Instances - DuckBrain

Every instance is a fully separate brain: its own catalog, lake, sidecars, and state.sql, at ~/.duckbrain/<instance>/.

duckbrain init --instance cindy          # ~/.duckbrain/cindy/
duckbrain search "..." --instance cindy  # flag form
DUCKBRAIN_INSTANCE=cindy duckbrain ...   # env form
DUCKBRAIN_ROOT=/path duckbrain ...       # relocate the whole tree

Two isolation levels: instances are physical (separate files — one per agent principal); namespaces/container-tags scope logically within an instance (per-workspace views of a shared brain). Moving an instance directory requires re-init or OVERRIDE_DATA_PATH — the DuckLake catalog stores its data path internally.