So you don’t have to worry about disk space every time you save — introducing REFLO’s delta

While introducing REFLO’s features so far — especially in the timeline post — I talked about “a record that stacks by itself, without you touching it.” Hearing that, some of you may have worried: “If saves keep stacking like that, how much space does it actually take?” Today I want to talk about the feature that answers that question: delta.

A moment almost everyone has had

Files you work on in Photoshop or Illustrator are never light. As layers stack and images attach, a single file can jump to hundreds of megabytes, even well into the gigabytes. So what happens if every save copies that heavy file all over again, whole? Save fifty times in a day, and tens of gigabytes pile up in no time.

A lot of people have the habit of copying files “just in case,” and at the same time have watched that habit fill storage almost immediately. The moment you see the laptop-storage-full warning and start deleting old backup files one by one, wishing you didn’t have to. The moment a cloud-storage-full notice makes you debate which file to delete. Almost everyone has had that.

That burden is why we built delta

When we made the timeline we promised “it’s recorded automatically every time you save.” To keep that promise, there was a problem we had to solve alongside it. If denser records made users hesitate to save because of disk space, the timeline would have missed the point.

Stacking a full copy of the whole file every time would, no matter how good the timeline, still put the burden on the user. It would be like saying “save with peace of mind” and then making them worry about storage behind the scenes.

“How do we leave a dense record, and still keep the space light?”

That’s the question where delta started.

What delta is after

The goal is clear. Even if you save often and densely, it shouldn’t use as much storage as copying the whole file. Reduce the burden of calculating capacity or deleting old records you wish you could keep, and let the timeline keep stacking naturally.

How delta works

“Delta” originally means “amount of change” in mathematics. In REFLO the meaning is similar. Instead of copying the whole file again on every save, the file is split into pieces (chunks), overlapping pieces from the previous version are reused, and only the pieces that changed are newly recorded. (Right now that’s byte-level chunking; comparison that understands format — layers, slides, and so on — is an area we’ll keep refining.)

Take a thick dictionary as an example. If every revised edition reprinted the entire dictionary from scratch, it would take an enormous amount of paper and money. In practice it’s far more efficient to reprint only the pages that changed and slot them into the existing edition. REFLO’s delta is similar. From the version you just saved, it keeps only the chunks that are newly needed.

What delta looks like

Delta is not always on by default. It runs when you turn on local-history delta in settings (usually aimed at large files of several megabytes or more). Small files, and periodic full-snapshot (keyframe) stretches, can still use a full save.

1. Once it’s on, the save UX stays the same

With delta on in settings, from the user’s point of view it’s no different from hitting save as usual. Behind the scenes, REFLO picks out only the chunks that changed and stores them efficiently.

2. When you open the timeline, it’s still a complete version

Just because it was saved as a delta doesn’t mean that opening some past moment shows you only a fragment. The stored differences are stitched together, so whichever point you pick on the timeline, you can check and restore the complete file as it was at that moment. The storage method got more efficient; the result the user gets is the same.

3. Smaller edits make an even lighter record

Most saves inside a single work session aren’t the whole file changing from scratch; they’re small changes — a bit of color, moving one layer. Because delta reuses overlapping chunks for those small changes, even saving dozens of times in one session often stays much lighter than copying the whole file dozens of times.

What’s next

Right now we’re refining delta as a byte-chunk approach that can work across file formats, but PSD, AI, docx, xlsx, and pptx each have different internal structures, so we keep working on finding “what actually changed” more precisely by format. The more efficiency we can pull per format, the less users will have to worry about capacity.

And although savings after turning delta on mostly happen quietly in the background, we’re also considering letting users see for themselves, when they want, “this is how much space you saved.” If you can see how much is being saved, the confidence that it’s okay to save with peace of mind should grow.

Closing

Delta is a quiet feature that doesn’t show much on screen. But it helps keep the promise from the timeline post — “the hand that hits save shouldn’t tremble” — without stacking large files only as wholes. Behind the comfort of being able to save as much as you like sits this choice that saves space.

Thank you for reading.