13. Appendix: Schema Reference

13.1 Schema Versions

Artifact / Config	Schema Version	Description / Location
Configuration	batho-config.v1	Unified YAML configuration (batho.yaml)
Entity Schema	Pydantic model	Frozen dataclass for code entities
Relationship Schema	Pydantic model	Frozen dataclass for code relationships
Arrow Bundle	batho-bundle.v1	Arrow IPC tables: file_tracking, file_artifacts, run_artifacts
BSG View	bsg.v1	Memory-mapped Arrow IPC views

Schema Dependency Graph

Figure 24: Schema Dependency Graph - Diagram showing the relationships between configuration schemas, database tables, and output views.

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13.2 Directory Structure

.batho/
├── artifact/
│   └── artifact_<dirname>.batho    # Arrow IPC transport artifact
└── cache/
    └── cache.json                  # Shared AST cache metadata

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13.3 Glossary

Term	Definition
AST	Abstract Syntax Tree — structured representation of source code
BSG	Batho Structured Graph — compressed, queryable code representation
Arrow Bundle	High-performance binary database file containing entities, dependencies, and BSG views
Entity	A node in the code graph (function, class, variable, etc.)
Hypergraph	Graph where edges can connect any number of nodes
Patch	Incremental update to the database based on content-hash changes
Relationship	A directed edge between entities
Symbol Index	Cross-file lookup table for imports and exports
Syntax Glue	Whitespace, comments, braces, and non-semantic gaps recorded for lossless file reconstruction

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13.4 Error Codes

Code	Description
E001	File not found
E002	Parse error
E003	Cache corruption
E004	Snapshot mismatch
E005	Permission denied
E100	Configuration error
E200	Plugin load failure
E300	Storage registry error