csharp: consolidated gaps from agent dogfooding (Razor files, proto routes, round 3)

[swapnilpaliwal-sd]

Summary

Agents dogfooding impact, path, changed and test-impact on real C# projects (ASP.NET Core services with MediatR, Razor Pages and Blazor apps) found the gaps below. Round 1 fixes are in flight; round 3 is queued.

Root cause

• C# indexing reads only .cs files, so a call in a .razor @code block or a .cshtml view is never a caller (csharp: a call in a .razor @code block is not a caller, so a service method used only from a component is called local #1435).
• HTTP routes are derived from controller attributes and Map* calls only; a route declared in a .proto google.api.http option is never served (csharp: an HTTP call to a gRPC JSON-transcoded route stays unserved #1490).
• Indexing cost on the dogfood projects (12 to 19 minutes each) blocks round 3; that is the vendored-code and process-tree work in fix/index-skip-unneeded.

@inject IOrderService Orders
<button @onclick="Go">Delete</button>
@code {
    private Task Go() => Orders.Delete(Id);
}

impact IOrderService.Delete should list the component's Go as a caller.

In progress

• fix/csharp-dogfood-r1: qualified new, changed constructor edits, MediatR and Razor test routes, record header, empty primary constructor, Send to handler, mocked mediator.
• fix/index-skip-unneeded: skip vendored code, report the main language first, kill the process tree.

Checklist

• Land fix/csharp-dogfood-r1.
• Dogfood round 3, once fix/index-skip-unneeded lands.
• csharp: a call in a .razor @code block is not a caller, so a service method used only from a component is called local #1435: calls in .razor @code blocks and .cshtml views are callers. Distinct, left open with its own repro.
• csharp: an HTTP call to a gRPC JSON-transcoded route stays unserved #1490: an HTTP call to a gRPC JSON-transcoded route reaches the rpc. Distinct, left open with its own repro.

[swapnilpaliwal-sd]

#1435 and #1490 are now closed into this issue. Their checklist lines above stand; each closed issue keeps its full repro and root cause.