From 256e93605ae95faebc97fad8b7351d8bb3b87b7b Mon Sep 17 00:00:00 2001
From: digua <i@digua.me>
Date: Mon, 3 Aug 2026 16:13:40 +0800
Subject: [PATCH] refactor(database): remove legacy session FTS

---
 apps/cli/src/http/routes/web/index.ts         |  2 +-
 apps/cli/src/import/stream-import.ts          |  4 +-
 apps/desktop/main/database/migrations.test.ts | 10 +-
 apps/desktop/main/database/migrations.ts      |  5 +-
 apps/desktop/main/i18n/locales/en-US.ts       |  6 +-
 apps/desktop/main/i18n/locales/ja-JP.ts       |  6 +-
 apps/desktop/main/i18n/locales/zh-CN.ts       |  6 +-
 apps/desktop/main/i18n/locales/zh-TW.ts       |  6 +-
 apps/desktop/main/worker/query/messages.ts    |  2 +-
 .../main/worker/query/session/aiTools.ts      |  2 +-
 packages/core/src/query/message-queries.ts    |  6 +-
 .../core/src/query/message-query-functions.ts |  2 +-
 packages/core/src/schema/migrations.ts        |  2 +-
 packages/core/src/schema/tables.ts            |  6 +-
 .../node-runtime/src/database-manager.test.ts | 93 +++++++++++++++++--
 packages/node-runtime/src/database-manager.ts | 22 +----
 .../src/import/streaming-importer.ts          |  2 +-
 packages/node-runtime/src/index.ts            |  3 -
 .../src/migrations/chat-db-migrations.ts      | 67 +++----------
 packages/node-runtime/src/migrations/index.ts |  2 +-
 .../src/nlp/__tests__/fts-tokenizer.test.ts   | 53 -----------
 .../src/nlp/__tests__/segmenter-cache.test.ts |  2 +-
 .../node-runtime/src/nlp/fts-tokenizer.ts     | 75 ---------------
 packages/node-runtime/src/nlp/index.ts        |  3 -
 packages/node-runtime/src/nlp/segmenter.ts    |  2 +-
 packages/parser/src/types.ts                  |  2 +-
 .../src/definitions/deep-search-messages.ts   |  3 +-
 27 files changed, 148 insertions(+), 246 deletions(-)
 delete mode 100644 packages/node-runtime/src/nlp/__tests__/fts-tokenizer.test.ts
 delete mode 100644 packages/node-runtime/src/nlp/fts-tokenizer.ts

diff --git a/apps/cli/src/http/routes/web/index.ts b/apps/cli/src/http/routes/web/index.ts
index 4fabf720..62271013 100644
--- a/apps/cli/src/http/routes/web/index.ts
+++ b/apps/cli/src/http/routes/web/index.ts
@@ -9,7 +9,7 @@
  *   members   – Member management
  *   analytics – Stats and advanced analytics
  *   sql       – SQL Lab and plugin query
- *   sessionIndex – Session index generation + FTS
+ *   sessionIndex – Session index generation
  *   summaries – LLM summary generation
  *   import    – File / directory / incremental import + demo
  *   merge     – Merge parse / conflicts / execute
diff --git a/apps/cli/src/import/stream-import.ts b/apps/cli/src/import/stream-import.ts
index 50427516..e2778e33 100644
--- a/apps/cli/src/import/stream-import.ts
+++ b/apps/cli/src/import/stream-import.ts
@@ -3,7 +3,7 @@
  *
  * Replaces the old buffered-in-memory approach with the same high-performance
  * streaming pipeline used by Electron (batched transactions, deferred indexes,
- * nickname history, FTS, format fallback).
+ * nickname history, indexes, and format fallback).
  */
 
 import type { DatabaseManager } from '@openchatlab/node-runtime'
@@ -142,7 +142,7 @@ function deleteSessionDatabase(dbManager: DatabaseManager, sessionId: string): v
 
 /**
  * High-performance streaming import: parse a file and write to DB
- * with batched transactions, deferred indexes, and FTS.
+ * with batched transactions and deferred indexes.
  */
 async function streamImportUnlocked(
   dbManager: DatabaseManager,
diff --git a/apps/desktop/main/database/migrations.test.ts b/apps/desktop/main/database/migrations.test.ts
index e9bb8689..c55fdc32 100644
--- a/apps/desktop/main/database/migrations.test.ts
+++ b/apps/desktop/main/database/migrations.test.ts
@@ -86,11 +86,15 @@ test('migrateDatabase writes data directory compatibility meta after segment sch
 })
 
 test('getPendingMigrationInfos maps each version to its own localized message', () => {
+  const v4 = getPendingMigrationInfos(3)[0]
+  assert.equal(v4.version, 4)
+  assert.doesNotMatch(v4.userMessage, /FTS|full-text|全文/i)
+
   const migrations = getPendingMigrationInfos(6)
 
   assert.deepEqual(
     migrations.map((m) => m.version),
-    [7, 8]
+    [7, 8, 9]
   )
 
   const v7 = migrations[0]
@@ -101,4 +105,8 @@ test('getPendingMigrationInfos maps each version to its own localized message',
   const v8 = migrations[1]
   assert.match(v8.userMessage, /index|索引|インデックス/i)
   assert.doesNotMatch(v8.userMessage, /Owner/)
+
+  const v9 = migrations[2]
+  assert.match(v9.userMessage, /search|index|搜索|搜尋|検索|索引|インデックス/i)
+  assert.doesNotMatch(v9.userMessage, /Owner/)
 })
diff --git a/apps/desktop/main/database/migrations.ts b/apps/desktop/main/database/migrations.ts
index fa7681bb..ae50368e 100644
--- a/apps/desktop/main/database/migrations.ts
+++ b/apps/desktop/main/database/migrations.ts
@@ -20,7 +20,6 @@ import {
 } from '@openchatlab/node-runtime/src/migrations/chat-db-migrations'
 import { raiseDataDirMinRuntimeVersion, type RuntimeIdentity } from '@openchatlab/node-runtime/src/data-dir-compat'
 import { t } from '../i18n'
-import { tokenizeForFts } from '@openchatlab/node-runtime/src/nlp/fts-tokenizer'
 
