2026 Week 07 | Sigma: Building a Custom Plugin with AI

Prepare your Sigma workbook

• Open the challenge workbook and identify the 3 required fields:
  • Issue Month
  • Loan Amount
  • Annual Income
• Create:
  • Build page (visible)
  • Prompt Lab page (hidden, for prompt drafts and QA tables)

Hint: Your prompt quality depends on naming clarity. Clean field names first.

Set up a prompt-first build flow

• In Cortex, start with a clear objective prompt:
  • “Build a two-panel story: left bar for magnitude by income cohort, right line for monthly trend by cohort.”
• Ask Cortex to generate:
  • cohort bucketing logic
  • aggregation logic
  • insight helper functions
  • plugin layout scaffold

Hint: Don’t ask for “a dashboard.” Ask for specific outputs (fields, functions, chart behaviors).

Prompt for cohort logic

• Ask Cortex to create cohort definitions:
  • Low < 50k
  • Middle 50k–120k
  • High > 120k
• Validate with a table before charting.

Hint: Prompt Cortex to return both formula + a quick validation method.

Prompt for chronological correctness

• Ask Cortex to parse and sort Issue Month as real dates.
• Require explicit month ordering check in output.

Hint: Add this to your prompt: “Do not sort months lexicographically.”

Prompt for narrative functions

• Ask Cortex to generate:
  • getBarInsight(barData) -> max/min cohort + ratio sentence
  • getLineInsight(linePoints) -> first vs last month % change sentence
• Require non-placeholder text tied to computed values.

Hint: Tell Cortex the exact sentence structure you want.

Prompt for Sigma plugin wiring

• Ask Cortex to include Sigma API hooks:
  • workbook.addColumns(…)
  • workbook.on(“change”, …)
• Require dynamic updates on filtering.

Hint: Include: “Recompute charts + insight text whenever filters change.”

Prompt for visual storytelling standards

• Ask Cortex for:
  • side-by-side flex layout (50/50 columns, 40px gap)
  • strong title/subtitle
  • cohort definition text
  • axis labels and numeric data labels
  • slower reveal animation (bars + line draw)

Hint: Add “presentation-ready for LinkedIn” to enforce polish.

Prompt for performance refinement

• After first version, run a second prompt:
  • “Optimize render speed without removing storytelling animation.”
• Ask Cortex to reduce expensive label rendering and tune transition timings.

Hint: Use iterative prompting: build -> test -> refine.

QA prompts (final pass)

Use Cortex with targeted QA prompts:

• “What breaks with only one month selected?”
• “What breaks with null income?”
• “How should empty states read?”
• “Are axes aligned and labels non-overlapping?”

Hint: Prompt Cortex to return a short bug checklist, not just code.