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>

backend/app/api/chat.py

@@ -12,6 +12,7 @@ from app.core.memory_kb import memory as mem
 from app.core import llm
 from app.core.memory_kb import knowledge
 from app.core.memory_kb import local_knowledge
+from app.core import notes
 from app.core.notes import NOTE_TOOLS
 from app.core.search.websearch import WEB_SEARCH_TOOL
 from app.core.config import DEFAULT_MODEL
@@ -25,6 +26,13 @@ class ChatRequest(BaseModel):
     session_id: str | None = None
     message: str
     model: str | None = None
+    # このセッションで本文をプロンプトに載せるノートのページID。
+    # 新規セッションではまだ session_id が無く PUT できないため、送信時にまとめて反映する。
+    note_page_ids: list[int] | None = None
+
+
+class SessionNotesRequest(BaseModel):
+    page_ids: list[int]
 
 
 class SessionResponse(BaseModel):
@@ -161,6 +169,22 @@ def import_session(req: ImportRequest, db: DBSession = Depends(get_db)):
     return session
 
 
+@router.get("/sessions/{session_id}/notes")
+def get_session_notes(session_id: str, db: DBSession = Depends(get_db)):
+    """このセッションで本文をプロンプトに載せるよう指定された共有ノートのページIDを返す。"""
+    if not db.get(Session, session_id):
+        raise HTTPException(status_code=404, detail="Session not found")
+    return {"page_ids": notes.get_attached_page_ids(db, session_id)}
+
+
+@router.put("/sessions/{session_id}/notes")
+def put_session_notes(session_id: str, req: SessionNotesRequest, db: DBSession = Depends(get_db)):
+    """このセッションに紐付けるノートのページIDを丸ごと置き換える。存在しないIDは無視する。"""
+    if not db.get(Session, session_id):
+        raise HTTPException(status_code=404, detail="Session not found")
+    return {"page_ids": notes.set_attached_pages(db, session_id, req.page_ids)}
+
+
 @router.delete("/sessions/{session_id}", status_code=204)
 def delete_session(session_id: str, db: DBSession = Depends(get_db)):
     session = db.get(Session, session_id)
@@ -202,6 +226,11 @@ async def stream_chat(req: ChatRequest, db: DBSession = Depends(get_db)):
     record_message(req.message)
     asyncio.create_task(tag_message_by_id(user_msg.id))
 
+    # 紐付けるノートは送信のたびに送られてくる。新規セッションだとフロントは事前に
+    # PUT できないため、コンテキストを組み立てる前にここで反映しておく。
+    if req.note_page_ids is not None:
+        notes.set_attached_pages(db, session.id, req.note_page_ids)
+
     context = await mem.get_context_messages(db, session.id)
 
     async def generate():