From 5e8742f4312a8923f3da92172a7247470ef34516 Mon Sep 17 00:00:00 2001
From: Adam <2363879+adamdotdevin@users.noreply.github.com>
Date: Mon, 2 Mar 2026 18:23:59 -0600
Subject: [PATCH] fix(app): timeline jank

---
 packages/app/src/pages/session.tsx            |   4 +-
 .../src/pages/session/message-timeline.tsx    |   4 +-
 packages/ui/src/components/message-part.tsx   | 170 +++++++++++-------
 packages/ui/src/hooks/create-auto-scroll.tsx  |   5 +-
 4 files changed, 114 insertions(+), 69 deletions(-)

diff --git a/packages/app/src/pages/session.tsx b/packages/app/src/pages/session.tsx
index 4f01badf4..2c49489ba 100644
--- a/packages/app/src/pages/session.tsx
+++ b/packages/app/src/pages/session.tsx
@@ -1091,7 +1091,9 @@ export default function Page() {
 
       const el = scroller
       const delta = next - dockHeight
-      const stick = el ? el.scrollHeight - el.clientHeight - el.scrollTop < 10 + Math.max(0, delta) : false
+      const stick = el
+        ? !autoScroll.userScrolled() || el.scrollHeight - el.clientHeight - el.scrollTop < 10 + Math.max(0, delta)
+        : false
 
       dockHeight = next
 
diff --git a/packages/app/src/pages/session/message-timeline.tsx b/packages/app/src/pages/session/message-timeline.tsx
index 0aa07bf74..19d6e09d9 100644
--- a/packages/app/src/pages/session/message-timeline.tsx
+++ b/packages/app/src/pages/session/message-timeline.tsx
@@ -689,7 +689,9 @@ export function MessageTimeline(props: {
                   if (!item || active()) return false
                   return messageID > item.id
                 })
-                const comments = createMemo(() => messageComments(sync.data.part[messageID] ?? []))
+                const comments = createMemo(() => messageComments(sync.data.part[messageID] ?? []), [], {
+                  equals: (a, b) => JSON.stringify(a) === JSON.stringify(b),
+                })
                 const commentCount = createMemo(() => comments().length)
                 return (
                   <div
diff --git a/packages/ui/src/components/message-part.tsx b/packages/ui/src/components/message-part.tsx
index b59dd47b8..2490f5c17 100644
--- a/packages/ui/src/components/message-part.tsx
+++ b/packages/ui/src/components/message-part.tsx
@@ -9,6 +9,7 @@ import {
   Show,
   Switch,
   onCleanup,
+  Index,
   type JSX,
 } from "solid-js"
 import stripAnsi from "strip-ansi"
@@ -458,50 +459,67 @@ export function AssistantParts(props: {
   const last = createMemo(() => grouped().at(-1)?.key)
 
   return (
-    <For each={grouped()}>
-      {(entry) => {
-        if (entry.type === "context") {
-          const parts = createMemo(
-            () =>
-              entry.refs
-                .map((ref) => partByID(list(data.store.part?.[ref.messageID], emptyParts), ref.partID))
-                .filter((part): part is ToolPart => !!part && isContextGroupTool(part)),
-            emptyTools,
-            { equals: same },
-          )
-          const busy = createMemo(() => props.working && last() === entry.key)
-
-          return (
-            <Show when={parts().length > 0}>
-              <ContextToolGroup parts={parts()} busy={busy()} />
-            </Show>
-          )
-        }
-
-        const message = createMemo(() => props.messages.find((item) => item.id === entry.ref.messageID))
-        const part = createMemo(() =>
-          partByID(list(data.store.part?.[entry.ref.messageID], emptyParts), entry.ref.partID),
-        )
+    <Index each={grouped()}>
+      {(entryAccessor) => {
+        const entryType = createMemo(() => entryAccessor().type)
 
