diff --git a/docs/storage-architecture.md b/docs/storage-architecture.md
index 3d5e9266..c76331b7 100644
--- a/docs/storage-architecture.md
+++ b/docs/storage-architecture.md
@@ -39,6 +39,49 @@ SQLite / workspace-portable files / application preferences
 | Application preferences | `electron-store` | user configuration directory | small values only; localStorage may be a disposable UI cache, never authority |
 | Runtime queues and previews | memory/sessionStorage | renderer lifetime | explicitly non-durable |
 
+## SQLite boundaries
+
+Adnify owns exactly two SQLite domains. They intentionally do not share a file,
+connection, schema, or retention policy:
+
+| Database | Location | Authority | Main access pattern |
+| --- | --- | --- | --- |
+| Workspace session database | user configuration `session-storage/<workspace-id>.sqlite3` | authoritative | catalog ordering, one active thread's ordered messages, incremental tail replacement |
+| Structural index cache | workspace cache `structural-index.sqlite` | disposable and rebuildable | generation-scoped bulk writes, composite-key pagination, per-file replacement |
+
+Both databases are accessed only by dedicated workers. Renderer and Electron's
+main event loop never execute SQLite statements. The SQLite MCP preset is user
+configuration for an external MCP server and is not an Adnify storage backend.
+
+The session schema normalizes threads, messages, branches, plans, large blobs,
+and message-to-blob references. Blob liveness is determined by indexed foreign
+key relationships; commits never scan or parse the complete message history.
+The structural cache normalizes file metadata away from chunks and uses
+`(generation, relative_path, id)` as its storage and pagination order.
+
+## I/O budget
+
+- No SQLite task walks a drive or searches outside its explicit database and
+  companion blob directory.
+- WAL checkpoints are passive and triggered by write count or a 30-second quiet
+  period. Clean shutdown may truncate the WAL once.
+- Incremental vacuum runs only when at least 1,024 pages are free and free pages
+  exceed 20% of the database. It reclaims at most 256 pages per maintenance pass.
+- Recovery snapshots are copied only after committed changes and at most once per
+  24 hours. They are never refreshed on every message.
+- Full SQLite integrity checks run after an unclean shutdown, a schema migration,
+  or when the previous check is at least seven days old. Clean restarts do not
+  reread the complete session database.
+- Structural index reads use 512-row keyset pages. There is no offset scan and no
+  periodic full-project polling associated with SQLite.
+- The native workspace watcher updates an index only after that index has been
+  explicitly built or loaded. Editing a file cannot silently create a partial
+  index database.
+- Dependency, build-output, and application-cache globs are passed into the
+  native watcher backend, so those trees do not generate events that are merely
+  discarded later. Full indexing stats files before reading and uses four
+  bounded consumers; files above the configured limit are never read in full.
+
 JSONL is not an online session backend. The session worker may read the legacy
 format exactly once inside a transaction. A migration marker prevents old data
 from being imported again after the user clears the database.
@@ -104,5 +147,5 @@ The reproducible write-amplification benchmark is:
 
 ```sh
 pnpm build
-node scripts/benchmark-session-storage.cjs
+node scripts/benchmark-sqlite-storage.cjs
 ```
diff --git a/scripts/benchmark-sqlite-storage.cjs b/scripts/benchmark-sqlite-storage.cjs
new file mode 100644
index 00000000..0eb765f2
--- /dev/null
+++ b/scripts/benchmark-sqlite-storage.cjs
@@ -0,0 +1,184 @@
+const { Worker } = require('node:worker_threads')
+const { mkdtemp, rm, stat } = require('node:fs/promises')
+const { tmpdir } = require('node:os')
+const path = require('node:path')
+const { performance } = require('node:perf_hooks')
+const { randomUUID } = require('node:crypto')
+
+function createClient(workerPath) {
+  const worker = new Worker(workerPath)
+  const pending = new Map()
+  worker.on('message', response => {
+    const request = pending.get(response.requestId)
+    if (!request) return
+    pending.delete(response.requestId)
+    if (response.ok) request.resolve(response.result)
+    else request.reject(new Error(response.error))
+  })
+  worker.on('error', error => {
+    for (const request of pending.values()) request.reject(error)
+    pending.clear()
+  })
+  return {
+    request(operation) {
+      const requestId = randomUUID()
+      return new Promise((resolve, reject) => {
+        pending.set(requestId, { resolve, reject })
+        worker.postMessage({ requestId, operation })
+      })
+    },
+    terminate: () => worker.terminate(),
+  }
+}
+
+async function fileBytes(filePath) {
+  return stat(filePath).then(value => value.size).catch(() => 0)
+}
+
+async function benchmarkStructural(root) {
+  const workerPath = path.resolve('dist/main/structuralIndexStore.worker.js')
+  const databasePath = path.join(root, 'structural.sqlite')
+  const client = createClient(workerPath)
+  const generation = randomUUID()
+  const fileCount = 2_000
+  const chunkCount = 10_000
+  const chunks = Array.from({ length: chunkCount }, (_, index) => {
+    const fileIndex = Math.floor(index / 5)
+    const relativePath = `src/file-${fileIndex}.ts`
+    return {
+      id: `chunk-${index}`,
+      filePath: path.join(root, relativePath),
+      relativePath,
+      fileHash: `hash-${fileIndex}`,
+      content: `export function symbol${index}() { return ${index} }`,
+      startLine: index % 5,
+      endLine: index % 5,
+      type: 'function',
+      language: 'typescript',
+      symbols: [`symbol${index}`],
+    }
+  })
+
+  const writeStart = performance.now()
+  await client.request({ type: 'beginReplace', databasePath, generation })
+  for (let offset = 0; offset < chunks.length; offset += 512) {
+    await client.request({
+      type: 'appendReplace', databasePath, generation,
+      chunks: chunks.slice(offset, offset + 512),
+    })
+  }
+  await client.request({
+    type: 'commitReplace', databasePath, generation,
+    metadata: { totalFiles: fileCount, totalChunks: chunkCount, savedAt: Date.now() },
+  })
+  const writeMs = performance.now() - writeStart
+
+  const readStart = performance.now()
+  let cursor
+  let loaded = 0
+  let pages = 0
+  do {
+    const result = await client.request({ type: 'loadPage', databasePath, cursor })
+    loaded += result.chunks.length
+    pages += 1
+    cursor = result.nextCursor || undefined
+  } while (cursor)
+  const readMs = performance.now() - readStart
+  await client.request({ type: 'close', databasePath })
+  await client.terminate()
+
+  return {
+    files: fileCount,
+    chunks: loaded,
+    pages,
+    writeMs: Math.round(writeMs),
+    readMs: Math.round(readMs),
+    databaseBytes: await fileBytes(databasePath),
+  }
+}
+
+async function benchmarkSessions(root) {
+  const workerPath = path.resolve('dist/main/sessionStorage.worker.js')
+  const databasePath = path.join(root, 'sessions.sqlite3')
+  const client = createClient(workerPath)
+  const threadCount = 100
+  const messagesPerThread = 100
+  const payloadText = 'session-payload-'.repeat(32)
+  const threads = Array.from({ length: threadCount }, (_, threadIndex) => ({
+    metadata: {
+      id: `thread-${threadIndex}`,
+      createdAt: threadIndex,
+      lastModified: threadIndex,
+      title: `Thread ${threadIndex}`,
+      messageCount: messagesPerThread,
+      data: {},
+    },
+    replaceFrom: 0,
+    messages: Array.from({ length: messagesPerThread }, (_, ordinal) => ({
+      ordinal,
+      id: `message-${threadIndex}-${ordinal}`,
+      role: ordinal % 2 === 0 ? 'user' : 'assistant',
+      timestamp: ordinal,
+      payload: { id: `message-${threadIndex}-${ordinal}`, content: payloadText },
+    })),
+  }))
+
+  await client.request({ type: 'open', databasePath })
+  const writeStart = performance.now()
+  await client.request({
+    type: 'applyPatch', databasePath,
+    patch: { threads, deletedThreadIds: [], branchThreads: [] },
+  })
+  const writeMs = performance.now() - writeStart
+
+  const catalogStart = performance.now()
+  await client.request({ type: 'loadCatalog', databasePath })
+  const catalogMs = performance.now() - catalogStart
+  const threadStart = performance.now()
+  await client.request({ type: 'loadMessages', databasePath, threadId: 'thread-50' })
+  const threadMs = performance.now() - threadStart
+
+  const tailStart = performance.now()
+  await client.request({
+    type: 'applyPatch', databasePath,
+    patch: {
+      deletedThreadIds: [], branchThreads: [],
+      threads: [{
+        metadata: { ...threads[50].metadata, lastModified: Date.now() },
+        replaceFrom: 99,
+        messages: [{ ...threads[50].messages[99], payload: { id: 'tail', content: 'updated' } }],
+      }],
+    },
+  })
+  const tailWriteMs = performance.now() - tailStart
+  const stats = await client.request({ type: 'getStats', databasePath })
+  await client.request({ type: 'closeAll' })
+  await client.terminate()
+
+  return {
+    threads: threadCount,
+    messages: threadCount * messagesPerThread,
+    writeMs: Math.round(writeMs),
+    catalogMs: Math.round(catalogMs),
+    activeThreadMs: Math.round(threadMs),
+    tailWriteMs: Math.round(tailWriteMs),
+    databaseBytes: stats.stats.databaseBytes,
+    walBytesBeforeClose: stats.stats.walBytes,
+  }
+}
+
+async function main() {
+  const root = await mkdtemp(path.join(tmpdir(), 'adnify-sqlite-benchmark-'))
+  try {
+    const structural = await benchmarkStructural(root)
+    const sessions = await benchmarkSessions(root)
+    process.stdout.write(`${JSON.stringify({ structural, sessions }, null, 2)}\n`)
+  } finally {
+    await rm(root, { recursive: true, force: true })
+  }
+}
+
+main().catch(error => {
+  process.stderr.write(`${error.stack || error}\n`)
+  process.exitCode = 1
+})
diff --git a/src/main/indexing/indexService.ts b/src/main/indexing/indexService.ts
index 152432f0..a1a09387 100644
--- a/src/main/indexing/indexService.ts
+++ b/src/main/indexing/indexService.ts
@@ -11,8 +11,6 @@ import { randomUUID } from 'crypto'
 import type { BrowserWindow } from 'electron'
 import { Worker } from 'worker_threads'
 import { logger, normalizePath } from '@shared/utils'
-import { TreeSitterChunker } from './treeSitterChunker'
-import { ChunkerService } from './chunker'
 import { EmbeddingService } from './embedder'
 import { VectorStoreService } from './vectorStore'
 import { BM25Index, SymbolIndex, rerankCandidates } from './search'
@@ -29,7 +27,19 @@ import { getUserConfigDir, getWorkspaceCacheDir } from '../services/configPath'
 interface WorkerStructuralResultMessage { type: 'structural_result'; requestId: number; chunks: CodeChunk[]; processed: number; total: number }
 interface WorkerResultMessage { type: 'result'; chunks: IndexedChunk[]; processed: number; total: number }
 interface WorkerUpdateResultMessage { type: 'update_result'; filePath: string; chunks: IndexedChunk[]; deleted: boolean }
-interface WorkerBatchUpdateResultMessage { type: 'batch_update_result'; requestId: number; results: Array<{ filePath: string; chunks: IndexedChunk[]; deleted: boolean }> }
+type WorkerBatchUpdateResultMessage =
+  | {
+      type: 'batch_update_result'
+      mode: 'structural'
+      requestId: number
+      results: Array<{ filePath: string; chunks: CodeChunk[]; deleted: boolean }>
+    }
+  | {
+      type: 'batch_update_result'
+      mode: 'semantic'
+      requestId: number
+      results: Array<{ filePath: string; chunks: IndexedChunk[]; deleted: boolean }>
+    }
 interface WorkerCompleteMessage { type: 'complete'; totalChunks: number }
 interface WorkerErrorMessage { type: 'error'; error: string; requestId?: number }
 type WorkerMessage =
@@ -49,8 +59,6 @@ export class CodebaseIndexService {
   private mainWindow: BrowserWindow | null = null
 
   // 结构化索引组件
-  private chunker: TreeSitterChunker
-  private fallbackChunker: ChunkerService
   private bm25Index: BM25Index
   private symbolIndex: SymbolIndex
   private summaryGenerator: ProjectSummaryGenerator
@@ -95,8 +103,6 @@ export class CodebaseIndexService {
     this.status.mode = this.config.mode
 
     // 初始化结构化索引组件
-    this.chunker = new TreeSitterChunker(this.config)
-    this.fallbackChunker = new ChunkerService(this.config)
     this.bm25Index = new BM25Index()
     this.symbolIndex = new SymbolIndex()
     this.summaryGenerator = new ProjectSummaryGenerator(
@@ -130,8 +136,6 @@ export class CodebaseIndexService {
     if (this.initialized) return
     if (this.destroyed) throw new Error('Index service has been destroyed')
 
-    await this.chunker.init()
-
     // 加载缓存的项目摘要
     this.projectSummary = await this.summaryGenerator.loadCache()
 
