docs: document session preparation flow

docs/config-catalog.md

@@ -108,7 +108,7 @@ export interface Config {
 
 Depends on: [`AgentOptions`](core-data-structures/core.md) · [`SessionId`](core-data-structures/core.md)
 
-Source: [`packages/core/agent-loop/src/index.ts:212`](../packages/core/agent-loop/src/index.ts)
+Source: [`packages/core/agent-loop/src/index.ts:235`](../packages/core/agent-loop/src/index.ts)
 
 ## `@deepseek-ai/dsh-agent-spine-demo`
 
@@ -1135,6 +1135,8 @@ export interface Config {
   packChunks?: boolean
   /** Physical encoding; defaults to checksummed Zstandard frames. */
   compression?: JsonlCompression
+  /** Maximum cold Session preparations retained for history-to-resume reuse. */
+  preparedSessionCacheSize?: number
 }
 
 /** Physical encoding selected for JSONL session artifacts. */
@@ -1167,6 +1169,8 @@ export interface Config {
    * (network mounts). See {@link JournalMode}.
    */
   journalMode?: JournalMode
+  /** Maximum cold Session preparations retained for history-to-resume reuse. */
+  preparedSessionCacheSize?: number
 }
 
 /**