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name: Easy Stat Edu Developer description: Expert guidance, MCP workflow, and patterns for the Easy Stat Edu project.

Easy Stat Edu Developer Skill

This skill outlines the architecture, development patterns, testing strategies, and MCP workflow for the Easy Stat Edu project. Follow these guidelines to ensure consistency and efficiency.

1. MCP Workflow & Agentic Behavior

Leverage your specialized MCP tools to act as an autonomous, intelligent partner.

Sequential Thinking (Complex Logic)

When facing multi-step analytical problems (e.g., implementing a new ANOVA logic with multiple error terms):

1. Call sequential-thinking: Break the problem down.
   • Step 1: Understand the statistical formula (SS, df, MS, F).
   • Step 2: Map formula terms to code variables (cleanData, factors).
   • Step 3: Plan the data transformation (e.g., "Pivot long to wide?").
   • Step 4: Verification strategy.
2. Iterate: If a test fails, trigger a new thought sequence to hypothesize the root cause (e.g., "Is it a floating-point error or a wrong degree of freedom?").

Serena (Codebase Navigation)

Before editing any file, understand the context:

1. Exploration: Use get_symbols_overview or find_symbol to see available functions in js/utils.js or js/analyses/*.js.
2. References: If modifying a core utility (e.g., createVariableSelector), use find_referencing_symbols to check impact on other analyses.
3. Search: Use search_for_pattern to find usage of specific HTML IDs or CSS classes across the project.

Context7 (Documentation)

If you are unsure about a library's specific syntax:

1. Call context7: "How to calculate non-central F distribution in jStat?" or "Plotly.js grouped bar chart with error bars syntax".
2. Don't Guess: Verify the API before implementing, especially for jStat and Plotly.

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2. Project Architecture

• Type: Client-side SPA (Vanilla JS + HTML). No build step (no Webpack/Vite).
• Entry: index.html loads all libraries and js/main.js (module entry).
• Libraries (Global Scope):
  • jStat (Statistics)
  • Plotly (Visualization)
  • XLSX (Excel import/export)
  • math (Math.js)
  • vis (Network graphs)

Directory Structure

• js/analyses/: Individual analysis modules (must export render()).
• js/utils.js: Core UI/Logic helpers. Check this file first for reusable functions.
• css/style.css: Main styling.
• tests/: Playwright end-to-end tests.

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3. Development Patterns

Common UI Helpers (js/utils.js)

• showLoadingMessage(msg) / hideLoadingMessage(): Manage global spinner.
• toggleCollapsible(header): Handle accordion UI.
• toHtmlTable(headers, rows, data): Quick HTML table generation.
• createVariableSelector(...): Standardize variable input UI.

Coding Standards

• Japanese UI: All user-facing text must be Japanese.
• English Internals: Variable names and comments should be English.
• Error Handling: Use showLoadingMessage for progress and alert (or custom UI) for errors.
• Async Rendering: Use setTimeout(() => { ... }, 0) when rendering heavy Plotly charts to allow the DOM to update first.

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4. Testing Strategy (Playwright)

Test Template

const { test, expect } = require('@playwright/test');
const path = require('path');

test('Feature Verification', async ({ page }) => {
    // 0. Console Debugging
    page.on('console', msg => console.log(`[Browser]: ${msg.text()}`));

    // 1. Initial Load & Wait
    await page.goto('http://127.0.0.1:8080/');
    await expect(page.locator('#loading-screen')).toBeHidden({ timeout: 10000 });

    // 2. Data Upload
    const filePath = path.join(__dirname, '../datasets/demo.xlsx');
    await page.locator('#main-data-file').setInputFiles(filePath);
    await expect(page.locator('#dataframe-container')).toBeVisible({ timeout: 10000 });

    // 3. Navigation
    await page.click('.feature-card[data-analysis="your_analysis"]');
    await expect(page.locator('#analysis-area')).toBeVisible();

    // 4. Interaction (Handle async UI updates)
    await page.selectOption('#var-selector', 'ColumnName');
    
    // 5. Execution
    await page.click('#run-btn');

    // 6. Assertions
    // Check Table
    const table = page.locator('#results-table');
    await expect(table).toContainText('Expected Value');
    
    // Check Plotly
    await expect(page.locator('.js-plotly-plot')).toBeVisible();
});

Debugging Tips

• Console Logs: Always add page.on('console', ...) to see browser errors in the terminal.
• Screenshots: If a test fails ("element not visible"), use await page.screenshot({ path: 'debug.png' }) to see the state.
• Timeouts: Initial load and heavy calcs might take time. Increase timeouts if needed ({ timeout: 30000 }).