@@ -173,9 +177,8 @@ export class CodebaseIndexService {
         return
       }
 
-      this.bm25Index.build()
       this.status.totalChunks = metadata.totalChunks
-      this.status.indexedFiles = this.symbolIndex.fileCount
+      this.status.indexedFiles = this.bm25Index.fileCount
       this.status.totalFiles = metadata.totalFiles
       this.status.lastIndexedAt = metadata.savedAt
       logger.index.info(`[IndexService] Loaded structural index: ${this.bm25Index.size} chunks, ${this.symbolIndex.size} symbols`)
@@ -430,74 +433,24 @@ export class CodebaseIndexService {
   /** 批量更新文件（用于文件监听） */
   async updateFiles(filePaths: string[]): Promise<void> {
     if (filePaths.length === 0 || this.destroyed) return
-    return this.enqueueMutation(() => this.performUpdateFiles(filePaths))
+    // The shared native watcher exists independently of code search. Do not
+    // create a partial SQLite index merely because an ordinary file changed.
+    if (!this.initialized && !this.pendingFullIndex) return
+    if (!this.pendingFullIndex && this.status.lastIndexedAt === undefined) return
+    return this.enqueueMutation(async () => {
+      // A queued full build may have failed. Never turn its trailing watcher
+      // events into an incomplete index.
+      if (this.status.lastIndexedAt === undefined) return
+      await this.performUpdateFiles(filePaths)
+    })
   }
 
   private async performUpdateFiles(filePaths: string[]): Promise<void> {
     logger.index.info(`[IndexService] Updating ${filePaths.length} files...`)
 
-    // 结构化模式：增量更新
-    if (this.config.mode === 'structural') {
-      let updated = 0
-      const persistedFiles: Array<{ relativePath: string; chunks: CodeChunk[] }> = []
-      for (const filePath of filePaths) {
-        try {
-          const ext = path.extname(filePath).toLowerCase()
-          if (!this.config.includedExts.includes(ext)) continue
-          const relativePath = path.relative(this.workspacePath, filePath)
-
-          // 检查文件是否存在
-          if (!fs.existsSync(filePath)) {
-            // 文件被删除，从索引中移除
-            await this.deleteFileFromStructuralIndex(filePath)
-            persistedFiles.push({ relativePath, chunks: [] })
-            updated++
-            continue
-          }
-
-          const content = await fs.promises.readFile(filePath, 'utf-8')
-          if (content.length > this.config.maxFileSize) {
-            await this.deleteFileFromStructuralIndex(filePath)
-            persistedFiles.push({ relativePath, chunks: [] })
-            updated++
-            continue
-          }
-
-          const chunks = await this.chunkFile(filePath, content)
-
-          // 先删除该文件的旧索引
-          await this.deleteFileFromStructuralIndex(filePath)
-          this.addStructuralChunks(chunks)
-          persistedFiles.push({ relativePath, chunks })
-          updated++
-        } catch (e) {
-          logger.index.warn(`[IndexService] Failed to update ${filePath}: `, e)
-        }
-      }
-
-      if (updated > 0) {
-        // 重建 BM25 索引（必须调用以更新 IDF）
-        this.bm25Index.build()
-        this.status.totalChunks = this.bm25Index.size
-        this.status.indexedFiles = this.symbolIndex.fileCount
-        await this.structuralStore.request({
-          type: 'applyFiles',
-          databasePath: this.structuralIndexPath,
-          files: persistedFiles,
-          metadata: {
-            totalFiles: this.status.totalFiles,
-            totalChunks: this.status.totalChunks,
-            savedAt: Date.now(),
-          },
-        })
-        logger.index.info(`[IndexService] Updated ${updated} files in structural index`)
-      }
-      return
-    }
-
-    // 语义模式：通过 worker 处理。Promise 只在向量存储提交完成后解析，
+    // 两种模式都通过 worker 处理。Promise 只在内存索引和持久化提交完成后解析，
     // 这样文件监听缓冲器才能提供真正的背压，而不是无限 postMessage。
-    await this.initSemanticComponents()
+    if (this.config.mode === 'semantic') await this.initSemanticComponents()
     if (!this.worker) this.initWorker()
     if (!this.worker) throw new Error('Index worker is unavailable')
 
@@ -528,7 +481,12 @@ export class CodebaseIndexService {
   /** 删除文件索引 */
   async deleteFileIndex(filePath: string): Promise<void> {
     if (this.destroyed) return
-    return this.enqueueMutation(() => this.performDeleteFileIndex(filePath))
+    if (!this.initialized && !this.pendingFullIndex) return
+    if (!this.pendingFullIndex && this.status.lastIndexedAt === undefined) return
+    return this.enqueueMutation(async () => {
+      if (this.status.lastIndexedAt === undefined) return
+      await this.performDeleteFileIndex(filePath)
+    })
   }
 
   private async performDeleteFileIndex(filePath: string): Promise<void> {
@@ -537,9 +495,8 @@ export class CodebaseIndexService {
     // 结构化模式：从索引中删除
     if (this.config.mode === 'structural') {
       await this.deleteFileFromStructuralIndex(filePath)
-      this.bm25Index.build()
       this.status.totalChunks = this.bm25Index.size
-      this.status.indexedFiles = this.symbolIndex.fileCount
+      this.status.indexedFiles = this.bm25Index.fileCount
       await this.structuralStore.request({
         type: 'applyFiles',
         databasePath: this.structuralIndexPath,
@@ -614,7 +571,7 @@ export class CodebaseIndexService {
       await this.startWorkerIndex()
       if (this.destroyed) return
 
-      this.bm25Index.build()
+      this.status.indexedFiles = this.bm25Index.fileCount
       this.projectSummary = this.summaryGenerator.generate(
         this.structuralBuildFileSymbols,
         this.structuralBuildLanguages,
@@ -747,11 +704,39 @@ export class CodebaseIndexService {
               break
 
             case 'batch_update_result':
-              for (const res of message.results) {
-                if (res.deleted) {
-                  await this.vectorStore!.deleteFile(res.filePath)
-                } else if (res.chunks?.length > 0) {
-                  await this.vectorStore!.upsertFile(res.filePath, res.chunks)
+              if (message.mode === 'structural') {
+                const persistedFiles: Array<{ relativePath: string; chunks: CodeChunk[] }> = []
+                for (const result of message.results) {
+                  const relativePath = path.relative(this.workspacePath, result.filePath)
+                  await this.deleteFileFromStructuralIndex(result.filePath)
+                  if (!result.deleted) this.addStructuralChunks(result.chunks)
+                  persistedFiles.push({
+                    relativePath,
+                    chunks: result.deleted ? [] : result.chunks,
+                  })
+                }
+                this.status.totalChunks = this.bm25Index.size
+                this.status.indexedFiles = this.bm25Index.fileCount
+                if (persistedFiles.length > 0) {
+                  await this.structuralStore.request({
+                    type: 'applyFiles',
+                    databasePath: this.structuralIndexPath,
+                    files: persistedFiles,
+                    metadata: {
+                      totalFiles: this.status.totalFiles,
+                      totalChunks: this.status.totalChunks,
+                      savedAt: Date.now(),
+                    },
+                  })
+                }
+                logger.index.info(`[IndexService] Updated ${persistedFiles.length} files in structural index`)
+              } else {
+                for (const result of message.results) {
+                  if (result.deleted) {
+                    await this.vectorStore!.deleteFile(result.filePath)
+                  } else if (result.chunks.length > 0) {
+                    await this.vectorStore!.upsertFile(result.filePath, result.chunks)
+                  }
                 }
               }
               this.emitProgress()
@@ -869,15 +854,6 @@ export class CodebaseIndexService {
   }
 
   // ==================== 工具方法 ====================
-
-  private async chunkFile(filePath: string, content: string): Promise<CodeChunk[]> {
-    let chunks = await this.chunker.chunkFile(filePath, content, this.workspacePath)
-    if (chunks.length === 0) {
-      chunks = this.fallbackChunker.chunkFile(filePath, content, this.workspacePath)
-    }
-    return chunks
-  }
-
   private extractKeywords(query: string): string[] {
     return query.split(/[\s,.:;!?()[\]{}'"<>]+/).map(t => t.trim()).filter(t => t.length >= 2 && !/^\d+$/.test(t))
   }
diff --git a/src/main/indexing/indexer.worker.ts b/src/main/indexing/indexer.worker.ts
index a6c3b2be..d9241151 100644
--- a/src/main/indexing/indexer.worker.ts
+++ b/src/main/indexing/indexer.worker.ts
@@ -27,7 +27,18 @@ type WorkerResponse =
   | { type: 'structural_result'; requestId: number; chunks: CodeChunk[]; processed: number; total: number }
   | { type: 'result'; chunks: IndexedChunk[]; processed: number; total: number }
   | { type: 'update_result'; filePath: string; chunks: IndexedChunk[]; deleted: boolean }
-  | { type: 'batch_update_result'; requestId: number; results: Array<{ filePath: string; chunks: IndexedChunk[]; deleted: boolean }> }
+  | {
+      type: 'batch_update_result'
+      mode: 'structural'
+      requestId: number
+      results: Array<{ filePath: string; chunks: CodeChunk[]; deleted: boolean }>
+    }
+  | {
+      type: 'batch_update_result'
+      mode: 'semantic'
+      requestId: number
+      results: Array<{ filePath: string; chunks: IndexedChunk[]; deleted: boolean }>
+    }
   | { type: 'complete'; totalChunks: number }
   | { type: 'error'; error: string; requestId?: number }
 
@@ -131,7 +142,6 @@ async function handleIndex(
 
   const { regexChunker, tsChunker } = await getChunkers(config)
   const embedder = config.mode === 'semantic' ? new EmbeddingService(config.embedding) : null
-  const limit = pLimit(4)
 
   // 预热 Embedder (触发模型加载) 并通知 UI
   if (config.mode === 'semantic' && config.embedding.provider === 'transformers') {
@@ -149,7 +159,7 @@ async function handleIndex(
   let skippedFiles = 0
   let pendingChunks: IndexedChunk[] = []
   let pendingStructuralChunks: CodeChunk[] = []
-  const RESULT_BATCH_SIZE = 50
+  const resultBatchSize = config.mode === 'structural' ? 512 : 50
 
   const flushChunks = async (): Promise<void> => {
     if (pendingStructuralChunks.length > 0) {
@@ -162,8 +172,13 @@ async function handleIndex(
     }
   }
 
-  const tasks = files.map(filePath => limit(async () => {
+  const processFile = async (filePath: string): Promise<void> => {
     try {
+      const stats = await fs.stat(filePath)
+      if (!stats.isFile() || stats.size > config.maxFileSize) {
+        processedFiles++
+        return
+      }
       const content = await fs.readFile(filePath, 'utf-8')
 
       if (content.length > config.maxFileSize) {
@@ -171,16 +186,17 @@ async function handleIndex(
         return
       }
 
-      const currentHash = crypto.createHash('sha256').update(content).digest('hex')
-
-      // 使用对象属性访问（不是 Map.get）
-      if (existingHashes && existingHashes[filePath] === currentHash) {
-        skippedFiles++
-        processedFiles++
-        if (processedFiles % 10 === 0) {
-          postResponse({ type: 'progress', processed: processedFiles, total: totalFiles })
+      if (existingHashes) {
+        const currentHash = crypto.createHash('sha256').update(content).digest('hex')
+        // 使用对象属性访问（不是 Map.get）
+        if (existingHashes[filePath] === currentHash) {
+          skippedFiles++
+          processedFiles++
+          if (processedFiles % 10 === 0) {
+            postResponse({ type: 'progress', processed: processedFiles, total: totalFiles })
+          }
+          return
         }
-        return
       }
 
       const chunks = await chunkFile(tsChunker, regexChunker, filePath, content, workspacePath)
@@ -203,7 +219,7 @@ async function handleIndex(
 
       processedFiles++
 
-      if (pendingChunks.length >= RESULT_BATCH_SIZE || pendingStructuralChunks.length >= RESULT_BATCH_SIZE) {
+      if (pendingChunks.length >= resultBatchSize || pendingStructuralChunks.length >= resultBatchSize) {
         await flushChunks()
       } else if (processedFiles % 10 === 0) {
         postResponse({ type: 'progress', processed: processedFiles, total: totalFiles })
@@ -212,9 +228,16 @@ async function handleIndex(
       logger.index.error(`Error processing file ${filePath}:`, error)
       processedFiles++
     }
-  }))
+  }
 
-  await Promise.all(tasks)
+  let nextFileIndex = 0
+  const consumers = Array.from({ length: Math.min(4, files.length) }, async () => {
+    while (nextFileIndex < files.length) {
+      const filePath = files[nextFileIndex++]
+      await processFile(filePath)
+    }
+  })
+  await Promise.all(consumers)
   await flushChunks()
 
   logger.index.info(`[Worker] Indexing complete. Total: ${totalFiles}, Skipped: ${skippedFiles}, Chunks: ${totalChunks}`)
@@ -231,42 +254,60 @@ async function handleBatchUpdate(
   config: IndexConfig,
 ): Promise<void> {
   const { regexChunker, tsChunker } = await getChunkers(config)
-  const embedder = new EmbeddingService(config.embedding)
-  const limit = pLimit(5) // 批量更新时降低并发
-
-  const results: Array<{ filePath: string; chunks: IndexedChunk[]; deleted: boolean }> = []
+  const embedder = config.mode === 'semantic' ? new EmbeddingService(config.embedding) : null
+  const limit = pLimit(4)
+  const structuralResults: Array<{ filePath: string; chunks: CodeChunk[]; deleted: boolean }> = []
+  const semanticResults: Array<{ filePath: string; chunks: IndexedChunk[]; deleted: boolean }> = []
 
   const tasks = files.map(filePath => limit(async () => {
     try {
-      // 检查文件是否存在
+      const ext = path.extname(filePath).toLowerCase()
+      if (!config.includedExts.includes(ext)) return
+
+      let stats
       try {
-        await fs.access(filePath)
+        stats = await fs.stat(filePath)
       } catch {
-        results.push({ filePath, chunks: [], deleted: true })
+        if (config.mode === 'structural') structuralResults.push({ filePath, chunks: [], deleted: true })
+        else semanticResults.push({ filePath, chunks: [], deleted: true })
+        return
+      }
+
+      if (!stats.isFile() || stats.size > config.maxFileSize) {
+        if (config.mode === 'structural') structuralResults.push({ filePath, chunks: [], deleted: true })
+        else semanticResults.push({ filePath, chunks: [], deleted: true })
         return
       }
 
       const content = await fs.readFile(filePath, 'utf-8')
 
       if (content.length > config.maxFileSize) {
+        if (config.mode === 'structural') structuralResults.push({ filePath, chunks: [], deleted: true })
+        else semanticResults.push({ filePath, chunks: [], deleted: true })
         return
       }
 
       const chunks = await chunkFile(tsChunker, regexChunker, filePath, content, workspacePath)
 
       if (chunks.length === 0) {
-        results.push({ filePath, chunks: [], deleted: true })
+        if (config.mode === 'structural') structuralResults.push({ filePath, chunks: [], deleted: true })
+        else semanticResults.push({ filePath, chunks: [], deleted: true })
+        return
+      }
+
+      if (config.mode === 'structural') {
+        structuralResults.push({ filePath, chunks, deleted: false })
         return
       }
 
       const texts = chunks.map(c => prepareTextForEmbedding(c))
-      const vectors = await embedder.embedBatch(texts)
+      const vectors = await embedder!.embedBatch(texts)
 
       const indexedChunks: IndexedChunk[] = chunks
         .map((chunk, idx) => vectors[idx] ? { ...chunk, vector: vectors[idx] } : null)
         .filter((c): c is IndexedChunk => c !== null)
 
