refactor(tvix/castore): move *Node and Directory to crate root r/8486

*Node and Directory are types of the tvix-castore model, not the tvix
DirectoryService model. A DirectoryService only happens to send
Directories.

Move types into individual files in a nodes/ subdirectory, as it's
gotten too cluttered in a single file, and (re-)export all types from
the crate root.

This has the effect that we now cannot poke at private fields directly
from other files inside `crate::directoryservice` (as it's not all in
the same file anymore), but that's a good thing, it now forces us to go
through the proper accessors.

For the same reasons, we currently also need to introduce the `rename`
functions on each *Node directly.

A followup is gonna move the names out of the individual enum kinds, so
we can better represent "unnamed nodes".

Change-Id: Icdb34dcfe454c41c94f2396e8e99973d27db8418
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12199
Reviewed-by: yuka <yuka@yuka.dev>
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

24 files changed, 588 insertions, 584 deletions

diff --git a/tvix/castore/src/directoryservice/directory_graph.rs b/tvix/castore/src/directoryservice/directory_graph.rs
index aa60f68a3197..0cf2f71adb06 100644
--- a/tvix/castore/src/directoryservice/directory_graph.rs
+++ b/tvix/castore/src/directoryservice/directory_graph.rs
@@ -10,8 +10,7 @@ use petgraph::{
 use tracing::instrument;
 
 use super::order_validator::{LeavesToRootValidator, OrderValidator, RootToLeavesValidator};
-use super::{Directory, DirectoryNode};
-use crate::B3Digest;
+use crate::{B3Digest, Directory, DirectoryNode, NamedNode};
 
 #[derive(thiserror::Error, Debug)]
 pub enum Error {
@@ -72,11 +71,11 @@ pub struct ValidatedDirectoryGraph {
 
 fn check_edge(dir: &DirectoryNode, child: &Directory) -> Result<(), Error> {
     // Ensure the size specified in the child node matches our records.
-    if dir.size != child.size() {
+    if dir.size() != child.size() {
         return Err(Error::ValidationError(format!(
             "'{}' has wrong size, specified {}, recorded {}",
-            dir.name.as_bstr(),
-            dir.size,
+            dir.get_name().as_bstr(),
+            dir.size(),
             child.size(),
         )));
     }
@@ -145,7 +144,7 @@ impl<O: OrderValidator> DirectoryGraph<O> {
         for subdir in directory.directories() {
             let child_ix = *self
                 .digest_to_node_ix
-                .entry(subdir.digest.clone())
+                .entry(subdir.digest().clone())
                 .or_insert_with(|| self.graph.add_node(None));
 
             let pending_edge_check = match &self.graph[child_ix] {
@@ -268,8 +267,8 @@ impl ValidatedDirectoryGraph {
 */
 #[cfg(test)]
 mod tests {
-    use crate::directoryservice::{Directory, DirectoryNode, Node};
     use crate::fixtures::{DIRECTORY_A, DIRECTORY_B, DIRECTORY_C};
+    use crate::{Directory, DirectoryNode, Node};
     use lazy_static::lazy_static;
     use rstest::rstest;
 
diff --git a/tvix/castore/src/directoryservice/mod.rs b/tvix/castore/src/directoryservice/mod.rs
index 0141a48f75bc..9f23176e31d0 100644
--- a/tvix/castore/src/directoryservice/mod.rs
+++ b/tvix/castore/src/directoryservice/mod.rs
@@ -1,9 +1,6 @@
 use crate::composition::{Registry, ServiceBuilder};
-use crate::proto;
-use crate::{B3Digest, Error};
-use crate::{ValidateDirectoryError, ValidateNodeError};
+use crate::{B3Digest, Directory, Error};
 
