Offline, only when asked

On 24 October 2026 littlebluepilot.com gained one service worker for the whole site, and from a reader’s first page it began saving an offline copy in the background: the homepage, the storybook, the music pages, every song’s page and Ask Little Blue, with the pictures and code they need. On 28 October that stopped. A first visit now saves nothing. The offline copy is made when a reader asks for it, with a button called “Save for offline”, and at no other time.

This entry is about that change: what the copy was, what the site does now, what we measured on 30 October, and what a family gives up in return. The site’s records say what changed and how it was checked. They do not say why, and we do not supply a reason after the fact.

What a first visit used to download

Two days before the change, on 26 October, we read the live worker’s list of files. It named 138 files, 7.04 MB before compression, and every family that opened a page fetched them in the background, whether or not they would ever be offline. The Website Changed. The Story Didn’t., published that day, called the figure “more than a phone should spend without being asked”. The offline guide in Learn set out the usual remedies: keep only the site’s shell when the worker installs, keep everything else as it is read, and skip the download when a browser reports that its reader wants to save data.

The change took none of those routes. It moved the question from how much a first visit should download to whether it should download anything at all.

What the site does now

The site’s header has a button for its reading and offline preferences. The dialog it opens holds three choices: the reading light (Daylight or Twilight), whether things on the page move, and a section called “A little trip offline”, which says what saving keeps and what it never keeps:

Save the storybook, the music pages, Ask Little Blue and the pages you visit next on this device, so they open without the internet. The songs, the films and the music services are never saved and still need a connection. Saving never includes anything you type, draw or add.

Until the button is pressed, the line beneath it reads “Offline saving is off. Nothing is saved on this device.”

Pressing “Save for offline” registers the worker, and the worker fetches the whole copy before it reports anything: saving is all or nothing. While it works, the dialog says “Saving the storybook, the music pages and Ask Little Blue on this device…”. When it has finished, it says what it holds:

Saved on this device: 132 files, about 6.2 MB. Pages you open next are saved too. Songs and films still need the internet.

From then on the site behaves as it did before 28 October. Pages come from the network first and are kept as they are read, up to the last 80 pages and 400 of the files they use. Code and pictures come from the saved copy first. Sound and film are never kept. A page that was never kept, opened with no connection, gets the site’s offline page, which says what is available. “Clear saved pages & preferences”, in the same dialog, removes the worker, every saved copy and the reading preferences together.

Two things did not change. The site still has one worker, written by its build, and only one way to install it. And the privacy page still states the size of the offline copy, with the build failing if the real figure drifts more than a quarter of a megabyte from what the page says.

What we measured

On 30 October we checked the live site in a browser that held nothing from it: no worker, no saved copy and nothing in its local storage.

1. A visit. We opened the homepage and the page for grown-ups. No worker was registered, no request was made for one, nothing was saved and nothing was written to local storage.
2. Saving. Pressing “Save for offline” produced the message above after about 19 seconds on our connection. The browser’s storage then held 132 files and 6,226,756 bytes from the site.
3. Saving again. A second press reported the same within about a second.
4. Reading on. Opening the Sky Map afterwards kept that page and three of its files, and the dialog added “and 1 more page kept as you read”.
5. Clearing. “Clear saved pages & preferences” answered “Saved pages and reading preferences are cleared from this browser.” No worker, no saved copy and nothing in local storage remained.

This is what the 132 files are, by the size each is stored at:

What	MB	Share
Pictures, one size of each	3.48	56%
Pages	1.55	25%
Fonts	0.38	6%
Scripts	0.31	5%
Ask Little Blue’s questions and answers	0.29	5%
Stylesheets	0.19	3%
Icons and the app manifest	0.04	1%

The shares are rounded, so they add to slightly more than 100. The sizes are before compression: pages, scripts, stylesheets and Ask Little Blue’s answers travel compressed, so the download is smaller than 6.2 MB. We did not measure it on the wire.

The copy is also smaller than the one a first visit fetched on 26 October: 132 files against 138, and about 0.8 MB less. Comparing the two lists of files, most of the difference is pictures the same redesign stopped using: the footer paintings, four of them at two sizes each, and the 366 KB painting the old menu showed on every page, about 0.7 MB between them. Four smaller pictures were added, about 0.1 MB in all; the rest of the difference is two more pictures that were dropped and code that was rebuilt.

What a family gives up

The old behaviour had one real advantage. A family who had visited once could lose their signal later, in a car or on a train, and still open the storybook without ever having thought about it. That is gone. A family who never presses the button has no offline copy, and with no worker on the device, a page that cannot load shows the browser’s own offline error rather than the site’s offline page, because the site has nothing on the device to answer with.

The button is also one step away from any page: it sits in a dialog behind the preferences button in the header, so a grown-up has to know to look for it. We have not tested whether families find it.

What a family gains is just as plain. A first visit costs only the page being read. Nothing is stored that a reader did not choose to store. And when a reader does choose, the dialog says how much it kept, in files and megabytes, and offers the button that removes it in the same place.

Browsers that saved without being asked

Between 24 and 28 October, every visit installed the worker. Those browsers keep it. The only record of a choice to save is the worker itself, so the site cannot tell a reader who received it on a visit from one who pressed the button, and it treats them the same: the worker updates as any other would, the dialog says that saving is on, and “Clear saved pages & preferences” removes it. Their saved pages were kept through the change.

How it was checked

The site’s own verification of the change, on 28 October and before it went live, covers more than our measurement could:

• A first visit registered nothing and requested no worker.
• A second press of the button fetched nothing. With two saved files deleted, the dialog said so, and the worker fetched exactly those two again.
• A file that failed during saving left no worker and no saved copy behind, and the dialog reported the failure. An update interrupted halfway left the previous copy in charge and working offline.
• With no connection, the homepage, the storybook, Ask Little Blue, the music pages, both records’ pages and a song page opened, by a full load and by the site’s own in-page navigation.
• After “Clear”, moving around the site saved nothing again.
• A browser that carried the worker from before 28 October moved to the new one without a click and kept its pages.
• In Firefox, saving, kept pages and in-page navigation worked offline. The site’s offline page did not appear in the automated Firefox run, which was also true before the change.

Not tested: real phones and tablets, Safari on any device, and the site installed as an app. Every check above, ours included, ran in desktop browsers, most of them automated.

Where to go next

• Try it: open the reading and offline preferences on littlebluepilot.com, from the button in the header.
• How the worker is built: Building offline-first experiences for families, which describes what it keeps and how its versions are managed.
• The rebuild that introduced it: The Website Changed. The Story Didn’t.