File Recovery

Lumi maintains two independent recovery systems (automatic background saves and manual incremental checkpoints), both accessible from a single dialog.

Access

File → Recover Image

The dialog opens pre-populated with recovery states for the currently open file. Use the file chooser at the top to switch to a different .lum file.

Autosave

Lumi saves a background snapshot of your work at regular intervals while editing. Autosaves are written to a separate cache directory, leaving the working .lum file untouched:

~/.cache/lumi/autosave/~home~user~projects~my-painting.lum/

The path encoding uses ~ as a separator to create a unique cache directory per file. This means autosaves are available even if the project file itself is lost or corrupted.

• Frequency: Configurable in Edit → Preferences → Performance → Autosave interval.
• Storage location: Also set in Preferences → Performance.
• Purpose: Crash recovery. The Autosave tab in the Recover Image dialog shows available autosave states with timestamps.

When you open a file that has newer autosave data, Lumi notifies you at open time.

Incremental Saves

Incremental saving is a manual checkpoint system stored inside the project file under recovery/. The structure is:

my-painting.lum/recovery/
  └── primary-01.lum/       (full baseline, created on first Ctrl+I)
      ├── delta-0001.lum/   (Ctrl+I checkpoint, only modified buffers)
      ├── delta-0002.lum/
      └── ...

A new primary-NN.lum/ baseline is written after File → Save. Subsequent File → Save Increment presses (Ctrl+I) create delta-NNNN.lum/ subdirectories containing only the buffers that changed since the last baseline. Autosave deltas and manual save deltas use separate counters so they do not interfere with each other’s history.

Save Increment is always available for saved .lum files:

1. Use File → Save (Ctrl+S) to create or update the main project file.
2. Use File → Save Increment (Ctrl+I) to create a recovery checkpoint.
3. After another full File → Save, the next Ctrl+I writes a fresh primary-NN.lum/ baseline before creating new deltas.

Recovered files named with the RECOVERED_ prefix must be saved normally first before Save Increment becomes available for them.

When you open a .lum file that has newer incremental saves than the primary save, Lumi shows an Incremental Save Detected prompt offering to load the most recent checkpoint.

Recover Image Dialog

The dialog has three tabs and two action buttons.

Autosave Tab

Lists all available autosave states for the selected file with timestamps and thumbnails (where available). Select a state and click Recover to open it.

Use this tab to:

• Recover after a crash.
• Revert to an earlier state from the same session.

Incremental Tab

Lists all checkpoint states stored inside the project file. Each entry shows the checkpoint timestamp. Select a checkpoint and click Recover to open it.

Use this tab to:

• Return to an earlier point in a session without having saved separate files.
• Browse through the version history of a project.

Latest Tab

The default tab when the dialog opens. Automatically identifies the newest available recovery state across both autosaves and incremental checkpoints, and shows its timestamp. Click Recover to load it immediately without browsing individual states.

Buttons

Clean Up Old States

Accumulating recovery states over time can consume significant disk space. The Clean Up Old States… button (bottom-left of the dialog) opens a cleanup prompt for the active tab (Autosave or Incremental).

The prompt shows:

• How many full saves exist for the file.
• The total disk space they occupy.
• A Keep most recent spin button to select how many saves to retain.

Setting Keep most recent to 0 deletes all recovery states. The next Ctrl+I after a full cleanup will write a fresh primary save.

Startup Recovery

On startup, if Lumi detects that the most recently opened file has newer autosave data than the last full save, it presents a recovery prompt before loading. You can accept (load the autosave) or dismiss (open the primary save as normal).