 export { CURRENT_SCHEMA_VERSION }
 
@@ -83,7 +82,7 @@ export function migrateDatabase(
   }
 
   const beforeVersion = getSchemaVersion(adapter)
-  const migrations = getChatDbMigrations({ tokenizeForFts })
+  const migrations = getChatDbMigrations()
   const migrated = runMigrations(adapter, migrations, forceRepair)
   if (!migrated || !options.pathProvider || !options.runtime) return migrated
 
@@ -114,7 +113,7 @@ export function needsMigration(db: Database.Database): boolean {
  * Get pending migration info for UI display (with i18n).
  */
 export function getPendingMigrationInfos(fromVersion = 0): MigrationInfo[] {
-  const migrations = getChatDbMigrations({ tokenizeForFts })
+  const migrations = getChatDbMigrations()
   return migrations
     .filter((m) => m.version > fromVersion)
     .map((m) => {
diff --git a/apps/desktop/main/i18n/locales/en-US.ts b/apps/desktop/main/i18n/locales/en-US.ts
index 3bfa84af..de6b991c 100644
--- a/apps/desktop/main/i18n/locales/en-US.ts
+++ b/apps/desktop/main/i18n/locales/en-US.ts
@@ -46,8 +46,8 @@ export default {
     migrationV2Message: 'Support member roles, message reply relationships and reply preview',
     migrationV3Desc: 'Add session index tables (segment, message_context) and session_gap_threshold field',
     migrationV3Message: 'Support session timeline browsing and AI-enhanced analysis',
-    migrationV4Desc: 'Create FTS5 full-text search index (message_fts) and build index data',
-    migrationV4Message: 'Enable full-text search for significantly faster keyword search',
+    migrationV4Desc: 'Keep the legacy database migration sequence compatible',
+    migrationV4Message: 'Apply a lightweight compatibility step without rebuilding removed search data',
     migrationV5Desc: 'Repair legacy member and message fields',
     migrationV5Message: 'Update legacy database fields for compatibility with the current version',
     migrationV6Desc: 'Upgrade the session index to the segment schema',
@@ -57,6 +57,8 @@ export default {
     migrationV8Desc: 'Add analysis tool performance indexes',
     migrationV8Message:
       'Add performance indexes for analysis tools to speed up queries without affecting existing data',
+    migrationV9Desc: 'Remove the obsolete per-session full-text search index',
+    migrationV9Message: 'Remove an unused derived search index while preserving all chat data',
     integrityError:
       'Database structure is incomplete: missing meta table. Please delete this database file and re-import.',
     checkFailed: 'Database check failed: {{error}}',
diff --git a/apps/desktop/main/i18n/locales/ja-JP.ts b/apps/desktop/main/i18n/locales/ja-JP.ts
index 75420d9b..fd3198ba 100644
--- a/apps/desktop/main/i18n/locales/ja-JP.ts
+++ b/apps/desktop/main/i18n/locales/ja-JP.ts
@@ -47,8 +47,8 @@ export default {
     migrationV3Desc:
       'セッションインデックス関連テーブル（segment、message_context）と session_gap_threshold フィールドを追加',
     migrationV3Message: 'セッションのタイムライン表示と AI 拡張分析に対応',
-    migrationV4Desc: 'FTS5 全文検索インデックス（message_fts）を作成しインデックスデータを構築',
-    migrationV4Message: '全文検索に対応し、キーワード検索速度が大幅に向上',
+    migrationV4Desc: '旧バージョンのデータベース移行順序を維持',
+    migrationV4Message: '廃止された検索データを再構築せず、軽量な互換処理のみ実行します',
     migrationV5Desc: '旧バージョンのメンバーおよびメッセージフィールドを修復',
     migrationV5Message: '現在のバージョンと互換性を保つため、旧データベースのフィールドを更新します',
     migrationV6Desc: 'セッションインデックスを segment スキーマに更新',
@@ -58,6 +58,8 @@ export default {
     migrationV8Desc: '分析ツールのパフォーマンスインデックスを追加',
     migrationV8Message:
       '分析ツールのクエリを高速化するパフォーマンスインデックスを追加します（既存データには影響しません）',
+    migrationV9Desc: '廃止された会話単位の全文検索インデックスを削除',
+    migrationV9Message: '使用されていない派生検索インデックスのみ削除し、チャットデータは保持します',
     integrityError:
       'データベース構造が不完全です：meta テーブルがありません。このデータベースファイルを削除して再インポートすることをお勧めします。',
     checkFailed: 'データベースチェックに失敗しました: {{error}}',
diff --git a/apps/desktop/main/i18n/locales/zh-CN.ts b/apps/desktop/main/i18n/locales/zh-CN.ts
index 10e5e331..82db05d3 100644
--- a/apps/desktop/main/i18n/locales/zh-CN.ts
+++ b/apps/desktop/main/i18n/locales/zh-CN.ts
@@ -45,8 +45,8 @@ export default {
     migrationV2Message: '支持成员角色、消息回复关系和回复内容预览',
     migrationV3Desc: '添加会话索引相关表（segment、message_context）和 session_gap_threshold 字段',
     migrationV3Message: '支持会话时间轴浏览和 AI 增强分析功能',
-    migrationV4Desc: '创建 FTS5 全文搜索索引（message_fts）并构建索引数据',
-    migrationV4Message: '支持全文搜索，大幅提升关键词搜索速度',
+    migrationV4Desc: '保留旧版数据库迁移序列',
+    migrationV4Message: '执行轻量兼容步骤，不再重建已停用的搜索索引',
     migrationV5Desc: '修复旧版成员和消息字段',
     migrationV5Message: '更新旧版数据库字段以兼容当前版本',
     migrationV6Desc: '将会话索引升级为 segment 结构',
@@ -55,6 +55,8 @@ export default {
     migrationV7Message: '修复会话索引中缺失的消息关联，并保留现有会话和摘要',
     migrationV8Desc: '添加分析工具性能索引',
     migrationV8Message: '为分析工具添加性能索引，提升查询速度，不影响现有数据',
+    migrationV9Desc: '移除已停用的会话全文搜索索引',
+    migrationV9Message: '清理不再使用的派生搜索索引，聊天数据不会受到影响',
     integrityError: '数据库结构不完整：缺少 meta 表。建议删除此数据库文件后重新导入。',
     checkFailed: '数据库检查失败: {{error}}',
   },
diff --git a/apps/desktop/main/i18n/locales/zh-TW.ts b/apps/desktop/main/i18n/locales/zh-TW.ts
index 47e696ea..a0d9f021 100644
--- a/apps/desktop/main/i18n/locales/zh-TW.ts
+++ b/apps/desktop/main/i18n/locales/zh-TW.ts
@@ -46,8 +46,8 @@ export default {
     migrationV2Message: '支援成員角色、訊息回覆關係和回覆內容預覽',
     migrationV3Desc: '新增會話索引相關資料表（segment、message_context）及 session_gap_threshold 欄位',
     migrationV3Message: '支援會話時間軸瀏覽與 AI 增強分析功能',
-    migrationV4Desc: '建立 FTS5 全文搜尋索引（message_fts）並建構索引資料',
-    migrationV4Message: '支援全文搜尋，大幅提升關鍵詞搜尋速度',
+    migrationV4Desc: '保留舊版資料庫遷移順序',
+    migrationV4Message: '執行輕量相容步驟，不再重建已停用的搜尋索引',
     migrationV5Desc: '修復舊版成員和訊息欄位',
     migrationV5Message: '更新舊版資料庫欄位以相容目前版本',
     migrationV6Desc: '將會話索引升級為 segment 結構',
@@ -56,6 +56,8 @@ export default {
     migrationV7Message: '修復會話索引中缺少的訊息關聯，並保留現有會話和摘要',
     migrationV8Desc: '新增分析工具效能索引',
     migrationV8Message: '為分析工具新增效能索引，提升查詢速度，不影響現有資料',
+    migrationV9Desc: '移除已停用的會話全文搜尋索引',
+    migrationV9Message: '清理不再使用的衍生搜尋索引，聊天資料不受影響',
     integrityError: '資料庫結構不完整：缺少 meta 資料表。建議刪除此資料庫檔案後重新匯入。',
     checkFailed: '資料庫檢查失敗: {{error}}',
   },
diff --git a/apps/desktop/main/worker/query/messages.ts b/apps/desktop/main/worker/query/messages.ts
index f3132ae5..02d789b4 100644
--- a/apps/desktop/main/worker/query/messages.ts
+++ b/apps/desktop/main/worker/query/messages.ts
@@ -99,7 +99,7 @@ export async function searchMessages(
 }
 
