fix: handle YAML parsing edge cases in CustomModesManager

[hannesrudolph]

Description

This PR addresses YAML parsing edge cases and formatting issues:

1. BOM and invisible character handling: Strips UTF-8/UTF-16 BOMs and cleans problematic invisible characters that can corrupt YAML parsing
2. Fancy quote normalization: Converts smart quotes and special dashes to standard ASCII equivalents
3. YAML line width control: Prevents automatic line wrapping by setting lineWidth: 0 and defaultStringType: 'PLAIN' options

Changes Made

CustomModesManager.ts

• Added stripBOM() method to remove Byte Order Marks
• Added cleanInvisibleCharacters() method to handle problematic Unicode characters
• Added parseYamlSafely() method with enhanced error handling
• Updated all yaml.stringify() calls to use { lineWidth: 0, defaultStringType: 'PLAIN' }

SimpleInstaller.ts & migrateSettings.ts

• Updated yaml.stringify() calls to use the same options for consistency

Testing

• Existing tests pass
• Manual testing with files containing BOMs and special characters
• Verified YAML output preserves user formatting without automatic line breaks

Notes

The YAML library may still convert between scalar styles (e.g., from folded >- to literal |-) when parsing and re-stringifying content. This is inherent to YAML normalization and ensures content integrity while minimizing formatting changes.

[delve-auditor]

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[Copilot]

Pull Request Overview

This PR enhances YAML parsing in CustomModesManager by preprocessing content to strip BOMs and normalize problematic Unicode characters, updating error handling, and adding extensive edge-case tests.

• Added private methods stripBOM and cleanInvisibleCharacters for content normalization.
• Refactored parseYamlSafely to apply preprocessing and surface user-friendly errors.
• Introduced a new test suite CustomModesManager.yamlEdgeCases.spec.ts covering BOMs, invisible characters, fancy quotes, dashes, error scenarios, and international characters.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/core/config/CustomModesManager.ts	Implemented BOM stripping, invisible character cleaning, and updated YAML parsing with enhanced error reporting
src/core/config/tests/CustomModesManager.yamlEdgeCases.spec.ts	Added comprehensive tests for YAML edge cases, including BOMs, invisible chars, quotes, dashes, errors, and UTF-8/Intl

Comments suppressed due to low confidence (2)

src/core/config/CustomModesManager.ts:76

• Add @param and @returns annotations to the JSDoc for stripBOM, cleanInvisibleCharacters, and parseYamlSafely to clarify expected input and output types.

	/**

src/core/config/tests/CustomModesManager.yamlEdgeCases.spec.ts:389

• Consider adding a test for files with Windows-style CRLF line endings to ensure the preprocessing handles all common line ending conventions.

			expect(modes[0].name).toBe("📝 Writing Mode")

[hannesrudolph]

Thanks for the thorough review! I've addressed all the feedback and pushed the changes. All tests are passing and the implementation is now more robust and performant.

[hannesrudolph]

✅ Added the YAML line width fix as requested!

I've updated all yaml.stringify() calls to include { lineWidth: 0 } option, which prevents the YAML library from automatically breaking long lines at the default 80-character limit.

Changes made:

• CustomModesManager.ts: 4 instances updated
• SimpleInstaller.ts: 2 instances updated
• migrateSettings.ts: 1 instance updated

This ensures that long strings in YAML output remain on a single line, improving readability as you requested.

[hannesrudolph]

I've pushed an additional update that adds defaultStringType: 'PLAIN' to all yaml.stringify() calls. This helps minimize formatting changes when possible.

However, I need to explain what's happening with the line breaks you're seeing:

1. Your original YAML uses folded scalars (>-) which join multiple lines into a single line with spaces
2. When the YAML library parses this, it creates a string with the lines joined
3. When re-stringifying, if the content has actual newlines, the library uses literal scalars (|-) to preserve them

The lineWidth: 0 option prevents the library from adding NEW line breaks due to length, but it doesn't prevent the style conversion from folded (>-) to literal (|-) scalars.

To truly preserve exact YAML formatting without any changes would require avoiding parsing/re-stringifying altogether, but that's not possible when we need to modify the content (add/remove modes).

The current solution ensures:

• No automatic line wrapping at 80 characters
• Plain scalars are used when possible
• User's manual line breaks are preserved

[daniel-lxs]

This PR is awesome!

LGTM

[mrubens]

I think we have a stripbom method elsewhere too - could we move to a shared utility file?

[mrubens]

Nice!

[HumanSpark]

Thanks folks