-      results.push({ filePath, chunks: indexedChunks, deleted: false })
+      semanticResults.push({ filePath, chunks: indexedChunks, deleted: false })
     } catch (error) {
       logger.index.error(`[Worker] Error updating file ${filePath}:`, error)
       // 出错的文件跳过，不影响其他文件
@@ -275,7 +316,11 @@ async function handleBatchUpdate(
 
   await Promise.all(tasks)
 
-  postResponse({ type: 'batch_update_result', requestId, results })
+  if (config.mode === 'structural') {
+    postResponse({ type: 'batch_update_result', mode: 'structural', requestId, results: structuralResults })
+  } else {
+    postResponse({ type: 'batch_update_result', mode: 'semantic', requestId, results: semanticResults })
+  }
 }
 
 /**
diff --git a/src/main/indexing/search/bm25.ts b/src/main/indexing/search/bm25.ts
index 3330f4f8..7666c3fa 100644
--- a/src/main/indexing/search/bm25.ts
+++ b/src/main/indexing/search/bm25.ts
@@ -23,9 +23,11 @@ export interface BM25Document {
 }
 
 export class BM25Index {
-  private documents: BM25Document[] = []
-  private avgDocLength = 0
-  private idf: Map<string, number> = new Map()
+  private documents = new Set<BM25Document>()
+  private documentsByFile = new Map<string, Set<BM25Document>>()
+  private documentFrequency = new Map<string, number>()
+  private totalDocumentLength = 0
+
   /** 添加文档 */
   addDocument(doc: Omit<BM25Document, 'termFreq' | 'docLength'>): void {
     const terms = this.tokenize(doc.content)
@@ -33,7 +35,15 @@ export class BM25Index {
     for (const term of terms) {
       termFreq.set(term, (termFreq.get(term) || 0) + 1)
     }
-    this.documents.push({ ...doc, termFreq, docLength: terms.length })
+    const indexedDocument = { ...doc, termFreq, docLength: terms.length }
+    this.documents.add(indexedDocument)
+    const fileDocuments = this.documentsByFile.get(doc.relativePath) || new Set<BM25Document>()
+    fileDocuments.add(indexedDocument)
+    this.documentsByFile.set(doc.relativePath, fileDocuments)
+    this.totalDocumentLength += indexedDocument.docLength
+    for (const term of termFreq.keys()) {
+      this.documentFrequency.set(term, (this.documentFrequency.get(term) || 0) + 1)
+    }
   }
 
   /** 批量添加文档 */
@@ -43,44 +53,17 @@ export class BM25Index {
     }
   }
 
-  /** 构建索引（计算 IDF） */
-  build(): void {
-    // 先清空：增量更新会让部分词彻底离开语料库，
-    // 若保留旧条目，这些词的 IDF 会一直参与评分，且 Map 无界增长。
-    this.idf.clear()
-
-    if (this.documents.length === 0) {
-      this.avgDocLength = 0
-      return
-    }
-
-    // 平均文档长度
-    const totalLength = this.documents.reduce((sum, doc) => sum + doc.docLength, 0)
-    this.avgDocLength = totalLength / this.documents.length
-
-    // 计算 IDF
-    const docFreq = new Map<string, number>()
-    for (const doc of this.documents) {
-      const seenTerms = new Set<string>()
-      for (const term of doc.termFreq.keys()) {
-        if (!seenTerms.has(term)) {
-          docFreq.set(term, (docFreq.get(term) || 0) + 1)
-          seenTerms.add(term)
-        }
-      }
-    }
-
-    const N = this.documents.length
-    for (const [term, df] of docFreq) {
-      this.idf.set(term, Math.log((N - df + 0.5) / (df + 0.5) + 1))
-    }
-  }
-
   /** 搜索 */
   search(query: string, topK: number = 10): SearchResult[] {
-    if (this.documents.length === 0) return []
+    if (this.documents.size === 0) return []
 
     const queryTerms = this.tokenize(query)
+    const documentCount = this.documents.size
+    const averageDocumentLength = this.totalDocumentLength / documentCount
+    const queryIdf = new Map(queryTerms.map(term => {
+      const frequency = this.documentFrequency.get(term) || 0
+      return [term, Math.log((documentCount - frequency + 0.5) / (frequency + 0.5) + 1)]
+    }))
     const scores: { doc: BM25Document; score: number }[] = []
 
     for (const doc of this.documents) {
@@ -90,9 +73,11 @@ export class BM25Index {
         const tf = doc.termFreq.get(term) || 0
         if (tf === 0) continue
 
-        const idf = this.idf.get(term) || 0
+        const idf = queryIdf.get(term) || 0
         const numerator = tf * (BM25_K1 + 1)
-        const denominator = tf + BM25_K1 * (1 - BM25_B + BM25_B * (doc.docLength / this.avgDocLength))
+        const denominator = tf + BM25_K1 * (
+          1 - BM25_B + BM25_B * (doc.docLength / averageDocumentLength)
+        )
         score += idf * (numerator / denominator)
       }
 
@@ -127,31 +112,46 @@ export class BM25Index {
 
   /** 清空 */
   clear(): void {
-    this.documents = []
-    this.idf.clear()
-    this.avgDocLength = 0
+    this.documents.clear()
+    this.documentsByFile.clear()
+    this.documentFrequency.clear()
+    this.totalDocumentLength = 0
   }
 
   /**
    * 删除文件的所有文档
    *
-   * 返回是否真的删除了内容，供调用者判断能否跳过 build()。
-   * 注意：文档数变化后 IDF 已失效，调用者需在批量删除结束后调用 build()。
+   * 返回是否真的删除了内容。
    */
   deleteFile(relativePath: string): boolean {
-    const before = this.documents.length
-    this.documents = this.documents.filter(doc => doc.relativePath !== relativePath)
-    return this.documents.length !== before
+    const fileDocuments = this.documentsByFile.get(relativePath)
+    if (!fileDocuments) return false
+
+    for (const doc of fileDocuments) {
+      this.documents.delete(doc)
+      this.totalDocumentLength -= doc.docLength
+      for (const term of doc.termFreq.keys()) {
+        const nextFrequency = (this.documentFrequency.get(term) || 0) - 1
+        if (nextFrequency <= 0) this.documentFrequency.delete(term)
+        else this.documentFrequency.set(term, nextFrequency)
+      }
+    }
+    this.documentsByFile.delete(relativePath)
+    return true
   }
 
   /** 获取文档数量 */
   get size(): number {
-    return this.documents.length
+    return this.documents.size
+  }
+
+  get fileCount(): number {
+    return this.documentsByFile.size
   }
 
   /** Number of searchable terms, useful for status and invariant checks. */
   get vocabularySize(): number {
-    return this.idf.size
+    return this.documentFrequency.size
   }
 
   /** 分词 */
diff --git a/src/main/indexing/structuralIndexStore.worker.ts b/src/main/indexing/structuralIndexStore.worker.ts
index 75c7d828..668cf7e7 100644
--- a/src/main/indexing/structuralIndexStore.worker.ts
+++ b/src/main/indexing/structuralIndexStore.worker.ts
@@ -1,5 +1,5 @@
 import { DatabaseSync } from 'node:sqlite'
-import { mkdirSync } from 'fs'
+import { mkdirSync, rmSync } from 'fs'
 import * as path from 'path'
 import { parentPort } from 'worker_threads'
 import type { CodeChunk } from './types'
@@ -13,21 +13,51 @@ import type {
 } from './structuralIndexStore.types'
 
 const databases = new Map<string, DatabaseSync>()
-const LOAD_BATCH_SIZE = 50
+// Keep worker IPC amortized without creating multi-megabyte structured-clone
+// payloads for the main process. The old size of 50 made a 1M-chunk cache
+// require 20,000 request/response turns during startup.
+const LOAD_BATCH_SIZE = 512
+const SCHEMA_VERSION = 1
 
-function openDatabase(databasePath: string): DatabaseSync {
-  const existing = databases.get(databasePath)
-  if (existing) return existing
+interface StoredChunkRow {
+  id: string
+  relative_path: string
+  file_path: string
+  file_hash: string
+  content: string
+  start_line: number
+  end_line: number
+  type: CodeChunk['type']
+  language: string
+  symbols_json: string
+}
 
-  mkdirSync(path.dirname(databasePath), { recursive: true })
-  const database = new DatabaseSync(databasePath)
+function removeDatabaseFiles(databasePath: string): void {
+  for (const target of [databasePath, `${databasePath}-wal`, `${databasePath}-shm`]) {
+    rmSync(target, { force: true })
+  }
+}
+
+function hasTables(database: DatabaseSync): boolean {
+  return Boolean(database.prepare(
+    "SELECT 1 FROM sqlite_master WHERE type = 'table' LIMIT 1",
+  ).get())
+}
+
+function createSchema(database: DatabaseSync): void {
   database.exec(`
+    PRAGMA page_size = 8192;
     PRAGMA journal_mode = WAL;
     PRAGMA synchronous = NORMAL;
+    PRAGMA foreign_keys = ON;
     PRAGMA temp_store = MEMORY;
     PRAGMA busy_timeout = 5000;
+    PRAGMA cache_size = -32768;
+    PRAGMA mmap_size = 268435456;
+    PRAGMA wal_autocheckpoint = 4096;
+    PRAGMA journal_size_limit = 16777216;
 
-    CREATE TABLE IF NOT EXISTS index_state (
+    CREATE TABLE index_state (
       singleton INTEGER PRIMARY KEY CHECK (singleton = 1),
       active_generation TEXT NOT NULL,
       total_files INTEGER NOT NULL CHECK (total_files >= 0),
@@ -35,21 +65,63 @@ function openDatabase(databasePath: string): DatabaseSync {
       saved_at INTEGER NOT NULL
     ) STRICT;
 
-    CREATE TABLE IF NOT EXISTS chunks (
+    CREATE TABLE files (
       generation TEXT NOT NULL,
-      id TEXT NOT NULL,
       relative_path TEXT NOT NULL,
-      payload_json TEXT NOT NULL,
-      PRIMARY KEY (generation, id)
+      file_path TEXT NOT NULL,
+      file_hash TEXT NOT NULL,
+      PRIMARY KEY (generation, relative_path)
     ) WITHOUT ROWID, STRICT;
 
-    CREATE INDEX IF NOT EXISTS chunks_generation_file
-      ON chunks(generation, relative_path);
+    CREATE TABLE chunks (
+      generation TEXT NOT NULL,
+      relative_path TEXT NOT NULL,
+      id TEXT NOT NULL,
+      content TEXT NOT NULL,
+      start_line INTEGER NOT NULL CHECK (start_line >= 0),
+      end_line INTEGER NOT NULL CHECK (end_line >= start_line),
+      type TEXT NOT NULL,
+      language TEXT NOT NULL,
+      symbols_json TEXT NOT NULL,
+      PRIMARY KEY (generation, relative_path, id),
+      FOREIGN KEY (generation, relative_path)
+        REFERENCES files(generation, relative_path) ON DELETE CASCADE
+    ) WITHOUT ROWID, STRICT;
+
+    PRAGMA user_version = ${SCHEMA_VERSION};
+  `)
+}
+
+function openDatabase(databasePath: string): DatabaseSync {
+  const existing = databases.get(databasePath)
+  if (existing) return existing
+
+  mkdirSync(path.dirname(databasePath), { recursive: true })
+  let database = new DatabaseSync(databasePath)
+  const version = Number(
+    (database.prepare('PRAGMA user_version').get() as { user_version: number }).user_version,
+  )
+  if (version !== SCHEMA_VERSION && (version !== 0 || hasTables(database))) {
+    database.close()
+    removeDatabaseFiles(databasePath)
+    database = new DatabaseSync(databasePath)
+  }
+  if (!hasTables(database)) createSchema(database)
+  else database.exec(`
+    PRAGMA journal_mode = WAL;
+    PRAGMA synchronous = NORMAL;
+    PRAGMA foreign_keys = ON;
+    PRAGMA temp_store = MEMORY;
+    PRAGMA busy_timeout = 5000;
+    PRAGMA cache_size = -32768;
+    PRAGMA mmap_size = 268435456;
+    PRAGMA wal_autocheckpoint = 4096;
+    PRAGMA journal_size_limit = 16777216;
   `)
   // A terminated rebuild may leave an uncommitted generation behind. Only the
   // active generation is authoritative, so orphan rows are safe to remove.
   database.exec(`
-    DELETE FROM chunks
+    DELETE FROM files
     WHERE generation NOT IN (SELECT active_generation FROM index_state WHERE singleton = 1)
   `)
   databases.set(databasePath, database)
@@ -67,13 +139,46 @@ function inTransaction(database: DatabaseSync, operation: () => void): void {
   }
 }
 