 /**
- * Deep search (always LIKE, no FTS).
+ * Deep search compatibility alias using the same LIKE implementation.
  */
 export async function deepSearchMessages(
   sessionId: string,
diff --git a/apps/desktop/main/worker/query/session/aiTools.ts b/apps/desktop/main/worker/query/session/aiTools.ts
index f113fee2..47992d03 100644
--- a/apps/desktop/main/worker/query/session/aiTools.ts
+++ b/apps/desktop/main/worker/query/session/aiTools.ts
@@ -1,7 +1,7 @@
 /**
  * AI tool session queries — Electron worker wrappers.
  * Core search/messages logic lives in @openchatlab/core;
- * Electron adds FTS tokenization and DB lifecycle.
+ * Electron adds database lifecycle management.
  */
 
 import { getSegmentMessages as coreGetSessionMessages } from '@openchatlab/core'
diff --git a/packages/core/src/query/message-queries.ts b/packages/core/src/query/message-queries.ts
index f1a46d57..50789762 100644
--- a/packages/core/src/query/message-queries.ts
+++ b/packages/core/src/query/message-queries.ts
@@ -2,7 +2,7 @@
  * 消息查询模块（平台无关）
  *
  * 提供消息搜索、分页等基础查询能力。
- * 复杂的 FTS 搜索留在 Electron/Server 层处理（依赖分词器）。
+ * 所有运行时统一使用平台无关的 LIKE 查询。
  */
 
 import type { TimeFilter } from '@openchatlab/shared-types'
@@ -140,7 +140,7 @@ export function queryMessages(db: DatabaseAdapter, options?: QueryMessagesOption
 
