Naming, layout and comments: descriptive full-word names, one item per line in wrapped calls and literals, and doc comments on exported names

Short and single-letter names in application code become full words (tests
keep theirs). Wrapped calls, signatures and composite literals put one item
per line, and one-line function bodies are expanded. Exported names and
groups of constants get doc comments, and comments refer to the renamed
identifiers.

internal/websocket/messages.go

@@ -37,28 +37,36 @@ type Envelope struct {
 // Envelope types. TypeEvent, TypeRequest and TypeAck are reserved: nothing
 // sends or handles them yet.
 const (
+	// TypeWelcome is sent to a client when it connects, with its client ID.
 	TypeWelcome = "welcome"
-	TypePing    = "ping"
-	TypePong    = "pong"
-	TypeEcho    = "echo"
-	TypeEvent   = "event"
+	// TypePing asks the server for a TypePong.
+	TypePing = "ping"
+	// TypePong answers a TypePing, with the server's time.
+	TypePong = "pong"
+	// TypeEcho is sent back to the client with the same ID and payload.
+	TypeEcho = "echo"
+	// TypeEvent is reserved for events pushed to clients.
+	TypeEvent = "event"
+	// TypeRequest is reserved for requests from clients.
 	TypeRequest = "request"
-	TypeAck     = "ack"
-	TypeError   = "error"
+	// TypeAck is reserved for acknowledging a request.
+	TypeAck = "ack"
+	// TypeError reports an error, with the ID of the message it answers.
+	TypeError = "error"
 )
 
-// mustRaw returns v as raw JSON: v itself if it is already json.RawMessage,
-// nil if v is nil or can't be marshalled.
-func mustRaw(v any) json.RawMessage {
-	if v == nil {
+// mustRaw returns value as raw JSON: value itself if it is already
+// json.RawMessage, nil if value is nil or can't be marshalled.
+func mustRaw(value any) json.RawMessage {
+	if value == nil {
 		return nil
 	}
-	if raw, ok := v.(json.RawMessage); ok {
+	if raw, ok := value.(json.RawMessage); ok {
 		return raw
 	}
-	b, err := json.Marshal(v)
+	encoded, err := json.Marshal(value)
 	if err != nil {
 		return nil
 	}
-	return b
+	return encoded
 }