feat(session): bound persistence write batching

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,
     })
   }