-use bytes::Bytes;
 use futures::stream::BoxStream;
 use tonic::async_trait;
 mod combinators;
@@ -148,461 +145,3 @@ pub(crate) fn register_directory_services(reg: &mut Registry) {
         reg.register::<Box<dyn ServiceBuilder<Output = dyn DirectoryService>>, super::directoryservice::BigtableParameters>("bigtable");
     }
 }
-
-/// A Directory can contain Directory, File or Symlink nodes.
-/// Each of these nodes have a name attribute, which is the basename in that
-/// directory and node type specific attributes.
-/// While a Node by itself may have any name, the names of Directory entries:
-///  - MUST not contain slashes or null bytes
-///  - MUST not be '.' or '..'
-///  - MUST be unique across all three lists
-#[derive(Default, Debug, Clone, PartialEq, Eq)]
-pub struct Directory {
-    nodes: Vec<Node>,
-}
-
-/// A DirectoryNode is a pointer to a [Directory], by its [Directory::digest].
-/// It also gives it a `name` and `size`.
-/// Such a node is either an element in the [Directory] it itself is contained in,
-/// or a standalone root node./
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct DirectoryNode {
-    /// The (base)name of the directory
-    name: Bytes,
-    /// The blake3 hash of a Directory message, serialized in protobuf canonical form.
-    digest: B3Digest,
-    /// Number of child elements in the Directory referred to by `digest`.
-    /// Calculated by summing up the numbers of nodes, and for each directory.
-    /// its size field. Can be used for inode allocation.
-    /// This field is precisely as verifiable as any other Merkle tree edge.
-    /// Resolve `digest`, and you can compute it incrementally. Resolve the entire
-    /// tree, and you can fully compute it from scratch.
-    /// A credulous implementation won't reject an excessive size, but this is
-    /// harmless: you'll have some ordinals without nodes. Undersizing is obvious
-    /// and easy to reject: you won't have an ordinal for some nodes.
-    size: u64,
-}
-
-impl DirectoryNode {
-    pub fn new(name: Bytes, digest: B3Digest, size: u64) -> Result<Self, ValidateNodeError> {
-        Ok(Self { name, digest, size })
-    }
-
-    pub fn digest(&self) -> &B3Digest {
-        &self.digest
-    }
-    pub fn size(&self) -> u64 {
-        self.size
-    }
-}
-
-/// A FileNode represents a regular or executable file in a Directory or at the root.
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct FileNode {
-    /// The (base)name of the file
-    name: Bytes,
-
-    /// The blake3 digest of the file contents
-    digest: B3Digest,
-
-    /// The file content size
-    size: u64,
-
-    /// Whether the file is executable
-    executable: bool,
-}
-
-impl FileNode {
-    pub fn new(
-        name: Bytes,
-        digest: B3Digest,
-        size: u64,
-        executable: bool,
-    ) -> Result<Self, ValidateNodeError> {
-        Ok(Self {
-            name,
-            digest,
-            size,
-            executable,
-        })
-    }
-
-    pub fn digest(&self) -> &B3Digest {
-        &self.digest
-    }
-
-    pub fn size(&self) -> u64 {
-        self.size
-    }
-
-    pub fn executable(&self) -> bool {
-        self.executable
-    }
-}
-
-/// A SymlinkNode represents a symbolic link in a Directory or at the root.
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct SymlinkNode {
-    /// The (base)name of the symlink
-    name: Bytes,
-    /// The target of the symlink.
-    target: Bytes,
-}
-
-impl SymlinkNode {
-    pub fn new(name: Bytes, target: Bytes) -> Result<Self, ValidateNodeError> {
-        if target.is_empty() || target.contains(&b'\0') {
-            return Err(ValidateNodeError::InvalidSymlinkTarget(target));
-        }
-        Ok(Self { name, target })
-    }
-
-    pub fn target(&self) -> &bytes::Bytes {
-        &self.target
-    }
-}
-
-/// A Node is either a [DirectoryNode], [FileNode] or [SymlinkNode].
-/// While a Node by itself may have any name, only those matching specific requirements
-/// can can be added as entries to a [Directory] (see the documentation on [Directory] for details).
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub enum Node {
-    Directory(DirectoryNode),
-    File(FileNode),
-    Symlink(SymlinkNode),
-}
-
-/// NamedNode is implemented for [FileNode], [DirectoryNode] and [SymlinkNode]
-/// and [Node], so we can ask all of them for the name easily.
-pub trait NamedNode {
-    fn get_name(&self) -> &bytes::Bytes;
-}
-
-impl NamedNode for &FileNode {
-    fn get_name(&self) -> &bytes::Bytes {
-        &self.name
-    }
-}
-impl NamedNode for FileNode {
-    fn get_name(&self) -> &bytes::Bytes {
-        &self.name
-    }
-}
-
-impl NamedNode for &DirectoryNode {
-    fn get_name(&self) -> &bytes::Bytes {
-        &self.name
-    }
-}
-impl NamedNode for DirectoryNode {
-    fn get_name(&self) -> &bytes::Bytes {
-        &self.name
-    }
-}
-
-impl NamedNode for &SymlinkNode {
-    fn get_name(&self) -> &bytes::Bytes {
-        &self.name
-    }
-}
-impl NamedNode for SymlinkNode {
-    fn get_name(&self) -> &bytes::Bytes {
-        &self.name
-    }
-}
-
-impl NamedNode for &Node {
-    fn get_name(&self) -> &bytes::Bytes {
-        match self {
-            Node::File(node_file) => &node_file.name,
-            Node::Directory(node_directory) => &node_directory.name,
-            Node::Symlink(node_symlink) => &node_symlink.name,
-        }
-    }
-}
-impl NamedNode for Node {
-    fn get_name(&self) -> &bytes::Bytes {
-        match self {
-            Node::File(node_file) => &node_file.name,
-            Node::Directory(node_directory) => &node_directory.name,
-            Node::Symlink(node_symlink) => &node_symlink.name,
-        }
-    }
-}
-
-impl Node {
-    /// Returns the node with a new name.
-    pub fn rename(self, name: bytes::Bytes) -> Self {
-        match self {
-            Node::Directory(n) => Node::Directory(DirectoryNode { name, ..n }),
-            Node::File(n) => Node::File(FileNode { name, ..n }),
-            Node::Symlink(n) => Node::Symlink(SymlinkNode { name, ..n }),
-        }
-    }
-}
-
-impl PartialOrd for Node {
-    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
-        Some(self.cmp(other))
-    }
-}
-
-impl Ord for Node {
-    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
-        self.get_name().cmp(other.get_name())
-    }
-}
-
-impl PartialOrd for FileNode {
-    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
-        Some(self.cmp(other))
-    }
-}
-
-impl Ord for FileNode {
-    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
-        self.get_name().cmp(other.get_name())
-    }
-}
-
-impl PartialOrd for DirectoryNode {
-    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
-        Some(self.cmp(other))
-    }
-}
-
-impl Ord for DirectoryNode {
-    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
-        self.get_name().cmp(other.get_name())
-    }
-}
-
-impl PartialOrd for SymlinkNode {
-    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
-        Some(self.cmp(other))
-    }
-}
-
-impl Ord for SymlinkNode {
-    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
-        self.get_name().cmp(other.get_name())
-    }
-}
-
-fn checked_sum(iter: impl IntoIterator<Item = u64>) -> Option<u64> {
-    iter.into_iter().try_fold(0u64, |acc, i| acc.checked_add(i))
-}
-
-impl Directory {
-    pub fn new() -> Self {
-        Directory { nodes: vec![] }
-    }
-
-    /// The size of a directory is the number of all regular and symlink elements,
-    /// the number of directory elements, and their size fields.
-    pub fn size(&self) -> u64 {
-        // It's impossible to create a Directory where the size overflows, because we
-        // check before every add() that the size won't overflow.
-        (self.nodes.len() as u64) + self.directories().map(|e| e.size).sum::<u64>()
-    }
-
-    /// Calculates the digest of a Directory, which is the blake3 hash of a
-    /// Directory protobuf message, serialized in protobuf canonical form.
-    pub fn digest(&self) -> B3Digest {
-        proto::Directory::from(self).digest()
-    }
-
-    /// Allows iterating over all nodes (directories, files and symlinks)
-    /// ordered by their name.
-    pub fn nodes(&self) -> impl Iterator<Item = &Node> + Send + Sync + '_ {
-        self.nodes.iter()
-    }
-
-    /// Allows iterating over the FileNode entries of this directory
-    /// ordered by their name
-    pub fn files(&self) -> impl Iterator<Item = &FileNode> + Send + Sync + '_ {
-        self.nodes.iter().filter_map(|node| match node {
-            Node::File(n) => Some(n),
-            _ => None,
-        })
-    }
-
-    /// Allows iterating over the subdirectories of this directory
-    /// ordered by their name
-    pub fn directories(&self) -> impl Iterator<Item = &DirectoryNode> + Send + Sync + '_ {
-        self.nodes.iter().filter_map(|node| match node {
-            Node::Directory(n) => Some(n),
-            _ => None,
-        })
-    }
-
-    /// Allows iterating over the SymlinkNode entries of this directory
-    /// ordered by their name
-    pub fn symlinks(&self) -> impl Iterator<Item = &SymlinkNode> + Send + Sync + '_ {
-        self.nodes.iter().filter_map(|node| match node {
-            Node::Symlink(n) => Some(n),
-            _ => None,
-        })
-    }
-
-    /// Checks a Node name for validity as a directory entry
-    /// We disallow slashes, null bytes, '.', '..' and the empty string.
-    pub(crate) fn validate_node_name(name: &[u8]) -> Result<(), ValidateNodeError> {
-        if name.is_empty()
-            || name == b".."
-            || name == b"."
-            || name.contains(&0x00)
-            || name.contains(&b'/')
-        {
-            Err(ValidateNodeError::InvalidName(name.to_owned().into()))
-        } else {
-            Ok(())
-        }
-    }
-
-    /// Adds the specified [Node] to the [Directory], preserving sorted entries.
-    ///
-    /// Inserting an element that already exists with the same name in the directory will yield an
-    /// error.
-    /// Inserting an element will validate that its name fulfills the stricter requirements for
-    /// directory entries and yield an error if it is not.
-    pub fn add(&mut self, node: Node) -> Result<(), ValidateDirectoryError> {
-        Self::validate_node_name(node.get_name())
-            .map_err(|e| ValidateDirectoryError::InvalidNode(node.get_name().clone().into(), e))?;
-
-        // Check that the even after adding this new directory entry, the size calculation will not
-        // overflow
-        // FUTUREWORK: add some sort of batch add interface which only does this check once with
-        // all the to-be-added entries
-        checked_sum([
-            self.size(),
-            1,
-            match node {
-                Node::Directory(ref dir) => dir.size,
-                _ => 0,
-            },
-        ])
-        .ok_or(ValidateDirectoryError::SizeOverflow)?;
-
-        // This assumes the [Directory] is sorted, since we don't allow accessing the nodes list
-        // directly and all previous inserts should have been in-order
-        let pos = match self
-            .nodes
-            .binary_search_by_key(&node.get_name(), |n| n.get_name())
-        {
-            Err(pos) => pos, // There is no node with this name; good!
-            Ok(_) => {
-                return Err(ValidateDirectoryError::DuplicateName(
-                    node.get_name().to_vec(),
-                ))
-            }
-        };
-
-        self.nodes.insert(pos, node);
-        Ok(())
-    }
-}
-
-#[cfg(test)]
-mod test {
-    use super::{Directory, DirectoryNode, FileNode, Node, SymlinkNode};
-    use crate::fixtures::DUMMY_DIGEST;
-    use crate::ValidateDirectoryError;
-
-    #[test]
-    fn add_nodes_to_directory() {
-        let mut d = Directory::new();
-
-        d.add(Node::Directory(
-            DirectoryNode::new("b".into(), DUMMY_DIGEST.clone(), 1).unwrap(),
-        ))
-        .unwrap();
-        d.add(Node::Directory(
-            DirectoryNode::new("a".into(), DUMMY_DIGEST.clone(), 1).unwrap(),
-        ))
-        .unwrap();
-        d.add(Node::Directory(
-            DirectoryNode::new("z".into(), DUMMY_DIGEST.clone(), 1).unwrap(),
-        ))
-        .unwrap();
-
-        d.add(Node::File(
-            FileNode::new("f".into(), DUMMY_DIGEST.clone(), 1, true).unwrap(),
-        ))
-        .unwrap();
-        d.add(Node::File(
-            FileNode::new("c".into(), DUMMY_DIGEST.clone(), 1, true).unwrap(),
-        ))
-        .unwrap();
-        d.add(Node::File(
-            FileNode::new("g".into(), DUMMY_DIGEST.clone(), 1, true).unwrap(),
-        ))
-        .unwrap();
-
-        d.add(Node::Symlink(
-            SymlinkNode::new("t".into(), "a".into()).unwrap(),
-        ))
-        .unwrap();
-        d.add(Node::Symlink(
-            SymlinkNode::new("o".into(), "a".into()).unwrap(),
-        ))
-        .unwrap();
-        d.add(Node::Symlink(
-            SymlinkNode::new("e".into(), "a".into()).unwrap(),
-        ))
-        .unwrap();
-
-        // Convert to proto struct and back to ensure we are not generating any invalid structures
-        crate::directoryservice::Directory::try_from(crate::proto::Directory::from(d))
-            .expect("directory should be valid");
-    }
-
-    #[test]
-    fn validate_overflow() {
-        let mut d = Directory::new();
-
-        assert_eq!(
-            d.add(Node::Directory(
-                DirectoryNode::new("foo".into(), DUMMY_DIGEST.clone(), u64::MAX).unwrap(),
-            )),
-            Err(ValidateDirectoryError::SizeOverflow)
-        );
-    }
-
-    #[test]
-    fn add_duplicate_node_to_directory() {
-        let mut d = Directory::new();
-
-        d.add(Node::Directory(
-            DirectoryNode::new("a".into(), DUMMY_DIGEST.clone(), 1).unwrap(),
-        ))
-        .unwrap();
-        assert_eq!(
-            format!(
-                "{}",
-                d.add(Node::File(
-                    FileNode::new("a".into(), DUMMY_DIGEST.clone(), 1, true).unwrap(),
-                ))
-                .expect_err("adding duplicate dir entry must fail")
-            ),
-            "\"a\" is a duplicate name"
-        );
-    }
-
-    /// Attempt to add a directory entry with a name which should be rejected.
-    #[tokio::test]
-    async fn directory_reject_invalid_name() {
-        let mut dir = Directory::new();
-        assert!(
-            dir.add(Node::Symlink(
-                SymlinkNode::new(
-                    "".into(), // wrong! can not be added to directory
-                    "doesntmatter".into(),
-                )
-                .unwrap()
-            ))
-            .is_err(),
-            "invalid symlink entry be rejected"
-        );
-    }
-}
diff --git a/tvix/castore/src/directoryservice/order_validator.rs b/tvix/castore/src/directoryservice/order_validator.rs
index 17431fc8d3b0..f03bb7ff9a86 100644
--- a/tvix/castore/src/directoryservice/order_validator.rs
+++ b/tvix/castore/src/directoryservice/order_validator.rs
@@ -50,7 +50,7 @@ impl RootToLeavesValidator {
 
