GitWriter Docs

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Architecture & Internals ​

A short map of the code, for anyone who wants to read or change it. The source is on GitHub.

Layers ​

GitWriter is written in Kotlin Multiplatform with Compose Multiplatform. Almost everything, from the UI down to the sync, is shared code. Only the app entry points and the Git implementation differ per platform.

Shared code: Compose UI, ViewModels, features, persistence and Git interfaces. Platform code: the app entry points, JGit and libgit2Shared code: Compose UI, ViewModels, features, persistence and Git interfaces. Platform code: the app entry points, JGit and libgit2

Modules ​

ModuleWhat's in it
shared · feature/editorThe live preview editor, find, edit history, LaTeX, spell check, shortcuts
shared · feature/editor_sidebarThe file tree, drag and drop, context menus
shared · feature/git_syncSync, conflict resolution, encryption
shared · feature/notebooks_managementNotebooks in Room; creating, cloning, importing
shared · feature/pdf_export, feature/settingsPDF export, settings
shared · coreDatabase, Koin modules, platform abstractions
desktopApp, androidApp, iosAppEntry points, packaging, the Android widget (Glance)

Platform code lives in the usual source sets: jvmAndAndroidMain (JGit), jvmMain, androidMain and iosMain (libgit2).

The live preview editor ​

The whole note is one text field, so selecting, copying, undo and cursor movement work across the whole note. The formatting is only a view of it:

Note text is parsed into a syntax tree, turned into decorations, transformed into the shown text, and widgets are drawn over itNote text is parsed into a syntax tree, turned into decorations, transformed into the shown text, and widgets are drawn over it
  1. Parse the note with JetBrains' Markdown parser (GitHub Flavored Markdown).
  2. Decorations say how each range is shown: bold, hidden **, a heading, a checkbox. A decoration that touches the cursor shows its source instead.
  3. Shown text comes from a VisualTransformation that hides the syntax and maps cursor offsets between the note and what you see.
  4. Overlays (images, tables, maths, checkboxes) are composables placed over placeholders in the same layout pass, so they never lag behind the text.

Git ​

  • JGit on desktop and Android, libgit2 on iOS through C interop (built by tools/build-libgit2.sh).
  • Both implement the same interfaces (GitSyncRepository, MirrorRepository, MailboxRepository), and the same contract tests run against both, so every platform syncs the same way.
  • What a sync does is in Syncing & Conflicts; encrypted notebooks are in How Encryption Works.

Data ​

  • Notes are plain files in a Git repository per notebook. Nothing else is needed to read them.
  • Room (SQLite) keeps the list of notebooks: folder, remote, credentials and, for encrypted notebooks, the key.
  • DataStore keeps the settings.