feat(session): bound persistence write batching

packages/session-persistence/session-persistence-jsonl/README.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write packages/session-persistence/session-persistence-jsonl/README.md
-README.md: cd087539bde2433fcdb70b2c511ff30880a877e1
-README.zh.md: 144b404e04f8a5fd3623d9329e4fbcafd328524d
+README.md: b7fa8fc2918711dd24eeba67132a267452d401f9
+README.zh.md: 59d21c6171e857849c4ab48940d66962fffbfdeb

packages/session-persistence/session-persistence-jsonl/README.md

@@ -27,6 +27,7 @@ The JSONL durable session-persistence backend — a concrete `SessionPersistence
 | `packChunks` | `boolean` (default `true`) | Write eligible delta-chunk runs as packed rows (~60% smaller logical logs measured on a real coding session). Set `false` for one-event-per-line diagnostics; reading packed rows works regardless of this write-side switch. |
 | `compression` | `'zstd' \| 'none'` | Defaults to `'zstd'`; `'none'` retains newline-delimited UTF-8 text. |
 | `preparedSessionCacheSize` | positive integer (default `5`) | Maximum unpublished Sessions retained after cold history inspection for reuse by resume. |
+| `writeBatchMaxDelayMs` | positive integer (default `200`) | Fixed coalescing window after an idle live-event queue receives work. Later events do not reset it; flush and teardown bypass it. It does not bound event-loop, serialized-operation, or backend latency. At most Node's `2_147_483_647` ms timer limit. |
 
 `locate(meta)` returns `{ kind: 'jsonl', path }` for the fixed transcript inside the resolved project/session directories. It performs no filesystem I/O: the target can be returned before the directory or file exists, and an existing file contains only the last flushed prefix.
 
@@ -48,7 +49,7 @@ A root belongs to one encoding. Startup discovery and targeted lookup reject the
 
 ## Write path
 
-The plugin copies frozen session events into one controller per live session and starts an eager drain. Concurrent events share the current write; events admitted during it form a follow-up batch, while `session/flush` waits until both current and pending batches are durable. A per-session cursor prevents resumed sessions from re-appending stored events, and live sessions are seeded when the plugin loads. The owning backend instance serializes operations for one session; disposal drains every retained controller before teardown.
+The plugin copies frozen session events into one controller per live session. The first pending event starts the configured fixed batching window, and later events join without resetting it. Expiry starts one durable append; events admitted during that write form a separately bounded follow-up batch. `session/flush` cancels the wait and drains current and pending batches. A per-session cursor prevents resumed sessions from re-appending stored events, and live sessions are seeded when the plugin loads. The owning backend instance serializes operations for one session; disposal drains every retained controller before teardown. Every logical event remains present: batching only lets one compressed frame or raw fsync carry more records.
 
 ## Model Experience
 

packages/session-persistence/session-persistence-jsonl/README.zh.md

@@ -27,6 +27,7 @@ JSONL 持久会话存储后端：`SessionPersistence` 的一个具体实现（`d
 | `packChunks` | `boolean`（默认 `true`） | 将符合条件的 delta 分片连续段写为打包行（在真实编码会话上测得逻辑日志约小 60%）。设为 `false` 可用于每事件一行诊断；无论该写入侧开关如何，都能读取打包行。 |
 | `compression` | `'zstd' \| 'none'` | 默认 `'zstd'`；`'none'` 保留换行分隔 UTF-8 文本。 |
 | `preparedSessionCacheSize` | 正整数（默认 `5`） | 冷历史检查后保留、供恢复复用的未发布 Session 数量上限。 |
+| `writeBatchMaxDelayMs` | 正整数（默认 `200`） | 空闲的活动事件队列收到待写入事件后开启的固定合并窗口。后续事件不会重置窗口；flush 与 teardown 会绕过它。该值不限制事件循环、串行化操作或后端延迟。最大值为 Node 计时器上限 `2_147_483_647` ms。 |
 
 `locate(meta)` 返回已解析项目/会话目录内固定 transcript 的 `{ kind: 'jsonl', path }`。它不执行文件系统 I/O：可以在目录或文件存在前返回目标，现有文件也只包含最近一次 flush 完成的前缀。
 
