# mbbill/undotree architecture

> Architecture diagram of the GitHub repository mbbill/undotree, generated by GitDiagram from its file tree, README and a sample of source files (last updated 2026-09-30). It is an AI-made overview: check details against the source.

- Interactive diagram: https://gitdiagram.com/mbbill/undotree
- Repository: https://github.com/mbbill/undotree

## Overview

Undotree is a Vim plugin for browsing Vim’s undo-history tree and switching between its branches. The documented workflow is: a Vim user runs `:UndotreeToggle`, browses the history panel, and selects a state; changes are temporary buffer edits, not disk writes. The README also documents persistent-undo setup and cleanup, plus opt-in debug logging. Source excerpts were unavailable, so links below rely only on README statements; implementation details and unshown dispatches are omitted.

Main entry points: [`autoload/undotree.vim`](https://github.com/mbbill/undotree/blob/master/autoload/undotree.vim) (History panel), [`plugin/undotree.vim`](https://github.com/mbbill/undotree/blob/master/plugin/undotree.vim) (Toggle command)

## Diagram (Mermaid)

```mermaid
flowchart TD

subgraph group_history["Undo history"]
  node_undo_history[("Undo branches")]
  node_buffer_state["Current buffer"]
end

subgraph group_runtime["Plugin runtime"]
  node_toggle_command["Toggle command<br/>[undotree.vim]"]
  node_history_panel["History panel<br/>[undotree.vim]"]
  node_syntax["Panel syntax<br/>[undotree.vim]"]
end

subgraph group_support["Persistence and debug"]
  node_persistent_undo[("Persistent undo")]
  node_undo_cleanup["Undo cleanup<br/>[undotree.vim]"]
  node_debug_log["Debug log"]
end

node_user(("Vim user"))
node_vim["Vim editor"]

node_user -->|"runs"| node_toggle_command
node_toggle_command -->|"opens panel"| node_history_panel
node_vim -->|"maintains branches"| node_undo_history
node_history_panel -->|"browses branches"| node_undo_history
node_user -->|"selects state"| node_history_panel
node_history_panel -->|"temporarily changes"| node_buffer_state
node_vim -->|"saves history"| node_persistent_undo
node_user -->|"enables"| node_persistent_undo
node_user -->|"requests cleanup"| node_undo_cleanup
node_vim -->|"appends debug"| node_debug_log

click node_toggle_command "https://github.com/mbbill/undotree/blob/master/plugin/undotree.vim"
click node_history_panel "https://github.com/mbbill/undotree/blob/master/autoload/undotree.vim"
click node_syntax "https://github.com/mbbill/undotree/blob/master/syntax/undotree.vim"
click node_undo_cleanup "https://github.com/mbbill/undotree/blob/master/autoload/undotree.vim"

classDef toneNeutral fill:#f8fafc,stroke:#334155,stroke-width:1.5px,color:#0f172a
classDef toneBlue fill:#dbeafe,stroke:#2563eb,stroke-width:1.5px,color:#172554
classDef toneAmber fill:#fef3c7,stroke:#d97706,stroke-width:1.5px,color:#78350f
classDef toneMint fill:#dcfce7,stroke:#16a34a,stroke-width:1.5px,color:#14532d
classDef toneRose fill:#ffe4e6,stroke:#e11d48,stroke-width:1.5px,color:#881337
classDef toneIndigo fill:#e0e7ff,stroke:#4f46e5,stroke-width:1.5px,color:#312e81
classDef toneTeal fill:#ccfbf1,stroke:#0f766e,stroke-width:1.5px,color:#134e4a
class node_undo_history,node_buffer_state,node_user toneBlue
class node_toggle_command,node_history_panel,node_syntax toneAmber
class node_persistent_undo,node_undo_cleanup,node_debug_log toneMint
class node_vim toneIndigo
```

## Components

### Undo history

- **Undo branches**
- **Current buffer**

### Plugin runtime

- [Toggle command](https://github.com/mbbill/undotree/blob/master/plugin/undotree.vim): `plugin/undotree.vim`
- [History panel](https://github.com/mbbill/undotree/blob/master/autoload/undotree.vim): `autoload/undotree.vim`
- [Panel syntax](https://github.com/mbbill/undotree/blob/master/syntax/undotree.vim): `syntax/undotree.vim`

### Persistence and debug

- **Persistent undo**
- [Undo cleanup](https://github.com/mbbill/undotree/blob/master/autoload/undotree.vim): `autoload/undotree.vim`
- **Debug log**

### Other components

- **Vim user**
- **Vim editor**

## Connections

- Vim user → Toggle command: runs (evidence: `README.md`)
- Toggle command → History panel: opens panel (evidence: `README.md`)
- Vim editor → Undo branches: maintains branches (evidence: `README.md`)
- History panel → Undo branches: browses branches (evidence: `README.md`)
- Vim user → History panel: selects state (evidence: `README.md`)
- History panel → Current buffer: temporarily changes (evidence: `README.md`)
- Vim editor → Persistent undo: saves history (evidence: `README.md`)
- Vim user → Persistent undo: enables (evidence: `README.md`)
- Vim user → Undo cleanup: requests cleanup (evidence: `README.md`)
- Vim editor → Debug log: appends debug (evidence: `README.md`)