         return (
-          <Show when={message()}>
-            {(message) => (
-              <Show when={part()}>
-                {(part) => (
-                  <Part
-                    part={part()}
-                    message={message()}
-                    showAssistantCopyPartID={props.showAssistantCopyPartID}
-                    turnDurationMs={props.turnDurationMs}
-                    defaultOpen={partDefaultOpen(part(), props.shellToolDefaultOpen, props.editToolDefaultOpen)}
-                  />
-                )}
-              </Show>
-            )}
-          </Show>
+          <Switch>
+            <Match when={entryType() === "context"}>
+              {(() => {
+                const parts = createMemo(
+                  () => {
+                    const entry = entryAccessor() as { type: "context"; refs: PartRef[] }
+                    return entry.refs
+                      .map((ref) => partByID(list(data.store.part?.[ref.messageID], emptyParts), ref.partID))
+                      .filter((part): part is ToolPart => !!part && isContextGroupTool(part))
+                  },
+                  emptyTools,
+                  { equals: same },
+                )
+                const busy = createMemo(() => props.working && last() === entryAccessor().key)
+
+                return (
+                  <Show when={parts().length > 0}>
+                    <ContextToolGroup parts={parts()} busy={busy()} />
+                  </Show>
+                )
+              })()}
+            </Match>
+            <Match when={entryType() === "part"}>
+              {(() => {
+                const message = createMemo(() => {
+                  const entry = entryAccessor() as { type: "part"; ref: PartRef }
+                  return props.messages.find((item) => item.id === entry.ref.messageID)
+                })
+                const part = createMemo(() => {
+                  const entry = entryAccessor() as { type: "part"; ref: PartRef }
+                  return partByID(list(data.store.part?.[entry.ref.messageID], emptyParts), entry.ref.partID)
+                })
+
+                return (
+                  <Show when={message()}>
+                    {(msg) => (
+                      <Show when={part()}>
+                        {(p) => (
+                          <Part
+                            part={p()}
+                            message={msg()}
+                            showAssistantCopyPartID={props.showAssistantCopyPartID}
+                            turnDurationMs={props.turnDurationMs}
+                            defaultOpen={partDefaultOpen(p(), props.shellToolDefaultOpen, props.editToolDefaultOpen)}
+                          />
+                        )}
+                      </Show>
+                    )}
+                  </Show>
+                )
+              })()}
+            </Match>
+          </Switch>
         )
       }}
-    </For>
+    </Index>
   )
 }
 
@@ -632,36 +650,56 @@ export function AssistantMessageDisplay(props: {
   )
 
   return (
-    <For each={grouped()}>
-      {(entry) => {
-        if (entry.type === "context") {
-          const parts = createMemo(
-            () =>
-              entry.refs
-                .map((ref) => partByID(props.parts, ref.partID))
-                .filter((part): part is ToolPart => !!part && isContextGroupTool(part)),
-            emptyTools,
-            { equals: same },
-          )
-
-          return (
-            <Show when={parts().length > 0}>
-              <ContextToolGroup parts={parts()} />
-            </Show>
-          )
-        }
-
-        const part = createMemo(() => partByID(props.parts, entry.ref.partID))
+    <Index each={grouped()}>
+      {(entryAccessor) => {
+        const entryType = createMemo(() => entryAccessor().type)
 
         return (
-          <Show when={part()}>
-            {(part) => (
-              <Part part={part()} message={props.message} showAssistantCopyPartID={props.showAssistantCopyPartID} />
-            )}
-          </Show>
+          <Switch>
+            <Match when={entryType() === "context"}>
+              {(() => {
+                const parts = createMemo(
+                  () => {
+                    const entry = entryAccessor() as { type: "context"; refs: PartRef[] }
+                    return entry.refs
+                      .map((ref) => partByID(props.parts, ref.partID))
+                      .filter((part): part is ToolPart => !!part && isContextGroupTool(part))
+                  },
+                  emptyTools,
+                  { equals: same },
+                )
+
+                return (
+                  <Show when={parts().length > 0}>
+                    <ContextToolGroup parts={parts()} />
+                  </Show>
+                )
+              })()}
+            </Match>
+            <Match when={entryType() === "part"}>
+              {(() => {
+                const part = createMemo(() => {
+                  const entry = entryAccessor() as { type: "part"; ref: PartRef }
+                  return partByID(props.parts, entry.ref.partID)
+                })
+
+                return (
+                  <Show when={part()}>
+                    {(p) => (
+                      <Part
+                        part={p()}
+                        message={props.message}
+                        showAssistantCopyPartID={props.showAssistantCopyPartID}
+                      />
+                    )}
+                  </Show>
+                )
+              })()}
+            </Match>
+          </Switch>
         )
       }}
-    </For>
+    </Index>
   )
 }
 
diff --git a/packages/ui/src/hooks/create-auto-scroll.tsx b/packages/ui/src/hooks/create-auto-scroll.tsx
index c32017739..8483915a8 100644
--- a/packages/ui/src/hooks/create-auto-scroll.tsx
+++ b/packages/ui/src/hooks/create-auto-scroll.tsx
@@ -142,7 +142,10 @@ export function createAutoScroll(options: AutoScrollOptions) {
 
   const handleInteraction = () => {
     if (!active()) return
-    stop()
+    const selection = window.getSelection()
+    if (selection && selection.toString().length > 0) {
+      stop()
+    }
   }
 
   const updateOverflowAnchor = (el: HTMLElement) => {