@@ -48,7 +49,7 @@ JSONL 持久会话存储后端：`SessionPersistence` 的一个具体实现（`d
 
 ## 写入路径
 
-插件将冻结的会话事件复制到每个活动会话各自的 controller，并启动主动排空流程。并发事件共享当前写入；期间接纳的事件形成后续批次，`session/flush` 则等待当前和待处理批次完成持久化。每会话游标防止恢复后的会话重新 append 已存储事件，插件加载时会为活动会话设置初始状态。所属后端实例串行化单会话操作；dispose（资源释放）会在拆卸前排空每个保留的 controller。
+插件将冻结的会话事件复制到每个活动会话各自的 controller。第一个待处理事件会开启配置的固定批处理窗口，后续事件会加入但不会重置截止时间。窗口到期后会启动一次持久化追加；该次写入期间接纳的事件会形成另一个独立有界的后续批次。`session/flush` 会取消等待并排空当前与待处理批次。每会话游标防止恢复后的会话重新 append 已存储事件，插件加载时会为活动会话设置初始状态。所属后端实例串行化单会话操作；dispose（资源释放）会在拆卸前排空每个保留的 controller。每个逻辑事件都会保留：批处理只让单个压缩帧或一次原始 JSONL fsync 承载更多记录。
 
 ## 模型体验
 

packages/session-persistence/session-persistence-jsonl/src/index.ts

@@ -15,7 +15,8 @@ import { performance } from 'node:perf_hooks'
 import { scheduler } from 'node:timers/promises'
 import { randomBytes } from 'node:crypto'
 import {
-  DEFAULT_PREPARED_SESSION_CACHE_SIZE, SessionPersistence, SessionPersistenceRevision, PersistenceCoordinator,
+  DEFAULT_PREPARED_SESSION_CACHE_SIZE, DEFAULT_WRITE_BATCH_MAX_DELAY_MS, MAX_WRITE_BATCH_DELAY_MS,
+  SessionPersistence, SessionPersistenceRevision, PersistenceCoordinator,
   type PersistenceBackend, type SessionLocation, type SessionPersistenceSnapshot,
   type SessionInspection, type SessionPersistenceRevision as PersistenceRevision, type StoredPrefix,
 } from '@deepseek-ai/dsh-session-persistence'
@@ -76,6 +77,8 @@ export interface Config {
   compression?: JsonlCompression
   /** Maximum cold Session preparations retained for history-to-resume reuse. */
   preparedSessionCacheSize?: number
+  /** Fixed live-event coalescing window; not a backend completion deadline. */
+  writeBatchMaxDelayMs?: number
 }
 
 /** Opaque coordinator token for replacing bytes recovered from a torn frame. */
@@ -122,6 +125,8 @@ export class SessionPersistenceJsonl extends SessionPersistence implements Persi
     packChunks: z.boolean().default(DEFAULT_PACK_CHUNKS),
     compression: JsonlCompressionSchema,
     preparedSessionCacheSize: z.number().step(1).min(1).default(DEFAULT_PREPARED_SESSION_CACHE_SIZE),
+    writeBatchMaxDelayMs: z.number().step(1).min(1).max(MAX_WRITE_BATCH_DELAY_MS)
+      .default(DEFAULT_WRITE_BATCH_MAX_DELAY_MS),
   })
 
   /**
@@ -144,11 +149,14 @@ export class SessionPersistenceJsonl extends SessionPersistence implements Persi
     // Programmatic wrappers may construct the backend without Schemastery normalization.
     const preparedSessionCacheSize = config.preparedSessionCacheSize
       ?? DEFAULT_PREPARED_SESSION_CACHE_SIZE
+    const writeBatchMaxDelayMs = config.writeBatchMaxDelayMs
+      ?? DEFAULT_WRITE_BATCH_MAX_DELAY_MS
     this.packChunks = config.packChunks ?? DEFAULT_PACK_CHUNKS
     this.compression = config.compression ?? DEFAULT_COMPRESSION
     this.assertUsableRoot()
     this.coordinator = new PersistenceCoordinator<JsonlTornMarker>(this.ctx, this, {
       preparedSessionCacheSize,
+      writeBatchMaxDelayMs,
     })
   }
 

packages/session-persistence/session-persistence-jsonl/tests/jsonl.spec.ts

@@ -166,6 +166,7 @@ describe('SessionPersistenceJsonl: format helpers', () => {
     const fiber = await ctx.plugin(SessionPersistenceJsonl, {
       root: relative(process.cwd(), absoluteRoot),
       compression: 'none',
+      writeBatchMaxDelayMs: 1,
     })
     const m = meta('relative-location', '/work')
     expect(ctx.sessionPersistence.locate(m)).toEqual({