-function insertChunks(database: DatabaseSync, generation: string, chunks: CodeChunk[]): void {
-  const insert = database.prepare(`
-    INSERT OR REPLACE INTO chunks(generation, id, relative_path, payload_json)
+function createChunkStatements(database: DatabaseSync) {
+  const insertFile = database.prepare(`
+    INSERT INTO files(generation, relative_path, file_path, file_hash)
     VALUES (?, ?, ?, ?)
+    ON CONFLICT(generation, relative_path) DO UPDATE SET
+      file_path = excluded.file_path,
+      file_hash = excluded.file_hash
   `)
+  const insertChunk = database.prepare(`
+    INSERT INTO chunks(
+      generation, relative_path, id, content, start_line, end_line,
+      type, language, symbols_json
+    ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
+  `)
+  return { insertFile, insertChunk }
+}
+
+function insertChunks(
+  statements: ReturnType<typeof createChunkStatements>,
+  generation: string,
+  chunks: CodeChunk[],
+): void {
+  const { insertFile, insertChunk } = statements
+  const insertedFiles = new Set<string>()
   for (const chunk of chunks) {
-    insert.run(generation, chunk.id, chunk.relativePath, JSON.stringify(chunk))
+    if (!insertedFiles.has(chunk.relativePath)) {
+      insertFile.run(generation, chunk.relativePath, chunk.filePath, chunk.fileHash)
+      insertedFiles.add(chunk.relativePath)
+    }
+    insertChunk.run(
+      generation,
+      chunk.relativePath,
+      chunk.id,
+      chunk.content,
+      chunk.startLine,
+      chunk.endLine,
+      chunk.type,
+      chunk.language,
+      JSON.stringify(chunk.symbols || []),
+    )
   }
 }
 
@@ -106,31 +211,45 @@ function loadPage(
 
   const rows = cursor
     ? database.prepare(`
-        SELECT id, relative_path, payload_json FROM chunks
-        WHERE generation = ?
-          AND (relative_path > ? OR (relative_path = ? AND id > ?))
-        ORDER BY relative_path, id LIMIT ?
+        SELECT
+          c.id, c.relative_path, f.file_path, f.file_hash, c.content,
+          c.start_line, c.end_line, c.type, c.language, c.symbols_json
+        FROM chunks c
+        JOIN files f USING (generation, relative_path)
+        WHERE c.generation = ?
+          AND (c.relative_path, c.id) > (?, ?)
+        ORDER BY c.relative_path, c.id LIMIT ?
       `).all(
         metadata.generation,
         cursor.relativePath,
-        cursor.relativePath,
         cursor.id,
         LOAD_BATCH_SIZE,
-      ) as Array<{ id: string; relative_path: string; payload_json: string }>
+      ) as unknown as StoredChunkRow[]
     : database.prepare(`
-        SELECT id, relative_path, payload_json FROM chunks
-        WHERE generation = ? ORDER BY relative_path, id LIMIT ?
-      `).all(metadata.generation, LOAD_BATCH_SIZE) as Array<{
-        id: string
-        relative_path: string
-        payload_json: string
-      }>
+        SELECT
+          c.id, c.relative_path, f.file_path, f.file_hash, c.content,
+          c.start_line, c.end_line, c.type, c.language, c.symbols_json
+        FROM chunks c
+        JOIN files f USING (generation, relative_path)
+        WHERE c.generation = ? ORDER BY c.relative_path, c.id LIMIT ?
+      `).all(metadata.generation, LOAD_BATCH_SIZE) as unknown as StoredChunkRow[]
   const { generation: _generation, ...result } = metadata
   const last = rows.at(-1)
   return {
     type: 'loadedPage',
     metadata: result,
-    chunks: rows.map(row => JSON.parse(row.payload_json) as CodeChunk),
+    chunks: rows.map(row => ({
+      id: row.id,
+      filePath: row.file_path,
+      relativePath: row.relative_path,
+      fileHash: row.file_hash,
+      content: row.content,
+      startLine: row.start_line,
+      endLine: row.end_line,
+      type: row.type,
+      language: row.language,
+      symbols: JSON.parse(row.symbols_json) as string[],
+    })),
     nextCursor: rows.length === LOAD_BATCH_SIZE && last
       ? { relativePath: last.relative_path, id: last.id }
       : null,
@@ -145,10 +264,12 @@ export function executeStructuralIndexStoreOperation(
     case 'loadPage':
       return loadPage(database, operation.cursor)
     case 'beginReplace':
-      database.prepare('DELETE FROM chunks WHERE generation = ?').run(operation.generation)
+      database.prepare('DELETE FROM files WHERE generation = ?').run(operation.generation)
       return { type: 'ok' }
     case 'appendReplace':
-      inTransaction(database, () => insertChunks(database, operation.generation, operation.chunks))
+      inTransaction(database, () => {
+        insertChunks(createChunkStatements(database), operation.generation, operation.chunks)
+      })
       return { type: 'ok' }
     case 'commitReplace': {
       const row = database.prepare(
@@ -174,23 +295,24 @@ export function executeStructuralIndexStoreOperation(
           operation.metadata.totalChunks,
           operation.metadata.savedAt,
         )
-        database.prepare('DELETE FROM chunks WHERE generation <> ?').run(operation.generation)
+        database.prepare('DELETE FROM files WHERE generation <> ?').run(operation.generation)
       })
       return { type: 'ok' }
     }
     case 'abortReplace':
-      database.prepare('DELETE FROM chunks WHERE generation = ?').run(operation.generation)
+      database.prepare('DELETE FROM files WHERE generation = ?').run(operation.generation)
       return { type: 'ok' }
     case 'applyFiles': {
       const current = readMetadata(database)
       const generation = current?.generation || `incremental-${operation.metadata.savedAt}`
       inTransaction(database, () => {
+        const statements = createChunkStatements(database)
         const remove = database.prepare(
-          'DELETE FROM chunks WHERE generation = ? AND relative_path = ?',
+          'DELETE FROM files WHERE generation = ? AND relative_path = ?',
         )
         for (const file of operation.files) {
           remove.run(generation, file.relativePath)
-          insertChunks(database, generation, file.chunks)
+          insertChunks(statements, generation, file.chunks)
         }
         const row = database.prepare(
           'SELECT COUNT(*) AS count FROM chunks WHERE generation = ?',
@@ -218,10 +340,11 @@ export function executeStructuralIndexStoreOperation(
     }
     case 'clear':
       inTransaction(database, () => {
-        database.exec('DELETE FROM chunks; DELETE FROM index_state;')
+        database.exec('DELETE FROM files; DELETE FROM index_state;')
       })
       return { type: 'ok' }
     case 'close':
+      database.exec('PRAGMA optimize')
       database.exec('PRAGMA wal_checkpoint(TRUNCATE)')
       database.close()
       databases.delete(operation.databasePath)
diff --git a/src/main/security/fileWatcher.ts b/src/main/security/fileWatcher.ts
index 51e06fcb..78ab6d78 100644
--- a/src/main/security/fileWatcher.ts
+++ b/src/main/security/fileWatcher.ts
@@ -36,7 +36,10 @@ interface WatcherEntry {
 }
 
 const DEFAULT_CONFIG: FileWatcherConfig = {
-  ignored: [/node_modules/, /\.git/, /dist/, /build/, /\.adnify/, '**/*.tmp', '**/*.temp'],
+  // String globs are passed to the native backend, preventing dependency and
+  // build trees from generating events at all. Git stays post-filtered because
+  // repositories whose metadata lives inside the workspace still need state signals.
+  ignored: ['**/node_modules/**', /\.git/, '**/dist/**', '**/build/**', '**/.adnify/**', '**/*.tmp', '**/*.temp'],
   persistent: true,
   ignoreInitial: true,
   bufferTimeMs: 500,
@@ -64,7 +67,7 @@ function createIgnoreMatcher(patterns: (string | RegExp)[]): (path: string) => b
     for (const regex of regexPatterns) {
       if (regex.test(filePath)) return true
     }
-    if (globMatcher && globMatcher(filePath)) return true
+    if (globMatcher && globMatcher(filePath.replace(/\\/g, '/'))) return true
     return false
   }
 }
diff --git a/src/main/services/session/sessionStorage.worker.ts b/src/main/services/session/sessionStorage.worker.ts
index ffb0efb5..ed060e7f 100644
--- a/src/main/services/session/sessionStorage.worker.ts
+++ b/src/main/services/session/sessionStorage.worker.ts
@@ -23,6 +23,7 @@ interface OpenDatabase {
   writesSinceCheckpoint: number
   dirtySinceBackup: boolean
   idleCheckpoint: ReturnType<typeof setTimeout> | null
+  protectedBackupBlobHashes: Set<string> | null
 }
 
 interface BlobDescriptor {
@@ -52,14 +53,16 @@ const DEFAULT_STATE: SessionStateRecord = {
   activeBranchId: {},
   version: 0,
 }
-const LATEST_SCHEMA_VERSION = 4
+const LATEST_SCHEMA_VERSION = 5
 const BLOB_THRESHOLD_BYTES = 256 * 1024
 const IDLE_CHECKPOINT_MS = 30_000
 const CHECKPOINT_WRITE_THRESHOLD = 32
 const BACKUP_MIN_INTERVAL_MS = 24 * 60 * 60 * 1_000
+const INTEGRITY_CHECK_INTERVAL_MS = 7 * 24 * 60 * 60 * 1_000
 
 function configure(database: DatabaseSync): void {
   database.exec(`
+    PRAGMA page_size = 8192;
     PRAGMA journal_mode = WAL;
     PRAGMA synchronous = FULL;
     PRAGMA foreign_keys = ON;
@@ -67,6 +70,9 @@ function configure(database: DatabaseSync): void {
     PRAGMA wal_autocheckpoint = 0;
     PRAGMA journal_size_limit = 16777216;
     PRAGMA temp_store = MEMORY;
+    PRAGMA cache_size = -32768;
+    PRAGMA mmap_size = 268435456;
+    PRAGMA trusted_schema = OFF;
   `)
 }
 
@@ -233,6 +239,113 @@ function migrateV4(database: DatabaseSync): void {
   `)
 }
 
+function migrateV5(database: DatabaseSync): void {
+  if (tableExists(database, 'message_blobs') && tableExists(database, 'branch_message_blobs')) {
+    database.exec(`
+      CREATE INDEX IF NOT EXISTS threads_last_modified_id
+        ON threads(last_modified DESC, id ASC);
+      DROP INDEX IF EXISTS plans_updated_at;
+      CREATE INDEX IF NOT EXISTS plans_updated_at_id
+        ON plans(updated_at DESC, id ASC);
+      DROP INDEX IF EXISTS messages_thread_id_id;
+      CREATE TABLE IF NOT EXISTS maintenance_state (
+        singleton INTEGER PRIMARY KEY CHECK (singleton = 1),
+        last_quick_check_at INTEGER NOT NULL,
+        clean_shutdown INTEGER NOT NULL CHECK (clean_shutdown IN (0, 1))
+      ) STRICT;
+      INSERT OR IGNORE INTO maintenance_state(singleton, last_quick_check_at, clean_shutdown)
+        VALUES (1, 0, 1);
+    `)
+    return
+  }
+
+  database.exec(`
+    CREATE INDEX IF NOT EXISTS threads_last_modified_id
+      ON threads(last_modified DESC, id ASC);
+
+    DROP INDEX IF EXISTS plans_updated_at;
+    DROP INDEX IF EXISTS messages_thread_id_id;
+    CREATE INDEX IF NOT EXISTS plans_updated_at_id
+      ON plans(updated_at DESC, id ASC);
+
+    CREATE TABLE blobs_v5 (
+      hash TEXT PRIMARY KEY,
+      encoding TEXT NOT NULL CHECK (encoding IN ('utf8', 'base64')),
+      byte_length INTEGER NOT NULL CHECK (byte_length >= 0),
+      created_at INTEGER NOT NULL
+    ) STRICT;
+
+    INSERT INTO blobs_v5(hash, encoding, byte_length, created_at)
+      SELECT hash, encoding, byte_length, created_at FROM blobs;
+
+    CREATE TABLE message_blobs (
+      thread_id TEXT NOT NULL,
+      ordinal INTEGER NOT NULL,
+      hash TEXT NOT NULL REFERENCES blobs_v5(hash) ON DELETE RESTRICT,
+      PRIMARY KEY (thread_id, ordinal, hash),
+      FOREIGN KEY (thread_id, ordinal)
+        REFERENCES messages(thread_id, ordinal) ON DELETE CASCADE
+    ) WITHOUT ROWID, STRICT;
+
+    CREATE INDEX message_blobs_hash ON message_blobs(hash);
+
+    CREATE TABLE branch_message_blobs (
+      thread_id TEXT NOT NULL,
+      branch_id TEXT NOT NULL,
+      ordinal INTEGER NOT NULL,
+      hash TEXT NOT NULL REFERENCES blobs_v5(hash) ON DELETE RESTRICT,
+      PRIMARY KEY (thread_id, branch_id, ordinal, hash),
+      FOREIGN KEY (thread_id, branch_id, ordinal)
+        REFERENCES branch_messages(thread_id, branch_id, ordinal) ON DELETE CASCADE
+    ) WITHOUT ROWID, STRICT;
+
+    CREATE INDEX branch_message_blobs_hash ON branch_message_blobs(hash);
+
+    CREATE TABLE IF NOT EXISTS maintenance_state (
+      singleton INTEGER PRIMARY KEY CHECK (singleton = 1),
+      last_quick_check_at INTEGER NOT NULL,
+      clean_shutdown INTEGER NOT NULL CHECK (clean_shutdown IN (0, 1))
+    ) STRICT;
+
+    INSERT OR IGNORE INTO maintenance_state(singleton, last_quick_check_at, clean_shutdown)
+      VALUES (1, 0, 1);
+  `)
+
+  const insertMessageBlob = database.prepare(`
+    INSERT OR IGNORE INTO message_blobs(thread_id, ordinal, hash) VALUES (?, ?, ?)
+  `)
+  const insertBranchMessageBlob = database.prepare(`
+    INSERT OR IGNORE INTO branch_message_blobs(thread_id, branch_id, ordinal, hash)
+    VALUES (?, ?, ?, ?)
+  `)
+  const messages = database.prepare(
+    'SELECT thread_id, ordinal, payload_json FROM messages',
+  ).all() as Array<{ thread_id: string; ordinal: number; payload_json: string }>
+  for (const row of messages) {
+    for (const reference of blobReferences(row.payload_json)) {
+      insertMessageBlob.run(row.thread_id, row.ordinal, reference.hash)
+    }
+  }
+  const branchMessages = database.prepare(
+    'SELECT thread_id, branch_id, ordinal, payload_json FROM branch_messages',
+  ).all() as Array<{
+    thread_id: string
+    branch_id: string
+    ordinal: number
+    payload_json: string
+  }>
+  for (const row of branchMessages) {
+    for (const reference of blobReferences(row.payload_json)) {
+      insertBranchMessageBlob.run(row.thread_id, row.branch_id, row.ordinal, reference.hash)
+    }
+  }
+
+  database.exec(`
+    DROP TABLE blobs;
+    ALTER TABLE blobs_v5 RENAME TO blobs;
+  `)
+}
+
 function migrateSchema(database: DatabaseSync): boolean {
   let version = Number((database.prepare('PRAGMA user_version').get() as { user_version: number }).user_version)
   if (version > LATEST_SCHEMA_VERSION) {
@@ -240,7 +353,7 @@ function migrateSchema(database: DatabaseSync): boolean {
   }
 
