Implement enhanced CLI error formatting

[anivar]

Fixes #45717

Summary

This PR implements the enhanced error formatting proposed in #45717, improving the readability and visual structure of TypeScript compiler error messages.

Changes

Before:

index.ts:2:1 - error TS2588: Cannot assign to 'a' because it is a constant.

2 a = "123"
  ~

After:

● index.ts:2:1 TS2588
 | a = "123" 
 ▔ 
 Cannot assign to 'a' because it is a constant.

Implementation Details

• Added visual bullet points (●) as markers for each diagnostic
• Moved error codes (TS####) to the right and de-emphasized with grey color
• Replaced tilde (~) underlines with overlines (▔) for cleaner appearance
• Added vertical bars (|) to frame code snippets
• Implemented terminal width detection (minimum 60 columns required)
• Falls back to original formatting for narrow terminals
• Maintains full backwards compatibility

Testing

• Tested with various error types and edge cases
• Verified fallback behavior for narrow terminals
• Ensured related information is properly formatted
• All existing tests pass

Notes

• The enhanced formatting only activates when terminal width >= 60 columns
• Environment variables (COLORTERM, TERM_PROGRAM, TERM) are checked for terminal capability detection
• No breaking changes to existing API

[Copilot]

Pull Request Overview

This PR implements enhanced CLI error formatting for TypeScript compiler diagnostics to improve readability and visual structure. The changes introduce a more modern error display format with visual markers, cleaner code presentation, and improved terminal compatibility detection.

Key Changes

• Replaces traditional tilde underlines with overlines and adds visual bullet points for error markers
• Implements terminal width detection to determine when to use enhanced formatting (minimum 60 columns)
• Maintains full backwards compatibility by falling back to original formatting for narrow terminals

[anivar]

@microsoft-github-policy-service agree company="Foodhub"

[i-ayushh18]

🤖 AI Assistant: Task completed: PR #62130: Implement enhanced CLI error formatting

URL: https://github.com/microsoft/TypeScript/pul...

[anivar]

Closing this PR in favor of a much simpler approach. The original implementation was over-engineered with complex terminal detection and Unicode characters.

Creating a new PR with a minimal solution:

• Uses existing --pretty flag
• ASCII-only characters for compatibility
• 6 lines changed vs 200+
• No new compiler options needed

Thanks for the feedback on complexity!