Pin notes to a chat, and import notes from files

Two additions to the shared notes, both about getting content in and out of
the prompt.

Per-chat pinning. Notes normally reach the model as a title list only, and
the body arrives just if the model decides to call read_note. A 📌 on the tab
now puts a page's full body in the system prompt for the chat that is open,
every turn, no tool round trip. The selection is per session (new table
session_note_pages, unique on session_id + page_id), so different
conversations carry different pages. The title list marks pinned pages so the
model does not read them twice, and bodies are capped per page by
SESSION_NOTES_CONTENT_LIMIT.

A new chat has no session row until its first message, so the front end
cannot PUT the selection yet. POST /chat/stream therefore accepts
note_page_ids and applies it before building the context, which makes the
pins count from the very first turn.

File import. Dropping .md/.txt on the editor - or picking them with the new
⬆ button - creates pages, and a .zip is unpacked into one page per text
entry with the first path component as the section. That is exactly the
shape the export writes, so a downloaded zip round-trips back in. Titles that
collide get a " (2)" suffix rather than overwriting, since restoring a backup
into a live workspace should not destroy anything. UploadFile needs
python-multipart, added to the lockfile.

Toasts grew a kind: the import success message was rendering in the red error
toast, as was the existing session-import message. Both are green now.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

frontend/src/stores/notes.ts

@@ -9,6 +9,9 @@ import {
   exportAllNotePages,
   renameNoteSection,
   reorderNotePages,
+  fetchSessionNotes,
+  updateSessionNotes,
+  importNotePages,
   type NotePage,
 } from '../api/client'
 
@@ -20,6 +23,13 @@ export const useNotesStore = defineStore('notes', () => {
   const error = ref<string | null>(null)
   /** 未保存の編集があるページID。AIによる更新で上書きしないために使う。 */
   const dirtyIds = ref<Set<number>>(new Set())
+  /**
+   * 本文をシステムプロンプトに載せるページID。チャットセッションごとの設定で、
+   * セッションを切り替えるたびに loadAttached() で読み直す。
+   */
+  const attachedIds = ref<Set<number>>(new Set())
+  /** attachedIds がどのセッションのものか。null は「まだ保存先が無い新規チャット」。 */
+  const attachedSessionId = ref<string | null>(null)
 
   let saveTimer: number | null = null
 
@@ -99,11 +109,50 @@ export const useNotesStore = defineStore('notes', () => {
     }
   }
 
+  /** セッションに紐付いたページを読み込む。sessionId が null（新規チャット）なら選択を空にする。 */
+  async function loadAttached(sessionId: string | null): Promise<void> {
+    attachedSessionId.value = sessionId
+    if (sessionId === null) {
+      attachedIds.value = new Set()
+      return
+    }
+    try {
+      attachedIds.value = new Set(await fetchSessionNotes(sessionId))
+    } catch (e) {
+      error.value = e instanceof Error ? e.message : '参照ノートの取得に失敗しました'
+    }
+  }
+
+  /**
+   * ページをプロンプトに載せる/載せないを切り替える。
+   * まだセッションが無い新規チャットではローカルに保持するだけで、最初の送信時にまとめて保存される。
+   */
+  async function toggleAttached(id: number): Promise<void> {
+    const next = new Set(attachedIds.value)
+    if (next.has(id)) next.delete(id)
+    else next.add(id)
+    attachedIds.value = next
+
+    const sessionId = attachedSessionId.value
+    if (sessionId === null) return
+    try {
+      attachedIds.value = new Set(await updateSessionNotes(sessionId, [...next]))
+    } catch (e) {
+      error.value = e instanceof Error ? e.message : '参照ノートの更新に失敗しました'
+    }
+  }
+
   async function removePage(id: number): Promise<void> {
     error.value = null
     try {
       await deleteNotePage(id)
       dirtyIds.value.delete(id)
+      // 紐付けはサーバー側でもカスケード削除される
+      if (attachedIds.value.has(id)) {
+        const next = new Set(attachedIds.value)
+        next.delete(id)
+        attachedIds.value = next
+      }
       pages.value = pages.value.filter((p) => p.id !== id)
       if (activeId.value === id) activeId.value = pages.value[0]?.id ?? null
     } catch (e) {
@@ -154,6 +203,24 @@ export const useNotesStore = defineStore('notes', () => {
     return Promise.all([...dirtyIds.value].map((id) => save(id))).then(() => undefined)
   }
 
+  /**
+   * ファイルをページとして取り込み、最初に作られたページを開く。
+   * 戻り値は作成されたページ（失敗時は空配列）。
+   */
+  async function importFiles(files: File[]): Promise<NotePage[]> {
+    error.value = null
+    await flush()
+    try {
+      const created = await importNotePages(files)
+      await load()
+      if (created.length > 0) activeId.value = created[0].id
+      return created
+    } catch (e) {
+      error.value = e instanceof Error ? e.message : 'ファイルの取り込みに失敗しました'
+      return []
+    }
+  }
+
   /** 編集中の内容を保存してから、そのページを Markdown としてダウンロードする。 */
   async function downloadPage(id: number): Promise<void> {
     await flush()
@@ -172,6 +239,10 @@ export const useNotesStore = defineStore('notes', () => {
     activePage,
     error,
     dirtyIds,
+    attachedIds,
+    attachedSessionId,
+    loadAttached,
+    toggleAttached,
     load,
     selectPage,
     addPage,
@@ -181,6 +252,7 @@ export const useNotesStore = defineStore('notes', () => {
     renameSection,
     reorder,
     flush,
+    importFiles,
     downloadPage,
     downloadAll,
   }