   const startingVersion = version
-  const migrations = [migrateV1, migrateV2, migrateV3, migrateV4]
+  const migrations = [migrateV1, migrateV2, migrateV3, migrateV4, migrateV5]
   while (version < LATEST_SCHEMA_VERSION) {
     const nextVersion = version + 1
     database.exec('BEGIN IMMEDIATE')
@@ -264,11 +377,10 @@ function assertHealthy(database: DatabaseSync): void {
   }
 }
 
-function openCheckedDatabase(databasePath: string): DatabaseSync {
+function openConfiguredDatabase(databasePath: string): DatabaseSync {
   const database = new DatabaseSync(databasePath)
   try {
     configure(database)
-    assertHealthy(database)
     return database
   } catch (error) {
     try { database.close() } catch { /* preserve original failure */ }
@@ -321,21 +433,43 @@ async function recoverFromBackup(databasePath: string, openError: unknown): Prom
     if (await fileExists(source)) await fs.rename(source, `${source}${suffix}`)
   }
   await fs.copyFile(backupPath, databasePath)
-  return openCheckedDatabase(databasePath)
+  return openConfiguredDatabase(databasePath)
 }
 
 async function openHealthyDatabase(databasePath: string): Promise<{ database: DatabaseSync; migrated: boolean }> {
-  let database: DatabaseSync
+  let database: DatabaseSync | undefined
+  let checkedAt = 0
   try {
-    database = openCheckedDatabase(databasePath)
+    database = openConfiguredDatabase(databasePath)
+    const maintenance = tableExists(database, 'maintenance_state')
+      ? database.prepare(`
+          SELECT last_quick_check_at, clean_shutdown
+          FROM maintenance_state WHERE singleton = 1
+        `).get() as { last_quick_check_at: number; clean_shutdown: number } | undefined
+      : undefined
+    const now = Date.now()
+    if (!maintenance || maintenance.clean_shutdown !== 1 ||
+      now - maintenance.last_quick_check_at >= INTEGRITY_CHECK_INTERVAL_MS) {
+      assertHealthy(database)
+      checkedAt = now
+    }
   } catch (error) {
+    try { database?.close() } catch { /* recovery owns the next connection */ }
     database = await recoverFromBackup(databasePath, error)
+    checkedAt = Date.now()
   }
 
+  if (!database) throw new Error('Session database failed to open')
   try {
     if (!tableExists(database, 'threads')) database.exec('PRAGMA auto_vacuum = INCREMENTAL')
     const schemaMigrated = migrateSchema(database)
     const payloadsMigrated = await externalizeLegacyPayloads(database, databasePath)
+    database.prepare(`
+      UPDATE maintenance_state
+      SET last_quick_check_at = CASE WHEN ? > 0 THEN ? ELSE last_quick_check_at END,
+          clean_shutdown = 0
+      WHERE singleton = 1
+    `).run(checkedAt, checkedAt)
     return { database, migrated: schemaMigrated || payloadsMigrated }
   } catch (error) {
     database.close()
@@ -356,6 +490,7 @@ async function getDatabase(databasePath: string): Promise<OpenDatabase> {
     writesSinceCheckpoint: 0,
     dirtySinceBackup: initialized.migrated,
     idleCheckpoint: null,
+    protectedBackupBlobHashes: null,
   }
   databases.set(databasePath, opened)
   return opened
@@ -370,7 +505,11 @@ function blobPath(databasePath: string, hash: string): string {
   return path.join(blobDirectory(databasePath), hash.slice(0, 2), hash)
 }
 
-async function writeBlob(databasePath: string, bytes: Buffer): Promise<string> {
+async function writeBlob(
+  databasePath: string,
+  bytes: Buffer,
+  createdHashes: Set<string>,
+): Promise<string> {
   const hash = createHash('sha256').update(bytes).digest('hex')
   const target = blobPath(databasePath, hash)
   if (await fileExists(target)) return hash
@@ -387,6 +526,7 @@ async function writeBlob(databasePath: string, bytes: Buffer): Promise<string> {
   try {
     await fs.rename(temporary, target)
     await syncDirectory(path.dirname(target))
+    createdHashes.add(hash)
   } catch (error) {
     await fs.rm(temporary, { force: true })
     if (!await fileExists(target)) throw error
@@ -406,6 +546,7 @@ async function externalizeValue(
   value: unknown,
   databasePath: string,
   blobs: BlobDescriptor[],
+  createdHashes: Set<string>,
   key?: string,
   parent?: Record<string, unknown>,
 ): Promise<unknown> {
@@ -414,7 +555,7 @@ async function externalizeValue(
     const bytes = isBase64 ? Buffer.from(value, 'base64') : Buffer.from(value, 'utf8')
     if (bytes.byteLength < BLOB_THRESHOLD_BYTES) return value
     const descriptor: BlobDescriptor = {
-      hash: await writeBlob(databasePath, bytes),
+      hash: await writeBlob(databasePath, bytes, createdHashes),
       encoding: isBase64 ? 'base64' : 'utf8',
       byteLength: bytes.byteLength,
     }
@@ -422,23 +563,27 @@ async function externalizeValue(
     return { __adnifyBlob: 1, hash: descriptor.hash, encoding: descriptor.encoding } satisfies BlobReference
   }
   if (Array.isArray(value)) {
-    return Promise.all(value.map(item => externalizeValue(item, databasePath, blobs)))
+    return Promise.all(value.map(item => externalizeValue(item, databasePath, blobs, createdHashes)))
   }
   if (!value || typeof value !== 'object') return value
 
   const record = value as Record<string, unknown>
   const entries = await Promise.all(Object.entries(record).map(async ([childKey, child]) => [
     childKey,
-    await externalizeValue(child, databasePath, blobs, childKey, record),
+    await externalizeValue(child, databasePath, blobs, createdHashes, childKey, record),
   ] as const))
   return Object.fromEntries(entries)
 }
 
-async function prepareMessage(databasePath: string, message: SessionMessageWrite): Promise<PreparedMessage> {
+async function prepareMessage(
+  databasePath: string,
+  message: SessionMessageWrite,
+  createdHashes: Set<string>,
+): Promise<PreparedMessage> {
   // Preserve JSON.stringify semantics (including rejecting BigInt) before any transaction begins.
   const compatible = JSON.parse(JSON.stringify(message.payload)) as unknown
   const blobs: BlobDescriptor[] = []
-  const externalized = await externalizeValue(compatible, databasePath, blobs)
+  const externalized = await externalizeValue(compatible, databasePath, blobs, createdHashes)
   return {
     ordinal: message.ordinal,
     id: message.id,
@@ -461,20 +606,31 @@ async function externalizeLegacyPayloads(database: DatabaseSync, databasePath: s
   ).all() as Array<{ thread_id: string; branch_id: string; ordinal: number; payload_json: string }>
   const preparedMessages: Array<typeof messageRows[number] & { nextJson: string; blobs: BlobDescriptor[] }> = []
   const preparedBranches: Array<typeof branchRows[number] & { nextJson: string; blobs: BlobDescriptor[] }> = []
+  const createdHashes = new Set<string>()
 
-  for (const row of messageRows) {
-    const blobs: BlobDescriptor[] = []
-    const nextJson = JSON.stringify(await externalizeValue(JSON.parse(row.payload_json), databasePath, blobs))
-    if (blobs.length > 0) preparedMessages.push({ ...row, nextJson, blobs })
-  }
-  for (const row of branchRows) {
-    const blobs: BlobDescriptor[] = []
-    const nextJson = JSON.stringify(await externalizeValue(JSON.parse(row.payload_json), databasePath, blobs))
-    if (blobs.length > 0) preparedBranches.push({ ...row, nextJson, blobs })
+  try {
+    for (const row of messageRows) {
+      const blobs: BlobDescriptor[] = []
+      const nextJson = JSON.stringify(await externalizeValue(
+        JSON.parse(row.payload_json), databasePath, blobs, createdHashes,
+      ))
+      if (blobs.length > 0) preparedMessages.push({ ...row, nextJson, blobs })
+    }
+    for (const row of branchRows) {
+      const blobs: BlobDescriptor[] = []
+      const nextJson = JSON.stringify(await externalizeValue(
+        JSON.parse(row.payload_json), databasePath, blobs, createdHashes,
+      ))
+      if (blobs.length > 0) preparedBranches.push({ ...row, nextJson, blobs })
+    }
+  } catch (error) {
+    await removeUnreferencedCreatedBlobs(database, databasePath, createdHashes)
+    throw error
   }
 
   database.exec('BEGIN IMMEDIATE')
   try {
+    const blobStatements = createBlobStatements(database)
     const updateMessage = database.prepare(
       'UPDATE messages SET payload_json = ? WHERE thread_id = ? AND ordinal = ?',
     )
@@ -482,18 +638,24 @@ async function externalizeLegacyPayloads(database: DatabaseSync, databasePath: s
       'UPDATE branch_messages SET payload_json = ? WHERE thread_id = ? AND branch_id = ? AND ordinal = ?',
     )
     for (const row of preparedMessages) {
-      incrementBlobRefs(database, row.blobs)
       updateMessage.run(row.nextJson, row.thread_id, row.ordinal)
+      insertBlobReferences(blobStatements, {
+        type: 'message', threadId: row.thread_id, ordinal: row.ordinal,
+      }, row.blobs)
     }
     for (const row of preparedBranches) {
-      incrementBlobRefs(database, row.blobs)
       updateBranch.run(row.nextJson, row.thread_id, row.branch_id, row.ordinal)
+      insertBlobReferences(blobStatements, {
+        type: 'branchMessage', threadId: row.thread_id,
+        branchId: row.branch_id, ordinal: row.ordinal,
+      }, row.blobs)
     }
     database.prepare('INSERT INTO migration_log(name, completed_at) VALUES (?, ?)')
       .run(migrationName, Date.now())
     database.exec('COMMIT')
   } catch (error) {
     database.exec('ROLLBACK')
+    await removeUnreferencedCreatedBlobs(database, databasePath, createdHashes)
     throw error
   }
   return true
@@ -527,53 +689,126 @@ function blobReferences(payloadJson: string): BlobReference[] {
   return found
 }
 
-function incrementBlobRefs(database: DatabaseSync, blobs: BlobDescriptor[]): void {
-  const statement = database.prepare(`
-    INSERT INTO blobs(hash, encoding, byte_length, ref_count, created_at)
-    VALUES (?, ?, ?, 1, ?)
-    ON CONFLICT(hash) DO UPDATE SET ref_count = ref_count + 1
-  `)
-  for (const blob of blobs) statement.run(blob.hash, blob.encoding, blob.byteLength, Date.now())
-}
-
-function decrementRowsBlobRefs(database: DatabaseSync, rows: Array<{ payload_json: string }>): void {
-  const decrement = database.prepare(`
-    UPDATE blobs SET ref_count = ref_count - 1 WHERE hash = ? AND ref_count > 0
-  `)
-  for (const row of rows) {
-    for (const reference of blobReferences(row.payload_json)) decrement.run(reference.hash)
+function createBlobStatements(database: DatabaseSync) {
+  return {
+    insertBlob: database.prepare(`
+      INSERT OR IGNORE INTO blobs(hash, encoding, byte_length, created_at)
+      VALUES (?, ?, ?, ?)
+    `),
+    insertMessageBlob: database.prepare(`
+      INSERT OR IGNORE INTO message_blobs(thread_id, ordinal, hash) VALUES (?, ?, ?)
+    `),
+    insertBranchMessageBlob: database.prepare(`
+      INSERT OR IGNORE INTO branch_message_blobs(thread_id, branch_id, ordinal, hash)
+      VALUES (?, ?, ?, ?)
+    `),
   }
 }
 
