[jeremydmiller]

Problem

A Wolverine.HTTP parameter bound from the query string ignored its declared C# default when the request omitted the value. int limit = 100 bound 0 and string name = "all" bound null. The generated code initialized the variable to default, and nothing read ParameterInfo.DefaultValue. ASP.NET Core Minimal APIs bind the declared default. CritterWatch's audit-log endpoint returned [] for every request without ?limit because of this.

Fix

• ReadHttpFrame takes the declared default of the parameter it binds and emits it as a C# literal through the new DeclaredDefaultValue helper. It escapes strings and chars, adds numeric suffixes, and casts enums from their underlying number.
• A parsed value with a declared default now parses into a temporary, as a nullable value already did. A failed TryParse writes the type's default into its out argument, and bool and enum parsing run even on a missing value. Parsing straight into the variable would wipe out the default.
• A string value becomes (string?)raw ?? "default".
• The default applies wherever a method parameter binds:
  • the query string, including [FromQuery(Name = ...)]
  • the form
  • headers, including postprocessor headers
  • optional route values
  • [AsParameters] constructor parameters
• The OpenAPI description now carries the default on query and form parameters.
• In lenient mode, a value that is present but unparseable now keeps the declared default instead of the type default. Strict mode still returns 400.

Tests

New declared_default_values_5099 in Wolverine.Http.Tests, with endpoints in WolverineWebApi:

• Defaults for int, string, bool, enum, double, negative short and int?.
• An explicit value still wins, and an unparseable value keeps the default.
• A renamed query key, an escaped string literal, headers, form values and [AsParameters].
• The OpenAPI default and the literal helper.

Results:

• 7 of the new integration tests fail when the default is not applied.
• The full Wolverine.Http.Tests suite passes on net10.0: 1307 passed, 10 skipped, 0 failed.
• dotnet build wolverine.slnx -c Release -f net9.0 has 0 errors.

F# code generation is unchanged.

Closes #5099

🤖 Generated with Claude Code

https://claude.ai/code/session_01DCggXgxnG3EBXoR9rrq37U