 /**
  * 基于 LIKE 的简单关键词搜索
- * 不依赖 FTS 索引，适用于 CLI/MCP 场景
+ * 使用 LIKE 子串匹配，适用于 CLI/MCP 场景。
  */
 export function searchMessagesLike(
   db: DatabaseAdapter,
@@ -202,7 +202,7 @@ export function searchMessagesLike(
 /**
  * 多关键词 LIKE 子串搜索（关键词之间 OR，命中任一即返回）
  *
- * 适用于 CLI/MCP/Web 等无 FTS 的场景，行为与 Electron worker 的
+ * 适用于 CLI/MCP/Web 等场景，行为与 Electron worker 的
  * searchMessagesLikeAsync 一致：支持时间范围、发送者过滤，并排除系统消息。
  */
 export function searchMessagesByKeywords(
diff --git a/packages/core/src/query/message-query-functions.ts b/packages/core/src/query/message-query-functions.ts
index ba9cdb26..b4f44d05 100644
--- a/packages/core/src/query/message-query-functions.ts
+++ b/packages/core/src/query/message-query-functions.ts
@@ -5,7 +5,7 @@
  * consume via their respective AsyncSqlExecutor implementations.
  *
  * SQL templates, row mapping, and condition builders come from ./message-sql.ts.
- * FTS/tokenisation search remains platform-specific — only LIKE-based search is shared here.
+ * All runtimes share the LIKE-based message search implemented here.
  */
 
 import type { TimeFilter } from '@openchatlab/shared-types'
diff --git a/packages/core/src/schema/migrations.ts b/packages/core/src/schema/migrations.ts
index bf751ff6..00504787 100644
--- a/packages/core/src/schema/migrations.ts
+++ b/packages/core/src/schema/migrations.ts
@@ -2,7 +2,7 @@
  * 数据库迁移框架（平台无关）
  *
  * 提供 Schema 版本检测和通用迁移执行逻辑。
- * 具体的迁移脚本由各平台运行时注册（因为某些迁移依赖 NLP 分词器等平台特性）。
+ * 具体的迁移脚本由运行时注册，迁移本身只依赖 DatabaseAdapter。
  */
 
 import type { DatabaseAdapter } from '../interfaces'
diff --git a/packages/core/src/schema/tables.ts b/packages/core/src/schema/tables.ts
index a8e68027..4122b6cd 100644
--- a/packages/core/src/schema/tables.ts
+++ b/packages/core/src/schema/tables.ts
@@ -4,11 +4,11 @@
  * 所有 CREATE TABLE / INDEX 语句的单一事实来源。
  * 新建数据库时使用完整 Schema，现有数据库通过迁移脚本演进。
  *
- * 当前 Schema 版本：7
+ * 当前 Schema 版本：9
  */
 
 /** 当前 Schema 版本（最新迁移的版本号） */
-export const CURRENT_SCHEMA_VERSION = 8
+export const CURRENT_SCHEMA_VERSION = 9
 
 /**
  * Table DDL only (no indexes). Used by bulk-import workflows that defer
@@ -92,7 +92,7 @@ export const CHAT_DB_INDEXES = `
 `
 
 /**
- * Combined tables + indexes DDL (Schema Version 4).
+ * Combined tables + indexes DDL for the current schema.
  * For new database creation where deferred indexing is not needed.
  */
 export const CHAT_DB_SCHEMA = CHAT_DB_TABLES + CHAT_DB_INDEXES
diff --git a/packages/node-runtime/src/database-manager.test.ts b/packages/node-runtime/src/database-manager.test.ts
index ec7fd56f..19f84090 100644
--- a/packages/node-runtime/src/database-manager.test.ts
+++ b/packages/node-runtime/src/database-manager.test.ts
@@ -114,7 +114,7 @@ test('open migrates legacy member name columns before readonly queries', () => {
   manager.closeAll()
 })
 
-test('open backfills FTS index when migrating legacy sessions', () => {
+test('open upgrades v3 sessions without building the removed FTS index', () => {
   const root = makeTempDir()
   const dbDir = path.join(root, 'data', 'databases')
   fs.mkdirSync(dbDir, { recursive: true })
@@ -130,7 +130,7 @@ test('open backfills FTS index when migrating legacy sessions', () => {
       schema_version INTEGER DEFAULT 3
     );
     INSERT INTO meta (name, platform, type, imported_at, schema_version)
-    VALUES ('FTS Legacy Chat', 'qq', 'group', 1000, 3);
+    VALUES ('Legacy Chat', 'qq', 'group', 1000, 3);
 
     CREATE TABLE member (
       id INTEGER PRIMARY KEY AUTOINCREMENT,
@@ -158,13 +158,88 @@ test('open backfills FTS index when migrating legacy sessions', () => {
   const version = db.prepare('SELECT schema_version FROM meta LIMIT 1').get() as { schema_version: number }
   assert.equal(version.schema_version, CURRENT_SCHEMA_VERSION)
 
-  const ftsCount = db.prepare('SELECT COUNT(*) as total FROM message_fts').get() as { total: number }
-  assert.equal(ftsCount.total, 1)
+  const messages = db.prepare('SELECT type, content FROM message ORDER BY id').all()
+  assert.deepEqual(messages, [
+    { type: 0, content: 'hello searchable history' },
+    { type: 1, content: 'image message ignored' },
+  ])
+  const ftsTable = db.prepare("SELECT name FROM sqlite_master WHERE type = 'table' AND name = 'message_fts'").get()
+  assert.equal(ftsTable, undefined)
 
