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Repository Layer

The repository layer is the low-level data exchange boundary for KEG data.

Repository Contract

pkg/keg/repository.go defines Repository, the core interface used by high-level keg operations.

It covers:

  • node lifecycle (next/list/move/delete)
  • node data (content/meta/stats)
  • indexes (dex/*)
  • keg config (keg file)
  • optional capabilities (files/images/snapshots)

Commands and services rely on this contract instead of directly accessing files.

Implementations

Primary implementations in pkg/keg:

  • repo_memory.go for in-memory repositories
  • repo_filesystem.go for filesystem-backed repositories
  • repo_memory_snapshots.go for in-memory revision history
  • repo_filesystem_snapshots.go for on-disk snapshot storage

NewKegFromTarget in pkg/keg/keg.go selects an implementation from a kegurl.Target scheme (memory or file).

High-Level KEG Service

pkg/keg/keg.go wraps the repository with a stateful API:

  • Init for keg bootstrap (config + zero node + indexes)
  • Create, Read, Move, Delete for node lifecycle
  • index and query-oriented operations over dex data

This separation allows command code to stay simple while storage behavior stays centralized and testable.

Snapshot Support

RepositorySnapshots is implemented for both shipped repositories:

  • MemoryRepo stores fully materialized revisions in memory for tests and fast local flows
  • FsRepo stores per-node history under snapshots/ with index.json, revision content blobs, and revision metadata/stats files

This powers tap and keg snapshot/history commands plus archive import/export workflows. Archive import reuses source node IDs and overwrites matching nodes in the target keg.

Why The Boundary Matters

  • storage can change without rewriting command handlers
  • tests can run against memory repos for fast behavior checks
  • file-backed behavior can be exercised independently in filesystem tests