-async function collectGarbageBlobs(database: DatabaseSync, databasePath: string): Promise<void> {
+type BlobOwner =
+  | { type: 'message'; threadId: string; ordinal: number }
+  | { type: 'branchMessage'; threadId: string; branchId: string; ordinal: number }
+
+function insertBlobReferences(
+  statements: ReturnType<typeof createBlobStatements>,
+  owner: BlobOwner,
+  blobs: BlobDescriptor[],
+): void {
+  const inserted = new Set<string>()
+  for (const blob of blobs) {
+    if (inserted.has(blob.hash)) continue
+    inserted.add(blob.hash)
+    statements.insertBlob.run(blob.hash, blob.encoding, blob.byteLength, Date.now())
+    if (owner.type === 'message') {
+      statements.insertMessageBlob.run(owner.threadId, owner.ordinal, blob.hash)
+    } else {
+      statements.insertBranchMessageBlob.run(
+        owner.threadId, owner.branchId, owner.ordinal, blob.hash,
+      )
+    }
+  }
+}
+
+async function removeUnreferencedCreatedBlobs(
+  database: DatabaseSync,
+  databasePath: string,
+  createdHashes: Set<string>,
+): Promise<void> {
+  if (createdHashes.size === 0) return
+  const isTracked = database.prepare('SELECT 1 FROM blobs WHERE hash = ?')
+  await Promise.all([...createdHashes].map(async hash => {
+    if (isTracked.get(hash)) return
+    await fs.rm(blobPath(databasePath, hash), { force: true }).catch(() => undefined)
+  }))
+}
+
+function readBackupBlobHashes(backup: DatabaseSync): Set<string> {
+  const hashes = new Set<string>()
+  if (tableExists(backup, 'message_blobs') && tableExists(backup, 'branch_message_blobs')) {
+    const rows = backup.prepare(`
+      SELECT hash FROM message_blobs
+      UNION
+      SELECT hash FROM branch_message_blobs
+    `).all() as Array<{ hash: string }>
+    for (const row of rows) hashes.add(row.hash)
+    return hashes
+  }
+
+  // A pre-v5 recovery snapshot can survive the first application upgrade.
+  // Parse it once per worker lifetime, then the next snapshot rotation removes
+  // this compatibility path from the hot commit loop.
+  for (const table of ['messages', 'branch_messages'] as const) {
+    if (!tableExists(backup, table)) continue
+    const rows = backup.prepare(`SELECT payload_json FROM ${table}`).all() as Array<{ payload_json: string }>
+    for (const row of rows) {
+      for (const reference of blobReferences(row.payload_json)) hashes.add(reference.hash)
+    }
+  }
+  return hashes
+}
+
+async function protectedBackupBlobHashes(opened: OpenDatabase): Promise<Set<string> | null> {
+  if (opened.protectedBackupBlobHashes) return opened.protectedBackupBlobHashes
   const protectedHashes = new Set<string>()
-  for (const backupPath of [`${databasePath}.bak`, `${databasePath}.bak.previous`]) {
+  for (const backupPath of [`${opened.path}.bak`, `${opened.path}.bak.previous`]) {
     if (!await fileExists(backupPath)) continue
     let backup: DatabaseSync | undefined
     try {
       backup = new DatabaseSync(backupPath, { readOnly: true })
       assertHealthy(backup)
-      for (const table of ['messages', 'branch_messages'] as const) {
-        if (!tableExists(backup, table)) continue
-        const rows = backup.prepare(`SELECT payload_json FROM ${table}`).all() as Array<{ payload_json: string }>
-        for (const row of rows) for (const reference of blobReferences(row.payload_json)) {
-          protectedHashes.add(reference.hash)
-        }
-      }
+      for (const hash of readBackupBlobHashes(backup)) protectedHashes.add(hash)
     } catch {
       // Fail closed: an unreadable snapshot must never cause companion data loss.
-      return
+      return null
     } finally {
       backup?.close()
     }
   }
+  opened.protectedBackupBlobHashes = protectedHashes
+  return protectedHashes
+}
 
-  const rows = database.prepare('SELECT hash FROM blobs WHERE ref_count = 0').all() as Array<{ hash: string }>
-  const removeRow = database.prepare('DELETE FROM blobs WHERE hash = ? AND ref_count = 0')
+async function collectGarbageBlobs(opened: OpenDatabase): Promise<void> {
+  const rows = opened.database.prepare(`
+    SELECT b.hash
+    FROM blobs b
+    WHERE NOT EXISTS (SELECT 1 FROM message_blobs m WHERE m.hash = b.hash)
+      AND NOT EXISTS (SELECT 1 FROM branch_message_blobs bm WHERE bm.hash = b.hash)
+  `).all() as Array<{ hash: string }>
+  if (rows.length === 0) return
+
+  const protectedHashes = await protectedBackupBlobHashes(opened)
+  if (!protectedHashes) return
+  const removeRow = opened.database.prepare(`
+    DELETE FROM blobs
+    WHERE hash = ?
+      AND NOT EXISTS (SELECT 1 FROM message_blobs m WHERE m.hash = blobs.hash)
+      AND NOT EXISTS (SELECT 1 FROM branch_message_blobs bm WHERE bm.hash = blobs.hash)
+  `)
   for (const row of rows) {
     if (protectedHashes.has(row.hash)) continue
     try {
-      await fs.rm(blobPath(databasePath, row.hash), { force: true })
+      await fs.rm(blobPath(opened.path, row.hash), { force: true })
       removeRow.run(row.hash)
     } catch { /* retry during the next maintenance cycle */ }
   }
@@ -597,7 +832,7 @@ function readState(database: DatabaseSync): SessionStateRecord {
 function readThreads(database: DatabaseSync): SessionThreadMetadata[] {
   const rows = database.prepare(`
     SELECT id, created_at, last_modified, title, message_count, metadata_json
-    FROM threads ORDER BY last_modified DESC
+    FROM threads ORDER BY last_modified DESC, id ASC
   `).all() as Array<{
     id: string
     created_at: number
@@ -664,16 +899,21 @@ async function readBranchMessages(
   const branches = database.prepare(
     'SELECT branch_id FROM branches WHERE thread_id = ? ORDER BY ordinal',
   ).all(threadId) as Array<{ branch_id: string }>
-  return Promise.all(branches.map(async branch => {
-    const rows = database.prepare(`
-      SELECT payload_json FROM branch_messages
-      WHERE thread_id = ? AND branch_id = ? ORDER BY ordinal
-    `).all(threadId, branch.branch_id) as Array<{ payload_json: string }>
-    return {
-      id: branch.branch_id,
-      messages: await Promise.all(rows.map(row => hydrateValue(JSON.parse(row.payload_json), databasePath))),
-    }
-  }))
+  const rows = database.prepare(`
+    SELECT branch_id, payload_json FROM branch_messages
+    WHERE thread_id = ? ORDER BY branch_id, ordinal
+  `).all(threadId) as Array<{ branch_id: string; payload_json: string }>
+  const payloadsByBranch = new Map<string, string[]>()
+  for (const row of rows) {
+    const payloads = payloadsByBranch.get(row.branch_id) || []
+    if (!payloadsByBranch.has(row.branch_id)) payloadsByBranch.set(row.branch_id, payloads)
+    payloads.push(row.payload_json)
+  }
+  return Promise.all(branches.map(async branch => ({
+    id: branch.branch_id,
+    messages: await Promise.all((payloadsByBranch.get(branch.branch_id) || [])
+      .map(payload => hydrateValue(JSON.parse(payload), databasePath))),
+  })))
 }
 
 function upsertThread(database: DatabaseSync, thread: SessionThreadMetadata): void {
@@ -707,6 +947,7 @@ function insertMessages(
     throw new Error('branchId is required for branch messages')
   }
   const messageBranchId = branchId ?? ''
+  const blobStatements = createBlobStatements(database)
   const insert = table === 'messages'
     ? database.prepare(`
         INSERT INTO messages(thread_id, ordinal, message_id, role, timestamp, payload_json)
@@ -718,51 +959,56 @@ function insertMessages(
         ) VALUES (?, ?, ?, ?, ?, ?, ?)
       `)
   for (const message of messages) {
-    incrementBlobRefs(database, message.blobs)
     if (table === 'messages') {
       insert.run(threadId, message.ordinal, message.id, message.role, message.timestamp, message.payloadJson)
+      insertBlobReferences(blobStatements, {
+        type: 'message', threadId, ordinal: message.ordinal,
+      }, message.blobs)
     } else {
       insert.run(threadId, messageBranchId, message.ordinal, message.id, message.role, message.timestamp, message.payloadJson)
+      insertBlobReferences(blobStatements, {
+        type: 'branchMessage', threadId, branchId: messageBranchId, ordinal: message.ordinal,
+      }, message.blobs)
     }
   }
 }
 
-function deleteThreadBlobRefs(database: DatabaseSync, threadId: string): void {
-  const rows = [
-    ...database.prepare('SELECT payload_json FROM messages WHERE thread_id = ?').all(threadId),
-    ...database.prepare('SELECT payload_json FROM branch_messages WHERE thread_id = ?').all(threadId),
-  ] as Array<{ payload_json: string }>
-  decrementRowsBlobRefs(database, rows)
-}
-
-async function applyPatch(database: DatabaseSync, databasePath: string, patch: SessionPatch): Promise<void> {
-  const preparedThreads = await Promise.all(patch.threads.map(async thread => ({
-    ...thread,
-    messages: await Promise.all((thread.messages || []).map(message => prepareMessage(databasePath, message))),
-  })))
-  const preparedBranchThreads = await Promise.all(patch.branchThreads.map(async entry => ({
-    threadId: entry.threadId,
-    branches: await Promise.all(entry.branches.map(async branch => ({
-      ...branch,
-      messages: await Promise.all(branch.messages.map(message => prepareMessage(databasePath, message))),
-    } satisfies PreparedBranch))),
-  })))
+async function applyPatch(opened: OpenDatabase, patch: SessionPatch): Promise<void> {
+  const { database, path: databasePath } = opened
+  const createdHashes = new Set<string>()
+  let preparedThreads: Array<Omit<SessionPatch['threads'][number], 'messages'> & {
+    messages: PreparedMessage[]
+  }>
+  let preparedBranchThreads: Array<{ threadId: string; branches: PreparedBranch[] }>
+  try {
+    preparedThreads = await Promise.all(patch.threads.map(async thread => ({
+      ...thread,
+      messages: await Promise.all((thread.messages || [])
+        .map(message => prepareMessage(databasePath, message, createdHashes))),
+    })))
+    preparedBranchThreads = await Promise.all(patch.branchThreads.map(async entry => ({
+      threadId: entry.threadId,
+      branches: await Promise.all(entry.branches.map(async branch => ({
+        ...branch,
+        messages: await Promise.all(branch.messages
+          .map(message => prepareMessage(databasePath, message, createdHashes))),
+      } satisfies PreparedBranch))),
+    })))
+  } catch (error) {
+    await removeUnreferencedCreatedBlobs(database, databasePath, createdHashes)
+    throw error
+  }
 
   database.exec('BEGIN IMMEDIATE')
   try {
     const deleteThread = database.prepare('DELETE FROM threads WHERE id = ?')
     for (const threadId of patch.deletedThreadIds) {
-      deleteThreadBlobRefs(database, threadId)
       deleteThread.run(threadId)
     }
 
     for (const threadPatch of preparedThreads) {
       upsertThread(database, threadPatch.metadata)
       if (threadPatch.replaceFrom !== undefined) {
-        const oldRows = database.prepare(`
-          SELECT payload_json FROM messages WHERE thread_id = ? AND ordinal >= ?
-        `).all(threadPatch.metadata.id, threadPatch.replaceFrom) as Array<{ payload_json: string }>
-        decrementRowsBlobRefs(database, oldRows)
         database.prepare('DELETE FROM messages WHERE thread_id = ? AND ordinal >= ?')
           .run(threadPatch.metadata.id, threadPatch.replaceFrom)
         insertMessages(database, 'messages', threadPatch.metadata.id, threadPatch.messages)
@@ -777,10 +1023,6 @@ async function applyPatch(database: DatabaseSync, databasePath: string, patch: S
       ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
     `)
     for (const entry of preparedBranchThreads) {
-      const oldRows = database.prepare(
-        'SELECT payload_json FROM branch_messages WHERE thread_id = ?',
-      ).all(entry.threadId) as Array<{ payload_json: string }>
-      decrementRowsBlobRefs(database, oldRows)
       deleteBranches.run(entry.threadId)
       for (const branch of entry.branches) {
         insertBranch.run(
@@ -807,9 +1049,12 @@ async function applyPatch(database: DatabaseSync, databasePath: string, patch: S
     database.exec('COMMIT')
   } catch (error) {
     database.exec('ROLLBACK')
+    await removeUnreferencedCreatedBlobs(database, databasePath, createdHashes)
     throw error
   }
-  await collectGarbageBlobs(database, databasePath)
+  const mayHaveOrphanedBlobs = patch.deletedThreadIds.length > 0 ||
+    patch.branchThreads.length > 0 || patch.threads.some(thread => thread.replaceFrom !== undefined)
+  if (mayHaveOrphanedBlobs) await collectGarbageBlobs(opened)
 }
 
 async function importLegacy(database: DatabaseSync, databasePath: string, sessionsDir: string): Promise<boolean> {
@@ -928,7 +1173,9 @@ async function importLegacy(database: DatabaseSync, databasePath: string, sessio
     }]
   })
 
