Undo/Redo System

Prisma Calendar features a powerful and reliable undo/redo system for every action you take. You can confidently make changes, knowing you can easily reverse them.

Per-Planning-System History

Each planning system has its own independent history. This means:

• Actions in one planning system don't affect another's undo history.
• The system remembers your last 100 actions for each planning system. Beyond that, the oldest entry drops off.
• Redo re-applies what you just undid. Once you do something new, the redo hotkey has nothing left to redo, as in most apps — but the undone operations aren't thrown away: they stay in the log, and you can still re-apply any of them from Operation history.

How to Use

Simply use Obsidian's hotkeys for undo and redo.

• Assign Shortcuts: Go to Settings -> Hotkeys and set your preferred shortcuts for Prisma Calendar: Undo and Prisma Calendar: Redo.
• Active Calendar: The undo/redo actions will always apply to the calendar pane you are currently focused on.

How Undo and Redo Pick a Step

Think of your history as a stack of sticky notes, one for each thing you did. Every note is either on (the change is in your note) or off (you undid it).

• Undo turns the newest on note off.
• Redo turns back on the note you just undid.
• Doing something new leaves Redo with nothing to bring back. The notes you undid before that stay in Operation history, but Redo skips them.

An example

You have an event, Workout, that ends at 8:00.

You do	Workout ends at	What Redo would bring back
Change the end to 9:00	9:00	nothing
Press Undo	8:00	the 9:00 change
Change the end to 10:00	10:00	nothing (you did something new)
Press Undo	8:00	the 10:00 change
Press Redo	10:00	nothing
Press Redo again	10:00	nothing, so you see "Nothing to redo"

Redo brings back 10:00, the change you just undid. It never jumps back to the 9:00 change you set aside before making a new one, so it can't overwrite your newer edit.

The 9:00 change isn't gone. It sits in Operation history marked Undone. If you want it back, click Redo on its row there, so you choose exactly what comes back.

Operation History

Undo and redo walk the stack one step at a time. The Operation history modal shows you the whole stack at once, so you can reach any operation directly.

Open it from the clock-rewind button in the calendar toolbar, or run Prisma Calendar: Show operation history (assign it a hotkey in Settings -> Hotkeys).

What you see

Every recorded operation, one row each, newest at the top — flip to oldest-first with the sort button. Each row shows:

• What happened — the action and the affected event, such as "Edit event: Team Meeting", "Delete event: Workout", or "Batch: 12 operations". A rename names both the old and new title.
• When — a relative time ("3 minutes ago"); hover for the exact timestamp.
• Applied or Undone — whether the operation is currently in effect.

The list is virtualized, so a full 100-entry log scrolls as smoothly as an empty one.

What you can do

• Undo / Redo one row — reverse (or re-apply) just that operation, leaving everything else alone. You can undo the twentieth-last operation and keep the nineteen that came after it. This is more surgical than Ctrl+Z, and correspondingly sharper: undoing a "create event" while a later edit to that same event is still applied leaves the edit pointing at a file that's gone. Prisma detects the common cases and refuses rather than corrupting anything, but prefer Revert to here when the operations are related.
• Revert to here — undo everything from the newest operation down to and including that row, newest first.
• Restore to here — the mirror: re-apply every undone operation from the oldest up to and including that row.
• Clear history — empty the log. This does not undo anything; it only forgets.

The log survives a restart, replay doesn't

The history log is saved on your device, so reopening Obsidian shows you what you did yesterday, with timestamps intact. Those older rows are marked Previous session and their Undo/Redo buttons are disabled.

That limit is deliberate. Undoing an edit means restoring the snapshot taken when it happened — and a snapshot from a previous session describes a vault that has since changed, possibly by your own hand or by sync from another device. Replaying it would silently overwrite everything you did in between. So history from earlier sessions is a record you can read, not a button you can press. Revert to here and Restore to here still work across such a row; they simply skip the entries that can't be replayed.

The log lives on the device, not in the vault, so it doesn't sync between machines — each device keeps its own record of what it did. Each vault keeps its own log too, so opening a second vault shows you that vault's history, not this one's. Deleting a planning system discards its log; the record only outlives a restart, not the calendar it describes.

What You Can Undo and Redo

Virtually every operation in the calendar is tracked, giving you complete control.

Single Event Actions

• Create Event: Undoing removes the newly created event file.
• Edit Event: Undoing reverts any changes made in the edit dialog.
• Delete Event: Undoing brings the deleted event right back.
• Clone Event: Undoing removes the cloned copy.
• Duplicate Current Event: Undoing removes the duplicated copy.
• Move Event: Undoing moves the event back to its original date.

Drag-and-Drop and Resizing

• Move by Dragging: Drag an event to a new day? You can undo it.
• Resize Duration: Lengthen or shorten an event by dragging its edge? You can undo that too.

Batch Operations

All batch selection operations are fully undoable, often as a single action:

• Batch Delete: Undo restores all selected events at once.
• Batch Duplicate: Undo removes all the duplicated copies.
• Batch Clone: Undo removes all cloned events from the target week.
• Batch Move: Undo moves the whole group of events back to their original dates.