think-cell Chart Generator

Generates .ppttc data files that populate think-cell charts in a PowerPoint template. The .ppttc file carries only data — all colours, fonts, axis formatting, and chart aesthetics are controlled by the underlying .pptx template.

Overview

think-cell is the charting layer on top of PowerPoint used for waterfall/bridge, Marimekko, stacked bar/column, combination, bubble/scatter, and Harvey ball charts. This skill:

1. Takes Jacob's analysis data and chart intent
2. Matches it to a registered template in templates.yaml
3. Structures the data into the ppttc JSON format
4. Runs generate_ppttc.py to produce the .ppttc output file
5. Delivers a file Jacob can double-click to render in PowerPoint

Workflow

Step 1 — Identify chart type

Read Jacob's request and classify the chart type. Common signals:

Step 2 — Find matching template

Read templates.yaml in this skill folder. Match on category and tags against the chart type and context (e.g. project name, sector, use case).

If no registered template matches: ask Jacob which .pptx template to use, then register it with register_template.py before proceeding.

Step 3 — Determine data shape

Read chart_types.md in this skill folder. Find the section for the matched chart type and confirm:

• What the categories array should contain
• How to structure the data rows (series × values)
• Any pitfalls (e.g. Marimekko column widths in row 0)

Step 4 — Structure the data JSON

Build the elements array:

{
  "elements": [
    {
      "name": "Chart1",
      "type": "chart",
      "categories": ["FY24A", "Cost-out", "Volume", "FY25F"],
      "data": [
        ["EBIT", 120, -15, 8, null]
      ]
    },
    {
      "name": "Title",
      "type": "text",
      "value": "EBIT Bridge FY24A–FY25F ($M)"
    }
  ]
}

Element names must match the placeholder names in the .pptx template exactly (case-sensitive). Check templates.yaml → elements[].name for the correct names.

Step 5 — Run generate_ppttc.py

source <workspace>/.venv/bin/activate && python3 <workspace>/.claude/skills/utility-thinkcell/generate_ppttc.py \
  --template <path/to/template.pptx> \
  --output <project_folder/output.ppttc> \
  --data '<json_string>'

Or pass a JSON file path to --data if the payload is large.

Step 6 — Save to active project folder

Output path convention: 4 - Projects/[project-name]/[chart-name].ppttc

Never save to the skill folder or to /tmp/ for production outputs.

Step 7 — Deliver to Jacob

Tell Jacob:

"Double-click [file].ppttc to render in PowerPoint with think-cell."

If the template .pptx path was provided by Jacob this session, also confirm which slide number the chart will populate.

Registering New Templates

When a new .pptx template is bootstrapped or Jacob provides a new slide deck:

source <workspace>/.venv/bin/activate && python3 <workspace>/.claude/skills/utility-thinkcell/register_template.py \
  --name "Client Waterfall" \
  --path "<workspace>/Template/thinkcell/client_waterfall.pptx" \
  --category waterfall \
  --use-case "cost-out bridge for a state-government facilities client, FY25-FY26" \
  --elements '[{"name": "Chart1", "type": "chart", "data_shape": "categories x signed values"}, {"name": "Title", "type": "text", "data_shape": "string"}]'

This appends the entry to templates.yaml. Store the .pptx file in Template/thinkcell/.

Supported Chart Types

Important Notes

• Chart formatting (colours, axis labels, number format, fonts) is entirely controlled by the .pptx template — do not attempt to set these in the ppttc JSON.
• Element name values are case-sensitive and must match the template placeholders exactly.
• Null values in data arrays create gaps in waterfall charts (think-cell treats them as subtotals or blank segments depending on template config).
• The thinkcell PyPI library wraps the Slideworks API. The generated .ppttc is standard JSON — always validate with python3 -m json.tool before delivery.