Add string.Truncate(int charCount) and string.TruncateBytes(int byteCount, Encoding?)

[Copilot]

Adds two distinct truncation methods on string with clear, non-ambiguous names.

• Truncate(int charCount) — truncates to at most charCount UTF-16 characters (simple slice)
• TruncateBytes(int byteCount, Encoding? encoding = null) — truncates so the encoded byte length doesn't exceed byteCount; defaults to UTF-8. Uses binary search over character count and guards against splitting surrogate pairs.

"héllo".Truncate(3)                        // "hél"
"héllo".TruncateBytes(4)                   // "hél"  (h=1, é=2, l=1 bytes)
"héllo".TruncateBytes(3, Encoding.UTF8)    // "hé"   (h=1, é=2 bytes)
"a𝄞b".TruncateBytes(5)                    // "a𝄞"  (a=1, 𝄞=4 bytes; surrogate pair kept intact)

[Copilot]

Pull request overview

This PR adds two new string extension APIs to PowerKit for truncating text either by UTF-16 character count or by encoded byte count, extending the library’s existing collection of convenience extensions for core BCL types.

Changes:

• Adds string.TruncateBytes(int byteCount, Encoding? encoding = null) with UTF-8 as the default encoding.
• Keeps the existing Truncate(int charCount) API alongside the new byte-based overload to make the truncation mode explicit.
• Adds unit tests covering basic ASCII, multi-byte UTF-8, surrogate-pair, default-encoding, and ASCII scenarios.

Reviewed changes

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

File	Description
PowerKit/Extensions/StringExtensions.cs	Adds the new byte-based truncation implementation and adjacent string truncation API docs.
PowerKit.Tests/Extensions/StringExtensionsTests.cs	Adds tests for the new TruncateBytes behavior across several common encoding/character scenarios.

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[Tyrrrz]

@copilot

[Copilot]

@copilot

Addressed all review comments in 3d55ce9: renamed enc→actualEncoding and lo/hi→charLo/charHi, added ArgumentOutOfRangeException guard for negative byteCount, fixed surrogate-safe probing via try/catch (EncoderFallbackException) in the binary search, and cleaned up tests (added // Act & assert, removed the two low-value assertions, fixed the "Emoji" label to "Supplementary character", dropped the explicit null arg, added a test for the negative byteCount case).

[Tyrrrz]

Can we add assertions with Encoding.ASCII for other strings in this test (one each, similar to this one) @copilot

[Copilot]

Done in b5f363a — added "héllo".TruncateBytes(3, Encoding.ASCII).Should().Be("hél") and "a𝄞b".TruncateBytes(1, Encoding.ASCII).Should().Be("a"). Also fixed a pre-existing incorrect assertion: "a𝄞b".TruncateBytes(10) should return "a𝄞b" (the full string, since it's only 6 UTF-8 bytes).

[codecov]

Codecov Report

❌ Patch coverage is 92.10526% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.82%. Comparing base (9e825ee) to head (14cde3e).
⚠️ Report is 1 commits behind head on prime.

Files with missing lines	Patch %	Lines
PowerKit/Extensions/StringExtensions.cs	85.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##            prime      #82      +/-   ##
==========================================
- Coverage   93.85%   93.82%   -0.03%     
==========================================
  Files         136      136              
  Lines        2717     2755      +38     
  Branches      217      223       +6     
==========================================
+ Hits         2550     2585      +35     
- Misses        123      125       +2     
- Partials       44       45       +1     

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