diff --git a/packages/node-runtime/src/import/streaming-importer.test.ts b/packages/node-runtime/src/import/streaming-importer.test.ts
index b54eac05..92b76e1e 100644
--- a/packages/node-runtime/src/import/streaming-importer.test.ts
+++ b/packages/node-runtime/src/import/streaming-importer.test.ts
@@ -4,7 +4,7 @@ import os from 'node:os'
 import path from 'node:path'
 import test from 'node:test'
 import Database from 'better-sqlite3'
-import { CHAT_DB_TABLES } from '@openchatlab/core'
+import { CHAT_DB_TABLES, type DatabaseAdapter } from '@openchatlab/core'
 import { isNativeFormatAvailable } from '@openchatlab/parser'
 import { BetterSqliteAdapter } from '../better-sqlite3-adapter'
 import { computeAndSetOverviewCache } from '../cache/session-cache'
@@ -25,12 +25,15 @@ function makeTempDir(): string {
   return fs.mkdtempSync(path.join(baseDir, 'chatlab-streaming-import-'))
 }
 
-function createImportDeps(dbPath: string): StreamImportDeps {
+function createImportDeps(
+  dbPath: string,
+  wrapDatabase: (db: DatabaseAdapter) => DatabaseAdapter = (db) => db
+): StreamImportDeps {
   return {
     openDatabase() {
       const db = new Database(dbPath, { nativeBinding })
       db.exec(CHAT_DB_TABLES)
-      return new BetterSqliteAdapter(db)
+      return wrapDatabase(new BetterSqliteAdapter(db))
     },
     deleteDatabase() {
       for (const suffix of ['', '-wal', '-shm']) {
@@ -47,6 +50,38 @@ function createImportDeps(dbPath: string): StreamImportDeps {
   }
 }
 
+function createDelayedTransactionAdapter(db: DatabaseAdapter, delayMs: number): DatabaseAdapter {
+  let delayedMessageCommit = false
+
+  return {
+    get readonly() {
+      return db.readonly
+    },
+    exec(sql) {
+      if (!delayedMessageCommit && sql.trim().toUpperCase() === 'COMMIT') {
+        delayedMessageCommit = true
+        Atomics.wait(new Int32Array(new SharedArrayBuffer(4)), 0, 0, delayMs)
+      }
+      db.exec(sql)
+    },
+    prepare(sql) {
+      return db.prepare(sql)
+    },
+    transaction(fn) {
+      return db.transaction(fn)
+    },
+    pragma(pragma) {
+      if (pragma === 'wal_checkpoint(TRUNCATE)') {
+        Atomics.wait(new Int32Array(new SharedArrayBuffer(4)), 0, 0, delayMs)
+      }
+      return db.pragma(pragma)
+    },
+    close() {
+      db.close()
+    },
+  }
+}
+
 function createCollectingLogger(messages: string[]): ImportLogger {
   return {
     info(message) {
@@ -570,6 +605,23 @@ test('streamingImport applies incremental-equivalent deduplication on first impo
   assert.equal(row.count, 3)
 })
 
+test('streamingImport attributes transaction and checkpoint work to their import phases', async (t) => {
+  const root = makeTempDir()
+  t.after(() => fs.rmSync(root, { recursive: true, force: true }))
+  const filePath = writeDuplicateChatLabExport(root)
+  const dbPath = path.join(root, 'transaction-timing-test.db')
+  const delayMs = 50
+  const deps = createImportDeps(dbPath, (db) => createDelayedTransactionAdapter(db, delayMs))
+
+  const result = await streamingImport(filePath, deps, { formatId: 'chatlab' }, 'transaction-timing-test')
+
+  assert.equal(result.success, true)
+  const timings = result.diagnostics?.performance.timings
+  assert.ok(timings)
+  assert.ok(timings.messageWriteMs >= delayMs * 0.8, 'message writes should include the final transaction commit')
+  assert.ok(timings.checkpointMs >= delayMs * 0.8, 'checkpoint timing should include the final WAL checkpoint')
+})
+
 test('streamingImport canonicalizes reserved SYSTEM senders and excludes them from overview counts', async (t) => {
   const root = makeTempDir()
   t.after(() => fs.rmSync(root, { recursive: true, force: true }))
diff --git a/packages/node-runtime/src/import/streaming-importer.ts b/packages/node-runtime/src/import/streaming-importer.ts
index 3cb48d44..03c41ed4 100644
--- a/packages/node-runtime/src/import/streaming-importer.ts
+++ b/packages/node-runtime/src/import/streaming-importer.ts
@@ -421,12 +421,30 @@ async function streamImportSingle(
   let lastCheckpointCount = 0
   let inTransaction = false
   let messageTransactionCount = 0
+  let messageTransactionMs = 0
 
