F# codegen: HTTP route/query binding — string + typed (GH-2969)

[jeremydmiller]

Extends ReadHttpFrame F# emit to typed (parsed) HTTP binding for method arguments, on top of the string binding.

⚠️ Includes the route/query string binding from #2980, which merged into the stacked #2979 branch and never reached main (the stacked-merge gotcha — base was the #2979 branch, not main). This PR re-lands that commit plus the new typed binding, both against main.

Typed binding

• writeParsedValueFSharp: F# auto-tuples the C# out-parameter TryParse into match Type.TryParse(raw, InvariantCulture) with | true, v -> … | _ -> ….
  • Route value: null or parse-failure 404s + aborts; success binds the variable and renders the rest of the chain in the success arm (no F# early return).
  • Query/form/header: binds the parsed value, or Unchecked.defaultof<T> on failure, then continues.
• Nullable/optional and enum parsed binding still throw NotSupported (deferred).

Generated F#

// GET /fsharp/things/{id}/items/{count}  (string + int route values)
let count_rawValue = (httpContext.GetRouteValue("count") :?> string)
if isNull count_rawValue then
    httpContext.Response.StatusCode <- 404
    ()
else
    match System.Int32.TryParse(count_rawValue, System.Globalization.CultureInfo.InvariantCulture) with
    | true, count -> ... thingEndpoints.GetItems(id, count) ...
    | _ -> httpContext.Response.StatusCode <- 404; ()

// GET /fsharp/paged?page=  (int query)
let page = match System.Int32.TryParse(page_rawValue, ...) with | true, v -> v | _ -> Unchecked.defaultof<int>

Verification

• Fixture renders + compiles GET /things/{id} (string route), /search (string query), /things/{id}/items/{count} (string + int route), /paged (int query), plus the existing string/JSON endpoints.
• Both F# gates green; full wolverine.slnx Release regression — 0 warnings, 0 errors.

Part of #2969.

🤖 Generated with Claude Code