fix(sistent): preserve sidebar scroll position across navigation

[dhruveshmishra]

Description

This PR fixes #7911
Preserves the scroll position of the Sistent TOC sidebar across page navigations by storing the scroll offset in sessionStorage on scroll and restoring it on component mount.

Screen recording

Screen.Recording.2026-08-05.at.12.44.09.AM.mov

Summary by CodeRabbit

• Bug Fixes
  • Preserved the table of contents scroll position when navigating away and returning to a page.
  • Restored the previous scroll position automatically for a smoother navigation experience.

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

This PR addresses #7911 by preserving the Sistent TOC sidebar’s scroll position across page navigations using sessionStorage.

Changes:

• Add a ref to the TOC list container so its scrollTop can be read/written.
• Persist the TOC scroll offset to sessionStorage on scroll.
• Restore the previous scroll offset on mount via useEffect.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 9fa19e48-52b0-43bc-8441-7bf7b514d859

📥 Commits

Reviewing files that changed from the base of the PR and between a8ab03b and f14803f.

📒 Files selected for processing (1)

• src/components/SistentNavigation/index.js

🚧 Files skipped from review as they are similar to previous changes (1)

• src/components/SistentNavigation/index.js

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📝 Walkthrough

Walkthrough

The navigation component tracks the TOC list with a ref. It restores the saved scroll position from sessionStorage on mount and saves the current position when the list scrolls.

Changes

TOC scroll position persistence

Layer / File(s)	Summary
Restore and save TOC scroll position src/components/SistentNavigation/index.js	The component imports useEffect and useRef, restores sistent-toc-scroll on mount, and saves the TOC scroll position during scrolling. Storage errors are handled without interrupting navigation.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes preserving the Sistent sidebar scroll position across navigation.
Linked Issues check	✅ Passed	The changes store and restore the sidebar scroll position, which satisfies issue #7911.
Out of Scope Changes check	✅ Passed	The changes are limited to sessionStorage-based sidebar scroll preservation in the navigation component.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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• Create PR with unit tests

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[coderabbitai]

🧹 Nitpick comments (1)

src/components/SistentNavigation/index.js (1)

81-81: 🚀 Performance & Scalability | 🔵 Trivial | ⚡ Quick win

Coalesce the sessionStorage write during scrolling.

onScroll fires repeatedly during a continuous scroll. sessionStorage.setItem is synchronous, so this handler can reduce scroll responsiveness. Keep the latest offset in a ref and throttle or debounce the write. Flush the latest value before navigation if the write is deferred.

As per coding guidelines, “debounce or throttle expensive event handlers” and maintain or improve Core Web Vitals.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@src/components/SistentNavigation/index.js` at line 81, Update the toc-list
scroll handler in SistentNavigation to store the latest scrollTop in a ref and
coalesce sessionStorage writes through throttling or debouncing instead of
writing synchronously on every scroll event. Ensure the deferred latest offset
is flushed before navigation, while preserving the existing "sistent-toc-scroll"
persistence behavior.

Source: Coding guidelines

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@src/components/SistentNavigation/index.js`:
- Line 81: Update the toc-list scroll handler in SistentNavigation to store the
latest scrollTop in a ref and coalesce sessionStorage writes through throttling
or debouncing instead of writing synchronously on every scroll event. Ensure the
deferred latest offset is flushed before navigation, while preserving the
existing "sistent-toc-scroll" persistence behavior.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 2f3e7cda-a798-431d-9097-86994b40d50d

📥 Commits

Reviewing files that changed from the base of the PR and between a730e5f and a8ab03b.

📒 Files selected for processing (1)

• src/components/SistentNavigation/index.js