Glossary

Project-specific terms used throughout the codebase. When a name has both a short form and a record-typed form (e.g. "shape" vs TLShape), the runtime types use the TL prefix.

Core concepts

• Editor — the central runtime object. Owns the store, the camera, the history manager, and the state-node tree. Defined in packages/editor/src/lib/editor/Editor.ts.
• Store — the in-memory reactive database of records. See packages/store/src/lib/Store.ts.
• Record — a single typed object stored in the store. Every record has an id of the form <type>:<unique>. Defined in packages/store/src/lib/BaseRecord.ts.
• Schema — the registry of record types and their migrations. See packages/tlschema/src/createTLSchema.ts.
• Migration — a versioned transformation of a record between schema versions. See packages/store/src/lib/migrate.ts and packages/tlschema/src/store-migrations.ts.
• Side effect — a hook that runs before or after store changes. Used by the editor to keep derived state correct. See packages/store/src/lib/StoreSideEffects.ts.

Document model

• TLShape — a shape record. TLBaseShape is the generic base; concrete types include TLArrowShape, TLDrawShape, TLGeoShape, TLNoteShape, TLLineShape, TLTextShape, TLImageShape, TLVideoShape, TLBookmarkShape, TLEmbedShape, TLFrameShape, TLHighlightShape, TLGroupShape. See packages/tlschema/src/shapes/.
• TLBinding — a relationship between two shapes (an arrow's endpoint bound to a shape, for instance). See packages/tlschema/src/records/TLBinding.ts and packages/tlschema/src/bindings/.
• TLAsset — a stored asset (image, video, bookmark) referenced by a shape. See packages/tlschema/src/records/TLAsset.ts.
• TLDocument — the root document record (singleton). One per store.
• TLPage — a page within a document.
• TLPageState — per-page editor state (selection, hovered shape, focus layer).
• TLInstance — per-instance editor state (current page, current tool, color theme).
• TLInstancePresence — multiplayer presence (cursor position, selection) for one user. See packages/tlschema/src/records/TLPresence.ts.
• TLCamera — viewport position and zoom for an instance/page.
• TLPointer — local pointer state.
• TLUser — user record (theme preferences, name, color).

Behavior

• ShapeUtil — the class that defines a shape's geometry, rendering, handles, hit-testing, and export behavior. Base class in packages/editor/src/lib/editor/shapes/ShapeUtil.ts. Concrete implementations live in packages/tldraw/src/lib/shapes/<kind>/<Kind>ShapeUtil.tsx.
• BindingUtil — analogous utility for bindings. Defined under packages/editor/src/lib/editor/bindings/ with concrete types in packages/tldraw/src/lib/bindings/.
• StateNode — a node in the editor's state-machine tree. Tools are state nodes; complex tools have child states. Defined in packages/editor/src/lib/editor/tools/StateNode.ts.
• Tool — a top-level state node bound to a UI affordance (Select, Hand, Draw, Eraser, Text, Frame, Note, Arrow, Geo, Line, Highlight, Laser, Zoom).
• Manager — a focused subsystem that the Editor composes. The set is in packages/editor/src/lib/editor/managers/.

Reactive primitives

• Atom — writable signal. From packages/state/src/lib/Atom.ts.
• Computed — derived signal that tracks its dependencies. From packages/state/src/lib/Computed.ts.
• Reactor / EffectScheduler — runs side-effecting reactions to signal changes. From packages/state/src/lib/EffectScheduler.ts.
• transact — batches signal mutations into a single notification cycle. See packages/state/src/lib/transactions.ts.
• react / useValue — React hooks from packages/state-react/.

Sync

• TLSocketRoom — server-side multiplayer room. packages/sync-core/src/lib/TLSocketRoom.ts.
• TLSyncRoom — the canonical record store and merge engine inside a room. packages/sync-core/src/lib/TLSyncRoom.ts.
• TLSyncClient — the client side of the sync protocol. packages/sync-core/src/lib/TLSyncClient.ts.
• ClientWebSocketAdapter / ServerSocketAdapter — transport-layer adapters.
• RoomSession — a single client's connection to a room. packages/sync-core/src/lib/RoomSession.ts.
• useSync / useSyncDemo — React hooks in packages/sync/src/.

SDK and apps

• tldraw (lowercase) — the npm package and React component. <Tldraw /> is exported from packages/tldraw/src/lib/Tldraw.tsx.
• tldraw.com — the hosted app at apps/dotcom/.
• tla — short for "tldraw app", the signed-in folders/files area at apps/dotcom/client/src/tla/.
• bemo-worker — the demo sync worker for useSyncDemo. apps/bemo-worker/.
• zero-cache — apps/dotcom/zero-cache/, the Zero view-syncer that replicates the Postgres app database to clients.
• dotcom-shared — packages/dotcom-shared/, types shared between the dotcom client and its workers.
• worker-shared — packages/worker-shared/, helpers used by multiple Cloudflare workers.
• lazyrepo — the task runner used for incremental builds.
• huppy — internal/huppy/, an internal automation bot (referenced in package.json and CI).

Conventions

• Sentence case for headings, labels, and PR titles.
• TL prefix for record-typed values shipped by the schema.
• @public / @internal TSDoc tags drive api-extractor reports under each package's api/ directory.