storage.session: additional information is needed

### MDN URL

https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/storage/session

### What specific section or headline is this issue about?

storage.session

### What information was incorrect, unhelpful, or incomplete?

> When the browser stops, all session storage is cleared. When the extension is uninstalled, its associated session storage is cleared.

### What did you expect to see?

Testing shows that session storage is cleared when the extension is restarted (e.g. disabled and re-enabled).

I am verifying with Mozilla engineers whether the same happens when an extension is upgraded or not.
What happens on browser upgrade, should also be verified.

It would be helpful to include the above information.

---

**Update:**
I tested browser upgrade on Nightly.
Although browsing session is expected to be restored, extensions' session storage is lost in Nightly upgrade.

### Do you have any supporting links, references, or citations?

_No response_

### Do you have anything more you want to share?

_No response_

### MDN metadata

Page report details

* Folder: `en-us/mozilla/add-ons/webextensions/api/storage/session`
* MDN URL: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/storage/session
* GitHub URL: https://github.com/mdn/content/blob/main/files/en-us/mozilla/add-ons/webextensions/api/storage/session/index.md
* Last commit: https://github.com/mdn/content/commit/89d941878af42738cbd429acaa06789db7fa55f6
* Document last modified: 2025-08-01T02:43:21.000Z

Open files/en-us/mozilla/add-ons/webextensions/api/storage/session/index.md and review the existing statement about when session storage is cleared. Compare it with the lifecycle behavior and testing details described in the issue, including extension restart, extension upgrade, and browser upgrade; done means the page accurately documents the verified behavior and distinguishes any behavior that still needs confirmation.

Written by the indexing model from the issue text.