         for subdir in directory.directories() {
             // Allow the children to appear next
-            self.expected_digests.insert(subdir.digest.clone());
+            self.expected_digests.insert(subdir.digest().clone());
         }
     }
 }
@@ -80,10 +80,10 @@ impl OrderValidator for LeavesToRootValidator {
         let digest = directory.digest();
 
         for subdir in directory.directories() {
-            if !self.allowed_references.contains(&subdir.digest) {
+            if !self.allowed_references.contains(subdir.digest()) {
                 warn!(
                     directory.digest = %digest,
-                    subdirectory.digest = %subdir.digest,
+                    subdirectory.digest = %subdir.digest(),
                     "unexpected directory reference"
                 );
                 return false;
diff --git a/tvix/castore/src/directoryservice/tests/mod.rs b/tvix/castore/src/directoryservice/tests/mod.rs
index 3923e66dc2c2..7a15f44a686e 100644
--- a/tvix/castore/src/directoryservice/tests/mod.rs
+++ b/tvix/castore/src/directoryservice/tests/mod.rs
@@ -8,8 +8,8 @@ use rstest_reuse::{self, *};
 
 use super::DirectoryService;
 use crate::directoryservice;
-use crate::directoryservice::{Directory, DirectoryNode, Node};
 use crate::fixtures::{DIRECTORY_A, DIRECTORY_B, DIRECTORY_C, DIRECTORY_D};
+use crate::{Directory, DirectoryNode, Node};
 
 mod utils;
 use self::utils::make_grpc_directory_service_client;
diff --git a/tvix/castore/src/directoryservice/traverse.rs b/tvix/castore/src/directoryservice/traverse.rs
index 3e6dc73a4d6b..ff667e0f65c0 100644
--- a/tvix/castore/src/directoryservice/traverse.rs
+++ b/tvix/castore/src/directoryservice/traverse.rs
@@ -1,5 +1,4 @@
-use super::{DirectoryService, NamedNode, Node};
-use crate::{Error, Path};
+use crate::{directoryservice::DirectoryService, Error, NamedNode, Node, Path};
 use tracing::{instrument, warn};
 
 /// This descends from a (root) node to the given (sub)path, returning the Node
@@ -25,15 +24,15 @@ where
                 // fetch the linked node from the directory_service.
                 let directory = directory_service
                     .as_ref()
-                    .get(&directory_node.digest)
+                    .get(directory_node.digest())
                     .await?
                     .ok_or_else(|| {
                         // If we didn't get the directory node that's linked, that's a store inconsistency, bail out!
-                        warn!("directory {} does not exist", directory_node.digest);
+                        warn!("directory {} does not exist", directory_node.digest());
 
                         Error::StorageError(format!(
                             "directory {} does not exist",
-                            directory_node.digest
+                            directory_node.digest()
                         ))
                     })?;
 
@@ -59,9 +58,8 @@ where
 mod tests {
     use crate::{
         directoryservice,
-        directoryservice::{DirectoryNode, Node},
         fixtures::{DIRECTORY_COMPLICATED, DIRECTORY_WITH_KEEP},
-        PathBuf,
+        DirectoryNode, Node, PathBuf,
     };
 
     use super::descend_to;
diff --git a/tvix/castore/src/directoryservice/utils.rs b/tvix/castore/src/directoryservice/utils.rs
index 352362811a97..f1133663ede7 100644
--- a/tvix/castore/src/directoryservice/utils.rs
+++ b/tvix/castore/src/directoryservice/utils.rs
@@ -59,7 +59,7 @@ pub fn traverse_directory<'a, DS: DirectoryService + 'static>(
             // This panics if the digest looks invalid, it's supposed to be checked first.
             for child_directory_node in current_directory.directories() {
                 // TODO: propagate error
-                let child_digest: B3Digest = child_directory_node.digest.clone();
+                let child_digest: B3Digest = child_directory_node.digest().clone();
 
                 if worklist_directory_digests.contains(&child_digest)
                     || sent_directory_digests.contains(&child_digest)
diff --git a/tvix/castore/src/fixtures.rs b/tvix/castore/src/fixtures.rs
index 0e423d348522..06366f2057ab 100644
--- a/tvix/castore/src/fixtures.rs
+++ b/tvix/castore/src/fixtures.rs
@@ -1,6 +1,5 @@
 use crate::{
-    directoryservice::{Directory, DirectoryNode, FileNode, Node, SymlinkNode},
-    B3Digest,
+    B3Digest, {Directory, DirectoryNode, FileNode, Node, SymlinkNode},
 };
 use lazy_static::lazy_static;
 
diff --git a/tvix/castore/src/fs/fuse/tests.rs b/tvix/castore/src/fs/fuse/tests.rs
index 726beb5858c5..3dad7d83aedd 100644
--- a/tvix/castore/src/fs/fuse/tests.rs
+++ b/tvix/castore/src/fs/fuse/tests.rs
@@ -15,10 +15,8 @@ use super::FuseDaemon;
 use crate::fs::{TvixStoreFs, XATTR_NAME_BLOB_DIGEST, XATTR_NAME_DIRECTORY_DIGEST};
 use crate::{
     blobservice::{BlobService, MemoryBlobService},
-    directoryservice::{
-        DirectoryNode, DirectoryService, FileNode, MemoryDirectoryService, Node, SymlinkNode,
-    },
-    fixtures,
+    directoryservice::{DirectoryService, MemoryDirectoryService},
+    fixtures, {DirectoryNode, FileNode, Node, SymlinkNode},
 };
 
 const BLOB_A_NAME: &str = "00000000000000000000000000000000-test";
diff --git a/tvix/castore/src/fs/inodes.rs b/tvix/castore/src/fs/inodes.rs
index 379d4ab87318..b04505c9fa98 100644
--- a/tvix/castore/src/fs/inodes.rs
+++ b/tvix/castore/src/fs/inodes.rs
@@ -4,8 +4,7 @@ use std::time::Duration;
 
 use bytes::Bytes;
 