-  const searchCount = db
-    .prepare("SELECT COUNT(*) as total FROM message_fts WHERE content MATCH 'searchable'")
-    .get() as { total: number }
-  assert.equal(searchCount.total, 1)
+  manager.closeAll()
+})
+
+test('open removes a populated v8 FTS table without changing canonical chat data or raising a new gate', () => {
+  const root = makeTempDir()
+  const dbDir = path.join(root, 'data', 'databases')
+  fs.mkdirSync(dbDir, { recursive: true })
+  const dbPath = path.join(dbDir, 'v8-with-fts.db')
+
+  const rawDb = new Database(dbPath, { nativeBinding })
+  rawDb.exec(CHAT_DB_SCHEMA)
+  rawDb.exec(`
+    INSERT INTO meta (name, platform, type, imported_at, schema_version)
+    VALUES ('V8 Chat', 'qq', 'group', 1000, 8);
+    INSERT INTO member (id, platform_id, account_name) VALUES (1, 'u1', 'Alice');
+    INSERT INTO message (id, sender_id, ts, type, content)
+    VALUES (1, 1, 1000, 0, 'canonical message');
+    CREATE VIRTUAL TABLE message_fts USING fts5(content, content='', content_rowid=id);
+    INSERT INTO message_fts(rowid, content) VALUES (1, 'canonical message');
+  `)
+  rawDb.close()
+
+  const manager = new DatabaseManager(createPathProvider(root), {
+    nativeBinding,
+    runtime: { version: '0.34.2', kind: 'cli' },
+  })
+  const db = manager.open('v8-with-fts')
+  assert.ok(db)
+
+  const version = db.prepare('SELECT schema_version FROM meta LIMIT 1').get() as { schema_version: number }
+  assert.equal(version.schema_version, CURRENT_SCHEMA_VERSION)
+  assert.deepEqual(db.prepare('SELECT id, content FROM message').get(), { id: 1, content: 'canonical message' })
+  assert.equal(
+    db.prepare("SELECT name FROM sqlite_master WHERE type = 'table' AND name = 'message_fts'").get(),
+    undefined
+  )
+
+  const compatibility = readDataDirCompatibilityMeta(path.join(root, 'data'))
+  assert.equal(compatibility?.minRuntimeVersion, '0.25.1')
+  assert.deepEqual(compatibility?.reasons, ['segment-schema'])
+
+  manager.closeAll()
+})
+
+test('open safely upgrades a v8 session that has no FTS table', () => {
+  const root = makeTempDir()
+  const dbDir = path.join(root, 'data', 'databases')
+  fs.mkdirSync(dbDir, { recursive: true })
+  const dbPath = path.join(dbDir, 'v8-without-fts.db')
+
+  const rawDb = new Database(dbPath, { nativeBinding })
+  rawDb.exec(CHAT_DB_SCHEMA)
+  rawDb.exec(`
+    INSERT INTO meta (name, platform, type, imported_at, schema_version)
+    VALUES ('V8 Chat', 'qq', 'group', 1000, 8);
+    INSERT INTO member (id, platform_id, account_name) VALUES (1, 'u1', 'Alice');
+    INSERT INTO message (id, sender_id, ts, type, content)
+    VALUES (1, 1, 1000, 0, 'message without FTS');
+  `)
+  rawDb.close()
+
+  const manager = new DatabaseManager(createPathProvider(root), { nativeBinding, allowMissingRuntimeForTests: true })
+  const db = manager.open('v8-without-fts')
+  assert.ok(db)
+
+  assert.deepEqual(db.prepare('SELECT schema_version, name FROM meta LIMIT 1').get(), {
+    schema_version: CURRENT_SCHEMA_VERSION,
+    name: 'V8 Chat',
+  })
+  assert.equal((db.prepare('SELECT COUNT(*) AS count FROM message').get() as { count: number }).count, 1)
+  assert.equal(
+    db.prepare("SELECT name FROM sqlite_master WHERE type = 'table' AND name = 'message_fts'").get(),
+    undefined
+  )
 
   manager.closeAll()
 })
@@ -744,8 +819,10 @@ test('openRawSessionDatabase can initialize current chat tables for controlled i
 
   const metaTable = db.prepare("SELECT 1 FROM sqlite_master WHERE type = 'table' AND name = 'meta'").get()
   const messageTable = db.prepare("SELECT 1 FROM sqlite_master WHERE type = 'table' AND name = 'message'").get()
+  const ftsTable = db.prepare("SELECT 1 FROM sqlite_master WHERE type = 'table' AND name = 'message_fts'").get()
   assert.ok(metaTable)
   assert.ok(messageTable)
+  assert.equal(ftsTable, undefined)
   db.close()
 })
 
diff --git a/packages/node-runtime/src/database-manager.ts b/packages/node-runtime/src/database-manager.ts
index 67b78019..603b3cb2 100644
--- a/packages/node-runtime/src/database-manager.ts
+++ b/packages/node-runtime/src/database-manager.ts
@@ -20,28 +20,14 @@ import {
 import { openBetterSqliteDatabase } from './better-sqlite3-adapter'
 import { deleteSessionCache } from './cache/session-cache'
 import { assertDataDirCompatible, type RuntimeIdentity } from './data-dir-compat'
-import {
-  CHAT_DB_COMPATIBILITY_RAISES,
-  getChatDbMigrations,
-  raiseChatDbCompatibilityGate,
-  type MigrationDeps,
-} from './migrations'
-import { tokenizeForFts } from './nlp/fts-tokenizer'
+import { CHAT_DB_COMPATIBILITY_RAISES, getChatDbMigrations, raiseChatDbCompatibilityGate } from './migrations'
 import { getContactsFactsCacheDir } from './services/contacts/paths'
 import { getGlobalInsightDir, getGlobalInsightFactsCacheDir } from './services/global-insight/paths'
 import { deleteAnnualSummarySnapshots } from './services/global-insight/snapshot'
 import { getPeopleRelationshipsFactsCacheDir } from './services/people/relationships/paths'
 
-function createMigrationDeps(overrides?: MigrationDeps): MigrationDeps {
-  return {
-    tokenizeForFts,
-    ...overrides,
-  }
-}
-
 interface DatabaseManagerOptions {
   nativeBinding?: string
-  migrationDeps?: MigrationDeps
   runtime?: RuntimeIdentity
   allowMissingRuntimeForTests?: boolean
 }
@@ -68,7 +54,6 @@ export function listDatabaseCandidateIds(databaseDir: string): string[] {
 export class DatabaseManager {
   private cache = new Map<string, DatabaseAdapter>()
   private nativeBinding?: string
-  private migrationDeps?: MigrationDeps
   private runtime: RuntimeIdentity | null
 
   constructor(
@@ -80,7 +65,6 @@ export class DatabaseManager {
     }
 
     this.nativeBinding = options?.nativeBinding
-    this.migrationDeps = createMigrationDeps(options?.migrationDeps)
     this.runtime = options?.runtime ?? null
   }
 
