fix(persistence): preserve subagent session origin

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

@@ -37,6 +37,7 @@ export interface HeaderLine {
   cwd?: string
   parentSession?: SessionId
   seedLength?: number
+  origin?: 'subagent'
   delegationDepth: number
 }
 
@@ -54,6 +55,7 @@ export function toHeaderLine(header: SessionHeader): HeaderLine {
     ...header.cwd !== undefined ? { cwd: header.cwd } : {},
     ...header.parentSession !== undefined ? { parentSession: header.parentSession } : {},
     ...header.seedLength !== undefined ? { seedLength: header.seedLength } : {},
+    ...header.origin !== undefined ? { origin: header.origin } : {},
     delegationDepth: header.delegationDepth ?? 0,
   }
 }
@@ -74,6 +76,7 @@ export function fromHeaderLine(line: HeaderLine): SessionHeader {
     ...line.cwd !== undefined ? { cwd: line.cwd } : {},
     ...line.parentSession !== undefined ? { parentSession: line.parentSession } : {},
     ...line.seedLength !== undefined ? { seedLength: line.seedLength } : {},
+    ...line.origin !== undefined ? { origin: line.origin } : {},
     delegationDepth: line.delegationDepth,
   }
 }
@@ -93,6 +96,8 @@ function isHeaderLine(value: unknown): value is HeaderLine {
     && Number.isSafeInteger((value as { delegationDepth: number }).delegationDepth)
     && (value as { delegationDepth: number }).delegationDepth >= 0
     && !Object.is((value as { delegationDepth: number }).delegationDepth, -0)
+    && ((value as { origin?: unknown }).origin === undefined
+      || (value as { origin?: unknown }).origin === 'subagent')
   )
 }