-use crate::directoryservice::{NamedNode, Node};
-use crate::B3Digest;
+use crate::{B3Digest, NamedNode, Node};
 
 #[derive(Clone, Debug)]
 pub enum InodeData {
diff --git a/tvix/castore/src/fs/mod.rs b/tvix/castore/src/fs/mod.rs
index 4a6ca88d73fd..90c1f371b546 100644
--- a/tvix/castore/src/fs/mod.rs
+++ b/tvix/castore/src/fs/mod.rs
@@ -17,8 +17,8 @@ use self::{
 };
 use crate::{
     blobservice::{BlobReader, BlobService},
-    directoryservice::{DirectoryService, NamedNode, Node},
-    B3Digest,
+    directoryservice::DirectoryService,
+    {B3Digest, NamedNode, Node},
 };
 use bstr::ByteVec;
 use bytes::Bytes;
diff --git a/tvix/castore/src/fs/root_nodes.rs b/tvix/castore/src/fs/root_nodes.rs
index 6d78b243d064..c237142c8d91 100644
--- a/tvix/castore/src/fs/root_nodes.rs
+++ b/tvix/castore/src/fs/root_nodes.rs
@@ -1,7 +1,6 @@
 use std::collections::BTreeMap;
 
-use crate::{directoryservice::Node, Error};
-use bytes::Bytes;
+use crate::{Error, Node};
 use futures::stream::BoxStream;
 use tonic::async_trait;
 
@@ -23,7 +22,7 @@ pub trait RootNodes: Send + Sync {
 /// the key is the node name.
 impl<T> RootNodes for T
 where
-    T: AsRef<BTreeMap<Bytes, Node>> + Send + Sync,
+    T: AsRef<BTreeMap<bytes::Bytes, Node>> + Send + Sync,
 {
     async fn get_by_basename(&self, name: &[u8]) -> Result<Option<Node>, Error> {
         Ok(self.as_ref().get(name).cloned())
diff --git a/tvix/castore/src/import/archive.rs b/tvix/castore/src/import/archive.rs
index 930f33f68b46..167f799efa0f 100644
--- a/tvix/castore/src/import/archive.rs
+++ b/tvix/castore/src/import/archive.rs
@@ -11,8 +11,9 @@ use tokio_tar::Archive;
 use tracing::{instrument, warn, Level};
 
 use crate::blobservice::BlobService;
-use crate::directoryservice::{DirectoryService, Node};
+use crate::directoryservice::DirectoryService;
 use crate::import::{ingest_entries, IngestionEntry, IngestionError};
+use crate::Node;
 
 use super::blobs::{self, ConcurrentBlobUploader};
 
diff --git a/tvix/castore/src/import/fs.rs b/tvix/castore/src/import/fs.rs
index f156c8a73527..1332fdfe57b5 100644
--- a/tvix/castore/src/import/fs.rs
+++ b/tvix/castore/src/import/fs.rs
@@ -15,8 +15,8 @@ use walkdir::DirEntry;
 use walkdir::WalkDir;
 
 use crate::blobservice::BlobService;
-use crate::directoryservice::{DirectoryService, Node};
-use crate::B3Digest;
+use crate::directoryservice::DirectoryService;
+use crate::{B3Digest, Node};
 
 use super::ingest_entries;
 use super::IngestionEntry;
diff --git a/tvix/castore/src/import/mod.rs b/tvix/castore/src/import/mod.rs
index 03e2b6c7db41..b40dfd74e9e4 100644
--- a/tvix/castore/src/import/mod.rs
+++ b/tvix/castore/src/import/mod.rs
@@ -4,15 +4,9 @@
 //! Specific implementations, such as ingesting from the filesystem, live in
 //! child modules.
 
-use crate::directoryservice::Directory;
-use crate::directoryservice::DirectoryNode;
-use crate::directoryservice::DirectoryPutter;
-use crate::directoryservice::DirectoryService;
-use crate::directoryservice::FileNode;
-use crate::directoryservice::Node;
-use crate::directoryservice::SymlinkNode;
+use crate::directoryservice::{DirectoryPutter, DirectoryService};
 use crate::path::{Path, PathBuf};
-use crate::B3Digest;
+use crate::{B3Digest, Directory, DirectoryNode, FileNode, Node, SymlinkNode};
 use futures::{Stream, StreamExt};
 use tracing::Level;
 
@@ -219,9 +213,9 @@ impl IngestionEntry {
 mod test {
     use rstest::rstest;
 
-    use crate::directoryservice::{Directory, DirectoryNode, FileNode, Node, SymlinkNode};
     use crate::fixtures::{DIRECTORY_COMPLICATED, DIRECTORY_WITH_KEEP, EMPTY_BLOB_DIGEST};
     use crate::{directoryservice::MemoryDirectoryService, fixtures::DUMMY_DIGEST};
+    use crate::{Directory, DirectoryNode, FileNode, Node, SymlinkNode};
 
     use super::ingest_entries;
     use super::IngestionEntry;
diff --git a/tvix/castore/src/lib.rs b/tvix/castore/src/lib.rs
index 91302e90996c..e09926afe70d 100644
--- a/tvix/castore/src/lib.rs
+++ b/tvix/castore/src/lib.rs
@@ -10,6 +10,9 @@ pub mod fixtures;
 #[cfg(feature = "fs")]
 pub mod fs;
 
+mod nodes;
+pub use nodes::*;
+
 mod path;
 pub use path::{Path, PathBuf};
 
