fix(retrieval): 保证删除一致性并完善 FTS 分页

backend/app/repository.py

@@ -120,20 +120,24 @@ def replace_note_metadata(
     return old_block_ids
 
 
-def delete_note(note_id: str) -> list[str]:
+def delete_note(
+    note_id: str, *, conn: sqlite3.Connection | None = None
+) -> list[str]:
     """删除笔记及其 Block、FTS5 索引；返回被删除的 block_id 供向量层清理。"""
-    conn = connect()
+    owns = conn is None
+    conn = conn or connect()
     try:
         block_ids = [
             row["block_id"]
             for row in conn.execute("SELECT block_id FROM blocks WHERE note_id = ?", (note_id,))
         ]
-        with transaction(conn):
+        with transaction(conn) if owns else nullcontext():
             conn.execute("DELETE FROM blocks_fts WHERE note_id = ?", (note_id,))
             conn.execute("DELETE FROM notes WHERE note_id = ?", (note_id,))  # blocks 级联删除
         return block_ids
     finally:
-        conn.close()
+        if owns:
+            conn.close()
 
 
 def get_note_record(note_id: str) -> NoteRecord | None:
@@ -215,6 +219,81 @@ def fts_search(match: str, limit: int = 100) -> list[FtsHit]:
         conn.close()
 
 
+def fts_search_page(
+    *,
+    match: str,
+    limit: int,
+    offset: int,
+    folders: list[str],
+    note_ids: list[str],
+    tags: list[str],
+    created_from: datetime | None,
+    created_to: datetime | None,
+    updated_from: datetime | None,
+    updated_to: datetime | None,
+) -> tuple[list[FtsHit], int]:
+    """执行带元数据过滤的 FTS 精确分页，并返回过滤后的完整命中数。"""
+    where = ["blocks_fts MATCH ?"]
+    params: list[object] = [match]
+
+    def add_in(column: str, values: list[str]) -> None:
+        if not values:
+            return
+        placeholders = ",".join("?" * len(values))
+        where.append(f"{column} IN ({placeholders})")
+        params.extend(values)
+
+    add_in("n.folder", folders)
+    add_in("n.note_id", note_ids)
+    if tags:
+        placeholders = ",".join("?" * len(tags))
+        where.append(
+            f"EXISTS (SELECT 1 FROM json_each(n.tags) AS tag WHERE tag.value IN ({placeholders}))"
+        )
+        params.extend(tags)
+
+    for column, lower, upper in (
+        ("n.created_at", created_from, created_to),
+        ("n.updated_at", updated_from, updated_to),
+    ):
+        if lower is not None:
+            where.append(f"julianday({column}) >= julianday(?)")
+            params.append(_iso(lower))
+        if upper is not None:
+            where.append(f"julianday({column}) <= julianday(?)")
+            params.append(_iso(upper))
+
+    from_sql = """
+        FROM blocks_fts
+        JOIN blocks AS b ON b.block_id = blocks_fts.block_id
+        JOIN notes AS n ON n.note_id = b.note_id
+    """
+    where_sql = " AND ".join(where)
+
+    conn = connect()
+    try:
+        total = conn.execute(
+            f"SELECT COUNT(*) {from_sql} WHERE {where_sql}", params
+        ).fetchone()[0]
+        rows = conn.execute(
+            f"""
+            SELECT blocks_fts.block_id, blocks_fts.note_id, bm25(blocks_fts) AS rank
+            {from_sql}
+            WHERE {where_sql}
+            ORDER BY rank
+            LIMIT ? OFFSET ?
+            """,
+            [*params, limit, offset],
+        ).fetchall()
+        return (
+            [FtsHit(block_id=row["block_id"], note_id=row["note_id"], bm25=row["rank"])
+             for row in rows],
+            total,
+        )
+    finally:
+        conn.close()
+
+
 def get_block_hits(block_ids: list[str]) -> list[BlockHit]:
     if not block_ids:
         return []

backend/app/retrieval/engine.py

@@ -31,8 +31,6 @@ CANDIDATE_POOL = 50
 MAX_CANDIDATE_POOL = 200
 # 带 metadata 过滤时放大召回倍数，缓解「先截断候选池再过滤」造成的漏召回
 OVERSCAN_FACTOR = 4
-# FTS 一次性取全量命中上限：保证 fts 模式 total 准确、过滤不漏召回；超出则截断
-FTS_FETCH_LIMIT = 1000
 
