DMK Intent Vocabulary

This skill translates informal developer requests into the correct DMK components and operations, so the right API is identified before any implementation begins. It is also loaded as a connector by ledger-dmk-implementation/SKILL.md when intent is unclear before execution.

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Conventions

Derivation paths are developer-set constants — never user input, never inferred by the agent. They must appear as literals in the application code (e.g. "44'/501'/0'/0'"). If a derivation path is missing from the calling context, stop and ask the developer — do not substitute, default, or guess one. An incorrect path produces a valid-looking result from a different key with no runtime error.

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Vocabulary

Device Discovery

Phrasings: "find my Ledger", "detect the hardware wallet", "scan for devices", "Ledger not showing up", "device not found", "USB not detecting", "WebHID not finding anything"

Maps to: dmk.startDiscovering() — returns Observable<DiscoveredDevice>

Note: First step before connecting. The developer must subscribe and wait for emissions before connecting.

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Device Connection and Session Management

Phrasings: "connect to the Ledger", "open a session", "establish connection", "reconnect after disconnect", "get a session ID", "device connected but can't send commands", "how do I disconnect?"

Maps to:

• dmk.connect({ device, sessionRefresherOptions: { isRefresherDisabled: false } }) — returns Promise<DeviceSessionId>
• dmk.disconnect({ sessionId })
• dmk.getConnectedDevice({ sessionId }) — device model and name, informational only

Note: The sessionId is required for all subsequent interactions.

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Device State and Status

Phrasings: "is the device locked?", "waiting for PIN", "what app is open?", "device is busy", "observe the device", "listen to device state changes", "battery level", "firmware version without sending a command", "device just disconnected"

Maps to: dmk.getDeviceSessionState({ sessionId }) — returns Observable<DeviceSessionState>

Note: Emits continuously. Includes device status (ready, busy, locked, disconnected), device name, OS info, battery, and currently open app. Prefer this over polling with commands.

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App Management

Phrasings: "open the Bitcoin app", "launch the Ethereum app", "switch apps", "app not opening", "waiting for user to confirm app launch", "make sure the right app is open before signing", "close the app", "detect which app is running"

Maps to:

• OpenAppDeviceAction — full flow including user confirmation on device (preferred for user-facing flows)
• OpenAppCommand — lower-level direct command
• CloseAppCommand
• GetAppAndVersionCommand — returns name and version of the running app

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Firmware and OS Information

Phrasings: "get firmware version", "what OS is on the device?", "MCU version", "bootloader version", "SE version", "is the firmware up to date?"

Maps to:

• GetOsVersionCommand — returns seVersion, mcuSephVersion, mcuBootloaderVersion
• Or from session state: dmk.getDeviceSessionState already includes OS info without an extra command

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Raw APDU Commands

Phrasings: "send a raw APDU", "low-level command", "custom CLA/INS", "APDU bytes", "the pre-built commands don't cover my use case"

Maps to:

• ApduBuilder + dmk.sendApdu({ sessionId, apdu })
• Or extend Command class and use dmk.sendCommand (recommended over raw APDU)

Do not use raw APDU for signing operations. If the goal is signing and a signer package exists for the chain, use it. Raw APDU bypasses the pre-flight, observable confirmation states, and error classification logic. Only appropriate for non-signing commands or genuinely unsupported chains.

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Get Crypto Address

Phrasings: "get my Ethereum address", "derive wallet address", "show address on device", "verify address on screen", "public key from Ledger", "get Bitcoin address", "get Solana public key"

Maps to (by chain):

• ETH: signerEth.getAddress(derivationPath, options)
• BTC: Bitcoin signer equivalent
• Solana: Solana signer equivalent

Note: Returns an observable. Use checkOnDevice: true for any flow where users are given a receiving address — skipping it means users never see the address on the device screen, the only place they can verify it against a compromised host display.