@@ -128,7 +112,7 @@ export class DatabaseManager {
     })
 
     try {
-      const migrations = getChatDbMigrations(this.migrationDeps)
+      const migrations = getChatDbMigrations()
       this.runMigrations(adapter, migrations)
     } finally {
       adapter.close()
@@ -159,7 +143,7 @@ export class DatabaseManager {
     })
 
     if (coreNeedsMigration(adapter, CURRENT_SCHEMA_VERSION)) {
-      const migrations = getChatDbMigrations(this.migrationDeps)
+      const migrations = getChatDbMigrations()
       this.runMigrations(adapter, migrations)
       this.assertCompatible()
     } else {
diff --git a/packages/node-runtime/src/import/streaming-importer.ts b/packages/node-runtime/src/import/streaming-importer.ts
index a9d8cd26..fce35da7 100644
--- a/packages/node-runtime/src/import/streaming-importer.ts
+++ b/packages/node-runtime/src/import/streaming-importer.ts
@@ -150,7 +150,7 @@ function elapsedMs(startedAt: number, now: () => number): number {
 /**
  * Let the event loop process pending I/O before a long synchronous step.
  * Without this, progress events written to an SSE socket stay buffered
- * until the blocking work (index/FTS build) finishes.
+ * until the blocking index work finishes.
  */
 const yieldToEventLoop = () => new Promise<void>((resolve) => setImmediate(resolve))
 
diff --git a/packages/node-runtime/src/index.ts b/packages/node-runtime/src/index.ts
index f5fb9c2d..7e6829a3 100644
--- a/packages/node-runtime/src/index.ts
+++ b/packages/node-runtime/src/index.ts
@@ -178,8 +178,6 @@ export {
   downloadDict,
   deleteDict,
   ensureDefaultDict,
-  tokenizeForFts,
-  tokenizeQueryForFts,
 } from './nlp'
 
 // AI 助手/技能解析器 + 对话管理
@@ -386,7 +384,6 @@ export type { OverviewCache, MembersCache, MemberStat } from './cache'
 
 // Chat DB migrations
 export { getChatDbMigrations } from './migrations'
-export type { MigrationDeps } from './migrations'
 
 // Electron data migration (CLI first-run) + data path verification
 export { migrateFromElectronIfNeeded, verifyCliDataPath, wasElectronUsed } from './migrations'
diff --git a/packages/node-runtime/src/migrations/chat-db-migrations.ts b/packages/node-runtime/src/migrations/chat-db-migrations.ts
index 73a0d6ac..a3e800b2 100644
--- a/packages/node-runtime/src/migrations/chat-db-migrations.ts
+++ b/packages/node-runtime/src/migrations/chat-db-migrations.ts
@@ -3,7 +3,6 @@
  *
  * Extracted from electron/main/database/migrations.ts.
  * Migration scripts use only DatabaseAdapter — no Electron or Node-specific APIs.
- * Version 4 (FTS backfill) requires a tokenizer injected via MigrationDeps.
  */
 
 import type { DatabaseAdapter } from '@openchatlab/core'
@@ -11,11 +10,6 @@ import type { PathProvider } from '@openchatlab/core'
 import type { Migration as CoreMigration } from '@openchatlab/core'
 import { raiseDataDirMinRuntimeVersion, type RuntimeIdentity } from '../data-dir-compat'
 
-export interface MigrationDeps {
-  /** FTS tokenizer — needed by v4 migration for backfilling the FTS index */
-  tokenizeForFts?: (content: string) => string | null
-}
-
 export interface ChatDbCompatibilityRaise {
   migrationVersion: number
   minRuntimeVersion: string
@@ -34,6 +28,9 @@ export const CHAT_DB_COMPATIBILITY_RAISES: ChatDbCompatibilityRaise[] = [
   },
 ]
 
