fix: preserve Pi projection continuity

tests/unit/pi-session-projector.test.ts

@@ -130,6 +130,19 @@ describe('Pi session projector', () => {
     expect(JSON.stringify(snapshot)).not.toContain('Abandoned answer');
   });
 
+  it('preserves seq for same-generation checkpoint hydration', async () => {
+    const live = baseSnapshot();
+    live.cursor.seq = 7;
+    const snapshot = await projectPiSessionSnapshot({
+      snapshot: live,
+      workerGeneration: 1,
+      state: { sessionId: 'pi-session-a', isStreaming: false, isCompacting: false },
+      entries: { entries: [], leafId: null },
+    });
+
+    expect(snapshot.cursor).toEqual({ workerGeneration: 1, seq: 7 });
+  });
+
   it('applies retained-tail compaction and reconciles durable entries without replacing live IDs', async () => {
     const live: ConversationSnapshot = {
       ...baseSnapshot(),