autoresearch iter 20: give the telegram poller a real long-poll window

telebot types LongPoller.Timeout as time.Duration and sends
int(timeout / time.Second) to getUpdates, so the literal 10 meant ten
nanoseconds: Telegram received timeout=0, long polling never held the
connection, and the adapter polled the Bot API in a tight loop instead.
Use 10 seconds and extract the settings so the conversion is asserted.

The adapter also has no media temp-dir cleanup (downloadMedia creates an
MkdirTemp per attachment and nothing removes it); that is left as a separate
change rather than bundled here.

backend/plugins/domain/message_gateway/channels/telegram/adapter.go

@@ -14,6 +14,7 @@ import (
 	"path/filepath"
 	"strconv"
 	"strings"
+	"time"
 
 	tele "gopkg.in/telebot.v4"
 )
@@ -41,16 +42,27 @@ func (a *Adapter) Capabilities() model.Capability {
 	return model.Capability{Text: true, Image: true, File: true, Reply: true}
 }
 
-// Connect starts long polling.
-func (a *Adapter) Connect(ctx context.Context) error {
+// longPollWindow is how long Telegram may hold a getUpdates call open before
+// returning empty. telebot converts it with int(timeout / time.Second), so a
+// bare integer here would mean nanoseconds, send timeout=0 and turn the poller
+// into a tight loop against the Bot API.
+const longPollWindow = 10 * time.Second
+
+// buildTeleSettings assembles the telebot settings.
+func buildTeleSettings(cfg model.ChannelConfig) tele.Settings {
 	pref := tele.Settings{
-		Token:  a.cfg.Credentials["bot_token"],
-		Poller: &tele.LongPoller{Timeout: 10},
+		Token:  cfg.Credentials["bot_token"],
+		Poller: &tele.LongPoller{Timeout: longPollWindow},
 	}
-	if base := strings.TrimSpace(a.cfg.Extra["base_url"]); base != "" {
+	if base := strings.TrimSpace(cfg.Extra["base_url"]); base != "" {
 		pref.URL = strings.TrimSuffix(base, "/")
 	}
-	bot, err := tele.NewBot(pref)
+	return pref
+}
+
+// Connect starts long polling.
+func (a *Adapter) Connect(ctx context.Context) error {
+	bot, err := tele.NewBot(buildTeleSettings(a.cfg))
 	if err != nil {
 		return fmt.Errorf("telegram: new bot: %w", err)
 	}

backend/plugins/domain/message_gateway/channels/telegram/adapter_test.go

@@ -7,10 +7,32 @@ import (
 	"Wavelet/plugins/domain/message_gateway/model"
 	"context"
 	"testing"
+	"time"
 
 	tele "gopkg.in/telebot.v4"
 )
 
+// TestBuildTeleSettingsLongPollWindow 回归：LongPoller.Timeout 是 time.Duration，
+// telebot 以 int(timeout/time.Second) 下发给 getUpdates。写成裸整数会被解释为
+// 纳秒，令 timeout=0，长轮询退化为对 Bot API 的空转轮询。
+func TestBuildTeleSettingsLongPollWindow(t *testing.T) {
+	pref := buildTeleSettings(model.ChannelConfig{
+		Credentials: map[string]string{"bot_token": "token"},
+		Extra:       map[string]string{"base_url": "https://tg.example.com/api/"},
+	})
+
+	poller, ok := pref.Poller.(*tele.LongPoller)
+	if !ok {
+		t.Fatalf("expected *tele.LongPoller, got %T", pref.Poller)
+	}
+	if got := int(poller.Timeout / time.Second); got != 10 {
+		t.Errorf("getUpdates would receive timeout=%d seconds, want 10", got)
+	}
+	if pref.URL != "https://tg.example.com/api" {
+		t.Errorf("base_url trailing slash should be trimmed, got %q", pref.URL)
+	}
+}
+
 func TestHandleUpdate_DropsGroups(t *testing.T) {
 	var got int
 	a := &Adapter{onInbound: func(ctx context.Context, msg model.InboundMessage) error {