util: create hex style cache and fast path

[araujogui]

Improve styleText performance by caching and fast-path

Benchmark

util/style-text.js n=1000 validateStream=0 format='#ff0000' messageType='boolean'                -0.71 %       ±1.04%  ±1.38%  ±1.80%
util/style-text.js n=1000 validateStream=0 format='#ff0000' messageType='invalid'                 0.80 %       ±0.86%  ±1.14%  ±1.49%
util/style-text.js n=1000 validateStream=0 format='#ff0000' messageType='number'                 -0.59 %       ±0.93%  ±1.24%  ±1.62%
util/style-text.js n=1000 validateStream=0 format='#ff0000' messageType='string'         ***   1135.88 %      ±31.19% ±42.04% ±55.81%
util/style-text.js n=1000 validateStream=0 format='invalid' messageType='boolean'                -0.09 %       ±1.43%  ±1.90%  ±2.47%
util/style-text.js n=1000 validateStream=0 format='invalid' messageType='invalid'                -0.02 %       ±0.98%  ±1.30%  ±1.69%
util/style-text.js n=1000 validateStream=0 format='invalid' messageType='number'                  0.83 %       ±1.79%  ±2.40%  ±3.15%
util/style-text.js n=1000 validateStream=0 format='invalid' messageType='string'           *     -1.19 %       ±0.97%  ±1.29%  ±1.68%
util/style-text.js n=1000 validateStream=0 format='italic' messageType='boolean'                 -0.24 %       ±1.16%  ±1.55%  ±2.02%
util/style-text.js n=1000 validateStream=0 format='italic' messageType='invalid'                  0.60 %       ±0.92%  ±1.23%  ±1.60%
util/style-text.js n=1000 validateStream=0 format='italic' messageType='number'                   0.81 %       ±1.22%  ±1.63%  ±2.14%
util/style-text.js n=1000 validateStream=0 format='italic' messageType='string'                   1.47 %       ±3.09%  ±4.12%  ±5.36%
util/style-text.js n=1000 validateStream=0 format='red' messageType='boolean'              *      1.17 %       ±1.03%  ±1.37%  ±1.79%
util/style-text.js n=1000 validateStream=0 format='red' messageType='invalid'                     0.73 %       ±0.99%  ±1.32%  ±1.72%
util/style-text.js n=1000 validateStream=0 format='red' messageType='number'                     -0.34 %       ±0.94%  ±1.25%  ±1.63%
util/style-text.js n=1000 validateStream=0 format='red' messageType='string'                      4.92 %       ±6.11%  ±8.17% ±10.72%
util/style-text.js n=1000 validateStream=1 format='#ff0000' messageType='boolean'                -0.50 %       ±1.32%  ±1.76%  ±2.29%
util/style-text.js n=1000 validateStream=1 format='#ff0000' messageType='invalid'                 0.62 %       ±0.89%  ±1.19%  ±1.56%
util/style-text.js n=1000 validateStream=1 format='#ff0000' messageType='number'                 -0.14 %       ±0.79%  ±1.06%  ±1.37%
util/style-text.js n=1000 validateStream=1 format='#ff0000' messageType='string'                 -0.27 %       ±1.23%  ±1.64%  ±2.14%
util/style-text.js n=1000 validateStream=1 format='invalid' messageType='boolean'                -0.31 %       ±0.97%  ±1.29%  ±1.68%
util/style-text.js n=1000 validateStream=1 format='invalid' messageType='invalid'                 0.61 %       ±0.85%  ±1.13%  ±1.48%
util/style-text.js n=1000 validateStream=1 format='invalid' messageType='number'                 -0.05 %       ±0.78%  ±1.04%  ±1.35%
util/style-text.js n=1000 validateStream=1 format='invalid' messageType='string'                  0.69 %       ±1.55%  ±2.07%  ±2.70%
util/style-text.js n=1000 validateStream=1 format='italic' messageType='boolean'                 -0.01 %       ±1.07%  ±1.42%  ±1.85%
util/style-text.js n=1000 validateStream=1 format='italic' messageType='invalid'                 -0.27 %       ±1.09%  ±1.45%  ±1.90%
util/style-text.js n=1000 validateStream=1 format='italic' messageType='number'                   0.04 %       ±1.04%  ±1.38%  ±1.80%
util/style-text.js n=1000 validateStream=1 format='italic' messageType='string'                  -0.41 %       ±0.91%  ±1.21%  ±1.58%
util/style-text.js n=1000 validateStream=1 format='red' messageType='boolean'                     0.56 %       ±1.18%  ±1.57%  ±2.05%
util/style-text.js n=1000 validateStream=1 format='red' messageType='invalid'                    -0.41 %       ±0.94%  ±1.26%  ±1.64%
util/style-text.js n=1000 validateStream=1 format='red' messageType='number'                     -0.88 %       ±0.96%  ±1.28%  ±1.67%
util/style-text.js n=1000 validateStream=1 format='red' messageType='string'                     -0.04 %       ±1.00%  ±1.33%  ±1.73%

[Copilot]

Pull request overview

This PR improves util.styleText() performance for hex colors by introducing a cached hex-style lookup and a fast path for the common case where validateStream: false.

Changes:

• Add a module-level hexStyleCache and helper (getHexStyle) to memoize computed ANSI sequences for #RGB/#RRGGBB.
• Reuse a shared close sequence constant for 24-bit foreground colors (\u001b[39m) and integrate hex handling into the validateStream: false fast path.
• Refactor hex handling in the main formatting loop to use cached sequences instead of re-parsing on every call.

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[ljharb]

isn't the maximum possible permutations here 16,781,312 - is the memory size of 17 million key/value pairs a massive concern?

[araujogui]

Great point, altought a LRU doesn't seem a bad idea

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.57%. Comparing base (27c7f4d) to head (10facb7).
⚠️ Report is 11 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #62999      +/-   ##
==========================================
- Coverage   89.67%   89.57%   -0.11%     
==========================================
  Files         707      708       +1     
  Lines      219509   220246     +737     
  Branches    42093    42188      +95     
==========================================
+ Hits       196851   197286     +435     
- Misses      14551    14828     +277     
- Partials     8107     8132      +25     

Files with missing lines	Coverage Δ
lib/util.js	94.49% <100.00%> (+0.23%)	⬆️

... and 66 files with indirect coverage changes

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