From 2f7b93ee95d1b4d98b8216c8fbfe0d731e7b0b5e Mon Sep 17 00:00:00 2001
From: Kit Langton <kit.langton@gmail.com>
Date: Wed, 21 Oct 2026 09:49:18 -0700
Subject: [PATCH] fix(app): stop history enrichment at the original turn
 (#57700)

---
 .../app/src/session/timeline/model.test.ts     |  9 +++++++--
 packages/app/src/session/timeline/model.ts     | 18 ++++++++++++++----
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/packages/app/src/session/timeline/model.test.ts b/packages/app/src/session/timeline/model.test.ts
index 7aa247fc425..bb79d8fbbe3 100644
--- a/packages/app/src/session/timeline/model.test.ts
+++ b/packages/app/src/session/timeline/model.test.ts
@@ -63,7 +63,12 @@ describe("timeline model", () => {
   })
 
   test("pauses between history pages and stops once the leading turn has its parent", async () => {
-    const pages: SessionMessageInfo[][] = [[assistant("msg_older")], [user("msg_parent")], [user("msg_earlier")]]
+    const pages: SessionMessageInfo[][] = [
+      [assistant("msg_older")],
+      [assistant("msg_previous_turn"), user("msg_parent")],
+      [user("msg_earlier")],
+    ]
+
     const messages: SessionMessageInfo[] = [assistant("msg_latest"), user("msg_next")]
     const calls: string[] = []
 
@@ -83,7 +88,7 @@ describe("timeline model", () => {
       maxPages: 3,
     })
 
-    expect(calls).toEqual(["pause", "load:msg_older", "pause", "load:msg_parent"])
+    expect(calls).toEqual(["pause", "load:msg_older", "pause", "load:msg_previous_turn"])
     expect(pages).toHaveLength(1)
   })
 })
diff --git a/packages/app/src/session/timeline/model.ts b/packages/app/src/session/timeline/model.ts
index 4a1ad3d1334..9b76dfe10e6 100644
--- a/packages/app/src/session/timeline/model.ts
+++ b/packages/app/src/session/timeline/model.ts
@@ -86,12 +86,21 @@ export async function enrichLeadingTurn(input: {
   pause: () => Promise<void>
   maxPages: number
 }) {
+  const assistant = input.messages().find((message) => message.type === "assistant")?.id
+
+  if (!assistant) return
+
   const load = async (pages: number): Promise<void> => {
-    if (!input.current() || pages >= input.maxPages || !leadingTurnNeedsParent(input.messages()) || !input.more())
+    if (
+      !input.current() ||
+      pages >= input.maxPages ||
+      !leadingTurnNeedsParent(input.messages(), assistant) ||
+      !input.more()
+    )
       return
     await input.pause()
 
-    if (!input.current() || !leadingTurnNeedsParent(input.messages()) || !input.more()) return
+    if (!input.current() || !leadingTurnNeedsParent(input.messages(), assistant) || !input.more()) return
 
     if (input.loading()) return load(pages)
     await input.loadMore()
@@ -102,8 +111,9 @@ export async function enrichLeadingTurn(input: {
   return load(0)
 }
 
-function leadingTurnNeedsParent(messages: SessionMessageInfo[]) {
-  const assistant = messages.findIndex((message) => message.type === "assistant")
+function leadingTurnNeedsParent(messages: SessionMessageInfo[], id: string) {
+  // Older pages can start mid-turn too; only complete the turn that was visible on entry.
+  const assistant = messages.findIndex((message) => message.id === id)
 
   if (assistant === -1) return false
   const boundary = messages.findIndex((message) => message.type === "user" || message.type === "shell")