starchild-ai-agent/@554/chart

Chart — Project-Based Interactive Charting

Generate interactive chart pages with Apache ECharts. Each chart lives in a dedicated project folder under output/chart-html/, making it easy to reuse and iterate.

When to Use

Any time the user wants a visual chart: price charts, comparisons, dashboards, business analytics, etc.

Architecture

• ECharts (CDN) for rendering
• ECharts native export (getDataURL) + canvas merge for reliable PNG output
• Project-based storage: one folder per chart project
• No gallery mode: all artifacts stay in the project folder

Project Structure (Required)

Each chart project should follow:

output/chart-html/
  <project-name>/
    index.html        # chart page
    generate.py       # generation script (for reproducibility)
    README.md         # title / description / data source notes
    data.json         # data snapshot
    screenshot.png    # saved image

Example folder name: btc-90d-20260401

Workflow

Step 1: Pick template or custom layout

Available templates:

| Template | Best for | |---|---| | line.html | Time-series trends, multi-series comparisons | | bar.html | Category comparisons, rankings | | pie.html | Composition / share breakdown | | candlestick.html | OHLCV price charts | | scatter.html | Correlation, distribution | | dashboard.html | KPI cards + 2×2 multi-chart grid | | radar.html | Multi-dimension scoring | | heatmap.html | Matrix / calendar intensity | | dual-axis.html | Two series with very different scales (e.g. market cap vs stablecoin supply) — left and right Y axes, each with its own label color | | multi-panel.html | Stacked panels sharing one X axis (e.g. price + volume + RSI) — single ECharts instance, tooltip/zoom synced across all panels | | waterfall.html | Incremental contribution breakdown (e.g. P&L attribution, budget variance) — positive/negative bars stacked on a floating base |

Step 2: Create project folder

Use create_project(name, description, data_sources) from scripts/build_chart.py.

Step 3: Build and save chart page

Use either:

• build_chart(template_name, ...)
• build_chart_custom(...)

Then save as index.html in the project folder:

• save_chart(html, project_dir=project_dir)

Step 4: Save reproducible assets

Also save:

• save_generate_script(script_content, project_dir) → generate.py
• save_data(data, project_dir) → data.json
• project README is created by create_project(...)

Step 5: Serve preview

Use project-root serving (recommended):

preview_serve(
  title="Chart Preview",
  dir="skills/chart/scripts",
  command="python3 chart_server.py /data/workspace/output/chart-html 7860",
  port=7860
)

Then open: /preview/<id>/<project-name>/index.html

Step 6: Export image

Two modes:

1. User wants web page + image: click "💾 Save Image" in page toolbar, saves to current project as screenshot.png
2. User wants image only: call screenshot_chart(project_dir) (Playwright) and send screenshot.png directly

Toolbar Requirements

Every chart page must include these buttons:

<div class="actions">
  <button onclick="downloadPNG(this)">📥 Download PNG</button>
  <button onclick="copyToClipboard(this)">📋 Copy Image</button>
  <button onclick="saveToProject(this)">💾 Save Image</button>
</div>

Do not include gallery entry.

Key Files

| File | Purpose | |------|---------| | skills/chart/scripts/base-styles.css | Base dark theme CSS | | skills/chart/scripts/base-export.js | Export helpers: download/copy/save-to-project | | skills/chart/scripts/build_chart.py | Project creation, HTML build, data/script save, screenshot | | skills/chart/scripts/chart_server.py | Static server + /save-chart API | | skills/chart/templates/*.html | Reusable chart templates | | output/chart-html/<project>/* | All generated chart artifacts |

Notes

• Embed data directly in HTML (const DATA = ...) to avoid iframe CORS issues.
• For multi-chart pages, register all chart instances in window.CHART_INSTANCES.
• Use meaningful project names (topic-range-date) for easy lookup.