Glossary

Action. One thing Tealhand can do on a computer, such as power.shutdown. All actions are in one fixed list: Actions.

Agent. An AI agent, such as Claude Code or Hermes. In Tealhand the word never means Tealhand Host.

AI apps. Claude Desktop, LM Studio, Cursor and other apps on a computer that may read your other computers through Tealhand’s MCP tools, and never change them. Off by default: Settings, AI apps in the Tealhand app, or tealhand-host mcp on. See Use Tealhand from your AI app.

ALPN. The protocol name a connection uses, such as tealhand/ctl/1. iroh picks it once per connection.

Capability version. One integer that says which protocol a build speaks (7 today, and it still talks to 6). Two devices use the lower of their versions, and refuse a peer below their minimum.

Card. The confirmation card the phone shows before any action: a title, one plain sentence, and one button. A later time shows only when the action doesn’t happen now, and an undo line only when it matters. Risky actions also ask for a fingerprint or PIN on it.

Certificate fingerprint. The SHA-256 fingerprint of a relay’s TLS certificate, written sha256: and 64 hex digits. tealhand-relay fingerprint prints it. Giving it to the phone and to tealhand-host --relay-pin pins the certificate: see Pin. Not the same as the fingerprint you touch on the phone.

Check code. Eight characters such as ABCD EFGH, shown on both the phone and the computer when a phone connects. If they match, nobody sits in between.

Close code. The number a device sends when it closes a connection: one of the error codes, or 0 for no error.

Computer. A device that is controlled, with or without a screen: it runs Tealhand Host. With the Tealhand app, a computer can also control your other computers: see Control your other computers from a computer.

Default for downloads. The shared folder a phone offers for a download on that computer, after the one it used last. The phone can pick any shared folder that is not read only for each download. The default can’t be read only, and only one folder can be it. Set it with Set as default in the Tealhand app, or with tealhand-host share add --downloads or tealhand-host share default <id>. See Share folders.

Device key. The phone’s main P-256 hardware key. It signs every command and every device list without a prompt. It is also the owner key.

Device list, roster. The list of your connected devices, with their names and keys, signed by your phone and chained by version. A computer only talks to devices on it.

Endpoint key. A device’s iroh key, its address on the network. Written thdev: and 64 hex digits. A phone’s cannot sign commands; a computer’s signs that computer’s commands to your other computers.

Fingerprint (on the phone). Your fingerprint, or the device PIN, that unlocks the presence key for risky actions. Not a certificate fingerprint.

Disconnect phone. device.forget: the computer wipes its saved connection and rules, and accepts nothing until a phone is connected again.

files/1. The protocol name (tealhand/files/1) for browsing, reading and uploading files in shared folders: Files.

iroh. The open-source network library Tealhand is built on: devices dial each other by key, punch through routers, and fall back to a relay.

Journal. The computer’s activity log: one plain line per event, 30 days, no content.

MCP. Model Context Protocol: how an AI app calls tools. Tealhand serves six read-only tools to AI apps on the same computer, through tealhand-host mcp.

mDNS. Multicast DNS: how devices find each other on the local network without a server.

Nonce. 16 random bytes in every command, so the same command cannot run twice.

Notice. The 60-second countdown before a shutdown, or before a rule’s sleep. It can be cancelled.

Owner. The phone whose device key signs the device list. A computer has exactly one owner.

Path jail. The one piece of code on the computer that turns a path from the phone into a path on the disk. It refuses anything outside a shared folder, any link, and any name that breaks the rules.

Connection door. The computer accepts connection attempts from a new phone only while a QR code is showing.

Phone. The controlling device: it runs the Tealhand app.

Pin. Accepting only one named certificate for a relay, recognised by its fingerprint, with no name check, instead of the public roots. Used for a relay with a self-signed certificate. There is no setting that turns certificate checks off.

Planner. Tealhand Planner: a service that turns a sentence into a proposed action. It holds no key.

Presence key. The phone’s second P-256 hardware key. It signs only after a fingerprint or PIN, for the actions that need you there.

Relay. Tealhand Relay: a server that passes encrypted traffic when two devices cannot connect directly. It holds no key.

Playback server. A tiny web server on the phone, on 127.0.0.1 only, that lets the phone’s media player play a file from a computer by turning its range requests into range reads.

Remote control. A switch on each computer. When off, phones and your other computers can still see the computer and cancel, but not change anything.

Rule. “When ⟨a program closes, or the GPU is idle for N minutes⟩, ⟨shut down, sleep or notify⟩”, saved and run on the computer.

Saved command. A command line kept on a computer under a name (a key and a label). A phone runs it by name and never sends a command line. With SSH access on, a phone can also add and remove saved commands, after its fingerprint. See The phone app.

Shared folder. A folder on a computer that you chose, at the computer, to let connected phones browse, in the Tealhand app or with tealhand-host share add. Phones see nothing else. It can be read-only. See Share folders.

Signed command. An action plus the issuer, the target computer, a nonce and a time window, signed by the phone or by one of your computers: How commands are signed.

SSH access. The switch on a computer that lets connected phones open a terminal on it and add or remove saved commands, after their fingerprint. Your other computers may open a terminal there from the Tealhand app, without one. Off by default. You turn it on at the computer, in Tealhand or with tealhand-host ssh on.

tealhand-power. The small helper on the computer that can only sleep, shut down and say whether another user is signed in.

thhw: key. The text form of a P-256 hardware key: thhw: and 66 hex digits. The relay’s allowed_owners uses it.