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Environment variables

Variable Meaning
FWL_DATA Root of the writable data tree. Required unless an explicit data_root is passed in code or --data-root on the CLI; there is no silent default location.
FWL_DATA_CACHE Optional read-only, pre-populated copy of the tree (for example a group share on a cluster). Consulted before any download, verified by checksum, never written to. Ignored when the directory does not exist.
FWL_IO_OFFLINE Set to 1 (or true, yes, on) to forbid all network access: a file fetch (Fetcher.fetch, Fetcher.fetch_all) raises OfflineDataError for a missing or corrupt data file instead of a download, a model fetch (fetch_for, fwl-io fetch <model>) reports each failed dataset in one RuntimeError, and a command that needs the network (sync, mirror, mirror-publish, mirror-sync, mirror-pin, check-mirrors, mirror-status, latest) raises OfflineModeError before it connects. The OfflineDataError message names the file and the resolved data root.