Resume sessions

[dawoodkhan82]

Description

Quick summary: an active queued job can now survive a refresh or short connection drop without being submitted again.

• While a job is running, the UI saves its session and event ID. On reload it reconnects to the same app/session, resumes that event, replays the pending output, then acknowledges it and clears the recovery state.
• This only applies to an in-flight job. Once the result has been shown, a normal later refresh starts clean and does not restore the user’s last output.
• Restored sessions are checked against the current app so state cannot leak between different apps on the same origin.
• The queue stream handoff was tightened so a normal stream close is not treated like a disconnect, and chained events reopen the stream after they join the queue.
• Existing clients keep the old behavior unless session resume is enabled, and normal load events still run immediately when there is nothing to resume.

Closes: #13584
Closes: #8368

Screen.Recording.2026-07-16.at.3.36.05.PM.mov

AI Disclosure

• I used AI to help review the issue, implementation, tests, and PR text. I self-reviewed the changes.
• I did not use AI

Testing and Formatting Your Code

• Client browser and Node unit tests
• Queue backend tests
• Existing functional tests in SSR and non-SSR mode
• Offline refresh and reconnect demo flow
• Frontend formatting, type checks, and builds

No Playwright tests were added.

[gradio-pr-bot]

🪼 branch checks and previews

•	Name	Status	URL
	Spaces	ready!	Spaces preview
	Website	ready!	Website preview
	Storybook	ready!	Storybook preview
🦄	Changes	detected!	Details

---

Install Gradio from this PR

pip install https://huggingface.co/buckets/gradio/pypi-previews/resolve/9df64cc56de2a16b1470e151150181f0d8d1bba5/gradio-6.20.0-py3-none-any.whl

Install Gradio Python Client from this PR

pip install "gradio-client @ git+https://github.com/gradio-app/gradio@9df64cc56de2a16b1470e151150181f0d8d1bba5#subdirectory=client/python"

Import Gradio JS Client from this PR via CDN

import { Client } from "https://huggingface.co/buckets/gradio/npm-previews/resolve/9df64cc56de2a16b1470e151150181f0d8d1bba5/browser.js";

[gradio-pr-bot]

🦄 change detected

This Pull Request includes changes to the following packages.

Package	Version
@gradio/client	minor
gradio	minor

---

• Resume queued jobs and restore undelivered output after temporary disconnects or page refreshes

---

Something isn't right?

• Maintainers can change the version label to modify the version bump.
• If the bot has failed to detect any changes, or if this pull request needs to update multiple packages to different versions or requires a more comprehensive changelog entry, maintainers can update the changelog file directly.