-  await applyPatch(database, databasePath, { state, threads, deletedThreadIds: [], branchThreads })
+  const opened = databases.get(databasePath)
+  if (!opened) throw new Error('Session database is not registered')
+  await applyPatch(opened, { state, threads, deletedThreadIds: [], branchThreads })
   markComplete()
   return true
 }
@@ -1020,7 +1267,18 @@ function scheduleCheckpoint(opened: OpenDatabase): void {
     opened.idleCheckpoint = null
     try {
       checkpoint(opened, false)
-      opened.database.exec('PRAGMA incremental_vacuum(256); PRAGMA optimize;')
+      const pageCount = Number(
+        (opened.database.prepare('PRAGMA page_count').get() as { page_count: number }).page_count,
+      )
+      const freePages = Number(
+        (opened.database.prepare('PRAGMA freelist_count').get() as { freelist_count: number }).freelist_count,
+      )
+      // Reclaim only meaningful fragmentation. Running incremental_vacuum on
+      // every quiet period creates needless SSD writes for normal append-only use.
+      if (freePages >= 1024 && freePages / Math.max(1, pageCount) >= 0.2) {
+        opened.database.exec(`PRAGMA incremental_vacuum(${Math.min(256, freePages)})`)
+      }
+      opened.database.exec('PRAGMA optimize')
     } catch { /* retry on next idle/close */ }
   }, delay)
 }
@@ -1028,6 +1286,11 @@ function scheduleCheckpoint(opened: OpenDatabase): void {
 async function closeAll(): Promise<void> {
   for (const opened of databases.values()) {
     if (opened.idleCheckpoint) clearTimeout(opened.idleCheckpoint)
+    try {
+      opened.database.prepare(
+        'UPDATE maintenance_state SET clean_shutdown = 1 WHERE singleton = 1',
+      ).run()
+    } catch { /* an older failed migration remains recoverable */ }
     try { checkpoint(opened, true) } catch { /* WAL remains recoverable */ }
     opened.database.close()
     try {
@@ -1072,18 +1335,7 @@ async function clearDatabase(opened: OpenDatabase): Promise<void> {
   await fs.rm(`${opened.path}.bak`, { force: true })
   await fs.rm(`${opened.path}.bak.previous`, { force: true })
   await fs.rm(blobDirectory(opened.path), { recursive: true, force: true })
-}
-
-async function directoryBytes(directory: string): Promise<number> {
-  let total = 0
-  let entries
-  try { entries = await fs.readdir(directory, { withFileTypes: true }) } catch { return 0 }
-  for (const entry of entries) {
-    const target = path.join(directory, entry.name)
-    if (entry.isDirectory()) total += await directoryBytes(target)
-    else if (entry.isFile()) total += await fs.stat(target).then(stat => stat.size).catch(() => 0)
-  }
-  return total
+  opened.protectedBackupBlobHashes = new Set()
 }
 
 async function readStats(database: DatabaseSync, databasePath: string): Promise<SessionStorageStats> {
@@ -1096,11 +1348,11 @@ async function readStats(database: DatabaseSync, databasePath: string): Promise<
   return {
     databaseBytes: await fileBytes(databasePath),
     walBytes: await fileBytes(`${databasePath}-wal`),
-    blobBytes: await directoryBytes(blobDirectory(databasePath)),
+    blobBytes: scalar('SELECT COALESCE(SUM(byte_length), 0) AS value FROM blobs', 'value'),
     threadCount: scalar('SELECT COUNT(*) AS value FROM threads', 'value'),
     messageCount: scalar('SELECT COUNT(*) AS value FROM messages', 'value'),
     branchCount: scalar('SELECT COUNT(*) AS value FROM branches', 'value'),
-    blobCount: scalar('SELECT COUNT(*) AS value FROM blobs WHERE ref_count > 0', 'value'),
+    blobCount: scalar('SELECT COUNT(*) AS value FROM blobs', 'value'),
     planCount: scalar('SELECT COUNT(*) AS value FROM plans', 'value'),
     pageSize: scalar('PRAGMA page_size', 'page_size'),
     freePages: scalar('PRAGMA freelist_count', 'freelist_count'),
@@ -1149,7 +1401,7 @@ export async function executeSessionStorageOperation(
       scheduleCheckpoint(opened)
       return { type: 'ok' }
     case 'applyPatch':
-      await applyPatch(opened.database, opened.path, operation.patch)
+      await applyPatch(opened, operation.patch)
       scheduleCheckpoint(opened)
       return { type: 'ok' }
     case 'clear':
@@ -1162,7 +1414,9 @@ export async function executeSessionStorageOperation(
   }
 }
 
-parentPort?.on('message', async (request: SessionWorkerRequest) => {
+const operationQueues = new Map<string, Promise<void>>()
+
+async function respond(request: SessionWorkerRequest): Promise<void> {
   let response: SessionWorkerResponse
   try {
     response = {
@@ -1178,4 +1432,20 @@ parentPort?.on('message', async (request: SessionWorkerRequest) => {
     }
   }
   parentPort?.postMessage(response)
+}
+
+parentPort?.on('message', (request: SessionWorkerRequest) => {
+  if (request.operation.type === 'closeAll') {
+    const pending = [...operationQueues.values()]
+    void Promise.allSettled(pending).then(() => respond(request))
+    return
+  }
+
+  const databasePath = request.operation.databasePath
+  const previous = operationQueues.get(databasePath) || Promise.resolve()
+  const next = previous.catch(() => undefined).then(() => respond(request))
+  operationQueues.set(databasePath, next)
+  void next.finally(() => {
+    if (operationQueues.get(databasePath) === next) operationQueues.delete(databasePath)
+  })
 })
diff --git a/tests/main/indexing/bm25.test.ts b/tests/main/indexing/bm25.test.ts
index 0501505d..5b09af6b 100644
--- a/tests/main/indexing/bm25.test.ts
+++ b/tests/main/indexing/bm25.test.ts
@@ -17,11 +17,10 @@ function doc(id: string, relativePath: string, content: string, symbols: string[
 }
 
 describe('BM25Index', () => {
-  it('returns nothing before build and finds matches after', () => {
+  it('is searchable immediately after documents are added', () => {
     const idx = new BM25Index()
     idx.addDocument(doc('a', 'a.ts', 'authentication token refresh handler'))
     idx.addDocument(doc('b', 'b.ts', 'unrelated rendering pipeline code'))
-    idx.build()
 
     const results = idx.search('authentication token')
     expect(results.length).toBeGreaterThan(0)
@@ -32,7 +31,6 @@ describe('BM25Index', () => {
     const idx = new BM25Index()
     idx.addDocument(doc('a', 'a.ts', 'cache invalidation cache eviction cache policy'))
     idx.addDocument(doc('b', 'b.ts', 'cache mentioned once here'))
-    idx.build()
 
     const results = idx.search('cache')
     expect(results[0].relativePath).toBe('a.ts')
@@ -42,7 +40,6 @@ describe('BM25Index', () => {
     const idx = new BM25Index()
     idx.addDocument(doc('a', 'a.ts', 'shared body text alpha', ['parseWorkspace']))
     idx.addDocument(doc('b', 'b.ts', 'shared body text alpha', []))
-    idx.build()
 
     const results = idx.search('parseworkspace')
     expect(results[0].relativePath).toBe('a.ts')
@@ -53,10 +50,8 @@ describe('BM25Index', () => {
     idx.addDocument(doc('a1', 'a.ts', 'authentication token part one'))
     idx.addDocument(doc('a2', 'a.ts', 'authentication token part two'))
     idx.addDocument(doc('b1', 'b.ts', 'unrelated rendering pipeline'))
-    idx.build()
 
     idx.deleteFile('a.ts')
-    idx.build()
 
     expect(idx.size).toBe(1)
     expect(idx.search('authentication token')).toHaveLength(0)
@@ -66,11 +61,9 @@ describe('BM25Index', () => {
     const idx = new BM25Index()
     idx.addDocument(doc('a', 'a.ts', 'zzuniqueterm appears only here'))
     idx.addDocument(doc('b', 'b.ts', 'unrelated rendering pipeline'))
-    idx.build()
     const vocabularyBefore = idx.vocabularySize
 
     idx.deleteFile('a.ts')
-    idx.build()
 
     // 该词已随文件移除，不应残留 IDF 条目（否则评分失真且内存无界增长）
     expect(idx.vocabularySize).toBeLessThan(vocabularyBefore)
@@ -82,14 +75,12 @@ describe('BM25Index', () => {
     for (let i = 0; i < 5; i++) {
       idx.addDocument(doc(`f${i}`, `f${i}.ts`, 'common filler text'))
     }
-    idx.build()
     const rareScoreBefore = idx.search('rare')[0].score
 
     // 让 "rare" 变成常见词，IDF 应当下降
     for (let i = 0; i < 5; i++) {
       idx.addDocument(doc(`g${i}`, `g${i}.ts`, 'rare term everywhere now'))
     }
-    idx.build()
     const rareScoreAfter = idx.search('rare')[0].score
 
     expect(rareScoreAfter).toBeLessThan(rareScoreBefore)
@@ -97,7 +88,6 @@ describe('BM25Index', () => {
 
   it('handles an empty index without throwing', () => {
     const idx = new BM25Index()
-    idx.build()
     expect(idx.search('anything')).toEqual([])
     expect(idx.size).toBe(0)
   })
@@ -105,7 +95,6 @@ describe('BM25Index', () => {
   it('clears all state', () => {
     const idx = new BM25Index()
     idx.addDocument(doc('a', 'a.ts', 'authentication token refresh'))
-    idx.build()
     idx.clear()
 
     expect(idx.size).toBe(0)
diff --git a/tests/main/indexing/indexServiceScheduling.test.ts b/tests/main/indexing/indexServiceScheduling.test.ts
index eabe6aa9..8326eb4e 100644
--- a/tests/main/indexing/indexServiceScheduling.test.ts
+++ b/tests/main/indexing/indexServiceScheduling.test.ts
@@ -36,12 +36,6 @@ vi.mock('worker_threads', () => ({
   },
 }))
 
-vi.mock('@main/indexing/treeSitterChunker', () => ({
-  TreeSitterChunker: class {
-    init = vi.fn(async () => {})
-  },
-}))
-
 vi.mock('@main/indexing/vectorStore', () => ({
   VectorStoreService: class {},
 }))
@@ -114,6 +108,7 @@ describe('CodebaseIndexService scheduling', () => {
     internals.performWorkspaceIndex = vi.fn(async () => {
       order.push('index:start')
       await fullIndex.promise
+      ;(service as unknown as { status: { lastIndexedAt?: number } }).status.lastIndexedAt = 1
       order.push('index:end')
     })
     internals.performUpdateFiles = vi.fn(async paths => {
@@ -222,6 +217,57 @@ describe('CodebaseIndexService scheduling', () => {
     await expect(service.search('cachedNeedle')).resolves.toHaveLength(1)
   })
 
+  it('processes structural watcher updates through the worker and persists them', async () => {
+    structuralStoreState.metadata = { totalFiles: 1, totalChunks: 0, savedAt: 123 }
+    await service.initialize()
+    const updating = service.updateFiles(['C:/workspace/src/updated.ts'])
+    await vi.waitFor(() => expect(workerState.instances).toHaveLength(1))
+    const worker = workerState.instances[0]
+    expect(worker.postMessage).toHaveBeenCalledWith(expect.objectContaining({
+      type: 'batch_update',
+      files: ['C:/workspace/src/updated.ts'],
+      config: expect.objectContaining({ mode: 'structural' }),
+    }))
+
+    worker.emit('message', {
+      type: 'batch_update_result',
+      mode: 'structural',
+      requestId: 1,
+      results: [{
+        filePath: 'C:/workspace/src/updated.ts',
+        deleted: false,
+        chunks: [{
+          id: 'updated-chunk',
+          filePath: 'C:/workspace/src/updated.ts',
+          relativePath: 'src/updated.ts',
+          fileHash: 'hash',
+          content: 'function updatedNeedle() {}',
+          startLine: 1,
+          endLine: 1,
+          type: 'function',
+          language: 'typescript',
+          symbols: ['updatedNeedle'],
+        }],
+      }],
+    })
+
+    await updating
+    expect(service.searchSymbols('updatedNeedle')).toHaveLength(1)
+    await expect(service.search('updatedNeedle')).resolves.toHaveLength(1)
+    expect(structuralStoreState.operations.at(-1)).toMatchObject({
+      type: 'applyFiles',
+      files: [{ relativePath: 'src\\updated.ts' }],
+    })
+  })
+
+  it('does not create a partial index from watcher events before indexing is enabled', async () => {
+    await service.updateFiles(['C:/workspace/src/updated.ts'])
+    await service.deleteFileIndex('C:/workspace/src/deleted.ts')
+
+    expect(workerState.instances).toHaveLength(0)
+    expect(structuralStoreState.operations).toHaveLength(0)
+  })
+
   it('finishes an active index with an error when the worker exits unexpectedly', async () => {
     const internals = service as unknown as { saveIndex(): Promise<void> }
     internals.saveIndex = vi.fn(async () => {})
diff --git a/tests/main/indexing/structuralIndexStore.test.ts b/tests/main/indexing/structuralIndexStore.test.ts
index 18f9670a..b50286e8 100644
--- a/tests/main/indexing/structuralIndexStore.test.ts
+++ b/tests/main/indexing/structuralIndexStore.test.ts
@@ -2,6 +2,7 @@ import { afterEach, beforeEach, describe, expect, it } from 'vitest'
 import { mkdtemp, rm } from 'fs/promises'
 import { tmpdir } from 'os'
 import * as path from 'path'
+import { DatabaseSync } from 'node:sqlite'
 import { executeStructuralIndexStoreOperation } from '@main/indexing/structuralIndexStore.worker'
 import type { CodeChunk } from '@main/indexing/types'
 
