fix(kap-server): remove the 64 MiB web session export limit (#2910)

.changeset/export-log-limit.md

@@ -0,0 +1,5 @@
+---
+"@moonshot-ai/kimi-code": patch
+---
+
+Remove the 64 MiB limit on web session exports, so large sessions no longer fail with a file-too-large error when downloaded from the web UI.

docs/en/guides/sessions.md

@@ -110,8 +110,6 @@ You can also export from inside the TUI without leaving the interactive session:
 
 In the web UI, `/export` downloads the current session as a diagnostic ZIP. It includes the persisted session data, diagnostic logs, and a bounded metadata-only `logs/kimi-web.jsonl` record of key browser events. Prompt text, WebSocket payloads, and console arguments are not copied into this browser log. This web command differs from the TUI `/export` alias above.
 
-The browser buffers the ZIP before saving it, so web exports are limited to 64 MiB. For a larger session, use `kimi export <sessionId>` or the TUI `/export-debug-zip` command.
-
 ::: tip
 Exported files may contain code, command output, and file paths that are sensitive. Review the content before sharing.
 :::

docs/zh/guides/sessions.md

@@ -110,8 +110,6 @@ kimi export <sessionId> -o ~/Desktop/my-session.zip
 
 在 web UI 中，`/export` 会把当前会话下载为诊断 ZIP。压缩包包含持久化的会话数据、诊断日志，以及记录浏览器关键事件且大小有上限、只含元数据的 `logs/kimi-web.jsonl`；提示词正文、WebSocket 内容和 console 参数不会写入这份浏览器日志。这里的 web 命令与上面的 TUI `/export` 别名行为不同。
 
-浏览器需要先把 ZIP 缓存在内存中再保存，因此 web 导出上限为 64 MiB。更大的会话请使用 `kimi export <sessionId>` 或 TUI 的 `/export-debug-zip`。
-
 ::: tip 提示
 导出文件可能包含代码、命令输出和路径等敏感信息，分享前请先确认内容。
 :::

packages/agent-core-v2/src/app/sessionExport/sessionExport.ts

@@ -58,7 +58,6 @@ export interface ExportSessionResult {
 export interface ExportSessionOptions {
   readonly webLog?: string;
   readonly signal?: AbortSignal;
-  readonly maxArchiveBytes?: number;
 }
 
 export interface ISessionExportService {

packages/agent-core-v2/src/app/sessionExport/sessionExportService.ts

@@ -99,7 +99,6 @@ export class SessionExportService implements ISessionExportService {
           : undefined,
       webLog: options.webLog,
       signal: options.signal,
-      maxArchiveBytes: options.maxArchiveBytes,
     });
   }
 
@@ -185,7 +184,6 @@ export async function exportSessionDirectory(input: {
   readonly desktopLogPath?: string | undefined;
   readonly webLog?: string;
   readonly signal?: AbortSignal;
-  readonly maxArchiveBytes?: number;
 }): Promise<ExportSessionResult> {
   input.signal?.throwIfAborted();
   const sessionDir = input.summary.sessionDir;
@@ -265,7 +263,6 @@ export async function exportSessionDirectory(input: {
       sessionFiles: selectedSessionFiles,
       extraEntries: extras,
       signal: input.signal,
-      maxArchiveBytes: input.maxArchiveBytes,
     });
     sessionLogSourceTransferred = sessionLogSource !== undefined;
     globalSourceTransferred = globalSource !== undefined;

packages/agent-core-v2/src/app/sessionExport/zip.ts

@@ -8,7 +8,7 @@
 
 import { createWriteStream } from 'node:fs';
 import { mkdir, mkdtemp, readdir, rename, rm, stat } from 'node:fs/promises';
-import { Readable, Transform } from 'node:stream';
+import { Readable } from 'node:stream';
 import { pipeline } from 'node:stream/promises';
 
 import { dirname, join, relative, resolve } from 'pathe';
@@ -49,7 +49,6 @@ export async function writeExportZip(args: {
   readonly sessionFiles: readonly SessionZipEntry[];
   readonly extraEntries?: readonly ExtraZipEntry[];
   readonly signal?: AbortSignal;
-  readonly maxArchiveBytes?: number;
 }): Promise<readonly string[]> {
   const unusedSources = new Set<ZipSource>([
     ...args.sessionFiles.flatMap((entry) => (typeof entry === 'string' ? [] : [entry.source])),
@@ -110,12 +109,7 @@ export async function writeExportZip(args: {
     args.signal?.addEventListener('abort', onAbort, { once: true });
 
