Terms whose meaning matters across T3 Code. Architecture and lifecycle constraints belong in the
overview , not in these definitions.
Workspace and conversation
Term
Meaning
Environment
One running server and the machine, credentials, workspace access, and state it owns.
Client
A web, desktop, or mobile UI connected to an environment. The desktop app can also host a server.
Project
An environment-local workspace record rooted at a directory.
Workspace root
The project's base filesystem directory on the environment.
Worktree
A separate Git checkout a thread can use instead of the project's main checkout.
Thread
The durable conversation and work history for a project. It survives provider process exits.
Turn
One user-to-agent work cycle. Provider work can finish before checkpoint and diff work settles.
Activity
A non-message timeline item, such as a tool action, approval, or failure.
T3 home
The base data directory. Runtime state normally lives under its userdata directory.
Term
Meaning
Command
A request to change domain state. Accepting it does not mean its side effects have finished.
Event
A persisted fact produced by a command.
Decider
The pure logic that turns a command and current state into events.
Projection / read model
A view of current state derived from persisted events.
Projector
The logic that applies events to a read model.
Reactor
A worker that performs follow-up work in response to recorded intent or runtime signals.
Command receipt
A durable record of a command's result, used to make retries idempotent.
Runtime receipt
A test-only signal that an asynchronous milestone completed.
Quiesced
The relevant follow-up workers have finished, beyond the provider turn merely ending.
Providers and checkpoints
Term
Meaning
Provider
The agent runtime T3 Code controls, such as Codex or Claude Code.
Driver
The integration for a provider kind.
Provider instance
One configured provider, with its own settings and lifecycle. Multiple instances can use the same driver.
Adapter
The boundary translating a provider's native protocol into T3 Code operations and events.
Session
The provider runtime attached to a thread. A session can be stopped and resumed without deleting the thread.
Runtime mode
The thread's permission policy. See permission modes .
Interaction mode
How the agent approaches the task, such as planning. Separate from permission policy.
Checkpoint
A saved workspace state used for diffs and restore, stored as a hidden Git ref.
Checkpoint baseline
The workspace state captured before the work being compared.
Turn diff
The workspace changes attributed to one turn.