fix: Livechat-Add check for scrollPosition before restoring scroll

[shacky]

Mobile - after loading widget with delay, website scrolls to top. This is unintended behaviour caused by this line of code. We should not call it without checking if scrollPosition has been saved.

Summary by CodeRabbit

• Bug Fixes
  • Fixed scroll position restoration when exiting the livechat widget's mobile full-screen mode. Scroll position is now correctly restored only when a previously saved position exists, preventing unexpected scroll behavior on mobile devices.

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Run ID: ef3adb63-71a0-4a70-909a-f5e1306202ba

📥 Commits

Reviewing files that changed from the base of the PR and between 9760d84 and 6026821.

📒 Files selected for processing (1)

• packages/livechat/src/widget.ts

📜 Recent review details

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• GitHub Check: cubic · AI code reviewer

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📓 Path-based instructions (1)

**/*.{ts,tsx,js}

📄 CodeRabbit inference engine (.cursor/rules/playwright.mdc)

**/*.{ts,tsx,js}: Write concise, technical TypeScript/JavaScript with accurate typing in Playwright tests
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Files:

• packages/livechat/src/widget.ts

🧠 Learnings (3)

📓 Common learnings

Learnt from: smirk-dev
Repo: RocketChat/Rocket.Chat PR: 39625
File: apps/meteor/app/api/server/v1/push.ts:85-97
Timestamp: 2026-03-14T14:58:58.834Z
Learning: In RocketChat/Rocket.Chat, the `push.token` POST/DELETE endpoints in `apps/meteor/app/api/server/v1/push.ts` were already migrated to the chained router API pattern on `develop` prior to PR `#39625`. `cleanTokenResult` (which strips `authToken` and returns `PushTokenResult`) and `isPushTokenPOSTProps`/`isPushTokenDELETEProps` validators already exist on `develop`. PR `#39625` only migrates `push.get` and `push.info` to the chained pattern. Do not flag `cleanTokenResult` or `PushTokenResult` as newly introduced behavior-breaking changes when reviewing this PR.

📚 Learning: 2026-02-26T19:25:44.063Z

Learnt from: gabriellsh
Repo: RocketChat/Rocket.Chat PR: 38778
File: packages/ui-voip/src/providers/useMediaSession.ts:192-192
Timestamp: 2026-02-26T19:25:44.063Z
Learning: In the Rocket.Chat repository, do not reference Biome lint rules in code review feedback. Biome is not used even if biome.json exists; only reference Biome rules if there is explicit, project-wide usage documented. For TypeScript files, review lint implications without Biome guidance unless the project enables Biome rules.

Applied to files:

• packages/livechat/src/widget.ts

📚 Learning: 2026-02-26T19:25:44.063Z

Learnt from: gabriellsh
Repo: RocketChat/Rocket.Chat PR: 38778
File: packages/ui-voip/src/providers/useMediaSession.ts:192-192
Timestamp: 2026-02-26T19:25:44.063Z
Learning: In this repository (RocketChat/Rocket.Chat), Biome lint rules are not used even if a biome.json exists. When reviewing TypeScript files (e.g., packages/ui-voip/src/providers/useMediaSession.ts), ensure lint suggestions do not reference Biome-specific rules. Rely on general ESLint/TypeScript lint rules and project conventions instead.

Applied to files:

• packages/livechat/src/widget.ts

🔇 Additional comments (1)

packages/livechat/src/widget.ts (1)

153-155: Good guard before restoring scroll state.

Line 153 now correctly restores document.documentElement.scrollTop only when a prior scrollPosition exists, which prevents the unintended jump-to-top path.

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Walkthrough

Added a null/undefined check before restoring scroll position during mobile small-screen mode exit. The code now only sets document.documentElement.scrollTop when scrollPosition is defined, preventing assignment of uninitialized values.

Changes

Cohort / File(s)	Summary
Mobile Scroll Restoration Fix packages/livechat/src/widget.ts	Added conditional check to restore scroll position only when scrollPosition is defined, preventing uninitialized value assignment during small-screen mode exit.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

Suggested labels

type: bug

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the main change: adding a check for scrollPosition before restoring scroll in the Livechat widget, which directly addresses the bug fix described in the PR objectives.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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[cubic-dev-ai]

No issues found across 1 file