diff --git a/tvix/castore/src/nodes/directory.rs b/tvix/castore/src/nodes/directory.rs
new file mode 100644
index 000000000000..1752681c89c3
--- /dev/null
+++ b/tvix/castore/src/nodes/directory.rs
@@ -0,0 +1,234 @@
+use crate::{
+    proto, B3Digest, DirectoryNode, FileNode, NamedNode, Node, SymlinkNode, ValidateDirectoryError,
+    ValidateNodeError,
+};
+
+/// A Directory can contain Directory, File or Symlink nodes.
+/// Each of these nodes have a name attribute, which is the basename in that
+/// directory and node type specific attributes.
+/// While a Node by itself may have any name, the names of Directory entries:
+///  - MUST not contain slashes or null bytes
+///  - MUST not be '.' or '..'
+///  - MUST be unique across all three lists
+#[derive(Default, Debug, Clone, PartialEq, Eq)]
+pub struct Directory {
+    nodes: Vec<Node>,
+}
+
+impl Directory {
+    pub fn new() -> Self {
+        Directory { nodes: vec![] }
+    }
+
+    /// The size of a directory is the number of all regular and symlink elements,
+    /// the number of directory elements, and their size fields.
+    pub fn size(&self) -> u64 {
+        // It's impossible to create a Directory where the size overflows, because we
+        // check before every add() that the size won't overflow.
+        (self.nodes.len() as u64) + self.directories().map(|e| e.size()).sum::<u64>()
+    }
+
+    /// Calculates the digest of a Directory, which is the blake3 hash of a
+    /// Directory protobuf message, serialized in protobuf canonical form.
+    pub fn digest(&self) -> B3Digest {
+        proto::Directory::from(self.clone()).digest()
+    }
+
+    /// Allows iterating over all nodes (directories, files and symlinks)
+    /// ordered by their name.
+    pub fn nodes(&self) -> impl Iterator<Item = &Node> + Send + Sync + '_ {
+        self.nodes.iter()
+    }
+
+    /// Allows iterating over the FileNode entries of this directory
+    /// ordered by their name
+    pub fn files(&self) -> impl Iterator<Item = &FileNode> + Send + Sync + '_ {
+        self.nodes.iter().filter_map(|node| match node {
+            Node::File(n) => Some(n),
+            _ => None,
+        })
+    }
+
+    /// Allows iterating over the subdirectories of this directory
+    /// ordered by their name
+    pub fn directories(&self) -> impl Iterator<Item = &DirectoryNode> + Send + Sync + '_ {
+        self.nodes.iter().filter_map(|node| match node {
+            Node::Directory(n) => Some(n),
+            _ => None,
+        })
+    }
+
+    /// Allows iterating over the SymlinkNode entries of this directory
+    /// ordered by their name
+    pub fn symlinks(&self) -> impl Iterator<Item = &SymlinkNode> + Send + Sync + '_ {
+        self.nodes.iter().filter_map(|node| match node {
+            Node::Symlink(n) => Some(n),
+            _ => None,
+        })
+    }
+
+    /// Checks a Node name for validity as a directory entry
+    /// We disallow slashes, null bytes, '.', '..' and the empty string.
+    pub(crate) fn validate_node_name(name: &[u8]) -> Result<(), ValidateNodeError> {
+        if name.is_empty()
+            || name == b".."
+            || name == b"."
+            || name.contains(&0x00)
+            || name.contains(&b'/')
+        {
+            Err(ValidateNodeError::InvalidName(name.to_owned().into()))
+        } else {
+            Ok(())
+        }
+    }
+
+    /// Adds the specified [Node] to the [Directory], preserving sorted entries.
+    ///
+    /// Inserting an element that already exists with the same name in the directory will yield an
+    /// error.
+    /// Inserting an element will validate that its name fulfills the stricter requirements for
+    /// directory entries and yield an error if it is not.
+    pub fn add(&mut self, node: Node) -> Result<(), ValidateDirectoryError> {
+        Self::validate_node_name(node.get_name())
+            .map_err(|e| ValidateDirectoryError::InvalidNode(node.get_name().clone().into(), e))?;
+
+        // Check that the even after adding this new directory entry, the size calculation will not
+        // overflow
+        // FUTUREWORK: add some sort of batch add interface which only does this check once with
+        // all the to-be-added entries
+        checked_sum([
+            self.size(),
+            1,
+            match node {
+                Node::Directory(ref dir) => dir.size(),
+                _ => 0,
+            },
+        ])
+        .ok_or(ValidateDirectoryError::SizeOverflow)?;
+
+        // This assumes the [Directory] is sorted, since we don't allow accessing the nodes list
+        // directly and all previous inserts should have been in-order
+        let pos = match self
+            .nodes
+            .binary_search_by_key(&node.get_name(), |n| n.get_name())
+        {
+            Err(pos) => pos, // There is no node with this name; good!
+            Ok(_) => {
+                return Err(ValidateDirectoryError::DuplicateName(
+                    node.get_name().to_vec(),
+                ))
+            }
+        };
+
+        self.nodes.insert(pos, node);
+        Ok(())
+    }
+}
+
+fn checked_sum(iter: impl IntoIterator<Item = u64>) -> Option<u64> {
+    iter.into_iter().try_fold(0u64, |acc, i| acc.checked_add(i))
+}
+
+#[cfg(test)]
+mod test {
+    use super::{Directory, DirectoryNode, FileNode, Node, SymlinkNode};
+    use crate::fixtures::DUMMY_DIGEST;
+    use crate::ValidateDirectoryError;
+
+    #[test]
+    fn add_nodes_to_directory() {
+        let mut d = Directory::new();
+
+        d.add(Node::Directory(
+            DirectoryNode::new("b".into(), DUMMY_DIGEST.clone(), 1).unwrap(),
+        ))
+        .unwrap();
+        d.add(Node::Directory(
+            DirectoryNode::new("a".into(), DUMMY_DIGEST.clone(), 1).unwrap(),
+        ))
+        .unwrap();
+        d.add(Node::Directory(
+            DirectoryNode::new("z".into(), DUMMY_DIGEST.clone(), 1).unwrap(),
+        ))
+        .unwrap();
+
+        d.add(Node::File(
+            FileNode::new("f".into(), DUMMY_DIGEST.clone(), 1, true).unwrap(),
+        ))
+        .unwrap();
+        d.add(Node::File(
+            FileNode::new("c".into(), DUMMY_DIGEST.clone(), 1, true).unwrap(),
+        ))
+        .unwrap();
+        d.add(Node::File(
+            FileNode::new("g".into(), DUMMY_DIGEST.clone(), 1, true).unwrap(),
+        ))
+        .unwrap();
+
+        d.add(Node::Symlink(
+            SymlinkNode::new("t".into(), "a".into()).unwrap(),
+        ))
+        .unwrap();
+        d.add(Node::Symlink(
+            SymlinkNode::new("o".into(), "a".into()).unwrap(),
+        ))
+        .unwrap();
+        d.add(Node::Symlink(
+            SymlinkNode::new("e".into(), "a".into()).unwrap(),
+        ))
+        .unwrap();
+
+        // Convert to proto struct and back to ensure we are not generating any invalid structures
+        crate::Directory::try_from(crate::proto::Directory::from(d))
+            .expect("directory should be valid");
+    }
+
+    #[test]
+    fn validate_overflow() {
+        let mut d = Directory::new();
+
+        assert_eq!(
+            d.add(Node::Directory(
+                DirectoryNode::new("foo".into(), DUMMY_DIGEST.clone(), u64::MAX).unwrap(),
+            )),
+            Err(ValidateDirectoryError::SizeOverflow)
+        );
+    }
+
+    #[test]
+    fn add_duplicate_node_to_directory() {
+        let mut d = Directory::new();
+
+        d.add(Node::Directory(
+            DirectoryNode::new("a".into(), DUMMY_DIGEST.clone(), 1).unwrap(),
+        ))
+        .unwrap();
+        assert_eq!(
+            format!(
+                "{}",
+                d.add(Node::File(
+                    FileNode::new("a".into(), DUMMY_DIGEST.clone(), 1, true).unwrap(),
+                ))
+                .expect_err("adding duplicate dir entry must fail")
+            ),
+            "\"a\" is a duplicate name"
+        );
+    }
+
+    /// Attempt to add a directory entry with a name which should be rejected.
+    #[tokio::test]
+    async fn directory_reject_invalid_name() {
+        let mut dir = Directory::new();
+        assert!(
+            dir.add(Node::Symlink(
+                SymlinkNode::new(
