feat: add context checkout by version

python/python/lance_context/api.py

@@ -19,7 +19,7 @@ def _is_module(value: Any, prefix: str) -> bool:
 
 def _get_pyarrow():
     try:
-        import pyarrow as pa  # pyright: ignore[reportMissingImports]
+        import pyarrow as pa  # pyright: ignore[reportMissingImports,reportMissingTypeStubs]
     except ImportError as exc:  # pragma: no cover - optional dependency
         raise ImportError(
             "pyarrow is required to serialize pandas/polars dataframes"
@@ -113,6 +113,9 @@ def branch(self) -> str:
     def entries(self) -> int:
         return self._inner.entries()
 
+    def version(self) -> int:
+        return self._inner.version()
+
     def add(
         self,
         role: str,
@@ -134,8 +137,8 @@ def fork(self, branch_name: str) -> Context:
         inner = self._inner.fork(branch_name)
         return self._from_inner(inner)
 
-    def checkout(self, snapshot_id: str) -> None:
-        self._inner.checkout(snapshot_id)
+    def checkout(self, version_id: int | str) -> None:
+        self._inner.checkout(int(version_id))
 
     def __repr__(self) -> str:
         return (

python/python/tests/test_context.py

@@ -10,6 +10,9 @@ def test_context_create_and_add():
     ctx.add("user", "hello")
     ctx.add("assistant", 123, data_type="text/plain")
     assert ctx.entries() == 2
+    version = ctx.version()
+    assert isinstance(version, int)
+    ctx.checkout(version)
 
 
 def test_context_snapshot_and_fork():
@@ -25,3 +28,4 @@ def test_context_snapshot_and_fork():
     fork = ctx.fork("branch-a")
     assert fork.branch() == "branch-a"
     assert fork.entries() == ctx.entries()
+    assert fork.version() == ctx.version()

python/src/lib.rs

@@ -54,6 +54,10 @@ impl Context {
         self.inner.entries()
     }
 
+    fn version(&self) -> u64 {
+        self.store.version()
+    }
+
     #[pyo3(signature = (role, content, data_type = None))]
     fn add(
         &mut self,
@@ -116,8 +120,12 @@ impl Context {
         }
     }
 
-    fn checkout(&mut self, snapshot_id: &str) {
-        self.inner.checkout(snapshot_id);
+    fn checkout(&mut self, version_id: u64) -> PyResult<()> {
+        self.runtime
+            .block_on(self.store.checkout(version_id))
+            .map_err(to_py_err)?;
+        self.run_id = new_run_id();
+        Ok(())
     }
 }
 

rust/lance-context/src/store.rs

@@ -61,6 +61,18 @@ impl ContextStore {
         Ok(self.dataset.manifest.version)
     }
 
+    /// Current dataset version.
+    pub fn version(&self) -> u64 {
+        self.dataset.manifest.version
+    }
+
+    /// Checkout a specific dataset version.
+    pub async fn checkout(&mut self, version_id: u64) -> LanceResult<()> {
+        let dataset = self.dataset.checkout_version(version_id).await?;
+        self.dataset = dataset;
+        Ok(())
+    }
+
     /// Lance schema for the context store.
     pub fn schema() -> Schema {
         Schema::new(vec![