How It Works

The Core Flow

  1. Select text anywhere on your Mac
  2. Press ⌥C (Option+C)
  3. Cai detects the content type and shows relevant actions
  4. Pick an action with ↑↓ arrows or ⌘1–9
  5. The result is auto-copied to your clipboard. Just ⌘V to paste. Or press ⌘1 to replace your original selection inline. You can also send it to an output destination like Slack, Bear, or a webhook.

Content Types & Actions

Cai automatically detects what you copied and offers the right actions:

Content Type Detection Actions
URL https://..., www. Open in Browser
JSON Valid JSON object or array Pretty Print
Meeting Date/time references Create Calendar Event, Open in Maps
Address Street patterns, “at [Place Name]“ Open in Maps
Word 1–2 words Define, Explain, Translate, Search
Short Text Less than 100 characters Explain, Reply, Fix Grammar, Translate, Search
Long Text 100+ characters Summarize, Reply, Fix Grammar, Translate, Search
Image Clipboard image or screenshot Extract Text (OCR), then all text actions

All text types also get Ask AI (⌘1) for free-form AI prompts.

Context Awareness

Cai is context-aware: it detects what app you’re in (email, Slack, code editor, etc.) and tailors its actions accordingly. For example, Reply uses this context to generate an appropriate response based on whether you’re replying to an email, a chat message, or a code review comment.

Type to Reveal Hidden Actions

The default action list is focused per content type. You won’t see Reply on a meeting invite, or Fix Grammar on a single word. When you need an action that isn’t shown, just start typing its name: filter-to-reveal surfaces every applicable action regardless of detection.

Examples

  • Select "serendipity" → Define, Explain, Translate, Search
  • Select an email body → Reply, Summarize, Translate
  • Select "Let's meet Tuesday at 3pm at Starbucks" → Create Calendar Event, Open in Maps
  • Select "123 Main St, NYC 10001" → Open in Maps
  • Select https://github.com/... → Open in Browser
  • Select {"name": "John"} → Pretty Print JSON

System Actions vs AI Actions

System actions work without any LLM server:

  • Open URL in browser
  • Open address in Maps (Apple or Google)
  • Create calendar event (via ICS file — works with any calendar app)
  • Web search
  • Pretty print JSON
  • Extract text from images (OCR via Apple Vision)

AI actions use the built-in model by default, or a connected external provider:

  • Summarize / Explain
  • Reply (context-aware responses)
  • Fix Grammar
  • Translate
  • Define
  • Ask AI (your own prompt)

Follow-up Questions

After any AI action returns a result, press Tab to ask a follow-up question. The full conversation history is sent to the LLM, so it has context from the previous result. You can chain multiple follow-ups in a single session.

Press ⌘N to start a new chat — ask anything without clipboard content.

Clipboard History

Press ⌘0 in the action window to open clipboard history. Features include:

  • Search: type to filter your history
  • Pinning: pin important items so they stay at the top
  • Configurable size: adjust the history limit in settings

Settings

Left-click the Cai menu bar icon to access Preferences:

Setting Description Default
Translation Language Target language for translations English
Search URL Base URL for web searches Brave Search
Maps Provider Apple Maps or Google Maps Apple Maps
Model Provider Built-in, LM Studio, Ollama, Cloud, or Custom Built-in
About You Personal context for AI responses (e.g. profession, tone) Empty
Launch at Login Start Cai automatically On

Limits

Cai is optimized for short-to-medium selections, not full documents. Two caps apply:

Cap Limit What happens when exceeded
Clipboard history entry 10,000 chars (2,500 words) Entries are clamped on save
LLM input (system + history + message) ~50,000 chars Oldest conversation history is dropped first

Apple Intelligence has a tighter 4K token context window. For long inputs, switch to Ministral 3B or an external provider. See troubleshooting for details.