Data Storage¶

Osmosis has no database. Every card, every schedule, every map style, and every review you have ever recorded is text in your vault — which is what makes the whole thing sync, back up, diff, and outlive the plugin.

This page is the complete map of what gets written where.

What Lives Where¶

Data	Written to
Card content	The `osmosis` fence, or the note's own lines
Fence card schedules	The fence header
Line card schedules	`osmosis-schedule` in the note's frontmatter
Occlusion masks	The fence header, or `osmosis-schedule`
Map layout and node styles	`osmosis-styles` in the note's frontmatter
Deck assignment	Folder path, `osmosis-deck` frontmatter, or `deck:` fence metadata
Review history	Markdown shards in the review log folder
Plugin settings, custom themes, panel order	`.obsidian/plugins/osmosis/data.json`

Fence Cards¶

Metadata sits at the top of the fence, above a blank line. Scheduling fields are added by Osmosis after the first review:

```osmosis
id: abc123
deck: geography/europe
due: 2026-03-15T00:00:00.000Z
stability: 4.5
difficulty: 5.2
reps: 3
lapses: 0
state: review
last-review: 2026-03-10T00:00:00.000Z
learning-steps: 0

What is the capital of France?
***
Paris
```

Derived cards nest¶

A fence can produce more than one card: a bidirectional fence makes two, a cloze fence one per group, an occluded image one per shape group. Each of those keeps its own schedule in a nested block named for the card it belongs to:

```osmosis
id: rivers
r:
  due: 2026-08-20T09:00:00
  stability: 6.10
  state: review
c1:
  due: 2026-08-12T09:00:00
  stability: 4.21
  state: review
c2:
  due: 2026-08-14T09:00:00
  state: learning

The ==Nile== flows into the ==Mediterranean==
```

Key	Card
(top level)	The fence's own card
`r:`	The reverse card of a `bidi:` fence
`c1:`, `c2:`, …	Cloze deletion, code cloze, or occlusion group N

Older notes still load

Earlier versions wrote flat, prefixed keys (c1-due:, r-stability:). Those are still read, and converted to the nested form the next time that card's schedule is written. Nothing needs converting by hand.

Line Cards¶

Line cards are lines tagged with a native Obsidian block ID, and their schedules live in the note's frontmatter keyed by that ID:

---
osmosis-cards: true
osmosis-deck: coffee
osmosis-schedule:
  os-a1b2c3:
    due: 2026-07-22T10:30:00
    stability: 4.2
    difficulty: 5.1
    lastReview: 2026-07-15T09:12:00
    reps: 3
    lapses: 0
    state: review
    learningSteps: 0
  os-d4e5f6:
    disabled: true
---

The key is written lazily — after a card's first review, not when its ID is generated.
Writes are debounced and coalesced: rating a run of cards produces one frontmatter write, flushed at the end of the session.
Timestamps are ISO 8601 local datetimes, so the file stays readable.
disabled: true marks a card excluded from study.
An occluded line nests an occlude: block plus one schedule block per group.

Obsidian hides frontmatter in reading view and shows osmosis-schedule as a single non-editable property, so it stays out of your way.

Map Styles¶

Everything the properties sidebar sets is written to osmosis-styles in the same frontmatter — layout, theme, spacing, branch lines, and per-node overrides keyed by block ID. Because it travels in the note, sending someone the note sends them the map.

Review History¶

Every answer you give is appended to a review log: an append-only history that the stats dashboard reads. It lives in Osmosis/Reviews by default (Settings > Osmosis > Review log folder).

Shards¶

The log is split into one file per month per device:

Osmosis/Reviews/
  2026-07.desktop.md
  2026-08.desktop.md
  2026-08.pixel-10a.md

One writer per file, ever. That's what the device name is for: two devices reviewing on the same day write two different files, so a sync conflict cannot interleave them. Set the label under Settings > Osmosis > Device name, or leave it empty to detect one.

A shard is Markdown holding one JSON line per review:

Osmosis review log — pixel-10a, 2026-08. Generated file; do not edit.

```osmosis-reviews
{"device":"pixel-10a","install":"a3f9","v":2}
{"t":1754500000000,"c":"os-wcfb3w","r":3,"s":"review","iv":345600,"pi":86400,"st":12.3,"d":6.4,"e":4200,"m":"sequential"}
```

Field	Meaning
`t`	When you answered, epoch ms
`c`	Card ID
`r`	Rating — 1 Again, 2 Hard, 3 Good, 4 Easy
`s`	Card state after the answer
`iv`	Interval the answer granted, seconds
`pi`	Interval the card was on before the answer, seconds
`st` / `d`	FSRS stability and difficulty after the answer
`e`	Milliseconds the card was on screen
`m`	Which study mode you answered in

The fence is deliberately never closed

An unclosed code fence runs to the end of the document, so every write is a pure append and the file is valid at every moment. Don't "fix" it by closing the fence.

Why Markdown? Obsidian Sync only carries non-Markdown files when Sync all other types is enabled, which is off by default and doesn't propagate between devices — a .jsonl log could silently never reach your phone. As Markdown, the log syncs the way your notes do, everywhere, with no configuration.

Keep the log out of search

Add the folder to Settings > Files & links > Excluded files. Osmosis already keeps shards out of its own card scanning, but Obsidian's search indexes them like any note.

Deleting the log costs you the graphs, not your scheduling: card schedules live in your notes and are unaffected.

Why This Matters¶

No external database — nothing to corrupt, migrate, or lose
Sync just works — Obsidian Sync, iCloud, Dropbox, Git; if it moves your notes, it moves your study data
Portable — your review history travels with the note it belongs to
Transparent — you can read every byte of it (and shouldn't hand-edit the scheduling fields)
AI-native — an assistant can read and write your cards natively, because they're just text