+// Migration 9 intentionally does not raise the data-directory gate. ChatLab 0.34.2 already treats the
+// derived FTS table as optional: searches fall back to LIKE and incremental writers skip missing tables.
+
 export function raiseChatDbCompatibilityGate(pathProvider: PathProvider, runtime: RuntimeIdentity): void {
   for (const compatibilityRaise of CHAT_DB_COMPATIBILITY_RAISES) {
     raiseDataDirMinRuntimeVersion(pathProvider, {
@@ -49,10 +46,9 @@ export function raiseChatDbCompatibilityGate(pathProvider: PathProvider, runtime
 /**
  * Build the chat DB migration list.
  *
- * @param deps Optional dependencies (tokenizer for FTS backfill)
  * @returns Array of migrations compatible with core `runMigrations`
  */
-export function getChatDbMigrations(deps?: MigrationDeps): CoreMigration[] {
+export function getChatDbMigrations(): CoreMigration[] {
   const hasColumn = (db: DatabaseAdapter, tableName: string, columnName: string): boolean => {
     const tableInfo = db.pragma(`table_info(${tableName})`) as Array<{ name: string }>
     return tableInfo.some((col) => col.name === columnName)
@@ -144,51 +140,9 @@ export function getChatDbMigrations(deps?: MigrationDeps): CoreMigration[] {
     },
     {
       version: 4,
-      description: 'Add FTS5 full-text search index',
-      up: (db: DatabaseAdapter) => {
-        const hasTable = db.prepare("SELECT name FROM sqlite_master WHERE type='table' AND name='message_fts'").get()
-        if (hasTable) return
-
-        db.exec(`
-          CREATE VIRTUAL TABLE IF NOT EXISTS message_fts USING fts5(
-            content,
-            content='',
-            content_rowid=id
-          )
-        `)
-
-        const tokenize = deps?.tokenizeForFts
-        if (!tokenize) return
-
-        const BATCH_SIZE = 5000
-        const insertFts = db.prepare('INSERT INTO message_fts(rowid, content) VALUES (?, ?)')
-
-        const countRow = db
-          .prepare("SELECT COUNT(*) as total FROM message WHERE type = 0 AND content IS NOT NULL AND content != ''")
-          .get() as { total: number } | undefined
-
-        const total = countRow?.total ?? 0
-        let offset = 0
-        while (offset < total) {
-          const rows = db
-            .prepare(
-              `SELECT id, content FROM message
-               WHERE type = 0 AND content IS NOT NULL AND content != ''
-               ORDER BY id ASC LIMIT ? OFFSET ?`
-            )
-            .all(BATCH_SIZE, offset) as Array<{ id: number; content: string }>
-
-          if (rows.length === 0) break
-
-          for (const row of rows) {
-            const tokens = tokenize(row.content)
-            if (tokens) {
-              insertFts.run(row.id, tokens)
-            }
-          }
-
-          offset += BATCH_SIZE
-        }
+      description: 'Preserve the legacy schema migration sequence',
+      up: () => {
+        // Version 4 remains as a compatibility marker. New runtimes no longer build the removed derived FTS table.
       },
     },
     {
@@ -411,5 +365,12 @@ export function getChatDbMigrations(deps?: MigrationDeps): CoreMigration[] {
         `)
       },
     },
+    {
+      version: 9,
+      description: 'Remove the obsolete per-session full-text index',
+      up: (db: DatabaseAdapter) => {
+        db.exec('DROP TABLE IF EXISTS message_fts')
+      },
+    },
   ]
 }
diff --git a/packages/node-runtime/src/migrations/index.ts b/packages/node-runtime/src/migrations/index.ts
index bbf939bd..774af103 100644
--- a/packages/node-runtime/src/migrations/index.ts
+++ b/packages/node-runtime/src/migrations/index.ts
@@ -1,5 +1,5 @@
 export { CHAT_DB_COMPATIBILITY_RAISES, getChatDbMigrations, raiseChatDbCompatibilityGate } from './chat-db-migrations'
-export type { ChatDbCompatibilityRaise, MigrationDeps } from './chat-db-migrations'
+export type { ChatDbCompatibilityRaise } from './chat-db-migrations'
 
 export { migrateFromElectronIfNeeded, verifyCliDataPath, wasElectronUsed } from './electron-data-migration'
 export type { ElectronMigrationResult } from './electron-data-migration'
diff --git a/packages/node-runtime/src/nlp/__tests__/fts-tokenizer.test.ts b/packages/node-runtime/src/nlp/__tests__/fts-tokenizer.test.ts
deleted file mode 100644
index 076ac06b..00000000
--- a/packages/node-runtime/src/nlp/__tests__/fts-tokenizer.test.ts
+++ /dev/null
@@ -1,53 +0,0 @@
-import assert from 'node:assert/strict'
-import { describe, it } from 'node:test'
-import { tokenizeForFts, tokenizeQueryForFts } from '../fts-tokenizer'
-
-describe('tokenizeForFts', () => {
-  it('returns empty string for null/undefined/empty', () => {
-    assert.equal(tokenizeForFts(null), '')
-    assert.equal(tokenizeForFts(undefined), '')
-    assert.equal(tokenizeForFts(''), '')
-    assert.equal(tokenizeForFts('   '), '')
-  })
-
-  it('tokenizes text and lowercases tokens', () => {
-    const result = tokenizeForFts('Hello World')
-    assert.ok(result.length > 0)
-    assert.equal(result, result.toLowerCase())
-  })
-
-  it('produces non-empty output for Chinese text', () => {
-    const result = tokenizeForFts('今天天气很好')
-    assert.ok(result.length > 0)
-  })
-
-  it('handles mixed CJK and Latin text', () => {
-    const result = tokenizeForFts('Hello 你好 World')
-    assert.ok(result.includes('hello'))
-  })
-})
-
-describe('tokenizeQueryForFts', () => {
-  it('returns empty string for empty array', () => {
-    assert.equal(tokenizeQueryForFts([]), '')
-  })
-
-  it('returns empty string for array of whitespace', () => {
-    assert.equal(tokenizeQueryForFts(['  ', '']), '')
-  })
-
-  it('wraps single simple keyword in quotes', () => {
-    const result = tokenizeQueryForFts(['hello'])
-    assert.ok(result.includes('"hello"'))
-  })
-
-  it('joins multiple keywords with OR', () => {
-    const result = tokenizeQueryForFts(['hello', 'world'])
-    assert.ok(result.includes('OR'))
-  })
-
-  it('handles Chinese keywords', () => {
-    const result = tokenizeQueryForFts(['今天开心'])
-    assert.ok(result.length > 0)
-  })
-})
diff --git a/packages/node-runtime/src/nlp/__tests__/segmenter-cache.test.ts b/packages/node-runtime/src/nlp/__tests__/segmenter-cache.test.ts
index fd5e8c49..1add5b1d 100644
--- a/packages/node-runtime/src/nlp/__tests__/segmenter-cache.test.ts
+++ b/packages/node-runtime/src/nlp/__tests__/segmenter-cache.test.ts
@@ -3,7 +3,7 @@
  *
  * Bug history: when no custom dict existed on disk, every getJieba() call
  * invalidated the cache and rebuilt a Jieba instance, making hot paths
- * (FTS indexing tokenizes every message) rebuild jieba per call and slowing
+ * (bulk NLP analysis tokenizes many messages) rebuild jieba per call and slowing
  * imports by seconds. The cache must only invalidate when the on-disk dict
  * state actually changes (dict added or removed).
  */
diff --git a/packages/node-runtime/src/nlp/fts-tokenizer.ts b/packages/node-runtime/src/nlp/fts-tokenizer.ts
deleted file mode 100644
index 9775240d..00000000
--- a/packages/node-runtime/src/nlp/fts-tokenizer.ts
+++ /dev/null
@@ -1,75 +0,0 @@
-/**
- * FTS5 tokenizer — shared implementation.
- *
- * Unlike NLP word-frequency analysis, FTS tokenization keeps all tokens
- * (no POS filtering, no stopwords) to maximize recall in search scenarios.
- *
- * Uses jieba for Chinese (naturally handles mixed CJK/Latin text),
- * falls back to whitespace split when jieba is unavailable.
- */
-
-import { getJieba } from './segmenter'
-
-export function tokenizeForFts(text: string | null | undefined): string {
-  if (!text || text.trim().length === 0) return ''
-
-  try {
-    const jieba = getJieba()
-    const tokens = jieba.cut(text, false)
-    return tokens
-      .map((t) => t.trim().toLowerCase())
-      .filter((t) => t.length > 0)
-      .join(' ')
-  } catch {
-    return fallbackTokenize(text)
-  }
-}
-
-function fallbackTokenize(text: string): string {
-  return text
-    .toLowerCase()
-    .split(/\s+/)
-    .filter((t) => t.length > 0)
-    .join(' ')
-}
-
-function escapeToken(token: string): string {
-  return `"${token.replace(/"/g, '""')}"`
-}
-
-/**
- * Convert a list of user search keywords into an FTS5 MATCH expression.
- *
- * - Single keyword: tokens joined with AND (all must appear)
- * - Multiple keywords: groups joined with OR (any match)
- */
-export function tokenizeQueryForFts(keywords: string[]): string {
-  if (keywords.length === 0) return ''
-
-  const groups = keywords
-    .map((kw) => {
-      const trimmed = kw.trim()
-      if (!trimmed) return ''
-
-      try {
-        const jieba = getJieba()
-        const tokens = jieba
-          .cut(trimmed, false)
-          .map((t) => t.trim().toLowerCase())
-          .filter((t) => t.length > 0)
-
-        if (tokens.length === 0) return ''
-        if (tokens.length === 1) return escapeToken(tokens[0])
-        return tokens.map(escapeToken).join(' ')
-      } catch {
-        const simple = trimmed.toLowerCase().trim()
-        return simple ? escapeToken(simple) : ''
-      }
-    })
-    .filter((g) => g.length > 0)
-
-  if (groups.length === 0) return ''
-  if (groups.length === 1) return groups[0]
-
-  return groups.map((g) => (g.includes(' ') ? `(${g})` : g)).join(' OR ')
-}
diff --git a/packages/node-runtime/src/nlp/index.ts b/packages/node-runtime/src/nlp/index.ts
index 38a2de2f..d40ff0fd 100644
--- a/packages/node-runtime/src/nlp/index.ts
+++ b/packages/node-runtime/src/nlp/index.ts
@@ -20,9 +20,6 @@ export {
 // 词频统计
 export { computeWordFrequency, segmentText } from './word-frequency'
 
