This page does one thing: explain, without a coding background, every term you meet on the way from install to your first message. Three groups, in the order you meet them. When a word is unfamiliar, look it up here and continue.
Before installing
Terminal
The window where you talk by typing: on macOS it is called Terminal (search it in Spotlight), on Windows use PowerShell (search the Start menu), and on Linux you almost certainly have one. Cetas lives there.
Node.js
The runtime that makes Cetas go — think of it as the engine. You need version
24 or newer; if you have never installed it, download the LTS build from
nodejs.org and follow the installer. Installing Node.js
also gives you the npm command.
npm
The package manager that ships with Node.js — think an app store for developer
tools. npm install -g @posoco/cetas means: install Cetas from that store, so
it is available everywhere on this machine.
Project directory (workspace)
The one folder you want Cetas to work in. Reads, edits, and shell commands all happen inside that folder — which is why you enter it before starting. No project yet? A freshly created empty folder works fine.
Repository
A code or documentation folder under version control (usually git). If you do not have one yet, ignore this word: an empty folder is enough to start.
Models and providers
Provider
The company that supplies the model, such as DeepSeek, OpenAI, or Kimi. Cetas does not ship a model of its own; it calls the provider you pick. First-time users need an account with one of them.
API key
A string the provider issues to you — think key and account in one: it proves the calls are yours and bills them to you. Create it on the provider’s “API Keys” page. Cetas stores it only on your own machine.
OAuth
The other way to sign in: instead of copying a key, you approve once in the
browser and the provider hands the credentials to Cetas directly. If /login
offers a browser option, that is OAuth.
Model
The “brain” a provider supplies, such as deepseek/deepseek-flash. One
provider usually offers several, differing in capability and price; /model
picks between them.
Reasoning effort
How hard the same model thinks: higher effort is smarter, slower, and pricier.
Decision model
A separate small model that serves judgment calls (such as the permission gate), kept apart from the conversation model. You can ignore it on day one.
Tokens and context
Models meter and bill by tokens — roughly one Chinese character or half an English word each. The context is everything the model can “see” in one session; when it fills up, Cetas compacts it automatically.
While using it
Permission posture
The session-level safety switch that decides whether the agent asks before it
acts: readonly look only, workspace_write confirm before writing,
interactive / auto / yolo progressively looser. workspace_write is the
right setting for day one — see Permissions.
Session
One full conversation with the agent, automatically journaled under
<CETAS_HOME>/.cetas/sessions/. /sessions reopens an old one and /rewind walks it
back to before a mistake — nothing needs “saving”.
Slash command
A command starting with / (/login, /model, /help). It executes
immediately, without going through the model.
Cetas home (<CETAS_HOME>/.cetas)
The single directory holding all durable state: configuration, credentials,
sessions, caches. <CETAS_HOME> means your user directory — %USERPROFILE% on
Windows, /Users/you or /home/you on macOS and Linux; a non-empty
CETAS_HOME environment variable moves it elsewhere. Backing up means copying
this directory — see Cetas Home.
MCP
The protocol for attaching external tool servers (databases, ticket systems,
internal APIs) to the agent; configured in mcp.json. Not needed on day one —
see MCP.
ACP
The Agent Client Protocol — how editors such as Zed talk to an agent. You only need it for the editor surface — see the Editor.
Skill
A folder with a SKILL.md holding instructions for one kind of work, loaded
only when a task needs it — see Skills.
Subagent
A child agent the main session spins up for one bounded piece of work, with narrower tools and permissions than the parent — a read-only reviewer, for example. See Subagents.