Phase 6: add PI_AUTO_COMPACT_FOLLOW_UP_PREFIXES — document pi-auto-compact phrases.

Constants match SPEC §16.9 for tests and docs; runtime v1 does not match follow-up text.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/auto-compact.ts

@@ -25,3 +25,11 @@ export function resolveDeliveryMode(
 ): ReinjectDeliveryMode {
 	return effectiveIntegration(settings, runtime.autoCompactDetected, sessionIntegrationOverride);
 }
+
+/** pi-auto-compact follow-up message prefixes (SPEC §16.9); documentation/tests only, not runtime v1. */
+export const PI_AUTO_COMPACT_FOLLOW_UP_PREFIXES = [
+	"Auto-compact ran before this turn.",
+	"Auto-compact ran mid-turn.",
+	"Emergency auto-compact ran.",
+	"Auto-compact ran on session resume.",
+] as const;