Add web search knowledge base, message tagging, and word-memory tip topics

Introduces websearch.py (Tavily) + knowledge.py to ground chat responses
in search results, tagging.py to tag user and assistant messages via LLM
and pick related topics for the Discord useless-tips job, and
word_memory.py to track recent conversation nouns (surfaced in the new
WordPool.vue sidebar) used to pick tip topics close to a related tag.

frontend/src/stores/chat.ts

@@ -1,12 +1,14 @@
 import { defineStore } from 'pinia'
 import { ref, computed } from 'vue'
-import { fetchSessions, fetchMessages, deleteSession, streamChat, type SessionInfo } from '../api/client'
+import { fetchSessions, fetchMessages, deleteSession, streamChat, type SessionInfo, type Source } from '../api/client'
 
 export interface Message {
   role: 'user' | 'assistant'
   content: string
   pending?: boolean
   error?: boolean
+  tags?: string[]
+  sources?: Source[]
 }
 
 export interface Toast {
@@ -21,7 +23,7 @@ export const useChatStore = defineStore('chat', () => {
   const currentSessionId = ref<string | null>(null)
   const messages = ref<Message[]>([])
   const isStreaming = ref(false)
-  const selectedModel = ref('gpt-5.4')
+  const selectedModel = ref('bedrock/jp.anthropic.claude-sonnet-4-6')
   const toasts = ref<Toast[]>([])
 
   const currentSession = computed(() =>
@@ -52,7 +54,7 @@ export const useChatStore = defineStore('chat', () => {
       const records = await fetchMessages(sessionId)
       messages.value = records
         .filter((r) => r.role === 'user' || r.role === 'assistant')
-        .map((r) => ({ role: r.role as 'user' | 'assistant', content: r.content }))
+        .map((r) => ({ role: r.role as 'user' | 'assistant', content: r.content, tags: r.tags }))
     } catch (e) {
       pushToast(`メッセージ取得失敗: ${e instanceof Error ? e.message : e}`)
     }
@@ -81,23 +83,27 @@ export const useChatStore = defineStore('chat', () => {
       selectedModel.value,
       (chunk) => {
         if (chunk.type === 'session_id' && chunk.value) {
-          currentSessionId.value = chunk.value
+          currentSessionId.value = chunk.value as string
           loadSessions().catch((e) => pushToast(`セッション更新失敗: ${e.message}`))
         } else if (chunk.type === 'chunk' && chunk.value) {
-          messages.value[msgIdx].content += chunk.value
+          messages.value[msgIdx].content += chunk.value as string
+        } else if (chunk.type === 'sources' && chunk.value) {
+          messages.value[msgIdx].sources = chunk.value as Source[]
         } else if (chunk.type === 'done') {
           messages.value[msgIdx].pending = false
           isStreaming.value = false
           loadSessions().catch((e) => pushToast(`セッション更新失敗: ${e.message}`))
         } else if (chunk.type === 'error') {
-          messages.value[msgIdx].content = chunk.value ?? 'バックエンドでエラーが発生しました。'
+          messages.value[msgIdx].content = (chunk.value as string) ?? 'バックエンドでエラーが発生しました。'
           messages.value[msgIdx].pending = false
           messages.value[msgIdx].error = true
           isStreaming.value = false
         }
       },
       (err) => {
-        messages.value[msgIdx].content = err.message
+        // 途中まで届いていた内容は残しつつ、エラーメッセージを付記する
+        const partial = messages.value[msgIdx].content
+        messages.value[msgIdx].content = partial ? `${partial}\n\n⚠️ ${err.message}` : err.message
         messages.value[msgIdx].pending = false
         messages.value[msgIdx].error = true
         isStreaming.value = false
@@ -105,6 +111,19 @@ export const useChatStore = defineStore('chat', () => {
     )
   }
 
+  /** エラーになったアシスタント応答のひとつ前にあるユーザーメッセージを再送信する。 */
+  function retryMessage(assistantIdx: number): void {
+    if (isStreaming.value) return
+    const userIdx = assistantIdx - 1
+    const userMsg = messages.value[userIdx]
+    if (!userMsg || userMsg.role !== 'user') return
+
+    const text = userMsg.content
+    // 失敗したユーザーメッセージとエラー応答を取り除いてから送信し直す
+    messages.value.splice(userIdx, 2)
+    sendMessage(text)
+  }
+
   return {
     sessions,
     currentSessionId,
@@ -119,5 +138,6 @@ export const useChatStore = defineStore('chat', () => {
     selectSession,
     removeSession,
     sendMessage,
+    retryMessage,
   }
 })