fix callback URL to use configurable public base

Separate callback URL generation from LISTEN_ADDR by introducing CALLBACK_BASE_URL with a localhost default for local development.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

internal/ai_client/client.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"strings"
 	"time"
 
 	"thuanle.me/claw-email-bridge/internal/config"
@@ -65,7 +66,7 @@ func (d *Dispatcher) Dispatch(task *database.Task) {
 	}
 
 	// Build callback URL.
-	callbackURL := fmt.Sprintf("http://%s/callback", d.cfg.ListenAddr)
+	callbackURL := buildCallbackURL(d.cfg.CallbackBaseURL)
 
 	payload := openClawRequest{
 		Input:       task.BodyPlain,
@@ -129,6 +130,14 @@ func (d *Dispatcher) Dispatch(task *database.Task) {
 	}
 }
 
+func buildCallbackURL(base string) string {
+	trimmed := strings.TrimRight(base, "/")
+	if trimmed == "" {
+		trimmed = "http://localhost"
+	}
+	return trimmed + "/callback"
+}
+
 // callAPI makes a single HTTP POST to OpenClaw.
 func (d *Dispatcher) callAPI(payload openClawRequest) error {
 	body, err := json.Marshal(payload)