HarmonyOS Device Automation CRITICAL RULES — VIOLATIONS WILL BREAK THE WORKFLOW: Never run midscene commands in the background. Each command must run synchronously so you can read its output (especially screenshots) before deciding the next action. Background execution breaks the screenshot-analyze-act loop. Run only one midscene command at a time. Wait for the previous command to finish, read the screenshot, then decide the next action. Never chain multiple commands together. Allow enough time for each command to complete. Midscene commands involve AI inference and screen interaction, which can take longer than typical shell commands. A typical command needs about 1 minute; complex act commands may need even longer. Automate HarmonyOS NEXT devices using npx @midscene/harmony@1 . Each CLI command maps directly to an MCP tool — you (the AI agent) act as the brain, deciding which actions to take based on screenshots. Prerequisites Midscene requires models with strong visual grounding capabilities. The following environment variables must be configured — either as system environment variables or in a .env file in the current working directory (Midscene loads .env automatically): MIDSCENE_MODEL_API_KEY = "your-api-key" MIDSCENE_MODEL_NAME = "model-name" MIDSCENE_MODEL_BASE_URL = "https://..." MIDSCENE_MODEL_FAMILY = "family-identifier" Example: Gemini (Gemini-3-Flash) MIDSCENE_MODEL_API_KEY = "your-google-api-key" MIDSCENE_MODEL_NAME = "gemini-3-flash" MIDSCENE_MODEL_BASE_URL = "https://generativelanguage.googleapis.com/v1beta/openai/" MIDSCENE_MODEL_FAMILY = "gemini" Example: Qwen 3.5 MIDSCENE_MODEL_API_KEY = "your-aliyun-api-key" MIDSCENE_MODEL_NAME = "qwen3.5-plus" MIDSCENE_MODEL_BASE_URL = "https://dashscope.aliyuncs.com/compatible-mode/v1" MIDSCENE_MODEL_FAMILY = "qwen3.5" MIDSCENE_MODEL_REASONING_ENABLED = "false"

If using OpenRouter, set:

MIDSCENE_MODEL_API_KEY="your-openrouter-api-key"

MIDSCENE_MODEL_NAME="qwen/qwen3.5-plus"

MIDSCENE_MODEL_BASE_URL="https://openrouter.ai/api/v1"

Example: Doubao Seed 2.0 Lite MIDSCENE_MODEL_API_KEY = "your-doubao-api-key" MIDSCENE_MODEL_NAME = "doubao-seed-2-0-lite" MIDSCENE_MODEL_BASE_URL = "https://ark.cn-beijing.volces.com/api/v3" MIDSCENE_MODEL_FAMILY = "doubao-seed" Commonly used models: Doubao Seed 2.0 Lite, Qwen 3.5, Zhipu GLM-4.6V, Gemini-3-Pro, Gemini-3-Flash. If the model is not configured, ask the user to set it up. See Model Configuration for supported providers. HDC Setup HDC (HarmonyOS Device Connector) must be installed and accessible. Common setup: Install via DevEco Studio Or set HDC_HOME environment variable to point to the HDC directory Verify HDC is working: hdc version hdc list targets Commands Connect to Device npx @midscene/harmony@1 connect npx @midscene/harmony@1 connect --deviceId 0123456789ABCDEF Take Screenshot npx @midscene/harmony@1 take_screenshot After taking a screenshot, read the saved image file to understand the current screen state before deciding the next action. Perform Action Use act to interact with the device and get the result. It autonomously handles all UI interactions internally — tapping, typing, scrolling, swiping, waiting, and navigating — so you should give it complex, high-level tasks as a whole rather than breaking them into small steps. Describe what you want to do and the desired effect in natural language:

specific instructions

npx @midscene/harmony@1 act --prompt "type hello world in the search field and press Enter" npx @midscene/harmony@1 act --prompt "long press the message bubble and tap Delete in the popup menu"

or target-driven instructions

npx @midscene/harmony@1 act

--prompt

"open Settings and navigate to Wi-Fi settings, tell me the connected network name"

Disconnect

npx @midscene/harmony@1 disconnect

Workflow Pattern

Since CLI commands are stateless between invocations, follow this pattern:

Connect

to establish a session

Launch the target app and take screenshot

to see the current state, make sure the app is launched and visible on the screen.

Execute action

using

act

to perform the desired action or target-driven instructions.

Disconnect

when done

Best Practices

Bring the target app to the foreground before using this skill

For best efficiency, launch the app using HDC (e.g.,

hdc shell aa start -a EntryAbility -b

)

before

invoking any midscene commands. Then take a screenshot to confirm the app is actually in the foreground. Only after visual confirmation should you proceed with UI automation using this skill. HDC commands are significantly faster than using midscene to navigate to and open apps.

Be specific about UI elements

Instead of vague descriptions, provide clear, specific details. Say

"the Wi-Fi toggle switch on the right side"

instead of

"the toggle"

.

Describe locations when possible

Help target elements by describing their position (e.g.,

"the search icon at the top right"

,

"the third item in the list"

).

Never run in background

Every midscene command must run synchronously — background execution breaks the screenshot-analyze-act loop.

Batch related operations into a single