Description

Stacked on #3490. Adds an optional version to branch checkout across the Rust core and the Python and TypeScript SDKs, so you can open a specific version on a branch ("version V of branch B"), not just the branch's latest version

Rust

// Open version 3 of branch "exp" (a read-only view): check out from an
// existing table, or open it directly from the connection.
let exp_v3 = table.checkout_branch("exp", Some(3)).await?;
let exp_v3 = db.open_table("items").branch("exp").version(3).execute().await?;
// checkout_latest re-attaches to the branch's writable HEAD.
exp_v3.checkout_latest().await?;

// With no branch, a version opens main at that version.
let main_v3 = db.open_table("items").version(3).execute().await?;

Python

# Open version 3 of branch "exp" (a read-only view): check out from an
# existing table, or open it directly from the connection.
branch_v3 = await table.branches.checkout("exp", version=3)
branch_v3 = await db.open_table("items", branch="exp", version=3)
# checkout_latest re-attaches to the branch's writable HEAD.
await branch_v3.checkout_latest()

# With no branch, a version opens main at that version.
main_v3 = await db.open_table("items", version=3)

TypeScript

// Open version 3 of branch "exp" (a read-only view): check out from an
// existing table, or open it directly from the connection.
const branchV3 = await (await table.branches()).checkout("exp", 3);
const opened = await db.openTable("items", undefined, { branch: "exp", version: 3 });
// checkoutLatest re-attaches to the branch's writable HEAD.
await branchV3.checkoutLatest();

// With no branch, a version opens main at that version.
const mainV3 = await db.openTable("items", undefined, { version: 3 });

Testing

• Added unit tests (Rust, Python sync + async, TypeScript): branch-scoped resolution at a version number shared with main and with another branch, read-only enforcement on a pinned handle, checkout_latest recovery to the branch's HEAD, fork-point reads, and the nonexistent-version/branch error paths.
• Ran smoke tests against the Python and TypeScript SDKs on local machine.