diff --git a/apps/web/src/components/diffs/DiffCommentAnnotation.tsx b/apps/web/src/components/diffs/DiffCommentAnnotation.tsx
index d210732b6b60..bce9f7e55f58 100644
--- a/apps/web/src/components/diffs/DiffCommentAnnotation.tsx
+++ b/apps/web/src/components/diffs/DiffCommentAnnotation.tsx
@@ -1,5 +1,5 @@
 import { MessageCircle, Trash2 } from "lucide-react";
-import { useState, type ReactNode } from "react";
+import { useLayoutEffect, useRef, useState, type ReactNode } from "react";
 
 import { Button } from "~/components/ui/button";
 import { Textarea } from "~/components/ui/textarea";
@@ -25,6 +25,7 @@ interface DiffCommentAnnotationProps {
   submitLabel?: string;
   pending?: boolean;
   secondaryAction?: DiffCommentSecondaryAction;
+  focusOnMount?: boolean;
 }
 
 /** The shared inline comment treatment for file previews, thread diffs, and pull-request diffs. */
@@ -40,10 +41,20 @@ export function DiffCommentAnnotation({
   submitLabel = "Comment",
   pending = false,
   secondaryAction,
+  focusOnMount = true,
 }: DiffCommentAnnotationProps) {
   const [localDraftText, setLocalDraftText] = useState("");
   const displayedText = kind === "draft" && !onTextChange ? localDraftText : text;
   const trimmedText = displayedText.trim();
+  const textareaRef = useRef<HTMLTextAreaElement | null>(null);
+
+  useLayoutEffect(() => {
+    if (kind !== "draft" || !focusOnMount) return;
+    const frame = window.requestAnimationFrame(() => {
+      textareaRef.current?.focus({ preventScroll: true });
+    });
+    return () => window.cancelAnimationFrame(frame);
+  }, [focusOnMount, kind]);
 
   if (kind === "comment") {
     return (
@@ -78,9 +89,10 @@ export function DiffCommentAnnotation({
       onPointerDown={(event) => event.stopPropagation()}
     >
       <Textarea
-        autoFocus
+        ref={textareaRef}
+        autoFocus={focusOnMount}
         unstyled
-        className="relative inline-flex w-full rounded-md border border-border/50 bg-background/20 font-sans text-foreground transition-colors focus-within:border-border/70 [&_[data-slot=textarea]]:min-h-12 [&_[data-slot=textarea]]:cursor-text [&_[data-slot=textarea]]:px-2.5 [&_[data-slot=textarea]]:py-1.5 [&_[data-slot=textarea]]:font-sans [&_[data-slot=textarea]]:text-xs [&_[data-slot=textarea]]:leading-5 max-sm:[&_[data-slot=textarea]]:min-h-12"
+        className="relative inline-flex w-full rounded-md border border-border/50 bg-background/20 font-sans text-foreground transition-colors focus-within:border-border/70 [&_[data-slot=textarea]]:min-h-12 [&_[data-slot=textarea]]:cursor-text [&_[data-slot=textarea]]:caret-foreground [&_[data-slot=textarea]]:px-2.5 [&_[data-slot=textarea]]:py-1.5 [&_[data-slot=textarea]]:font-sans [&_[data-slot=textarea]]:text-xs [&_[data-slot=textarea]]:leading-5 max-sm:[&_[data-slot=textarea]]:min-h-12"
         size="sm"
         value={displayedText}
         placeholder={placeholder}
diff --git a/apps/web/src/components/files/FilePreviewPanel.tsx b/apps/web/src/components/files/FilePreviewPanel.tsx
index 0ad18434d7e7..1160517a68cf 100644
--- a/apps/web/src/components/files/FilePreviewPanel.tsx
+++ b/apps/web/src/components/files/FilePreviewPanel.tsx
@@ -773,42 +773,47 @@ function EditableFileSurface({
     ],
   );
 
-  const beginComment = useCallback((range: SelectedLineRange) => {
-    const { startLine, endLine } = normalizeFileCommentRange(range);
-    const draftEntry: FileCommentAnnotationEntry = {
-      id: nextFileCommentId(),
-      kind: "draft",
-      startLine,
-      endLine,
-      text: "",
-    };
-    setLineAnnotations((current) => {
-      const withoutDraft = current.flatMap((annotation) => {
-        const entries = annotation.metadata.entries.filter((entry) => entry.kind !== "draft");
-        return entries.length > 0 ? [{ ...annotation, metadata: { entries } }] : [];
+  const beginComment = useCallback(
+    (range: SelectedLineRange) => {
+      editor.setSelections([]);
+      editor.blur();
+      const { startLine, endLine } = normalizeFileCommentRange(range);
+      const draftEntry: FileCommentAnnotationEntry = {
+        id: nextFileCommentId(),
+        kind: "draft",
+        startLine,
+        endLine,
+        text: "",
+      };
+      setLineAnnotations((current) => {
+        const withoutDraft = current.flatMap((annotation) => {
+          const entries = annotation.metadata.entries.filter((entry) => entry.kind !== "draft");
+          return entries.length > 0 ? [{ ...annotation, metadata: { entries } }] : [];
+        });
+        const existingIndex = withoutDraft.findIndex(
+          (annotation) => annotation.lineNumber === endLine,
+        );
+        if (existingIndex < 0) {
+          return [
+            ...withoutDraft,
+            {
+              lineNumber: endLine,
+              metadata: { entries: [draftEntry] },
+            },
+          ];
+        }
+        return withoutDraft.map((annotation, index) =>
+          index === existingIndex
+            ? {
+                ...annotation,
+                metadata: { entries: [...annotation.metadata.entries, draftEntry] },
+              }
+            : annotation,
+        );
       });
-      const existingIndex = withoutDraft.findIndex(
-        (annotation) => annotation.lineNumber === endLine,
-      );
-      if (existingIndex < 0) {
-        return [
-          ...withoutDraft,
-          {
-            lineNumber: endLine,
-            metadata: { entries: [draftEntry] },
-          },
-        ];
-      }
-      return withoutDraft.map((annotation, index) =>
-        index === existingIndex
-          ? {
-              ...annotation,
-              metadata: { entries: [...annotation.metadata.entries, draftEntry] },
-            }
-          : annotation,
-      );
-    });
-  }, []);
+    },
+    [editor],
+  );
   const hasOpenCommentForm = lineAnnotations.some((annotation) =>
     annotation.metadata.entries.some((entry) => entry.kind === "draft"),
   );