+                    "".into(), // wrong! can not be added to directory
+                    "doesntmatter".into(),
+                )
+                .unwrap()
+            ))
+            .is_err(),
+            "invalid symlink entry be rejected"
+        );
+    }
+}
diff --git a/tvix/castore/src/nodes/directory_node.rs b/tvix/castore/src/nodes/directory_node.rs
new file mode 100644
index 000000000000..afbae1695c63
--- /dev/null
+++ b/tvix/castore/src/nodes/directory_node.rs
@@ -0,0 +1,64 @@
+use crate::{B3Digest, NamedNode, ValidateNodeError};
+
+/// A DirectoryNode is a pointer to a [Directory], by its [Directory::digest].
+/// It also gives it a `name` and `size`.
+/// Such a node is either an element in the [Directory] it itself is contained in,
+/// or a standalone root node./
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct DirectoryNode {
+    /// The (base)name of the directory
+    name: bytes::Bytes,
+    /// The blake3 hash of a Directory message, serialized in protobuf canonical form.
+    digest: B3Digest,
+    /// Number of child elements in the Directory referred to by `digest`.
+    /// Calculated by summing up the numbers of nodes, and for each directory.
+    /// its size field. Can be used for inode allocation.
+    /// This field is precisely as verifiable as any other Merkle tree edge.
+    /// Resolve `digest`, and you can compute it incrementally. Resolve the entire
+    /// tree, and you can fully compute it from scratch.
+    /// A credulous implementation won't reject an excessive size, but this is
+    /// harmless: you'll have some ordinals without nodes. Undersizing is obvious
+    /// and easy to reject: you won't have an ordinal for some nodes.
+    size: u64,
+}
+
+impl DirectoryNode {
+    pub fn new(name: bytes::Bytes, digest: B3Digest, size: u64) -> Result<Self, ValidateNodeError> {
+        Ok(Self { name, digest, size })
+    }
+
+    pub fn digest(&self) -> &B3Digest {
+        &self.digest
+    }
+
+    pub fn size(&self) -> u64 {
+        self.size
+    }
+
+    pub fn rename(self, name: bytes::Bytes) -> Self {
+        Self { name, ..self }
+    }
+}
+
+impl PartialOrd for DirectoryNode {
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for DirectoryNode {
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        self.get_name().cmp(other.get_name())
+    }
+}
+
+impl NamedNode for &DirectoryNode {
+    fn get_name(&self) -> &bytes::Bytes {
+        &self.name
+    }
+}
+impl NamedNode for DirectoryNode {
+    fn get_name(&self) -> &bytes::Bytes {
+        &self.name
+    }
+}
diff --git a/tvix/castore/src/nodes/file_node.rs b/tvix/castore/src/nodes/file_node.rs
new file mode 100644
index 000000000000..5dd677c17b49
--- /dev/null
+++ b/tvix/castore/src/nodes/file_node.rs
@@ -0,0 +1,72 @@
+use crate::{B3Digest, NamedNode, ValidateNodeError};
+
+/// A FileNode represents a regular or executable file in a Directory or at the root.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct FileNode {
+    /// The (base)name of the file
+    name: bytes::Bytes,
+
+    /// The blake3 digest of the file contents
+    digest: B3Digest,
+
+    /// The file content size
+    size: u64,
+
+    /// Whether the file is executable
+    executable: bool,
+}
+
+impl FileNode {
+    pub fn new(
+        name: bytes::Bytes,
+        digest: B3Digest,
+        size: u64,
+        executable: bool,
+    ) -> Result<Self, ValidateNodeError> {
+        Ok(Self {
+            name,
+            digest,
+            size,
+            executable,
+        })
+    }
+
+    pub fn digest(&self) -> &B3Digest {
+        &self.digest
+    }
+
+    pub fn size(&self) -> u64 {
+        self.size
+    }
+
+    pub fn executable(&self) -> bool {
+        self.executable
+    }
+
+    pub fn rename(self, name: bytes::Bytes) -> Self {
+        Self { name, ..self }
+    }
+}
+
+impl PartialOrd for FileNode {
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for FileNode {
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        self.get_name().cmp(other.get_name())
+    }
+}
+
+impl NamedNode for &FileNode {
+    fn get_name(&self) -> &bytes::Bytes {
+        &self.name
+    }
+}
+impl NamedNode for FileNode {
+    fn get_name(&self) -> &bytes::Bytes {
+        &self.name
+    }
+}
diff --git a/tvix/castore/src/nodes/mod.rs b/tvix/castore/src/nodes/mod.rs
new file mode 100644
index 000000000000..bb8e14cf856e
--- /dev/null
+++ b/tvix/castore/src/nodes/mod.rs
@@ -0,0 +1,69 @@
+//! This holds types describing nodes in the tvix-castore model.
+mod directory;
+mod directory_node;
+mod file_node;
+mod symlink_node;
+
+use bytes::Bytes;
+pub use directory::Directory;
+pub use directory_node::DirectoryNode;
+pub use file_node::FileNode;
+pub use symlink_node::SymlinkNode;
+
+/// A Node is either a [DirectoryNode], [FileNode] or [SymlinkNode].
+/// While a Node by itself may have any name, only those matching specific requirements
+/// can can be added as entries to a [Directory] (see the documentation on [Directory] for details).
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum Node {
+    Directory(DirectoryNode),
+    File(FileNode),
+    Symlink(SymlinkNode),
+}
+
+impl Node {
+    /// Returns the node with a new name.
+    pub fn rename(self, name: Bytes) -> Self {
+        match self {
+            Node::Directory(n) => Node::Directory(n.rename(name)),
+            Node::File(n) => Node::File(n.rename(name)),
+            Node::Symlink(n) => Node::Symlink(n.rename(name)),
+        }
+    }
+}
+
+impl PartialOrd for Node {
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for Node {
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        self.get_name().cmp(other.get_name())
+    }
+}
+
+/// NamedNode is implemented for [FileNode], [DirectoryNode] and [SymlinkNode]
+/// and [Node], so we can ask all of them for the name easily.
+pub trait NamedNode {
+    fn get_name(&self) -> &Bytes;
+}
+
+impl NamedNode for &Node {
+    fn get_name(&self) -> &Bytes {
+        match self {
+            Node::File(node_file) => node_file.get_name(),
+            Node::Directory(node_directory) => node_directory.get_name(),
+            Node::Symlink(node_symlink) => node_symlink.get_name(),
+        }
+    }
+}
+impl NamedNode for Node {
+    fn get_name(&self) -> &Bytes {
+        match self {
+            Node::File(node_file) => node_file.get_name(),
+            Node::Directory(node_directory) => node_directory.get_name(),
+            Node::Symlink(node_symlink) => node_symlink.get_name(),
+        }
+    }
+}
diff --git a/tvix/castore/src/nodes/symlink_node.rs b/tvix/castore/src/nodes/symlink_node.rs
new file mode 100644
index 000000000000..2fac27231a85
--- /dev/null
+++ b/tvix/castore/src/nodes/symlink_node.rs
@@ -0,0 +1,50 @@
+use crate::{NamedNode, ValidateNodeError};
+
+/// A SymlinkNode represents a symbolic link in a Directory or at the root.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct SymlinkNode {
+    /// The (base)name of the symlink
+    name: bytes::Bytes,
+    /// The target of the symlink.
+    target: bytes::Bytes,
+}
+
+impl SymlinkNode {
+    pub fn new(name: bytes::Bytes, target: bytes::Bytes) -> Result<Self, ValidateNodeError> {
+        if target.is_empty() || target.contains(&b'\0') {
+            return Err(ValidateNodeError::InvalidSymlinkTarget(target));
+        }
+        Ok(Self { name, target })
+    }
+
+    pub fn target(&self) -> &bytes::Bytes {
+        &self.target
+    }
+
+    pub(crate) fn rename(self, name: bytes::Bytes) -> Self {
+        Self { name, ..self }
+    }
+}
+
+impl PartialOrd for SymlinkNode {
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for SymlinkNode {
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        self.get_name().cmp(other.get_name())
+    }
+}
+
+impl NamedNode for &SymlinkNode {
+    fn get_name(&self) -> &bytes::Bytes {
+        &self.name
+    }
+}
+impl NamedNode for SymlinkNode {
+    fn get_name(&self) -> &bytes::Bytes {
+        &self.name
+    }
+}
diff --git a/tvix/castore/src/path.rs b/tvix/castore/src/path.rs
index 77cabeccdb8c..fb340478c08c 100644
--- a/tvix/castore/src/path.rs
+++ b/tvix/castore/src/path.rs
@@ -10,7 +10,7 @@ use std::{
 
