fix(files): fix two scroll logic bugs introduced in previous streaming scroll fix

The prior fix introduced a regression for the "user was at bottom" case and
a false-disengagement bug from programmatic scroll events.

Bug 1 — Effect ordering: all three effects fire on the same render when
isStreamInteractionLocked flips true. Effect 2 called isAtBottom() AFTER
Effect 1 had already called model.setValue(), which grew scrollHeight. The
old "at bottom" scroll position was now 200px short of the new bottom, so
isAtBottom() returned false, textareaStuckRef was set false, and Effect 3
never called revealLine. Users at the bottom stopped following the stream.

Fix: measure isAtBottom() in Effect 1 BEFORE setValue, while scrollHeight
is still accurate. Set textareaStuckRef = true only (never false here).
Effect 2 no longer initializes the ref — only the listener disengages it.

Bug 2 — onDidScrollChange fires during model.setValue: Monaco fires
onDidScrollChange when scroll dimensions change, including when setValue
grows the document. This caused the listener to disengage auto-scroll on
every content update even with no user interaction.

Fix: add suppressScrollListenerRef, set true before setValue/restoreViewState
and false after. The listener exits early when suppressed, so only genuine
user scroll events (wheel, trackpad, keyboard, scrollbar) can disengage.

Both refs moved to the component's ref block for conventional placement.

Author: waleedlatif1

apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/file-viewer.tsx

@@ -799,6 +799,8 @@ function TextEditor({
   const lastSyncedContentRef = useRef('')
   const hasAutoFocusedRef = useRef(false)
   const contentRef = useRef('')
+  const textareaStuckRef = useRef(false)
+  const suppressScrollListenerRef = useRef(false)
 
   const [splitPct, setSplitPct] = useState(SPLIT_DEFAULT_PCT)
   const [isResizing, setIsResizing] = useState(false)
@@ -852,37 +854,49 @@ function TextEditor({
     if (monacoValue === content) return
 
     if (isStreamInteractionLocked || monacoValue === lastSyncedContentRef.current) {
-      // Preserve the user's scroll position during streaming updates, unless they
-      // are already at the bottom (in which case Effect 3 will scroll to the new bottom).
+      if (isStreamInteractionLocked) {
+        // Measure BEFORE setValue — scrollHeight hasn't grown yet, so the
+        // "at bottom" check is accurate. Re-engage auto-scroll if at bottom;
+        // never disengage here (user scroll events do that via Effect 2).
+        const scrollTop = editor.getScrollTop()
+        const scrollHeight = editor.getScrollHeight()
+        const { height } = editor.getLayoutInfo()
+        if (scrollHeight - scrollTop - height < 80) {
+          textareaStuckRef.current = true
+        }
+      }
+      // Preserve the user's scroll position when they've scrolled away from the
+      // bottom. Suppress the onDidScrollChange listener so programmatic scroll
+      // changes (setValue / restoreViewState) don't falsely disengage auto-scroll.
       const viewState =
         isStreamInteractionLocked && !textareaStuckRef.current ? editor.saveViewState() : null
+      suppressScrollListenerRef.current = true
       model.setValue(content)
       if (viewState) editor.restoreViewState(viewState)
+      suppressScrollListenerRef.current = false
       lastSyncedContentRef.current = content
     }
   }, [content, isStreamInteractionLocked])
 
-  const textareaStuckRef = useRef(true)
   useEffect(() => {
     const editor = monacoEditorRef.current
     if (!editor || !isStreamInteractionLocked || disableStreamingAutoScroll) {
       textareaStuckRef.current = false
       return
     }
 
-    const isAtBottom = () => {
+    // Effect 1 re-engages auto-scroll (sets true) immediately before each setValue,
+    // measuring scroll position while scrollHeight is still accurate. This listener
+    // only needs to disengage when the user physically scrolls away from the bottom.
+    // Suppressed during programmatic setValue/restoreViewState in Effect 1.
+    const disposable = editor.onDidScrollChange(() => {
+      if (suppressScrollListenerRef.current) return
       const scrollTop = editor.getScrollTop()
       const scrollHeight = editor.getScrollHeight()
       const { height } = editor.getLayoutInfo()
-      return scrollHeight - scrollTop - height < 80
-    }
-
-    // Initialize from actual position — only follow if already at the bottom.
-    textareaStuckRef.current = isAtBottom()
-
-    // Use Monaco's scroll API so trackpad, scrollbar drag, and keyboard all update the flag.
-    const disposable = editor.onDidScrollChange(() => {
-      textareaStuckRef.current = isAtBottom()
+      if (scrollHeight - scrollTop - height >= 80) {
+        textareaStuckRef.current = false
+      }
     })
 
     return () => {