CloseFiles lists files to release in the new snapshot. A file is only fully closed once every API client that opened it closes it.

CloseProjects lists tsconfig.json files to release in the new snapshot. A project is only unloaded once every API client that opened it closes it.

FileChanges describes file system changes since the last snapshot.

OpenFiles lists files to keep open for the API client, mirroring LSP's textDocument/didOpen. For each file, ancestor directories are searched for a tsconfig that contains it; if found, that configured project is loaded and becomes the file's default project. Otherwise the file is loaded into the inferred project (e.g. a node_modules d.ts not in any project's import graph). Opens persist across snapshots until the file is closed.

OpenProjects lists tsconfig.json files to open/load in the new snapshot. Opens are ref-counted and persist across snapshots until closed.

The record with nothing set: every field is either optional or a default of its own, so this serialises to `{}`. Copy-update it to fill in the fields you mean - `{ UpdateSnapshotParams.Default with ... }` - rather than writing all 5 out.