Feature Request: Automatic HEAD request handling

ルート登録のエントリーポイントである e.GET() から開始し、提案されている middleware.AutoHead() アプローチと比較してください。既存のルーターとルート登録の動作を確認し、明示的な HEAD ルートが存在しない場合に自動的な HEAD 処理がどのように機能すべきかを判断してください。GET ルートがレスポンスボディを省略して HEAD リクエストに応答し、明示的な HEAD の動作を変更しないことを完了条件とします。

Currently, Echo requires explicit HEAD route registration for every GET route. Some other frameworks like Fiber, Express and Fastify handle this automatically. According to HTTP semantics, HEAD should behave identically to GET except that the response body is omitted. Automatically supporting HEAD for GET routes aligns with this expectation and reduces boilerplate.

Related: #654

Proposal

Add automatic HEAD handling for GET routes when no explicit HEAD route is registered.

Implementation Options

Option 1: Middleware approach

e := echo.New()
e.Use(middleware.AutoHead())

Pros:

• Opt-in
• No changes to core routing
• Simple implementation

Cons:

• Must be registered last in the middleware chain. Otherwise, middlewares registered after it will not execute for HEAD requests, since the middleware directly invokes the handler and bypasses the remaining chain

I've already implemented this approach, but after testing I realized the middleware ordering requirement makes it less convenient and more error-prone.

Option 2: Core integration

Auto-register HEAD routes during e.GET() calls, controlled by config :

e := echo.New()
e.AutoHead = true

Default value could remain false to avoid breaking existing behavior.

Pros:

• No middleware ordering constraints
• Slightly better performance, since re-routing is avoided

Cons:

• Requires changes to core Echo router/route registration

Questions

1. Would the Echo team be interested in this functionality?
2. If so, which implementation approach would be preferred: middleware or core integration? Would you consider a PR for either approach?