Orca Emulator

Orca Emulator (serve-sim powered)

Drive an Apple Simulator (iOS / iPad / Watch) from within Orca using orca emulator ... commands (or orca emulator exec for raw power). This wraps the excellent serve-sim open-source tool so agents get a consistent Orca-native CLI surface, automatic helper management, and seamless integration with Orca's live emulator pane (the visual "preview" surface).

The underlying serve-sim helper captures the real simulator framebuffer (via private SimulatorKit / IOSurface for low-latency 60fps H.264 or MJPEG) and exposes a WebSocket control channel. Orca's bridge owns the helper processes and per-worktree "active emulator" state so unqualified commands "just work" on whatever device/pane is current for the worktree.

When to use

• The user/agent wants to tap, swipe, drag, pinch, or press hardware buttons on a running iOS simulator while seeing the live result in Orca.
• You want camera injection (placeholder, webcam, or file loop) for testing camera flows.
• You need to grant/revoke app permissions (camera, photos, notifications, location, etc.) or read the accessibility tree.
• Rotate the device, simulate memory warnings, toggle CoreAnimation debug overlays, etc.
• You are inside an Orca worktree/terminal and want the emulator to be workspace-scoped (like browser tabs) with explicit targeting when needed.
• The agent should use Orca's preview pane instead of external Simulator.app or raw serve-sim URLs.

When NOT to use

• Android emulators → use the orca-emulator-android skill (same orca emulator namespace, cross-platform via adb/emulator).
• Building or installing the app itself → use xcodebuild, xcrun simctl install, expo run:ios, etc. (launch the app, then use orca emulator to drive it).
• In-app debugging (state, network, views) → use the app's own tools or the browser pane if it's a webview.
• Remote/SSH worktrees for emulator control (currently out of scope / unsupported; simulator hardware is local to a Mac).

Prerequisites (enforced / surfaced by Orca)

• macOS host (with Xcode Command Line Tools: xcrun --version).
• A booted simulator (xcrun simctl list devices booted or let Orca/attach help boot one).
• Node available (for the serve-sim bits; Orca bundles the CLI surface).
• macOS 14+ recommended for full camera injection features.

Orca will give clear errors if these are missing (e.g. "emulator commands require macOS + Xcode tools").

An active emulator "session" for the worktree is required for most commands. Use orca emulator list / attach or open the emulator pane in the UI.

Mental model

┌────────────────────┐
│ Orca worktree      │
│  - active emulator │◄── orca emulator tap / type / ...
│  - live pane (UI)  │
└─────────┬──────────┘
          │ (registers active stream)
          ▼
┌────────────────────┐   WS / control   ┌─────────────────┐  framebuffer  ┌──────────────┐
│ Orca EmulatorBridge│ ───────────────► │ serve-sim-bin   │ ────────────► │ iOS Simulator│
│ (main process)     │ (or exec serve-sim) (per-device)   │               └──────────────┘
└────────────────────┘                  └─────────────────┘
          ▲
          │ (state + lifecycle)
┌────────────────────┐
│ orca CLI (agents)  │  e.g. orca emulator tap 0.5 0.7
│ orca-emulator skill│
└────────────────────┘

Orca owns:

• Starting/stopping the serve-sim helper (via --detach or direct).
• Per-worktree "active" emulator (like active browser tab).
• Explicit targeting with --worktree, --device, --emulator <id>.
• The visual live pane (renderer uses serve-sim-client for the stream).

Agents use the orca / orca-dev binary (on PATH in Orca terminals; orca-dev for dev builds) and never have to manage PIDs, state files in /tmp, or raw WS URLs themselves.

For pnpm dev testing: run pnpm build:cli first (rebuilds the CLI + ensures the orca-dev shim points at this worktree). Then inside the dev app use orca-dev emulator ... (or the direct ./config/scripts/orca-dev.mjs emulator ... from the repo root). The orchestration preambles and dev launchers automatically select the dev command name so the CLI reaches your in-memory EmulatorBridge / runtime. Plain orca reaches a packaged install instead.

Common operations

Use --json for agent-friendly output. Commands are workspace-scoped by default (current worktree's active emulator).

Most support --worktree <selector> and explicit --device <udid|name> or --emulator <id> (from list) for targeting.

Critical gotchas (teach agents)

• Prefer tap over gesture for single taps (same as raw serve-sim). Separate gesture begin/end can be interpreted as long-press due to WS overhead. The orca wrapper uses the reliable quick sequence.
• All coords normalized 0..1 (top-left origin). Never pixels.
• One "active" emulator per worktree for unqualified commands (like active browser tab). Discover ids with list, use explicit flags for multi-device or cross-worktree.
• Type = US keyboard only. Unsupported chars error clearly.
• Camera injection often requires (re)launching the target app bundle.
• The visual pane and CLI share the same underlying stream/helper. Closing the pane can stop the stream (configurable).
• Stale helpers / state are cleaned by Orca on quit, but agents should kill when done.
• Private APIs under the hood (SimulatorKit etc.) — version sensitive (Xcode updates can affect).

Targeting devices & worktrees

• Default: current worktree's active emulator (resolved from shell cwd or Orca context).
• Explicit worktree: --worktree id:abc123 or --worktree active.
• Explicit device: --device "iPhone 16 Pro" or --device <udid> (after list).
• Orca-generated emulator id (for stability, like browserPageId): use --emulator <id> returned by list (recommended for scripts that persist ids).

--worktree all only for listing.

Integration with the live pane (UI)

• Opening the emulator pane in Orca (or attach) makes that stream the "active" one for the worktree → CLI commands target it automatically.
• The pane shows the real 60fps stream (device frame, touch forwarding, toolbar).
• Agents can drive via CLI while the human watches/interacts in the pane.
• No automatic focus steal on CLI attach (use --focus if you really want the UI to switch; matches browser behavior).
• Multiple devices: list shows them; pane can grid; CLI uses active or explicit selector.

Cleanup

orca emulator kill --device "iPhone 16 Pro"
# or let Orca quit / close the pane

Orphans are cleaned by Orca (like agent-browser sessions).

Examples (agent-friendly)

orca status --json
orca emulator list --json
orca emulator attach "iPhone 16 Pro" --json
orca emulator tap 0.5 0.8 --json
orca emulator type "user@example.com" --json
orca emulator button home --json
orca emulator camera com.acme.MyApp --file /tmp/test.mp4 --json
orca emulator permissions grant camera com.acme.MyApp --json
orca emulator ax --json
orca emulator exec --command "ca-debug blended on" --json

After changes, re-snapshot / wait as needed (analogous to browser snapshot-interact loop).

Next action

Confirm orca status --json and orca emulator list --json, then drive the emulator while the live view is visible in Orca.

See also: orca-cli skill (terminals, worktrees, built-in browser), computer-use for desktop outside the simulator.

This skill is the Orca-native replacement for raw serve-sim when you want the visual + control integrated in the IDE.