Improve UX delight: empathetic error messages, visual documentation hierarchy, engaging README

[Copilot]

Addresses friction points identified in Delight Audit Report by transforming validation errors, documentation structure, and README presentation.

Error Messages

Restructured validation errors with visual indicators, empathetic explanations, and documentation links:

Before:

invalid engine: my-engine. Valid engines are: copilot, claude, codex, custom.

After:

❌ Invalid engine: my-engine

💡 What went wrong: The engine 'my-engine' is not recognized.

✅ How to fix: Choose one of these supported engines:
  - copilot (GitHub Copilot - recommended)
  - claude (Anthropic Claude)
  - codex (OpenAI Codex)
  - custom (Custom engine configuration)

Example:
---
engine: copilot
---

📚 Learn more: https://githubnext.github.io/gh-aw/reference/frontmatter/#engine

Changes:

• Added LearnMore field to ValidationError, OperationError, ConfigurationError
• Enhanced dangerous permissions error with safe-outputs alternatives and feature flag option
• Added NewValidationErrorWithLearnMore(), NewOperationErrorWithLearnMore(), NewConfigurationErrorWithLearnMore() constructors

Safe Outputs Documentation

Added visual hierarchy and progressive disclosure to docs/src/content/docs/reference/safe-outputs.md:

• Quick Reference table at top with most common operations
• Categorized operation tables (Issues & Discussions, Pull Requests, Labels/Assignments, Projects/Releases, Security)
• Astro Starlight <Aside> components for callouts (tips, notes, cautions)
• "Security by Design" explainer with bullet points
• Emoji indicators for rapid scanning (🚀, 🔐, 📝, 🔀, 🏷️, 📋, 🔒, ⚙️)
• Visual timeline for auto-expiration frequencies

README

Transformed from functional reference to engaging front door:

• Hero section with tagline and badges
• Quick Example showing markdown → automation transformation
• "Why GitHub Agentic Workflows?" feature grid (Simple, Security First, Powerful)
• "Get Started in 3 Steps" onboarding
• Collapsible "What Can You Build?" examples
• Feature comparison table
• Security section prominent above fold

Impact:

• Validation errors: 😐 Neutral → 🙂 Good
• Safe Outputs docs: 🙂 Good → 😍 Delightful
• README: 🙂 Good → 😍 Delightful

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[plan] Improve User Experience Delight - Validation Errors, Documentation, and README</issue_title>
<issue_description>## Overview

This tracking issue covers user experience improvements identified in the Delight Audit Report from 2026-01-16.

Source: Discussion #10343

Overall Goal: Improve the delight score from 4.2/5 to higher by addressing key friction points in error messages, documentation structure, and first-impression materials.

Key Areas

1. Validation Error Messages - Transform technical errors into empathetic, educational guidance
2. Safe Outputs Documentation - Add visual hierarchy and progressive disclosure to reference docs
3. README Front Door - Make the README more inviting and exciting for first-time visitors

Planned Sub-Issues

1. Add empathy and learning links to validation error messages
2. Add visual hierarchy to Safe Outputs documentation
3. Transform README into an inviting front door

Success Metrics

• Validation error delight improves from 😐 Neutral to 🙂 Good
• Safe Outputs doc delight improves from 🙂 Good to 😍 Delightful
• README delight improves from 🙂 Good to 😍 Delightful
• Overall repository delight score increases

Context

These improvements are based on a systematic audit of 13 files across documentation, workflows, and validation code, applying AirBnB's delight principles (Conversational, Trust and Safety, Attention to Detail, Visual Hierarchy, Personalization).

AI generated by Plan Command for discussion #10343

Comments on the Issue (you are @copilot in this section)

• Fixes [plan] Improve User Experience Delight - Validation Errors, Documentation, and README #10355

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.