fix(telegram): honor proxy fallbacks for bot api

internal/service/telegram_api_test.go

@@ -2,8 +2,10 @@ package service
 
 import (
 	"errors"
+	"net/http"
 	"strings"
 	"testing"
+	"time"
 )
 
 func TestTelegramMethodURLUsesCustomAPIBase(t *testing.T) {
@@ -90,13 +92,45 @@ func TestTelegramTargetChatIDsUsesLegacyPrivateChatID(t *testing.T) {
 func TestTelegramProxyCandidatesDefaultLocalFallbacks(t *testing.T) {
 	got := telegramProxyCandidates(map[string]string{})
 	joined := strings.Join(got, ",")
-	for _, want := range []string{"127.0.0.1:10808", "172.17.0.1:7890"} {
+	for _, want := range []string{"host.docker.internal:20171", "socks5://172.17.0.1:20170", "127.0.0.1:10808", "172.17.0.1:7890"} {
 		if !strings.Contains(joined, want) {
 			t.Fatalf("default proxy candidates %q missing %q", joined, want)
 		}
 	}
 }
 
+func TestTelegramHTTPClientsPreferConfiguredProxy(t *testing.T) {
+	clients := telegramHTTPClients(time.Second, map[string]string{
+		"proxy_url": "http://proxy.example:7890",
+	})
+	if len(clients) == 0 {
+		t.Fatal("expected telegram clients")
+	}
+	if got := telegramClientProxyString(t, clients[0]); got != "http://proxy.example:7890" {
+		t.Fatalf("first client proxy = %q, want configured proxy", got)
+	}
+}
+
+func telegramClientProxyString(t *testing.T, client *http.Client) string {
+	t.Helper()
+	transport, ok := client.Transport.(*http.Transport)
+	if !ok || transport.Proxy == nil {
+		return ""
+	}
+	req, err := http.NewRequest(http.MethodGet, defaultTelegramAPIBaseURL, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	proxyURL, err := transport.Proxy(req)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if proxyURL == nil {
+		return ""
+	}
+	return proxyURL.String()
+}
+
 func TestTelegramCommandFiltering(t *testing.T) {
 	if telegramIsCommandText("今天看什么") {
 		t.Fatal("plain chat message should not be treated as command")