Glossary

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 cycle, a V2 run. Provider work can end 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.

Orchestration

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.
Orchestrator	The service that serializes commands and decides their events from current state, without I/O.
Projection / read model	A persisted view of current state, committed in the same transaction as the events that change it.
Command receipt	A durable record of a command's result, used to make retries idempotent.
Outbox effect	Side-effect intent committed with the events, such as starting a provider turn or capturing a checkpoint.
Effect worker	The worker that runs outbox effects after commit and feeds their results back as commands.

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.
Text generation	App-owned one-shot writing, such as thread titles, commit messages, and transcript cleanup.
Text generator	A model API used only for text generation. Its id fills a model selection; agent surfaces never list it.
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.

Pull requests

Term	Meaning
Pull request link	A persisted thread association identified by host, repository, and number. Links can cross projects within an environment and carry a server-maintained snapshot.
Pull request sync	The worker that refreshes each distinct linked review once per cadence and discovers native stack layers. Explicit refreshes and failed stack reads trigger another read.
Current pull request	The link used by single-review controls and older clients. Open work takes precedence; a completed single chain points at its top layer. Unrelated terminal links use the latest update.

Composer context

Term	Meaning
Context record	The typed payload behind a composer chip, keyed by contextId in message.context.records. It never holds bytes.
Context reference	One occurrence of a record in message text: [label](https://github.com/pingdotgg/t3code/blob/d2c25950b4d9183ea342d5d5fc14c326b9e0172a/docs/internals/t3-context:/v1/<kind>/<contextId>). Several references can share one record.
Attachment binding	The link from an image or file record to its server-owned attachment. Its attachment ID can change without changing contextId.
Attachment inventory	The ordered image records shown as thumbnails above the prose, including images with no inline references.

See composer context references for the contract and lifecycle.