headers v0.21.3

Patch Changes

• Improve parsing performance for Accept, Accept-Encoding, Accept-Language, If-Match, and If-None-Match headers containing long whitespace runs while preserving existing list parsing behavior.

• Recognize ContentType parameter names case-insensitively while preserving media type and parameter value casing. Keep the first value when a boundary or charset parameter is repeated, including when the names use different casing.

  Read unterminated quoted parameter values through the end of the input, honoring backslash escapes and preserving quoted whitespace without interpreting embedded delimiters as new parameters. ContentType follows WHATWG quoted-string recovery: boundary="abc yields abc, while note="value; boundary=abc does not supply a boundary.

• Preserve subsequent Cookie pairs when quotes span semicolon delimiters while retaining existing value decoding. Cookie#toString() encodes semicolons in values as %3B; Cookie.from() preserves that encoding, so a value such as a;b is parsed back as a%3Bb (see #11906).

• SetCookie now accepts lowercase 'strict', 'lax', and 'none' values for sameSite and serializes them using canonical casing.

• Declare package modules as side-effect-free.