 use bstr::ByteSlice;
 
-use crate::directoryservice::Directory;
+use crate::Directory;
 
 /// Represents a Path in the castore model.
 /// These are always relative, and platform-independent, which distinguishes
diff --git a/tvix/castore/src/proto/mod.rs b/tvix/castore/src/proto/mod.rs
index 7e98cd74c591..8f8f3c08347a 100644
--- a/tvix/castore/src/proto/mod.rs
+++ b/tvix/castore/src/proto/mod.rs
@@ -8,7 +8,7 @@ mod grpc_directoryservice_wrapper;
 pub use grpc_blobservice_wrapper::GRPCBlobServiceWrapper;
 pub use grpc_directoryservice_wrapper::GRPCDirectoryServiceWrapper;
 
-use crate::directoryservice::NamedNode;
+use crate::NamedNode;
 use crate::{B3Digest, ValidateDirectoryError, ValidateNodeError};
 
 tonic::include_proto!("tvix.castore.v1");
@@ -82,22 +82,22 @@ fn update_if_lt_prev<'n>(
     Ok(())
 }
 
-impl TryFrom<&node::Node> for crate::directoryservice::Node {
+impl TryFrom<&node::Node> for crate::Node {
     type Error = ValidateNodeError;
 
-    fn try_from(node: &node::Node) -> Result<crate::directoryservice::Node, ValidateNodeError> {
+    fn try_from(node: &node::Node) -> Result<crate::Node, ValidateNodeError> {
         Ok(match node {
-            node::Node::Directory(n) => crate::directoryservice::Node::Directory(n.try_into()?),
-            node::Node::File(n) => crate::directoryservice::Node::File(n.try_into()?),
-            node::Node::Symlink(n) => crate::directoryservice::Node::Symlink(n.try_into()?),
+            node::Node::Directory(n) => crate::Node::Directory(n.try_into()?),
+            node::Node::File(n) => crate::Node::File(n.try_into()?),
+            node::Node::Symlink(n) => crate::Node::Symlink(n.try_into()?),
         })
     }
 }
 
-impl TryFrom<&Node> for crate::directoryservice::Node {
+impl TryFrom<&Node> for crate::Node {
     type Error = ValidateNodeError;
 
-    fn try_from(node: &Node) -> Result<crate::directoryservice::Node, ValidateNodeError> {
+    fn try_from(node: &Node) -> Result<crate::Node, ValidateNodeError> {
         match node {
             Node { node: None } => Err(ValidateNodeError::NoNodeSet),
             Node { node: Some(node) } => node.try_into(),
@@ -105,13 +105,11 @@ impl TryFrom<&Node> for crate::directoryservice::Node {
     }
 }
 
-impl TryFrom<&DirectoryNode> for crate::directoryservice::DirectoryNode {
+impl TryFrom<&DirectoryNode> for crate::DirectoryNode {
     type Error = ValidateNodeError;
 
-    fn try_from(
-        node: &DirectoryNode,
-    ) -> Result<crate::directoryservice::DirectoryNode, ValidateNodeError> {
-        crate::directoryservice::DirectoryNode::new(
+    fn try_from(node: &DirectoryNode) -> Result<crate::DirectoryNode, ValidateNodeError> {
+        crate::DirectoryNode::new(
             node.name.clone(),
             node.digest.clone().try_into()?,
             node.size,
@@ -119,21 +117,19 @@ impl TryFrom<&DirectoryNode> for crate::directoryservice::DirectoryNode {
     }
 }
 
-impl TryFrom<&SymlinkNode> for crate::directoryservice::SymlinkNode {
+impl TryFrom<&SymlinkNode> for crate::SymlinkNode {
     type Error = ValidateNodeError;
 
-    fn try_from(
-        node: &SymlinkNode,
-    ) -> Result<crate::directoryservice::SymlinkNode, ValidateNodeError> {
-        crate::directoryservice::SymlinkNode::new(node.name.clone(), node.target.clone())
+    fn try_from(node: &SymlinkNode) -> Result<crate::SymlinkNode, ValidateNodeError> {
+        crate::SymlinkNode::new(node.name.clone(), node.target.clone())
     }
 }
 
-impl TryFrom<&FileNode> for crate::directoryservice::FileNode {
+impl TryFrom<&FileNode> for crate::FileNode {
     type Error = ValidateNodeError;
 
-    fn try_from(node: &FileNode) -> Result<crate::directoryservice::FileNode, ValidateNodeError> {
-        crate::directoryservice::FileNode::new(
+    fn try_from(node: &FileNode) -> Result<crate::FileNode, ValidateNodeError> {
+        crate::FileNode::new(
             node.name.clone(),
             node.digest.clone().try_into()?,
             node.size,
@@ -142,80 +138,70 @@ impl TryFrom<&FileNode> for crate::directoryservice::FileNode {
     }
 }
 
-impl TryFrom<Directory> for crate::directoryservice::Directory {
+impl TryFrom<Directory> for crate::Directory {
     type Error = ValidateDirectoryError;
 
-    fn try_from(
-        directory: Directory,
-    ) -> Result<crate::directoryservice::Directory, ValidateDirectoryError> {
+    fn try_from(directory: Directory) -> Result<crate::Directory, ValidateDirectoryError> {
         (&directory).try_into()
     }
 }
 
-impl TryFrom<&Directory> for crate::directoryservice::Directory {
+impl TryFrom<&Directory> for crate::Directory {
     type Error = ValidateDirectoryError;
 
-    fn try_from(
-        directory: &Directory,
-    ) -> Result<crate::directoryservice::Directory, ValidateDirectoryError> {
-        let mut dir = crate::directoryservice::Directory::new();
+    fn try_from(directory: &Directory) -> Result<crate::Directory, ValidateDirectoryError> {
+        let mut dir = crate::Directory::new();
         let mut last_file_name: &[u8] = b"";
         for file in directory.files.iter().map(move |file| {
             update_if_lt_prev(&mut last_file_name, &file.name).map(|()| file.clone())
         }) {
             let file = file?;
-            dir.add(crate::directoryservice::Node::File(
-                (&file)
-                    .try_into()
-                    .map_err(|e| ValidateDirectoryError::InvalidNode(file.name.into(), e))?,
-            ))?;
+            dir.add(crate::Node::File((&file).try_into().map_err(|e| {
+                ValidateDirectoryError::InvalidNode(file.name.into(), e)
+            })?))?;
         }
         let mut last_directory_name: &[u8] = b"";
         for directory in directory.directories.iter().map(move |directory| {
             update_if_lt_prev(&mut last_directory_name, &directory.name).map(|()| directory.clone())
         }) {
             let directory = directory?;
-            dir.add(crate::directoryservice::Node::Directory(
-                (&directory)
-                    .try_into()
-                    .map_err(|e| ValidateDirectoryError::InvalidNode(directory.name.into(), e))?,
-            ))?;
+            dir.add(crate::Node::Directory((&directory).try_into().map_err(
+                |e| ValidateDirectoryError::InvalidNode(directory.name.into(), e),
+            )?))?;
         }
         let mut last_symlink_name: &[u8] = b"";
         for symlink in directory.symlinks.iter().map(move |symlink| {
             update_if_lt_prev(&mut last_symlink_name, &symlink.name).map(|()| symlink.clone())
         }) {
             let symlink = symlink?;
-            dir.add(crate::directoryservice::Node::Symlink(
-                (&symlink)
-                    .try_into()
-                    .map_err(|e| ValidateDirectoryError::InvalidNode(symlink.name.into(), e))?,
-            ))?;
+            dir.add(crate::Node::Symlink((&symlink).try_into().map_err(
+                |e| ValidateDirectoryError::InvalidNode(symlink.name.into(), e),
+            )?))?;
         }
         Ok(dir)
     }
 }
 
-impl From<&crate::directoryservice::Node> for node::Node {
-    fn from(node: &crate::directoryservice::Node) -> node::Node {
+impl From<&crate::Node> for node::Node {
+    fn from(node: &crate::Node) -> node::Node {
         match node {
-            crate::directoryservice::Node::Directory(n) => node::Node::Directory(n.into()),
-            crate::directoryservice::Node::File(n) => node::Node::File(n.into()),
-            crate::directoryservice::Node::Symlink(n) => node::Node::Symlink(n.into()),
+            crate::Node::Directory(n) => node::Node::Directory(n.into()),
+            crate::Node::File(n) => node::Node::File(n.into()),
+            crate::Node::Symlink(n) => node::Node::Symlink(n.into()),
         }
     }
 }
 
