Overview
Placet consists of three main components:- Web App: the inbox where humans review and respond to messages
- API: the REST endpoint agents and automations use to send messages and receive responses
- Plugin System: extensible message rendering via sandboxed plugins
Agent Communication
Agents interact with Placet through the Agent API (/api/v1/*), authenticated with API keys:
Supported patterns
| Pattern | Use Case |
|---|---|
| Fire & forget | Agent sends a message, no response needed |
| Webhook | Agent registers a webhook URL, receives responses asynchronously |
| Polling | Agent polls for review responses via the API |
| WebSocket | Real-time bidirectional communication |
Review System
Agents can request human input by attaching areview to any message. Placet supports 5 built-in review types:
| Type | Agent sends | User sees |
|---|---|---|
| Approval | options: [{id, label, style}] | Styled buttons with optional comment |
| Selection | mode: "single"|"multi", items: [...] | Radio buttons or checkboxes |
| Form | fields: [{name, type, label, required}] | Dynamic form (12 field types) |
| Text Input | placeholder?, markdown? | Textarea with optional markdown |
| Freeform | {} | JSON editor (for plugin UIs) |
File Storage
Agents can upload and attach files to messages via the API. The web app renders inline previews for many formats:| Category | Formats |
|---|---|
| Images | JPG, PNG, GIF, WebP, SVG |
| Video | MP4, WebM, MOV |
| Audio | MP3, WAV, OGG, M4A |
| Documents | PDF, DOCX, ODT |
| Spreadsheets | XLSX, XLS, ODS, CSV |
| Presentations | PPTX |
| Code | 40+ languages with syntax highlighting |
| Markdown | Rendered with GFM support |
- Canvas annotations: draw on images with pen, arrow, rectangle, and text tools
- Share links: JWT-based public download links (1h expiry)
- Bulk operations: download as ZIP or delete multiple files
- File browser: searchable gallery with type filters across all channels
Agent Status
Agents report their status via a heartbeat endpoint (POST /api/v1/status/ping). The frontend provides a dedicated Status page showing all agents with:
- Live status indicator (active, busy, error, offline)
- Uptime since last status change
- Message statistics (total, inbound/outbound, success/error)
- Status history timeline