Imports

An import reads an external source, verifies the resulting objects, and publishes them in a repository. A named root keeps the finished graph available. Importers share the repository’s object records, roots, and collection rules; each format does not need its own storage system.

Publication and failure

Importers stage payloads in a mutation session, which protects those bytes while the import runs. Each object is checked against its format before its record is published. Large imports can publish intermediate batches without a root, then move the named root once the complete graph is ready. If an import fails, those intermediate objects may remain until collection, but the destination root does not point to a partial graph.

The standard local repository checks disk pressure when a mutation starts and may run collection first. See Garbage Collection for the policy and explicit cleanup commands.

Filesystem imports

FilesystemImport reads regular files, builds directories from their children, and publishes the resulting directory under a root. For example:

$ casita --repository ./cache import ./project --root projects/demo

The walk opens the source directory and resolves descendants relative to that open handle. It refuses a linked root and does not follow symlinks or other reparse points encountered during the walk. A symlink inside the tree is stored as a link with its target, without reading the target.

On supported local platforms, a repeat import can skip reading a regular file when its device, inode, size, modification time, and change time match the last import. This is a speed optimization based on file metadata, not a fresh content check. A remembered result is used only while its object still exists in committed repository state. Platforms without a usable file identity reread every file.

To read and hash every regular file regardless of its metadata, use --filesystem-rehash or FilesystemImport::new(...).reread(true) in Rust. Read Capture and Restore a Filesystem Tree for the full workflow.

Other inputs

Input	What the importer publishes	Guide
Git repository	Native Git objects and an immutable ref view under git/<view>.	Git
Decompressed tar stream	A canonical filesystem tree, without extracting the archive first.	Tar
Casitar archive	Verified objects and destination-owned root mappings after the archive’s declared closure checks pass.	Casitar

IPLD and custom formats also publish through ordinary mutation sessions. See Add a New Importer for the Rust contract.