fix: address code review findings (critical + high + medium)

Critical:
- retryOnBusy: return lastErr after exhausted retries instead of nil

High:
- Remove debug console.log from use-paired-devices.ts

Medium:
- ChannelGeneralTab: sync state from instance prop via useEffect
- i18n: add MsgCannotRemoveLastWriter key + translations (en/vi/zh)
- use-channel-crud: refetch after delete instead of optimistic remove

internal/bootstrap/seed_store.go

@@ -14,20 +14,21 @@ import (
 
 // retryOnBusy retries fn up to 3 times on SQLITE_BUSY errors with 500ms delay.
 func retryOnBusy(fn func() error) error {
+	var lastErr error
 	for attempt := 0; attempt < 3; attempt++ {
-		err := fn()
-		if err == nil {
+		lastErr = fn()
+		if lastErr == nil {
 			return nil
 		}
-		if !strings.Contains(err.Error(), "SQLITE_BUSY") && !strings.Contains(err.Error(), "database is locked") {
-			return err
+		if !strings.Contains(lastErr.Error(), "SQLITE_BUSY") && !strings.Contains(lastErr.Error(), "database is locked") {
+			return lastErr
 		}
 		if attempt < 2 {
 			slog.Warn("bootstrap: retrying after SQLITE_BUSY", "attempt", attempt+1)
 			time.Sleep(500 * time.Millisecond)
 		}
 	}
-	return nil // unreachable, but satisfies compiler
+	return lastErr
 }
 
 // SeedToStore seeds embedded templates into agent_context_files (agent-level).

internal/http/channel_instances.go

@@ -437,7 +437,7 @@ func (h *ChannelInstancesHandler) handleRemoveWriter(w http.ResponseWriter, r *h
 		}
 	}
 	if allowCount <= 1 {
-		writeError(w, http.StatusConflict, protocol.ErrFailedPrecondition, "cannot remove the last file writer")
+		writeError(w, http.StatusConflict, protocol.ErrFailedPrecondition, i18n.T(locale, i18n.MsgCannotRemoveLastWriter))
 		return
 	}
 	if err := h.configPermStore.Revoke(r.Context(), agentID, groupID, "file_writer", userID); err != nil {

internal/i18n/catalog_en.go

@@ -95,6 +95,7 @@ func init() {
 
 		// Channels
 		MsgCannotDeleteDefaultInst: "cannot delete default channel instance",
+		MsgCannotRemoveLastWriter:  "cannot remove the last file writer",
 
 		// Skills
 		MsgSkillsUpdateNotSupported: "skills.update not supported for file-based skills",

internal/i18n/catalog_vi.go

@@ -95,6 +95,7 @@ func init() {
 
 		// Channels
 		MsgCannotDeleteDefaultInst: "không thể xóa phiên bản channel mặc định",
+		MsgCannotRemoveLastWriter:  "không thể xóa người quản lý cuối cùng",
 
 		// Skills
 		MsgSkillsUpdateNotSupported: "skills.update không được hỗ trợ với skill dựa trên tệp",

internal/i18n/catalog_zh.go

@@ -95,6 +95,7 @@ func init() {
 
 		// Channels
 		MsgCannotDeleteDefaultInst: "无法删除默认Channel实例",
+		MsgCannotRemoveLastWriter:  "无法移除最后一个文件管理员",
 
 		// Skills
 		MsgSkillsUpdateNotSupported: "基于文件的Skill不支持 skills.update",

internal/i18n/keys.go

@@ -96,6 +96,7 @@ const (
 
 	// --- Channels ---
 	MsgCannotDeleteDefaultInst  = "error.cannot_delete_default_inst"  // "cannot delete default channel instance"
+	MsgCannotRemoveLastWriter   = "error.cannot_remove_last_writer"   // "cannot remove the last file writer"
 
 	// --- Skills ---
 	MsgSkillsUpdateNotSupported = "error.skills_update_not_supported" // "skills.update not supported for file-based skills"

ui/desktop/frontend/src/components/settings/channels/ChannelGeneralTab.tsx

@@ -1,4 +1,4 @@
-import { useState, useCallback } from 'react'
+import { useState, useCallback, useEffect } from 'react'
 import { useTranslation } from 'react-i18next'
 import { Switch } from '../../common/Switch'
 import { Combobox } from '../../common/Combobox'
@@ -31,6 +31,16 @@ export function ChannelGeneralTab({ instance, agents, onUpdate }: ChannelGeneral
   )
   const [policyValues, setPolicyValues] = useState<Record<string, unknown>>(initialPolicyValues)
 
+  // Sync policy values when instance updates (e.g. after save)
+  useEffect(() => {
+    const config = (instance.config ?? {}) as Record<string, unknown>
+    const keys = ESSENTIAL_CONFIG_KEYS[instance.channel_type] ?? ESSENTIAL_CONFIG_KEYS._default ?? []
+    setPolicyValues(Object.fromEntries(keys.filter((k) => config[k] !== undefined).map((k) => [k, config[k]])))
+    setDisplayName(instance.display_name ?? '')
+    setAgentId(instance.agent_id)
+    setEnabled(instance.enabled)
+  }, [instance])
+
   const handlePolicyChange = useCallback((key: string, value: unknown) => {
     setPolicyValues((prev) => ({ ...prev, [key]: value }))
   }, [])

ui/desktop/frontend/src/hooks/use-channel-crud.ts

@@ -56,13 +56,13 @@ export function useChannelCrud() {
   const deleteInstance = useCallback(async (id: string) => {
     try {
       await getApiClient().delete(`/v1/channels/instances/${id}`)
-      setInstances((prev) => prev.filter((i) => i.id !== id))
+      await fetchInstances()
       toast.success('Channel deleted')
     } catch (err) {
       toast.error('Failed to delete channel', (err as Error).message)
       throw err
     }
-  }, [])
+  }, [fetchInstances])
 
   const telegramExists = instances.some((i) => i.channel_type === 'telegram')
   const discordExists = instances.some((i) => i.channel_type === 'discord')

ui/desktop/frontend/src/hooks/use-paired-devices.ts

@@ -10,14 +10,11 @@ export function usePairedDevices() {
   const fetchDevices = useCallback(async () => {
     try {
       const ws = getWsClient()
-      const raw = await ws.call('device.pair.list')
-      console.log('[paired-devices] raw response:', raw)
-      const res = raw as { pending: PendingPairing[]; paired: PairedDevice[] }
-      console.log('[paired-devices] pending:', res.pending?.length, 'paired:', res.paired?.length)
+      const res = (await ws.call('device.pair.list')) as { pending: PendingPairing[]; paired: PairedDevice[] }
       setPendingPairings(res.pending ?? [])
       setPairedDevices(res.paired ?? [])
-    } catch (err) {
-      console.error('[paired-devices] error:', err)
+    } catch {
+      // ignore — gateway may not be connected
     } finally {
       setLoading(false)
     }