-// FTS tokenizer
-export { tokenizeForFts, tokenizeQueryForFts } from './fts-tokenizer'
-
 // 词库管理
 export {
   isDictDownloaded,
diff --git a/packages/node-runtime/src/nlp/segmenter.ts b/packages/node-runtime/src/nlp/segmenter.ts
index c8fb0b77..5fba9143 100644
--- a/packages/node-runtime/src/nlp/segmenter.ts
+++ b/packages/node-runtime/src/nlp/segmenter.ts
@@ -69,7 +69,7 @@ export function getJieba(dictType: DictType = 'default'): JiebaInstance {
   if (cached) {
     // Only invalidate when the on-disk dict state changed since the instance
     // was built (dict added or removed). Instances built without a disk dict
-    // must stay cached, otherwise hot paths (e.g. FTS indexing) would rebuild
+    // must stay cached, otherwise bulk NLP hot paths would rebuild
     // a Jieba instance per call.
     if (cached.fromDiskDict === existsDictOnDisk(effectiveType)) return cached.instance
     jiebaInstances.delete(effectiveType)
diff --git a/packages/parser/src/types.ts b/packages/parser/src/types.ts
index 192f2586..444c544c 100644
--- a/packages/parser/src/types.ts
+++ b/packages/parser/src/types.ts
@@ -26,7 +26,7 @@ export interface ParsedMeta {
 export interface ParseProgress {
   /** 阶段 */
   // 导入流程会复用解析进度结构，因此这里补充导入阶段枚举：
-  // saving = 消息批量写库，indexing = 建索引/FTS/会话分段等后处理。
+  // saving = 消息批量写库，indexing = 建普通索引/会话分段等后处理。
   stage: 'detecting' | 'parsing' | 'saving' | 'indexing' | 'done' | 'error'
   /** 已读取字节数 */
   bytesRead: number
diff --git a/packages/tools/src/definitions/deep-search-messages.ts b/packages/tools/src/definitions/deep-search-messages.ts
index 14bd1643..9895bcd8 100644
--- a/packages/tools/src/definitions/deep-search-messages.ts
+++ b/packages/tools/src/definitions/deep-search-messages.ts
@@ -58,8 +58,7 @@ async function handler(params: Record<string, unknown>, context: ToolExecutionCo
 
 export const deepSearchMessagesTool: ToolDefinition = {
   name: 'deep_search_messages',
-  description:
-    '深度搜索消息（LIKE 子串匹配，速度较慢但不会遗漏），适用于全文搜索精确匹配或 FTS 搜索无结果时的补充搜索。',
+  description: '深度搜索消息（LIKE 子串匹配），适用于需要精确文本片段匹配的场景。',
   inputSchema,
   handler,
   category: 'core',