[matt-edmondson]

Fixes #310

What changed

• SemanticString<T>.WeakString is now { get; protected init; } instead of { get; init; }. Code outside the type hierarchy can no longer write uuid with { WeakString = "not a uuid" } or new Uuid { WeakString = "garbage" }, so the only way to get a value in is through Create, which canonicalizes and validates it.
• ISemanticString.WeakString is now get-only.
• The cached WeakStringSetter<TDest> delegate that Create uses (SemanticString.Create repeats type reflection on every call (~500 B and ~1.6 µs per value before any validator runs); cache per-type metadata #444) now looks up the non-public accessor (GetSetMethod(nonPublic: true)). A derived type can still set the value from its own constructor, which is what the existing SemanticStringExtensionsTests.TestSemanticString does.
• Stale path caches: AbsoluteDirectoryPath, AbsoluteFilePath and RelativeDirectoryPath are sealed, and nothing inside them uses with { WeakString = ... }. With the accessor closed, a with copy always has the same value as its source, so the copied Parent and related caches stay correct. The types need no copy constructor.

Breaking change

Removing a public accessor is a breaking API change, as the issue and its triage note, so the commit carries [major]. A caller that set WeakString in an object initializer or a with expression must call Create / As<T>() instead. dotnet pack with package validation on Semantics.Strings passes with no new suppressions, because the change is the same across every target framework.

Tests

• New WeakStringAccessTests:
  • WeakString has no public setter on MySemanticString, Uuid or the three path types;
  • ISemanticString.WeakString is read-only;
  • Create still sets the value for a Uuid, a plain semantic string and an AbsoluteDirectoryPath, including its Parent.
• With the Semantics.Strings change reverted, the two accessor tests fail and the two Create tests pass. With the change they all pass.
• dotnet build -c Release finished with 0 warnings and 0 errors. dotnet test -c Release had 0 failures (1993 passed, the rest skipped).

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Generated by Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

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