The canonical reference for Astrid OS: the kernel, the capsule model, the host ABI, the bus, and the security model.

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The reference appendices (capability catalog, host ABI error codes, topic registry) are generated from the Astrid source by tools/gen-appendices.sh. The cross-chapter "See also" footers are generated by tools/gen-see-also.pl. Both read the polyrepo source tree, so run them from a checkout that has core/, wit/, and capsules/ as siblings.

Dual-licensed under MIT and Apache 2.0.

Copyright (c) 2025-2026 Joshua J. Bouw and Unicity Labs.