Multiple Devices and Sync
Prisma Calendar works on every device your vault is synced to — desktop, laptop, tablet, phone — with any file-level sync tool: Self-hosted LiveSync, Obsidian Sync, iCloud, Syncthing, Google Drive, or git. Prisma does not coordinate devices with each other. Instead, everything it does on its own is deterministic: given the same notes and the same settings, every device computes the same file names and the same property values, so when the sync tool merges the two sides there is nothing to conflict over.
What Prisma does on its own
These are the automatic writes — the ones that happen without you clicking anything — and how each stays identical across devices:
| Automatic write | What makes it the same everywhere |
|---|---|
| Recurring instance notes | The file name is a function of the series id and the date (Standup 2026-09-04-<id>.md), so two devices generate the same file. If the other device's copy arrives while an instance is being created, that copy is used as-is — never re-created with a 1 suffix. |
Series id (RRuleID) | Derived from the source note: its ZettelID when the name carries one, otherwise a stable hash of its path. Two devices that both index a new series before the other's write has synced agree on the id. An id that a sync conflict changed on disk is adopted, and the instances are migrated to it. |
| Marking past events done | Writes the configured done value and nothing else — no timestamp — so both devices produce byte-identical files. Which device writes first only depends on which one is open. |
| Sort Date | Computed from the event's own start and end strings, never from the device clock or timezone. An all-day event's date is the same on every device. |
| Calendar Title | Computed from the file path. |
| CalDAV and ICS event notes | The file name is derived from the remote event UID, so every device names the note the same way and sync never sees two copies. |
| Duplicate cleanup | When two notes hold the same recurring instance or the same synced CalDAV/ICS event (UID), every device keeps the same survivor — the canonical name: the shortest path, then the alphabetically first — and trashes the other. |
| Property order | Prisma's own properties are written in the order configured under Properties, so files converge to identical bytes. |
Anything you do yourself — editing a note on two devices at once — is the sync tool's job to merge, exactly as with any other note.
What to sync
- Your notes — of course.
- Prisma's settings (
.obsidian/plugins/prisma-calendar/data.json). The property order, the done value, the recurring-instance count and the property names are inputs to every automatic write; devices with different settings produce different files. Most sync tools sync plugin settings by default; LiveSync needs Sync hidden files / plugin settings sync turned on. - Do not sync per-device state. Prisma keeps CalDAV sync tokens and the Writer/Reader choice in the browser's local storage, where each device can differ safely.
How automatic writes reach your notes
Every automatic write goes through one queue per note: it waits until Obsidian has finished indexing the vault, runs after any earlier write to the same note, writes Prisma's properties in the configured order, and is dropped when the note already holds exactly what it would write. A note another device already updated is therefore never rewritten just to end up identical, and a write queued for a note that is renamed in the meantime follows the note.
Limiting writes to one device
On first setup Prisma asks whether the device is a Writer or Reader. Choose Writer for a single device or your primary device—the one you use most. You can also use Writer on every device when the vault is not open simultaneously. If concurrent use produces conflicts, use Reader mode on the other devices. A Reader shows and lets you edit events normally, but performs no automatic writes of its own: no recurring instances, no marking done, no Sort Date or Calendar Title normalisation, no automatic ZettelID assignment, no CalDAV/ICS sync, no series propagation, no time-tracker progress saves, no reminder flags. Edits you make by hand are written as usual.
The choice lives in browser-local storage, never in the vault. Closing the prompt leaves the choice unresolved and uses safe Reader behavior for that session; Prisma asks again next startup and shows a warning under Settings → General.
Current Prisma versions derive recurring-series and integration-event identities from synchronized inputs, so equivalent automatic writes converge. Conflicts can still occur when plugin versions or settings differ, templates insert the current time or random values, or notes are edited concurrently. Avoiding simultaneous use substantially reduces those risks; if you see them during concurrent use, change the other devices to Reader.
What to be aware of
Everything above holds for the notes Prisma writes on its own. A few situations still depend on timing or on the device, and are worth knowing about:
- Auto-assigned ZettelIDs come from the device clock. With Auto-assign ZettelID on, each device renames an un-IDed note the moment it indexes it. If two devices index the same new note before the other's rename has synced, the note ends up with two names, one per device, and the duplicate stays. Create notes on one device, or turn auto-assign on (and Read-only mode off) on one device only. Deriving the id from the note itself is planned.
- Prisma waits for Obsidian's index, not for the sync tool. A device coming back online starts generating instances and marking events done from the notes it has, before the sync tool has delivered the latest changes. The results converge once they arrive — identical files merge, a changed recurrence rule regenerates its instances — but you may see a short burst of activity. A start that also waits for the sync tool is planned; sync tools that sync on launch (LiveSync with Sync on start, Obsidian Sync) keep the window short.
- Editing a series while another device is online. A change to a recurring source propagates to its instances on the device where you made it; the other device receives the changed files and, finding the values already equal, writes nothing. Changing the same series on two devices at the same time is a user conflict like any other note edit.
- The time tracker runs on one device. Its progress is saved into the event's end time from the device where you started it. Another device that has the vault open and Mark past instances as done enabled may mark the tracked event done once that saved end time passes; unmark it from the event menu if it does.
- Reminders fire on every device that has the vault open — see below.
- Different timezones. Event times are stored as wall-clock strings without a zone, so a 09:00 event shows at 09:00 on every device, and an all-day date never shifts. A device that travels between zones keeps every event at its wall-clock time.
These lists shrink as the planned changes land; the changelog announces each one.
Reminders on several devices
A reminder fires on every device that has the vault open at that moment; each one shows its own notification and writes the same Already Notified flag, so the note converges. Prisma does not elect one device to own reminders — there is no reliable way to tell which device you are looking at.
Templater and other plugins
An automatic write is only deterministic if everything it copies is. A Templater template that inserts the current time or a random value into recurring instances makes each device's copy different, and the sync tool will report a conflict on such notes. Keep instance templates free of tp.date.now()-style calls, or generate instances on one device only.
Related
- Integrations → Syncing and vault indexing — nothing is written before Obsidian has finished indexing.
- Properties → Property order — byte-identical frontmatter.
- Recurring events — how instances are generated.