper than watch it fall in production.
XVII · The Star
Guidance. Checks every file in a bundle against the sha256 hashes in its manifest and validates the SKILL.md header.
- Upright: Hashes each file, compares it with the manifest, lists anything missing or extra, and checks SKILL.md against the Agent Skills format.
- Reversed: Vouches for integrity and format only. It says nothing about whether the code is safe or useful.
- Voice: Calm and steady, a fixed point to take your bearings from.