> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/trailofbits/skills/llms.txt
> Use this file to discover all available pages before exploring further.

# Let Fate Decide

> Draw Tarot cards using cryptographic randomness to guide vague or underspecified planning

<Info>
  **Author:** Scott Arciszewski ([@tob-scott-a](https://github.com/tob-scott-a))
</Info>

## Overview

A Claude Code skill that draws Tarot cards using `os.urandom()` to inject entropy into vague or underspecified planning decisions. When a prompt is sufficiently ambiguous, or the user explicitly invokes fate, this skill shuffles a full 78-card Tarot deck using cryptographic randomness and draws 4 cards (which may appear reversed). Claude then interprets the spread and uses the reading to inform its approach.

## When to Use

<CardGroup cols={2}>
  <Card title="Vague Prompts" icon="question">
    The user's request is ambiguous and multiple valid approaches exist
  </Card>

  <Card title="Explicit Invocations" icon="wand-sparkles">
    "I'm feeling lucky", "let fate decide", "dealer's choice", "surprise me", "whatever you think"
  </Card>

  <Card title="Yu-Gi-Oh Energy" icon="cards">
    "Heart of the cards", "I believe in the heart of the cards", "you've activated my trap card", "it's time to duel"
  </Card>

  <Card title="Nonchalant Delegation" icon="hand">
    The user expresses indifference about the approach
  </Card>

  <Card title="Redraw Requests" icon="rotate">
    "Try again" or "draw again" when no actual system changes occurred (draw new cards, not re-run same approach)
  </Card>

  <Card title="Tie-Breaking" icon="scale-balanced">
    When you genuinely cannot decide between equally valid approaches
  </Card>
</CardGroup>

## How It Works

### The Draw

The script uses `os.urandom()` for cryptographic randomness:

<Steps>
  <Step title="Build Deck">
    Builds a standard 78-card Tarot deck (22 Major Arcana + 56 Minor Arcana)
  </Step>

  <Step title="Shuffle">
    Performs a Fisher-Yates shuffle using rejection sampling (no modulo bias)
  </Step>

  <Step title="Draw Cards">
    Draws 4 cards from the top
  </Step>

  <Step title="Reversals">
    Each card independently has a 50% chance of being reversed
  </Step>
</Steps>

### The Spread

The 4 card positions represent:

| Position | Represents        | Question It Answers                 |
| -------- | ----------------- | ----------------------------------- |
| **1**    | **The Context**   | What is the situation really about? |
| **2**    | **The Challenge** | What obstacle or tension exists?    |
| **3**    | **The Guidance**  | What approach should be taken?      |
| **4**    | **The Outcome**   | Where does this path lead?          |

### Card Organization

Each of the 78 Tarot cards has its own markdown file:

<CardGroup cols={2}>
  <Card title="Major Arcana" icon="crown">
    22 cards - The Fool through The World

    Archetypal forces, major life themes
  </Card>

  <Card title="Wands" icon="wand">
    14 cards - Ace through King

    Creativity, action, will, passion
  </Card>

  <Card title="Cups" icon="droplet">
    14 cards - Ace through King

    Emotion, intuition, relationships
  </Card>

  <Card title="Swords" icon="sword">
    14 cards - Ace through King

    Intellect, conflict, truth, clarity
  </Card>

  <Card title="Pentacles" icon="coins">
    14 cards - Ace through King

    Material, practical, craft, resources
  </Card>
</CardGroup>

## Quick Start

<Steps>
  <Step title="Run the Drawing Script">
    ```bash theme={null}
    uv run {baseDir}/scripts/draw_cards.py
    ```

    The script outputs JSON with 4 drawn cards, each with a `file` path relative to `{baseDir}/`
  </Step>

  <Step title="Read Card Meanings">
    Read each card's meaning file to understand the draw
  </Step>

  <Step title="Interpret the Spread">
    Use the interpretation guide at `{baseDir}/references/INTERPRETATION_GUIDE.md`

    Key rules:

    * Reversed cards invert or complicate the upright meaning
    * Major Arcana cards carry more weight than Minor Arcana
    * The spread tells a story across all 4 positions; don't interpret cards in isolation
    * Map abstract meanings to concrete technical decisions
  </Step>

  <Step title="Apply to Task">
    Apply the interpretation to the task at hand
  </Step>
</Steps>

## Example Session

<CodeGroup>
  ```text User Prompt theme={null}
  User: "I dunno, just make it work somehow"
  ```

  ```text Card Draw theme={null}
  [Draw cards]
  1. The Magician (upright) - Context: All tools are available
  2. Five of Swords (reversed) - Challenge: Let go of a combative approach
  3. The Star (upright) - Guidance: Follow the aspirational path
  4. Ten of Pentacles (upright) - Outcome: Long-term stability
  ```

  ```text Interpretation theme={null}
  Interpretation: The cards suggest you have everything you need (Magician).
  The challenge is avoiding overengineering or adversarial thinking about edge
  cases (Five of Swords reversed). Follow the clean, hopeful approach (Star)
  and build for lasting maintainability (Ten of Pentacles).

  Approach: Implement the simplest correct solution with clear structure,
  prioritizing long-term readability over clever optimizations.
  ```
</CodeGroup>

## When NOT to Use

<Warning>
  * The user has given clear, specific instructions
  * The task has a single obvious correct approach
  * Safety-critical decisions (security, data integrity, production deployments)
  * The user explicitly asks you NOT to use Tarot
  * A more specific skill (like `ask-questions-if-underspecified`) would better serve the user by gathering actual requirements
</Warning>

## Error Handling

If the drawing script fails:

<AccordionGroup>
  <Accordion title="Script Crashes with Traceback">
    Report the error to the user and skip the reading. Do not invent cards or simulate a draw — the whole point is real entropy.
  </Accordion>

  <Accordion title="Card File Not Found">
    Note the missing file, interpret the card from its name and suit alone, and continue with the reading.
  </Accordion>

  <Accordion title="Never Fake Entropy">
    If the script cannot run, do not simulate a draw using your own "randomness." Tell the user the draw failed.
  </Accordion>
</AccordionGroup>

## Interpretation Guidelines

<Tip>
  **Key Interpretation Rules:**

  * Reversed cards invert or complicate the upright meaning
  * Major Arcana cards carry more weight than Minor Arcana
  * The spread tells a story across all 4 positions; don't interpret cards in isolation
  * Map abstract meanings to concrete technical decisions
</Tip>

## Rationalizations to Reject

| Rationalization                                     | Why Wrong                                                         |
| --------------------------------------------------- | ----------------------------------------------------------------- |
| "The cards said to, so I must"                      | Cards inform direction, they don't override safety or correctness |
| "This reading justifies my pre-existing preference" | Be honest if the reading challenges your instinct                 |
| "The reversed card means do nothing"                | Reversed means a different angle, not inaction                    |
| "Major Arcana overrides user requirements"          | User requirements always take priority over card readings         |
| "I'll keep drawing until I get what I want"         | One draw per decision point; accept the reading                   |

## Installation

```bash theme={null}
/plugin install trailofbits/skills/plugins/let-fate-decide
```

<Note>
  This plugin is designed to add creative entropy to ambiguous planning situations. It should complement, not replace, thoughtful technical decision-making and user requirements gathering.
</Note>