-impl From<&crate::directoryservice::Node> for Node {
-    fn from(node: &crate::directoryservice::Node) -> Node {
+impl From<&crate::Node> for Node {
+    fn from(node: &crate::Node) -> Node {
         Node {
             node: Some(node.into()),
         }
     }
 }
 
-impl From<&crate::directoryservice::DirectoryNode> for DirectoryNode {
-    fn from(node: &crate::directoryservice::DirectoryNode) -> DirectoryNode {
+impl From<&crate::DirectoryNode> for DirectoryNode {
+    fn from(node: &crate::DirectoryNode) -> DirectoryNode {
         DirectoryNode {
             digest: node.digest().clone().into(),
             size: node.size(),
@@ -224,8 +210,8 @@ impl From<&crate::directoryservice::DirectoryNode> for DirectoryNode {
     }
 }
 
-impl From<&crate::directoryservice::FileNode> for FileNode {
-    fn from(node: &crate::directoryservice::FileNode) -> FileNode {
+impl From<&crate::FileNode> for FileNode {
+    fn from(node: &crate::FileNode) -> FileNode {
         FileNode {
             digest: node.digest().clone().into(),
             size: node.size(),
@@ -235,8 +221,8 @@ impl From<&crate::directoryservice::FileNode> for FileNode {
     }
 }
 
-impl From<&crate::directoryservice::SymlinkNode> for SymlinkNode {
-    fn from(node: &crate::directoryservice::SymlinkNode) -> SymlinkNode {
+impl From<&crate::SymlinkNode> for SymlinkNode {
+    fn from(node: &crate::SymlinkNode) -> SymlinkNode {
         SymlinkNode {
             name: node.get_name().clone(),
             target: node.target().clone(),
@@ -244,26 +230,26 @@ impl From<&crate::directoryservice::SymlinkNode> for SymlinkNode {
     }
 }
 
-impl From<crate::directoryservice::Directory> for Directory {
-    fn from(directory: crate::directoryservice::Directory) -> Directory {
+impl From<crate::Directory> for Directory {
+    fn from(directory: crate::Directory) -> Directory {
         (&directory).into()
     }
 }
 
-impl From<&crate::directoryservice::Directory> for Directory {
-    fn from(directory: &crate::directoryservice::Directory) -> Directory {
+impl From<&crate::Directory> for Directory {
+    fn from(directory: &crate::Directory) -> Directory {
         let mut directories = vec![];
         let mut files = vec![];
         let mut symlinks = vec![];
         for node in directory.nodes() {
             match node {
-                crate::directoryservice::Node::File(n) => {
+                crate::Node::File(n) => {
                     files.push(n.into());
                 }
-                crate::directoryservice::Node::Directory(n) => {
+                crate::Node::Directory(n) => {
                     directories.push(n.into());
                 }
-                crate::directoryservice::Node::Symlink(n) => {
+                crate::Node::Symlink(n) => {
                     symlinks.push(n.into());
                 }
             }
diff --git a/tvix/castore/src/proto/tests/directory.rs b/tvix/castore/src/proto/tests/directory.rs
index 78b2cf7668e3..7847b9c4c9cb 100644
--- a/tvix/castore/src/proto/tests/directory.rs
+++ b/tvix/castore/src/proto/tests/directory.rs
@@ -147,7 +147,7 @@ fn digest() {
 #[test]
 fn validate_empty() {
     let d = Directory::default();
-    assert!(crate::directoryservice::Directory::try_from(d).is_ok());
+    assert!(crate::Directory::try_from(d).is_ok());
 }
 
 #[test]
@@ -161,7 +161,7 @@ fn validate_invalid_names() {
             }],
             ..Default::default()
         };
-        match crate::directoryservice::Directory::try_from(d).expect_err("must fail") {
+        match crate::Directory::try_from(d).expect_err("must fail") {
             ValidateDirectoryError::InvalidNode(n, ValidateNodeError::InvalidName(_)) => {
                 assert_eq!(n, b"")
             }
@@ -178,7 +178,7 @@ fn validate_invalid_names() {
             }],
             ..Default::default()
         };
-        match crate::directoryservice::Directory::try_from(d).expect_err("must fail") {
+        match crate::Directory::try_from(d).expect_err("must fail") {
             ValidateDirectoryError::InvalidNode(n, ValidateNodeError::InvalidName(_)) => {
                 assert_eq!(n, b".")
             }
@@ -196,7 +196,7 @@ fn validate_invalid_names() {
             }],
             ..Default::default()
         };
-        match crate::directoryservice::Directory::try_from(d).expect_err("must fail") {
+        match crate::Directory::try_from(d).expect_err("must fail") {
             ValidateDirectoryError::InvalidNode(n, ValidateNodeError::InvalidName(_)) => {
                 assert_eq!(n, b"..")
             }
@@ -212,7 +212,7 @@ fn validate_invalid_names() {
             }],
             ..Default::default()
         };
-        match crate::directoryservice::Directory::try_from(d).expect_err("must fail") {
+        match crate::Directory::try_from(d).expect_err("must fail") {
             ValidateDirectoryError::InvalidNode(n, ValidateNodeError::InvalidName(_)) => {
                 assert_eq!(n, b"\x00")
             }
@@ -228,7 +228,7 @@ fn validate_invalid_names() {
             }],
             ..Default::default()
         };
-        match crate::directoryservice::Directory::try_from(d).expect_err("must fail") {
+        match crate::Directory::try_from(d).expect_err("must fail") {
             ValidateDirectoryError::InvalidNode(n, ValidateNodeError::InvalidName(_)) => {
                 assert_eq!(n, b"foo/bar")
             }
@@ -247,7 +247,7 @@ fn validate_invalid_digest() {
         }],
         ..Default::default()
     };
-    match crate::directoryservice::Directory::try_from(d).expect_err("must fail") {
+    match crate::Directory::try_from(d).expect_err("must fail") {
         ValidateDirectoryError::InvalidNode(_, ValidateNodeError::InvalidDigestLen(n)) => {
             assert_eq!(n, 2)
         }
@@ -274,7 +274,7 @@ fn validate_sorting() {
             ],
             ..Default::default()
         };
-        match crate::directoryservice::Directory::try_from(d).expect_err("must fail") {
+        match crate::Directory::try_from(d).expect_err("must fail") {
             ValidateDirectoryError::WrongSorting(s) => {
                 assert_eq!(s, b"a");
             }
@@ -299,7 +299,7 @@ fn validate_sorting() {
             ],
             ..Default::default()
         };
-        match crate::directoryservice::Directory::try_from(d).expect_err("must fail") {
+        match crate::Directory::try_from(d).expect_err("must fail") {
             ValidateDirectoryError::DuplicateName(s) => {
                 assert_eq!(s, b"a");
             }
@@ -325,7 +325,7 @@ fn validate_sorting() {
             ..Default::default()
         };
 
-        crate::directoryservice::Directory::try_from(d).expect("validate shouldn't error");
+        crate::Directory::try_from(d).expect("validate shouldn't error");
     }
 
     // [b, c] and [a] are both properly sorted.
@@ -350,6 +350,6 @@ fn validate_sorting() {
             ..Default::default()
         };
 
-        crate::directoryservice::Directory::try_from(d).expect("validate shouldn't error");
+        crate::Directory::try_from(d).expect("validate shouldn't error");
     }
 }
diff --git a/tvix/castore/src/tests/import.rs b/tvix/castore/src/tests/import.rs
index ba54078653e2..5dff61782cf2 100644
--- a/tvix/castore/src/tests/import.rs
+++ b/tvix/castore/src/tests/import.rs
@@ -1,9 +1,9 @@
 use crate::blobservice::{self, BlobService};
 use crate::directoryservice;
-use crate::directoryservice::{DirectoryNode, Node, SymlinkNode};
 use crate::fixtures::*;
 use crate::import::fs::ingest_path;
 use crate::proto;
+use crate::{DirectoryNode, Node, SymlinkNode};
 
 use tempfile::TempDir;