feat: add channel dimension to GA4 AI usage tracking

Distinguish claw402, blockrun, and native direct API calls in telemetry.

config/config.go

@@ -129,6 +129,7 @@ func Init() {
 		telemetry.TrackAIUsage(telemetry.AIUsageEvent{
 			ModelProvider: usage.Provider,
 			ModelName:     usage.Model,
+			Channel:       usage.Channel(),
 			InputTokens:   usage.PromptTokens,
 			OutputTokens:  usage.CompletionTokens,
 		})

mcp/client.go

@@ -44,13 +44,26 @@ var (
 
 // TokenUsage represents token usage from AI API response
 type TokenUsage struct {
-	Provider         string
+	Provider         string // payment channel: "claw402", "blockrun-base", "blockrun-sol", or native provider name
 	Model            string
 	PromptTokens     int
 	CompletionTokens int
 	TotalTokens      int
 }
 
+// Channel returns the payment channel category for telemetry.
+// Returns "claw402", "blockrun", or "native" based on the provider.
+func (u TokenUsage) Channel() string {
+	switch u.Provider {
+	case ProviderClaw402:
+		return "claw402"
+	case ProviderBlockRunBase, ProviderBlockRunSol:
+		return "blockrun"
+	default:
+		return "native"
+	}
+}
+
 // Client AI API configuration
 type Client struct {
 	Provider   string

telemetry/experience.go

@@ -42,6 +42,7 @@ type AIUsageEvent struct {
 	TraderID      string
 	ModelProvider string // openai, deepseek, anthropic, etc.
 	ModelName     string // gpt-4o, deepseek-chat, claude-3, etc.
+	Channel       string // payment channel: "claw402", "blockrun", or "native"
 	InputTokens   int
 	OutputTokens  int
 }
@@ -214,6 +215,7 @@ func TrackAIUsage(event AIUsageEvent) {
 					Params: map[string]interface{}{
 						"model_provider":       event.ModelProvider,
 						"model_name":           event.ModelName,
+						"channel":              event.Channel,
 						"input_tokens":         event.InputTokens,
 						"output_tokens":        event.OutputTokens,
 						"total_tokens":         event.InputTokens + event.OutputTokens,