Two edge alignments that have to land together, because the test for the
first asserts the messages of the second.
`String.prototype.trim` is not `char.IsWhiteSpace`. JavaScript counts U+FEFF,
which .NET does not; .NET counts U+0085, which JavaScript does not. Every
`trim()` in the shared verifier stood in for a C# `IsNullOrWhiteSpace` or
`Trim()`, so both were wrong at those two code points: a U+0085 signature was
an unsigned route to C# and a bad signature to TypeScript, and a U+FEFF
signature the other way round. `isCSharpWhiteSpace`, `trimCSharp` and
`isNullOrWhiteSpaceCSharp` are that set, and `isUnsignedCertificate` and the
signature trim now use it. The test pins all 34 code points Soul probed on
both sides against the answers .NET 10 gave on 2026-09-16.
The C# `Verify` also has three signature refusals, not one: a signature that
is not base64, a decoded length that is not 64, and a signature that decodes
but does not verify. TypeScript collapsed the first two into the third and
lost the distinction the reference draws. Split, with each message pinned by
its exact C# string. `verifyP256` keeps its own checks: it is the silent
`VerifySession` path, which returns false for all three.
Mutations: the whitespace-set site reverted to `String.prototype.trim`,
U+0085 dropped from the set, and the two new messages merged back into
"invalid" -- each killed by its test.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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