Preserve scroll when opening file viewer

Co-Authored-By: Paperclip <noreply@paperclip.ing>

ui/src/context/FileViewerContext.test.ts

@@ -2,10 +2,18 @@
 
 import { describe, expect, it } from "vitest";
 import {
+  FILE_VIEWER_NAVIGATE_OPTIONS,
   readFileViewerStateFromSearch,
   writeFileViewerStateToSearch,
 } from "./FileViewerContext";
 
+describe("FILE_VIEWER_NAVIGATE_OPTIONS", () => {
+  it("preserves page scroll when the viewer updates URL search params", () => {
+    expect(FILE_VIEWER_NAVIGATE_OPTIONS.preventScrollReset).toBe(true);
+    expect(FILE_VIEWER_NAVIGATE_OPTIONS.replace).toBe(false);
+  });
+});
+
 describe("readFileViewerStateFromSearch", () => {
   it("returns null when no file param is present", () => {
     expect(readFileViewerStateFromSearch("")).toBeNull();

ui/src/context/FileViewerContext.tsx

@@ -1,5 +1,5 @@
 import { createContext, useContext, useCallback, useMemo, type ReactNode } from "react";
-import { useLocation, useNavigate } from "@/lib/router";
+import { useLocation, useNavigate, type NavigateOptions } from "@/lib/router";
 import type { WorkspaceFileSelector } from "@paperclipai/shared";
 import type { ParsedWorkspaceFileRef } from "@/lib/workspace-file-parser";
 
@@ -31,6 +31,11 @@ export interface FileViewerContextValue {
 
 const FileViewerContext = createContext<FileViewerContextValue | null>(null);
 
+export const FILE_VIEWER_NAVIGATE_OPTIONS = {
+  replace: false,
+  preventScrollReset: true,
+} satisfies NavigateOptions;
+
 export function readFileViewerStateFromSearch(search: string): FileViewerUrlState | null {
   const params = new URLSearchParams(search);
   const path = params.get("file");
@@ -100,7 +105,7 @@ export function FileViewerProvider({ issueId, children }: FileViewerProviderProp
     (nextSearch: string) => {
       navigate(
         { pathname: location.pathname, hash: location.hash, search: nextSearch },
-        { state: location.state, replace: false },
+        { ...FILE_VIEWER_NAVIGATE_OPTIONS, state: location.state },
       );
     },
     [location.hash, location.pathname, location.state, navigate],