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Sign a Transaction

Phrasings: "sign a transaction", "sign ETH tx", "sign and broadcast", "clear signing", "user confirms transaction details on screen", "sign a Bitcoin transaction", "sign Solana transaction", "hardware wallet signing flow", "user rejected the transaction"

Maps to (by chain):

• ETH: signerEth.signTransaction(derivationPath, transaction, options)
• BTC: Bitcoin signer equivalent
• Solana: Solana signer equivalent

Note: Returns an observable. Handle Pending states (user action on device) and Completed to get the signature. User rejection surfaces as an error state.

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Sign a Message (personal_sign)

Phrasings: "sign a message", "personal_sign", "prove wallet ownership", "sign to authenticate", "wallet auth flow", "sign text with Ledger"

Maps to: signerEth.signMessage(derivationPath, message)

Note: Prepends \x19Ethereum Signed Message:\n before hashing — this prefix is what makes it safe. Different from typed data signing.

Do not map eth_sign to this method. eth_sign signs a raw hash without the safety prefix and is a known phishing vector. If a developer asks for eth_sign behavior, flag the security risk before proceeding.

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Sign Typed Data (EIP-712)

Phrasings: "sign typed data", "EIP-712", "signTypedData_v4", "domain separator", "MetaMask-style signature", "permit signature", "off-chain order"

Maps to: signerEth.signTypedData(derivationPath, typedData)

Note: Requires the typed data object in full (domain + types + message). Used for DeFi permits, off-chain orders, delegation.

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Delegation Authorization (EIP-7702)

Phrasings: "EIP-7702", "delegation authorization", "sign delegation", "account abstraction signing", "delegate authority to contract"

Maps to: signerEth.signDelegationAuthorization(derivationPath, delegationAuthorization)

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Testing and Debugging

Phrasings: "simulate a device", "test without a real Ledger", "mock the hardware wallet", "Speculos", "emulator", "CI testing with Ledger", "device logs", "debug APDU", "unit test DMK"

Maps to:

• Speculos transport: @ledgerhq/device-transport-kit-speculos
• Developer tools: DevToolsLogger, DevToolsDmkInspector, WebSocket connector or Rozenite
• React Native: Rozenite connector

For testing and CI only. Never configure Speculos, mock transports, or setStub(true) in production. They bypass real device interaction — the security model is void.

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Common Error States

Phrasings: "device locked", "wrong app open", "app not installed", "user rejected", "user cancelled on device", "device disconnected mid-flow", "status word not 9000", "observable never completes", "action stuck in pending", "HID error", "USB permission denied"

Note: Most commands reject if the device is locked — check DeviceSessionState first. Status word errors (!= 0x9000) surface via command parse logic. User rejection surfaces as DeviceActionStatus.Error. USB permission denied is a browser security constraint — device access must be triggered from a user gesture.

→ For full error classification and ABORT/ESCALATE routing, load ledger-dmk-implementation/SKILL.md.

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Genuine Check

Phrasings: "verify the device is authentic", "genuine check", "is this Ledger real?", "check device authenticity", "certify device", "is this a real Ledger?"

Maps to: GenuineCheckDeviceAction via dmk.executeDeviceAction()

Note: Requires secure channel (HSM backend). Returns output.isGenuine: boolean. Prompts AllowSecureConnection on first use per device reboot.

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List Installed Apps

Phrasings: "what apps are on the device?", "list apps", "which apps are installed?", "show installed applications", "check if Ethereum app is installed"

Maps to: ListInstalledAppsDeviceAction via dmk.executeDeviceAction()

Note: Returns output.installedApps: InstalledApp[]. Requires secure channel.

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Install / Uninstall App

Phrasings: "install the Ethereum app", "add an app to the Ledger", "remove an app", "uninstall Bitcoin app", "app not installed — install it", "deploy app to device"

Maps to:

• Install: InstallAppDeviceAction via dmk.executeDeviceAction()
• Uninstall: UninstallAppDeviceAction via dmk.executeDeviceAction()

Note: Install emits progress (0–100) in intermediateValue.progress. App name must match exactly what Ledger Live uses. Requires secure channel.

→ For secure channel code patterns, load ledger-dmk-implementation/SKILL.md.