Summary

Document that version-specific checkout is already supported via lance_dataset_open(uri, opts, version). Closes the "checkout" portion of the Version management row in the README Phase 3 roadmap.

Motivation

lance_dataset_open already accepts a version parameter that opens the dataset at a specific version. This capability is not advertised in the header examples or README, making it easy to miss. No new ABI surface is needed — just documentation.

Proposed change

Add a short example to include/lance.h and README.md:

/* Open a dataset at version 42 (0 means latest). */
LanceDataset* ds = lance_dataset_open("file:///path/to/ds", NULL, 42);

And in include/lance.hpp:

// Open at a specific version.
auto ds = lance::Dataset::open("file:///path/to/ds", /*version=*/42);

Out of scope

• Adding a new lance_dataset_checkout wrapper — not needed; the existing parameter covers the use case.

Tests

No new tests — existing lance_dataset_open tests already exercise the version parameter.

Locked design decisions

• Docs-only; no new ABI surface.

Related

• Part of the plan in docs/plan-write-path.md.
• Sibling tickets: A1 (versions list), A2 (restore), B1 (dataset write), B2 (write params).