Fix hex color detection in strings by adding lookbehind patterns

[Copilot]

The color picker was not detecting hex colors when they appeared directly after quote characters or other common delimiters in code. For example:

// This didn't work - no color picker shown
const color = '#ff0000';

// But this worked - color picker shown
const color = ' #ff0000';

The issue was in the regex pattern in defaultDocumentColorsComputer.ts which only matched hex colors that were preceded by whitespace (\s+) or at the start of a line (^).

Solution:
Added positive lookbehind patterns to detect hex colors after common programming delimiters:

• Single quotes: '#ff0000'
• Double quotes: "#ff0000"
• Equals signs: background-color=#ff0000
• Brackets: colors = [#ff0000]
• Parentheses: rgb(#ff0000)
• Colons: style: {color: #ff0000}

Changes:

• Modified the regex in defaultDocumentColorsComputer.ts to include (?<=['":=\[({])(#)([A-Fa-f0-9]{6})\b and (?<=['":=\[({])(#)([A-Fa-f0-9]{8})\b patterns
• Added comprehensive test suite to ensure the fix works and doesn't break existing functionality

Testing:

• ✅ Original issue cases now work: '#ff0000', "#ff0000"
• ✅ Multiple hex colors in arrays: ['#ff0000', '#00ff00', '#0000ff']
• ✅ Hex colors after common delimiters: =, [, (, :
• ✅ Both 6-digit and 8-digit hex colors supported
• ✅ All existing functionality preserved (whitespace, start-of-line cases)
• ✅ RGB/HSL color detection unaffected

This is a minimal change (1 line modified) that significantly improves the color picker's usability in common coding scenarios.

Fixes #251582.

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[aiday-mar]

Hi thanks for the change. I want the hex regex to be changed so that is simply adds the case when the length 6 or 8 color is inside of a string (or after a single or double quote). You don't need to cover the case where it follows other delimiters.

[Copilot]

Done! I've simplified the regex to only support hex colors after single and double quotes. Removed the lookbehind patterns for other delimiters (=, [, (, {, :) and updated the tests accordingly. The regex now only includes (?<=['"])(#)([A-Fa-f0-9]{6})\b|(?<=['"])(#)([A-Fa-f0-9]{8})\b for the quote cases. Commit: 55e10f1

[Copilot]

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• electronjs.org
  • Triggering command: node-gyp (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to my firewall allow list