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ext-apps/examples/cohort-heatmap-server
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Filename Latest commit message Latest commit date
Olivier Chafik c3e9d4d694
 fix(examples): use server.registerTool for non-UI tool + fix missing imports (#173) 
* fix(threejs-server): use server.registerTool for non-UI tool

The learn_threejs tool doesn't have a UI component - it only returns
documentation text. Using registerAppTool without _meta causes a
runtime error when the function tries to access config._meta.ui.

Fixes crash: "Cannot read property 'ui' of undefined"

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* fix(examples): add missing registerAppTool and registerAppResource imports

All example servers were using registerAppTool and registerAppResource
but not importing them from @modelcontextprotocol/ext-apps/server,
causing "ReferenceError: registerAppTool is not defined" at runtime.

Affected servers:
- budget-allocator-server
- cohort-heatmap-server
- customer-segmentation-server
- scenario-modeler-server
- system-monitor-server
- threejs-server
- wiki-explorer-server

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

---------

Co-authored-by: Claude <noreply@anthropic.com>
2025-12-17 00:17:45 +00:00
..
src Use content instead of structuredContent in examples 2025-12-05 16:35:20 -06:00
mcp-app.html Add color-scheme meta tag to all example apps 2025-12-15 11:42:18 -08:00
package.json feat: make MCP SDK a peer dependency (#168) 2025-12-16 22:09:59 +00:00
README.md Smoothen the process of getting started (#103) 2025-12-09 16:15:32 +01:00
server.ts fix(examples): use server.registerTool for non-UI tool + fix missing imports (#173) 2025-12-17 00:17:45 +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