[CNCF LFX Proposal] Apicurio Registry: Prompt Template Playground in the Registry UI

### CNCF Project

Apicurio Registry

### Term

2026 Term 3 (Sep-Nov)

### Program Name

Prompt Template Playground in the Registry UI

### Program Description

## Description
Apicurio Registry supports PROMPT_TEMPLATE artifacts — versioned prompt templates with variable schemas that can be rendered via the REST API and MCP server. But there's no way to work with prompts interactively in the UI. Users must use the raw API or external tools to test and compare templates.

This project builds a Prompt Template Playground into the Registry UI. The mentee will create an interactive prompt editor with syntax highlighting and live variable extraction, a test panel for rendering prompts with sample values, side-by-side version diff, and version tagging for lifecycle tracking (production/staging/experimental).

## Expected outcomes
- Interactive prompt editor with variable auto-detection and input form generation
- Test panel: fill in variables, see the fully rendered prompt in real-time
- Side-by-side version diff for prompt template text and variable schemas
- Version tagging using the existing labels system
- End-to-end tests for the playground UI

### Technologies

React, TypeScript, REST, Java, Quarkus

### Skills same as Technologies?

- [ ] Yes, the required skills are the same as the technologies listed above.

### Required/Desirable Skills

React, TypeScript, UI/UX design, REST APIs, prompt engineering concepts

### Mentors

Carles Arnal | @carlesarnal | carnalca@ibm.com | carnalca
Eric Wittmann | @EricWittmann | ewittman@ibm.com | ewittman

### Upstream Issue URL

https://github.com/Apicurio/apicurio-registry/issues/8425

### Application Prerequisites

- [x] Resume
- [x] Cover Letter
- [ ] School Enrollment Verification
- [ ] Participation Permission from school or employer
- [ ] Coding Challenge
- [ ] Custom Prerequisite (fill in details below)

### Coding Challenge URL

_No response_

### Custom Prerequisite Name

_No response_

### Custom Prerequisite Description

_No response_

### Custom Prerequisite — File Upload

- [ ] Yes — completion of this task requires the mentee to submit a file.

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**LFX program:** [CNCF - Apicurio Registry: Prompt Template Playground in the Registry UI (2026 Term 3)](https://mentorship.lfx.linuxfoundation.org/project/20cb824d-ab31-4d28-ae2e-f54c24ebb00e)

Start with upstream issue #8425 and the Registry UI's existing labels system; review how PROMPT_TEMPLATE artifacts are rendered through the REST API and MCP server. Done means the UI supports variable detection and input generation, live prompt rendering, side-by-side version diffs, version tagging, and end-to-end tests.

Written by the indexing model from the issue text.