feat(atlas): persist preferred task session reuse

src/hooks/atlas/subagent-session-id.ts

@@ -1,4 +1,10 @@
-export function extractSessionIdFromOutput(output: string): string {
-  const match = output.match(/Session ID:\s*(ses_[a-zA-Z0-9]+)/)
-  return match?.[1] ?? "<session_id>"
+export function extractSessionIdFromOutput(output: string): string | undefined {
+  const taskMetadataMatches = [...output.matchAll(/<task_metadata>[\s\S]*?session_id:\s*(ses_[a-zA-Z0-9_]+)[\s\S]*?<\/task_metadata>/gi)]
+  const lastTaskMetadataMatch = taskMetadataMatches.at(-1)
+  if (lastTaskMetadataMatch) {
+    return lastTaskMetadataMatch[1]
+  }
+
+  const explicitSessionMatches = [...output.matchAll(/Session ID:\s*(ses_[a-zA-Z0-9_]+)/g)]
+  return explicitSessionMatches.at(-1)?.[1]
 }