From 9d15f0d8e1e31a3381b59074e2e5de3c17da92ca Mon Sep 17 00:00:00 2001
From: Sam Han <sungsoo.han95@gmail.com>
Date: Wed, 5 Aug 2026 16:13:37 -0400
Subject: [PATCH] fix(server): preserve latest turn after session completion

---
 .../src/orchestration/Layers/ProjectionPipeline.test.ts    | 7 +++++++
 apps/server/src/orchestration/Layers/ProjectionPipeline.ts | 2 +-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/apps/server/src/orchestration/Layers/ProjectionPipeline.test.ts b/apps/server/src/orchestration/Layers/ProjectionPipeline.test.ts
index 926182a3ef0d..1910382f0678 100644
--- a/apps/server/src/orchestration/Layers/ProjectionPipeline.test.ts
+++ b/apps/server/src/orchestration/Layers/ProjectionPipeline.test.ts
@@ -1429,6 +1429,13 @@ it.layer(BaseTestLayer)("OrchestrationProjectionPipeline", (it) => {
       assert.deepEqual(settledRows, [
         { state: "completed", completedAt: "2026-01-01T00:01:00.000Z" },
       ]);
+
+      const threadRows = yield* sql<{ readonly latestTurnId: string | null }>`
+        SELECT latest_turn_id AS "latestTurnId"
+        FROM projection_threads
+        WHERE thread_id = ${threadId}
+      `;
+      assert.deepEqual(threadRows, [{ latestTurnId: turnId }]);
     }),
   );
 
diff --git a/apps/server/src/orchestration/Layers/ProjectionPipeline.ts b/apps/server/src/orchestration/Layers/ProjectionPipeline.ts
index fe683b08a3c8..f3a61eaf5d66 100644
--- a/apps/server/src/orchestration/Layers/ProjectionPipeline.ts
+++ b/apps/server/src/orchestration/Layers/ProjectionPipeline.ts
@@ -850,7 +850,7 @@ const makeOrchestrationProjectionPipeline = Effect.fn("makeOrchestrationProjecti
           }
           yield* projectionThreadRepository.upsert({
             ...existingRow.value,
-            latestTurnId: event.payload.session.activeTurnId,
+            latestTurnId: event.payload.session.activeTurnId ?? existingRow.value.latestTurnId,
             updatedAt: event.occurredAt,
           });
           yield* refreshThreadShellSummary(event.payload.threadId);