     const destination = createWriteStream(tempOutputPath, { flags: 'wx' });
-    writing =
-      args.maxArchiveBytes === undefined
-        ? pipeline(output, destination, { signal: args.signal })
-        : pipeline(output, createArchiveLimit(args.maxArchiveBytes), destination, {
-            signal: args.signal,
-          });
+    writing = pipeline(output, destination, { signal: args.signal });
 
     const activate = (source: ZipSource): Readable => {
       unusedSources.delete(source);
@@ -263,26 +257,6 @@ function abortReason(signal: AbortSignal): Error {
     : new DOMException('The operation was aborted.', 'AbortError');
 }
 
-function createArchiveLimit(maxArchiveBytes: number): Transform {
-  let archiveBytes = 0;
-  return new Transform({
-    transform(chunk: Buffer, _encoding, callback) {
-      archiveBytes += chunk.length;
-      if (archiveBytes > maxArchiveBytes) {
-        callback(
-          new Error2(
-            ErrorCodes.SESSION_EXPORT_TOO_LARGE,
-            `Session export exceeds the ${maxArchiveBytes} byte archive limit.`,
-            { details: { archiveBytes, maxArchiveBytes } },
-          ),
-        );
-        return;
-      }
-      callback(null, chunk);
-    },
-  });
-}
-
 async function findConflictingSource(args: {
   readonly outputPath: string;
   readonly sessionFiles: readonly SessionZipEntry[];

packages/agent-core-v2/test/app/sessionExport/sessionExport.test.ts

@@ -710,23 +710,6 @@ describe('sessionExport', () => {
     expect((await readdir(tmp)).toSorted()).toEqual(['export.zip', 'safe-output', 'state.json']);
   });
 
-  it('rejects with a coded error when compressed output exceeds the configured limit', async () => {
-    const tmp = await mkdtemp(join(tmpdir(), 'session-export-test-'));
-
-    await expect(
-      writeExportZip({
-        outputPath: join(tmp, 'too-large.zip'),
-        manifest: testManifest('ses_too_large'),
-        sessionDir: tmp,
-        sessionFiles: [],
-        maxArchiveBytes: 1,
-      }),
-    ).rejects.toMatchObject({
-      code: 'session.export_too_large',
-      details: { maxArchiveBytes: 1 },
-    });
-  });
-
   it('throws a coded error when the session is unknown', async () => {
     const tmp = await mkdtemp(join(tmpdir(), 'session-export-test-'));
     ix = createTestServices(tmp, {

packages/kap-server/src/routes/sessionExport.ts

@@ -29,8 +29,6 @@ import {
   exportSessionRequestSchema,
 } from '../protocol/rest-session';
 
-const MAX_WEB_SESSION_EXPORT_BYTES = 64 * 1024 * 1024;
-
 interface SessionExportRouteHost {
   post(
     path: string,
@@ -64,7 +62,6 @@ export function registerSessionExportRoute(
       errors: {
         [ErrorCode.VALIDATION_FAILED]: {},
         [ErrorCode.SESSION_NOT_FOUND]: {},
-        [ErrorCode.FILE_TOO_LARGE]: {},
         [ErrorCode.INTERNAL_ERROR]: {},
       },
       description: 'Export a session and diagnostic logs as a zip archive',
@@ -132,7 +129,6 @@ export function registerSessionExportRoute(
           {
             webLog: req.body.web_log,
             signal: exportAbort.signal,
-            maxArchiveBytes: MAX_WEB_SESSION_EXPORT_BYTES,
           },
         );
         if (aborted) {
@@ -200,16 +196,6 @@ function sendMappedError(reply: SessionExportReply, req: { id: string }, error:
       reply.send(errEnvelope(ErrorCode.SESSION_NOT_FOUND, error.message, requestId));
       return;
     }
-    if (error.code === ErrorCodes.SESSION_EXPORT_TOO_LARGE) {
-      reply.send(
-        errEnvelope(
-          ErrorCode.FILE_TOO_LARGE,
-          'session export exceeds the 64 MiB web limit',
-          requestId,
-        ),
-      );
-      return;
-    }
   }
   requestLog(req)?.error({ err: error }, 'session export failed');
   reply.send(