fix: finalize growth cost controls

internal/growthreport/avalai.go

@@ -80,6 +80,8 @@ type responseEnvelope struct {
 		InputTokens  int64 `json:"input_tokens"`
 		OutputTokens int64 `json:"output_tokens"`
 	} `json:"usage"`
+	EstimatedCost     json.RawMessage `json:"estimated_cost"`
+	ProviderRequestID string          `json:"-"`
 }
 
 type outputItem struct {
@@ -109,6 +111,8 @@ func (c *AvalAIClient) workflow(ctx context.Context, base map[string]any, eviden
 		}
 	}
 	usage := Usage{InputTokens: first.Usage.InputTokens, OutputTokens: first.Usage.OutputTokens, LatencyMS: latency}
+	usage.ProviderRequestID = first.ProviderRequestID
+	usage.EstimatedCost = costString(first.EstimatedCost)
 	final := first
 	if len(calls) > 0 {
 		if executor == nil {
@@ -144,6 +148,12 @@ func (c *AvalAIClient) workflow(ctx context.Context, base map[string]any, eviden
 		usage.InputTokens += second.Usage.InputTokens
 		usage.OutputTokens += second.Usage.OutputTokens
 		usage.LatencyMS += secondLatency
+		if second.ProviderRequestID != "" {
+			usage.ProviderRequestID = second.ProviderRequestID
+		}
+		if cost := costString(second.EstimatedCost); cost != "" {
+			usage.EstimatedCost = cost
+		}
 		final = second
 		for _, raw := range second.Output {
 			var item outputItem
@@ -195,9 +205,33 @@ func (c *AvalAIClient) do(parent context.Context, bodyValue map[string]any) (res
 	if result.Status != "completed" {
 		return responseEnvelope{}, 0, false, fmt.Errorf("avalai: incomplete response status %q", result.Status)
 	}
+	result.ProviderRequestID = resp.Header.Get("X-Request-ID")
 	return result, time.Since(started).Milliseconds(), false, nil
 }
 
+func costString(raw json.RawMessage) string {
+	if len(raw) == 0 {
+		return ""
+	}
+	var text string
+	if json.Unmarshal(raw, &text) == nil {
+		if len(text) <= 64 {
+			return text
+		}
+		return ""
+	}
+	text = strings.TrimSpace(string(raw))
+	if len(text) > 64 {
+		return ""
+	}
+	for _, r := range text {
+		if !(unicode.IsDigit(r) || r == '.' || r == '-' || r == 'e' || r == 'E') {
+			return ""
+		}
+	}
+	return text
+}
+
 func parseAICopy(result responseEnvelope, known map[string]struct{}) (AICopy, error) {
 	var text string
 	for _, raw := range result.Output {