   const beginTransaction = () => {
     if (!inTransaction) {
-      db.exec('BEGIN TRANSACTION')
-      inTransaction = true
-      messageTransactionCount++
+      const startedAt = performance.now()
+      try {
+        db.exec('BEGIN TRANSACTION')
+        inTransaction = true
+        messageTransactionCount++
+      } finally {
+        messageTransactionMs += elapsedMs(startedAt)
+      }
+    }
+  }
+
+  const commitTransaction = () => {
+    if (inTransaction) {
+      const startedAt = performance.now()
+      try {
+        db.exec('COMMIT')
+        inTransaction = false
+      } finally {
+        messageTransactionMs += elapsedMs(startedAt)
+      }
     }
   }
 
@@ -438,14 +456,22 @@ async function streamImportSingle(
     }
   }
 
+  const measureCheckpoint = () => {
+    const startedAt = performance.now()
+    try {
+      doCheckpoint()
+    } finally {
+      timings.checkpointMs += elapsedMs(startedAt)
+    }
+  }
+
   const commitAndBeginNew = () => {
     if (inTransaction) {
-      db.exec('COMMIT')
-      inTransaction = false
+      commitTransaction()
       logger?.perf('Commit transaction', totalMessageCount, BATCH_COMMIT_SIZE)
 
       if (totalMessageCount - lastCheckpointCount >= CHECKPOINT_INTERVAL) {
-        doCheckpoint()
+        measureCheckpoint()
         logger?.perf('WAL checkpoint', totalMessageCount)
         lastCheckpointCount = totalMessageCount
       }
@@ -486,7 +512,8 @@ async function streamImportSingle(
   const finishParserTiming = () => {
     if (parserTimingFinished) return
     const parsePipelineMs = elapsedMs(parsePipelineStartedAt)
-    const writeCallbackMs = timings.metaWriteMs + timings.memberWriteMs + timings.messageWriteMs
+    const writeCallbackMs =
+      timings.metaWriteMs + timings.memberWriteMs + timings.messageWriteMs + messageTransactionMs + timings.checkpointMs
     timings.parserMs = Math.max(0, parsePipelineMs - writeCallbackMs)
     parserTimingFinished = true
     sampleRss()
@@ -566,6 +593,8 @@ async function streamImportSingle(
 
         onMessageBatch: (messages: ParsedMessage[]) => {
           const startedAt = performance.now()
+          const transactionMsBefore = messageTransactionMs
+          const checkpointMsBefore = timings.checkpointMs
           try {
             callbackStats.onMessageBatchCalls++
             callbackStats.totalMessagesReceived += messages.length
@@ -635,7 +664,9 @@ async function streamImportSingle(
               }
             }
           } finally {
-            timings.messageWriteMs += elapsedMs(startedAt)
+            const nestedStageMs =
+              messageTransactionMs - transactionMsBefore + (timings.checkpointMs - checkpointMsBefore)
+            timings.messageWriteMs += Math.max(0, elapsedMs(startedAt) - nestedStageMs)
             sampleRss()
           }
         },
@@ -645,9 +676,9 @@ async function streamImportSingle(
     finishParserTiming()
 
     if (inTransaction) {
-      db.exec('COMMIT')
-      inTransaction = false
+      commitTransaction()
     }
+    timings.messageWriteMs += messageTransactionMs
 
     // Flush nickname history in batch
     onProgress({
@@ -719,9 +750,7 @@ async function streamImportSingle(
       message: '',
     })
     await yieldToEventLoop()
-    const checkpointStartedAt = performance.now()
-    doCheckpoint()
-    timings.checkpointMs = elapsedMs(checkpointStartedAt)
+    measureCheckpoint()
     sampleRss()
     logger?.perf('WAL checkpoint done', totalMessageCount)