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ext-apps/examples/cohort-heatmap-server
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Anton Pidkuiko 8550545ccb
 fix: add mimeType to resource declarations in examples (#149) 
According to spec, mimeType should be present in both the resource
declaration and the resource content. This adds the missing mimeType
to the registerResource() declaration (third parameter) in all example
servers and the quickstart documentation.

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Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: ochafik <olivier.chafik@gmail.com>
2025-12-15 12:09:47 +00:00
..
src Use content instead of structuredContent in examples 2025-12-05 16:35:20 -06:00
mcp-app.html Add cohort-heatmap-server example 2025-12-04 14:32:53 -06:00
package.json Implement BYO zod v3 or v4 2025-12-12 11:29:02 +01:00
README.md Smoothen the process of getting started (#103) 2025-12-09 16:15:32 +01:00
server.ts fix: add mimeType to resource declarations in examples (#149) 2025-12-15 12:09:47 +00:00
tsconfig.json Add cohort-heatmap-server example 2025-12-04 14:32:53 -06:00
vite.config.ts Add cohort-heatmap-server example 2025-12-04 14:32:53 -06:00

README.md

Example: Cohort Heatmap App

A demo MCP App that displays cohort retention data as an interactive heatmap, showing customer retention over time by signup month.

Initial view Hover state Low retention hover

Features

  • Cohort Retention Heatmap: Color-coded grid showing retention percentages across cohorts and time periods
  • Multiple Metrics: Switch between Retention %, Revenue Retention, and Active Users
  • Period Types: View data by monthly or weekly intervals
  • Interactive Exploration: Hover cells for detailed tooltips, click to highlight rows/columns
  • Color Scale: Green (high retention) through yellow to red (low retention)
  • Theme Support: Adapts to light/dark mode preferences

Running

  1. Install dependencies:

    npm install

  2. Build and start the server:

    npm run start:http  # for Streamable HTTP transport
# OR
npm run start:stdio  # for stdio transport

  3. View using the basic-host example or another MCP Apps-compatible host.

Architecture

Server (server.ts)

Exposes a single get-cohort-data tool that returns:

  • Cohort rows with signup month, original user count, and retention cells
  • Period headers and labels
  • Configurable parameters: metric type, period type, cohort count, max periods

The tool generates synthetic cohort data using an exponential decay model with configurable retention curves per metric type.

App (src/mcp-app.tsx)

  • Uses React for the heatmap visualization
  • Fetches data on mount and when filters change
  • Displays retention percentages in a grid with HSL color interpolation
  • Shows detailed tooltips on hover with user counts and exact retention values
  • Supports row/column highlighting on cell click