# Data Model: Obsidian MCP Bundle

**Phase**: 1 (Design & Contracts)  
**Date**: 2026-03-22  
**Purpose**: Define data structures and their relationships

## Overview

This MCP bundle operates on Obsidian's data model (vault, notes, properties, tasks, links, tags). The bundle does NOT maintain its own data store - it provides a typed interface layer over Obsidian CLI operations.

## Core Entities

### Vault

**Description**: An Obsidian knowledge base (collection of markdown files and folders)

**Attributes**:
- `name` (string, required): Vault identifier for user configuration
- `path` (string, readonly): Filesystem path to vault root
- `fileCount` (number, readonly): Total number of files
- `folderCount` (number, readonly): Total number of folders
- `size` (number, readonly): Total size in bytes

**Validation Rules**:
- Name must match an existing Obsidian vault
- Path must be accessible with read/write permissions

**State Transitions**: N/A (vault state managed by Obsidian)

**CLI Mapping**: `obsidian vault`, `obsidian vaults`

---

### Note

**Description**: A markdown file within the vault

**Attributes**:
- `name` (string, required): File name without extension OR exact path
- `path` (string, readonly): Full path relative to vault root
- `content` (string): File contents (markdown text)
- `size` (number, readonly): File size in bytes
- `created` (datetime, readonly): Creation timestamp
- `modified` (datetime, readonly): Last modification timestamp
- `properties` (Property[], readonly): Frontmatter metadata

**Validation Rules**:
- Name must be valid filename (no path separators in name-only mode)
- Path must be within vault (no directory traversal)
- Name ambiguity: If multiple files match name, require exact path
- Content must be valid UTF-8 text

**Relationships**:
- HAS_MANY Properties (frontmatter)
- HAS_MANY Tasks (checkbox items)
- HAS_MANY Links (outgoing)
- REFERENCED_BY Links (backlinks)
- HAS_MANY Tags

**State Transitions**:
- Created → Exists
- Exists → Modified (content/properties changed)
- Exists → Deleted (moved to trash or permanent delete)
- Deleted → Restored (from history)

**CLI Mapping**: `obsidian create`, `obsidian read`, `obsidian file`, `obsidian delete`

---

### Property

**Description**: Frontmatter metadata key-value pair

**Attributes**:
- `name` (string, required): Property key (alphanumeric, underscores)
- `value` (string|number|boolean|date|array, required): Property value
- `type` (enum, readonly): text|number|checkbox|date|datetime|list
- `file` (string, required): Note path containing this property

**Validation Rules**:
- Name must be valid YAML key
- Value must match type (enforced by Obsidian)
- List values must be array of strings
- Date/datetime must be ISO 8601 format

**Relationships**:
- BELONGS_TO Note

**CLI Mapping**: `obsidian property:set`, `obsidian property:read`, `obsidian property:remove`, `obsidian properties`

---

### Task

**Description**: Markdown checkbox item with status tracking

**Attributes**:
- `ref` (string, required): Task reference in format "path:line"
- `file` (string, required): Note path containing task
- `line` (number, required): Line number in file (1-indexed)
- `text` (string, readonly): Task description
- `status` (string, required): Empty (""), "x" (done), or custom character
- `done` (boolean, computed): True if status is "x"

**Validation Rules**:
- Line must exist in file
- Line must contain checkbox syntax: `- [ ]` or `- [x]` or `- [char]`
- Status character must be single character or empty

**Relationships**:
- BELONGS_TO Note
- MAY_REFERENCE other Notes (via wikilinks in task text)

**State Transitions**:
- todo (status="") → done (status="x")
- done (status="x") → todo (status="")
- Any status → custom status (status="char")

**CLI Mapping**: `obsidian tasks`, `obsidian task`

---

### Link

**Description**: Connection between notes (wikilink or markdown link)

**Attributes**:
- `source` (string, required): Source note path
- `target` (string, required): Target note name or path
- `type` (enum, readonly): wikilink|markdown|unresolved
- `count` (number, optional): Number of occurrences (for aggregation)
- `resolved` (boolean, readonly): False if target doesn't exist

**Validation Rules**:
- Source must be existing note
- Target format depends on type (wikilink uses `[[name]]`, markdown uses `[text](path)`)

**Relationships**:
- ORIGINATES_FROM Note (source)
- POINTS_TO Note (target, if resolved)

**CLI Mapping**: `obsidian links`, `obsidian backlinks`, `obsidian unresolved`

---

### Tag

**Description**: Categorization marker (e.g., #project, #important)

**Attributes**:
- `name` (string, required): Tag without # prefix
- `count` (number, optional): Number of occurrences in vault
- `files` (string[], optional): Files containing this tag

**Validation Rules**:
- Name must start with letter, can contain letters/numbers/hyphens/underscores
- Case-sensitive
- Nested tags use slash (e.g., "project/active")

**Relationships**:
- APPEARS_IN many Notes

**CLI Mapping**: `obsidian tags`, `obsidian tag`

---

### Alias

**Description**: Alternative name for a note (defined in frontmatter)

**Attributes**:
- `alias` (string, required): Alternative name
- `file` (string, required): Note path this alias refers to

**Validation Rules**:
- Alias must be defined in note's frontmatter `aliases` property

**Relationships**:
- BELONGS_TO Note

**CLI Mapping**: `obsidian aliases`

---

### Template

**Description**: Reusable note template

**Attributes**:
- `name` (string, required): Template name/path
- `content` (string, readonly): Template content (may include variables)
- `resolved` (string, optional): Template with variables resolved