@@ -57,7 +58,7 @@ describe('structural index SQLite store', () => {
   }
 
   it('streams a committed generation in bounded batches', () => {
-    const chunks = Array.from({ length: 125 }, (_, index) => chunk(`chunk-${index}`, `src/${index}.ts`))
+    const chunks = Array.from({ length: 1025 }, (_, index) => chunk(`chunk-${index}`, `src/${index}.ts`))
     executeStructuralIndexStoreOperation({ type: 'beginReplace', databasePath, generation: 'one' })
     executeStructuralIndexStoreOperation({
       type: 'appendReplace', databasePath, generation: 'one', chunks,
@@ -66,13 +67,13 @@ describe('structural index SQLite store', () => {
       type: 'commitReplace',
       databasePath,
       generation: 'one',
-      metadata: { totalFiles: 125, totalChunks: 125, savedAt: 10 },
+      metadata: { totalFiles: 1025, totalChunks: 1025, savedAt: 10 },
     })
 
     const loaded = load()
-    expect(loaded.chunks).toHaveLength(125)
-    expect(loaded.metadata).toEqual({ totalFiles: 125, totalChunks: 125, savedAt: 10 })
-    expect(loaded.batchSizes).toEqual([50, 50, 25])
+    expect(loaded.chunks).toHaveLength(1025)
+    expect(loaded.metadata).toEqual({ totalFiles: 1025, totalChunks: 1025, savedAt: 10 })
+    expect(loaded.batchSizes).toEqual([512, 512, 1])
   })
 
   it('keeps the previous generation when a replacement is incomplete', () => {
@@ -131,4 +132,48 @@ describe('structural index SQLite store', () => {
     expect(loaded.chunks.map(item => item.id)).toEqual(['a2'])
     expect(loaded.metadata).toEqual({ totalFiles: 2, totalChunks: 1, savedAt: 20 })
   })
+
+  it('stores file metadata once and uses the tuned database layout', () => {
+    executeStructuralIndexStoreOperation({ type: 'beginReplace', databasePath, generation: 'layout' })
+    executeStructuralIndexStoreOperation({
+      type: 'appendReplace',
+      databasePath,
+      generation: 'layout',
+      chunks: [
+        chunk('part-1', 'shared.ts'),
+        { ...chunk('part-2', 'shared.ts'), startLine: 2, endLine: 2 },
+      ],
+    })
+    executeStructuralIndexStoreOperation({
+      type: 'commitReplace',
+      databasePath,
+      generation: 'layout',
+      metadata: { totalFiles: 1, totalChunks: 2, savedAt: 10 },
+    })
+
+    const database = new DatabaseSync(databasePath, { readOnly: true })
+    try {
+      const fileCount = database.prepare('SELECT COUNT(*) AS count FROM files').get() as { count: number }
+      const chunkCount = database.prepare('SELECT COUNT(*) AS count FROM chunks').get() as { count: number }
+      const columns = database.prepare("PRAGMA table_info('chunks')").all() as Array<{ name: string }>
+      const pageSize = database.prepare('PRAGMA page_size').get() as { page_size: number }
+      const journalMode = database.prepare('PRAGMA journal_mode').get() as { journal_mode: string }
+      const pagePlan = database.prepare(`
+        EXPLAIN QUERY PLAN
+        SELECT * FROM chunks
+        WHERE generation = ? AND (relative_path, id) > (?, ?)
+        ORDER BY relative_path, id LIMIT ?
+      `).all('generation-layout', '', '', 512) as Array<{ detail: string }>
+
+      expect(Number(fileCount.count)).toBe(1)
+      expect(Number(chunkCount.count)).toBe(2)
+      expect(columns.map(column => column.name)).not.toContain('payload_json')
+      expect(Number(pageSize.page_size)).toBe(8192)
+      expect(journalMode.journal_mode).toBe('wal')
+      expect(pagePlan.map(row => row.detail).join('\n'))
+        .toContain('PRIMARY KEY (generation=? AND (relative_path,id)>(?,?))')
+    } finally {
+      database.close()
+    }
+  })
 })
diff --git a/tests/services/sessionSqliteStore.test.ts b/tests/services/sessionSqliteStore.test.ts
index 76988e68..bd25b713 100644
--- a/tests/services/sessionSqliteStore.test.ts
+++ b/tests/services/sessionSqliteStore.test.ts
@@ -1,7 +1,8 @@
 import { afterEach, describe, expect, it } from 'vitest'
-import { mkdtemp, mkdir, readdir, rm, writeFile } from 'fs/promises'
+import { access, mkdtemp, mkdir, readdir, rm, writeFile } from 'fs/promises'
 import { tmpdir } from 'os'
 import { join } from 'path'
+import { createHash } from 'crypto'
 import { DatabaseSync } from 'node:sqlite'
 import { executeSessionStorageOperation } from '@/main/services/session/sessionStorage.worker'
 import type { SessionPatch } from '@/shared/types/sessionPersistence'
@@ -38,6 +39,34 @@ afterEach(async () => {
 })
 
 describe('SQLite session store', () => {
+  it('records clean shutdowns and reuses a recent integrity check', async () => {
+    const { databasePath } = await temporaryDatabase()
+    await executeSessionStorageOperation({ type: 'open', databasePath })
+    let database = new DatabaseSync(databasePath, { readOnly: true })
+    const opened = database.prepare(`
+      SELECT last_quick_check_at, clean_shutdown FROM maintenance_state WHERE singleton = 1
+    `).get() as { last_quick_check_at: number; clean_shutdown: number }
+    expect(opened.last_quick_check_at).toBeGreaterThan(0)
+    expect(opened.clean_shutdown).toBe(0)
+    database.close()
+
+    await executeSessionStorageOperation({ type: 'closeAll' })
+    database = new DatabaseSync(databasePath, { readOnly: true })
+    expect((database.prepare(`
+      SELECT clean_shutdown FROM maintenance_state WHERE singleton = 1
+    `).get() as { clean_shutdown: number }).clean_shutdown).toBe(1)
+    database.close()
+
+    await executeSessionStorageOperation({ type: 'open', databasePath })
+    database = new DatabaseSync(databasePath, { readOnly: true })
+    const reopened = database.prepare(`
+      SELECT last_quick_check_at, clean_shutdown FROM maintenance_state WHERE singleton = 1
+    `).get() as { last_quick_check_at: number; clean_shutdown: number }
+    expect(reopened.last_quick_check_at).toBe(opened.last_quick_check_at)
+    expect(reopened.clean_shutdown).toBe(0)
+    database.close()
+  })
+
   it('replaces only a changed message tail', async () => {
     const { databasePath } = await temporaryDatabase()
     await executeSessionStorageOperation({ type: 'open', databasePath })
@@ -88,6 +117,28 @@ describe('SQLite session store', () => {
     expect(result.type === 'messages' ? result.messages : []).toHaveLength(2)
   })
 
+  it('removes only newly-created blob files when a database transaction rolls back', async () => {
+    const { databasePath } = await temporaryDatabase()
+    await executeSessionStorageOperation({ type: 'open', databasePath })
+    const content = 'rollback-blob-'.repeat(24_000)
+    const broken = initialPatch()
+    broken.threads[0].metadata.messageCount = 2
+    broken.threads[0].messages = [0, 1].map(index => ({
+      ordinal: 0,
+      id: `duplicate-${index}`,
+      role: 'assistant',
+      timestamp: index,
+      payload: { id: `duplicate-${index}`, content },
+    }))
+
+    await expect(executeSessionStorageOperation({
+      type: 'applyPatch', databasePath, patch: broken,
+    })).rejects.toThrow()
+
+    const hash = createHash('sha256').update(Buffer.from(content, 'utf8')).digest('hex')
+    await expect(access(join(`${databasePath}.blobs`, hash.slice(0, 2), hash))).rejects.toThrow()
+  })
+
   it('stores branch messages independently and replaces a thread branch set atomically', async () => {
     const { databasePath } = await temporaryDatabase()
     await executeSessionStorageOperation({ type: 'open', databasePath })
@@ -145,6 +196,13 @@ describe('SQLite session store', () => {
       threadCount: 1, messageCount: 2, blobCount: 1,
     })
     expect(stats.type === 'stats' ? stats.stats.blobBytes : 0).toBeGreaterThan(256 * 1024)
+
+    const database = new DatabaseSync(databasePath, { readOnly: true })
+    const blobColumns = database.prepare("PRAGMA table_info('blobs')").all() as Array<{ name: string }>
+    const references = database.prepare('SELECT COUNT(*) AS count FROM message_blobs').get() as { count: number }
+    expect(blobColumns.map(column => column.name)).not.toContain('ref_count')
+    expect(references.count).toBe(2)
+    database.close()
   })
 
   it('keeps blobs referenced by recovery snapshots until those snapshots rotate', async () => {
@@ -179,6 +237,52 @@ describe('SQLite session store', () => {
     ])
   })
 
+  it('migrates v4 blob counters to normalized message references', async () => {
+    const { databasePath } = await temporaryDatabase()
+    const content = 'v4-payload-'.repeat(30_000)
+    const patch = initialPatch()
+    patch.threads[0].metadata.messageCount = 1
+    patch.threads[0].messages = [{
+      ordinal: 0, id: 'large', role: 'assistant', timestamp: 1,
+      payload: { id: 'large', role: 'assistant', content },
+    }]
+    await executeSessionStorageOperation({ type: 'open', databasePath })
+    await executeSessionStorageOperation({ type: 'applyPatch', databasePath, patch })
+    await executeSessionStorageOperation({ type: 'closeAll' })
+
+    const legacy = new DatabaseSync(databasePath)
+    legacy.exec(`
+      DROP TABLE branch_message_blobs;
+      DROP TABLE message_blobs;
+      DROP INDEX threads_last_modified_id;
+      DROP INDEX plans_updated_at_id;
+      CREATE INDEX plans_updated_at ON plans(updated_at DESC);
+      CREATE TABLE blobs_v4 (
+        hash TEXT PRIMARY KEY,
+        encoding TEXT NOT NULL,
+        byte_length INTEGER NOT NULL,
+        ref_count INTEGER NOT NULL,
+        created_at INTEGER NOT NULL
+      ) STRICT;
+      INSERT INTO blobs_v4(hash, encoding, byte_length, ref_count, created_at)
+        SELECT hash, encoding, byte_length, 1, created_at FROM blobs;
+      DROP TABLE blobs;
+      ALTER TABLE blobs_v4 RENAME TO blobs;
+      PRAGMA user_version = 4;
+    `)
+    legacy.close()
+
+    await executeSessionStorageOperation({ type: 'open', databasePath })
+    const loaded = await executeSessionStorageOperation({ type: 'loadMessages', databasePath, threadId: 't1' })
+    expect(loaded.type === 'messages' ? loaded.messages : []).toEqual([
+      { id: 'large', role: 'assistant', content },
+    ])
+    const migrated = new DatabaseSync(databasePath, { readOnly: true })
+    expect((migrated.prepare('SELECT COUNT(*) AS count FROM message_blobs').get() as { count: number }).count)
+      .toBe(1)
+    migrated.close()
+  })
+
   it('migrates legacy inline branches with an atomic user_version migration', async () => {
     const { databasePath } = await temporaryDatabase()
     await executeSessionStorageOperation({ type: 'open', databasePath })
@@ -201,10 +305,27 @@ describe('SQLite session store', () => {
       expect.objectContaining({ id: 'b1', name: 'Legacy', messageCount: 1 }),
     ])
     const check = new DatabaseSync(databasePath, { readOnly: true })
-    expect((check.prepare('PRAGMA user_version').get() as { user_version: number }).user_version).toBe(4)
+    expect((check.prepare('PRAGMA user_version').get() as { user_version: number }).user_version).toBe(5)
     check.close()
   })
 
+  it('uses indexes for catalog and plan ordering without temporary sorting', async () => {
+    const { databasePath } = await temporaryDatabase()
+    await executeSessionStorageOperation({ type: 'open', databasePath })
+    const database = new DatabaseSync(databasePath, { readOnly: true })
+    const queryPlan = (sql: string): string => database.prepare(`EXPLAIN QUERY PLAN ${sql}`)
+      .all().map(row => String((row as { detail: string }).detail)).join('\n')
+
+    expect(queryPlan('SELECT * FROM threads ORDER BY last_modified DESC, id ASC'))
+      .toContain('threads_last_modified_id')
+    expect(queryPlan('SELECT payload_json FROM plans ORDER BY updated_at DESC, id ASC'))
+      .not.toContain('USE TEMP B-TREE')
+    expect(database.prepare(`
+      SELECT 1 FROM sqlite_master WHERE type = 'index' AND name = 'messages_thread_id_id'
+    `).get()).toBeUndefined()
+    database.close()
+  })
+
   it('does not quarantine a healthy database when its schema is newer than the app', async () => {
     const { root, databasePath } = await temporaryDatabase()
     const database = new DatabaseSync(databasePath)