 
 class RetrievalEngine:
@@ -47,6 +45,9 @@ class RetrievalEngine:
         self.vector_store = vector_store
 
     async def search(self, request: SearchRequest) -> SearchResponse:
+        if request.mode == SearchMode.fts:
+            return self._search_fts(request)
+
         has_filters = bool(
             request.folders or request.note_ids or request.tags
             or request.created_from or request.created_to
@@ -67,8 +68,7 @@ class RetrievalEngine:
         if request.mode in (SearchMode.fts, SearchMode.hybrid):
             match = match_query(request.query)
             if match:
-                fts_limit = FTS_FETCH_LIMIT if request.mode == SearchMode.fts else recall
-                fts_hits = repository.fts_search(match, fts_limit)
+                fts_hits = repository.fts_search(match, recall)
                 fts_ranked = [h.block_id for h in fts_hits]
                 # bm25 越小越相关，取反后统一为「越大越相关」
                 fts_scores = {h.block_id: -h.bm25 for h in fts_hits}
@@ -125,6 +125,43 @@ class RetrievalEngine:
             page=PageMeta(total=total, limit=request.limit, offset=request.offset),
         )
 
+    def _search_fts(self, request: SearchRequest) -> SearchResponse:
+        """FTS 专用路径：过滤、COUNT 与分页全部在 SQLite 中完成。"""
+        match = match_query(request.query)
+        if not match:
+            return self._empty(request)
+
+        fts_hits, total = repository.fts_search_page(
+            match=match,
+            limit=request.limit,
+            offset=request.offset,
+            folders=request.folders,
+            note_ids=request.note_ids,
+            tags=request.tags,
+            created_from=request.created_from,
+            created_to=request.created_to,
+            updated_from=request.updated_from,
+            updated_to=request.updated_to,
+        )
+        if not fts_hits:
+            return SearchResponse(
+                query=request.query,
+                mode=request.mode,
+                page=PageMeta(total=total, limit=request.limit, offset=request.offset),
+            )
+
+        hits = {h.block_id: h for h in repository.get_block_hits([hit.block_id for hit in fts_hits])}
+        ordered = normalize_scores(
+            [(hit.block_id, -hit.bm25) for hit in fts_hits if hit.block_id in hits]
+        )
+        items = [self._build_result(hits[block_id], request, score) for block_id, score in ordered]
+        return SearchResponse(
+            query=request.query,
+            mode=request.mode,
+            items=items,
+            page=PageMeta(total=total, limit=request.limit, offset=request.offset),
+        )
+
     def _matches(self, hit: BlockHit, request: SearchRequest) -> bool:
         if request.folders and hit.folder not in request.folders:
             return False

backend/app/services/note_service.py

@@ -9,6 +9,7 @@ from __future__ import annotations
 import re
 from datetime import datetime, timezone
 from pathlib import Path
+from uuid import uuid4
 
 from app import repository
 from app.config import get_settings
@@ -216,9 +217,30 @@ async def delete_note(note_id: str) -> bool:
     record = repository.get_note_record(note_id)
     if record is None:
         return False
-    block_ids = repository.delete_note(note_id)
-    await vector_store.delete(block_ids)
-    _delete_markdown(record.file_path)
+
+    path = _abs_path(record.file_path)
+    tombstone = path.with_name(f".{path.name}.{uuid4().hex}.deleting") if path.exists() else None
+    if tombstone is not None:
+        path.replace(tombstone)
+
+    conn = connect()
+    try:
+        with transaction(conn):
+            block_ids = repository.delete_note(note_id, conn=conn)
+            await vector_store.delete(block_ids, conn=conn)
+    except BaseException:
+        if tombstone is not None and tombstone.exists():
+            tombstone.replace(path)
+        raise
+    finally:
+        conn.close()
+
+    if tombstone is not None:
+        # 数据库已提交后，tombstone 即不再属于 Vault；清理失败不应把成功删除报告为失败。
+        try:
+            tombstone.unlink(missing_ok=True)
+        except OSError:
+            pass
     return True