**Validation Rules**:
- Name must match existing template file
- Variables use {{variable}} syntax

**CLI Mapping**: `obsidian templates`, `obsidian template:read`, `obsidian template:insert`

---

### DailyNote

**Description**: Special note type for daily journaling

**Attributes**:
- `date` (date, required): Date for the daily note
- `path` (string, readonly): Path to daily note file
- `content` (string): Daily note content

**Validation Rules**:
- Date must be valid ISO date (YYYY-MM-DD)
- Path follows Obsidian's daily note configuration

**Relationships**:
- IS_A Note (special type)

**State Transitions**:
- Not created → Created (on first daily:append or daily:prepend)

**CLI Mapping**: `obsidian daily`, `obsidian daily:read`, `obsidian daily:append`, `obsidian daily:prepend`, `obsidian daily:path`

---

### Plugin

**Description**: Obsidian plugin (core or community)

**Attributes**:
- `id` (string, required): Plugin identifier
- `name` (string, readonly): Display name
- `version` (string, readonly): Plugin version
- `enabled` (boolean, readonly): Activation status
- `type` (enum, readonly): core|community

**Validation Rules**:
- ID must match installed plugin

**CLI Mapping**: `obsidian plugins`, `obsidian plugins:enabled`, `obsidian plugin`

---

### Theme

**Description**: Obsidian visual theme

**Attributes**:
- `name` (string, required): Theme name
- `version` (string, readonly): Theme version
- `active` (boolean, readonly): Whether currently active

**Validation Rules**:
- Name must match installed theme or be empty string for default

**CLI Mapping**: `obsidian themes`, `obsidian theme`, `obsidian theme:set`

---

### Bookmark

**Description**: Saved reference to file, folder, search, or URL

**Attributes**:
- `title` (string, required): Bookmark display name
- `type` (enum, readonly): file|folder|search|url
- `target` (string, required): File path, folder path, search query, or URL

**Validation Rules**:
- File/folder targets must exist
- URLs must be valid HTTP/HTTPS
- Search queries must be non-empty

**CLI Mapping**: `obsidian bookmarks`, `obsidian bookmark`

---

## Tool Request/Response Schemas

Each MCP tool accepts parameters matching entity attributes and returns structured results.

### Common Patterns

**Success Response**:
```typescript
{
  success: true,
  data: { /* entity or array of entities */ }
}
```

**Error Response**:
```typescript
{
  success: false,
  error: {
    code: string,    // e.g., "NOTE_NOT_FOUND"
    message: string, // Human-readable error
    details?: unknown // Additional context
  }
}
```

### Parameter Validation

All tool parameters are validated using Zod schemas before CLI execution:

```typescript
// Example: Create note parameters
{
  name: string (1-255 chars),
  path?: string (valid path),
  content?: string,
  template?: string,
  overwrite?: boolean,
  open?: boolean,
  newtab?: boolean
}
```

## CLI Output Parsing

Obsidian CLI returns data in various formats. The bundle normalizes to JSON:

### Format Mapping
- **JSON output** → Direct parse
- **TSV output** → Parse to array of objects
- **CSV output** → Parse to array of objects
- **Text output** → Wrap in `{ raw: string }` object
- **Empty output** → Return `{ success: true }`

### Special Cases
- **Ambiguous file names**: CLI returns multiple paths → Error with path list
- **File not found**: CLI exits with error code → Map to NOT_FOUND error
- **Obsidian not running**: CLI connection fails → Map to OBSIDIAN_NOT_RUNNING error

## Data Flow

```
AI Assistant
    ↓
MCP Tool Call (JSON-RPC)
    ↓
Input Validation (Zod)
    ↓
Parameter Sanitization
    ↓
CLI Command Construction
    ↓
Obsidian CLI Execution (spawn with timeout)
    ↓
Output Parsing (JSON/TSV/CSV/Text)
    ↓
Error Mapping (if needed)
    ↓
Structured Response (JSON)
    ↓
MCP Tool Result (JSON-RPC)
    ↓
AI Assistant
```

## Concurrency & State

- **No shared state**: Each tool call is independent
- **Concurrent file modifications**: Rely on Obsidian's built-in conflict detection (per clarification)
- **Vault state**: Managed entirely by Obsidian (bundle is stateless)
- **CLI commands**: Sequential execution per tool call (no parallel CLI commands from single call)

## Error Handling

Errors are categorized and mapped to user-friendly messages:

| Error Category | Code | Message Pattern |
|----------------|------|-----------------|
| Obsidian not running | OBSIDIAN_NOT_RUNNING | "Obsidian application is not running. Please start Obsidian and try again." |
| Vault not found | VAULT_NOT_FOUND | "Vault '{name}' not found. Check your vault name in MCP settings." |
| File not found | FILE_NOT_FOUND | "Note '{name}' not found. Use exact path or check spelling." |
| Ambiguous name | AMBIGUOUS_NAME | "Multiple notes named '{name}' found: {paths}. Please specify exact path." |
| Permission denied | PERMISSION_DENIED | "Cannot access {path}. Check file permissions." |
| Timeout | TIMEOUT | "Operation took too long (>30s). Try with smaller scope." |
| Validation error | VALIDATION_ERROR | "{field} {constraint}" (e.g., "name must be 1-255 characters") |
| CLI error | CLI_ERROR | "{original CLI error message}" (for unexpected errors) |