diff --git a/lib/src/backend.rs b/lib/src/backend.rs
new file mode 100644
index 000000000..b01e40134
--- /dev/null
+++ b/lib/src/backend.rs
@@ -0,0 +1,318 @@
+// Copyright 2020 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::collections::BTreeMap;
+use std::fmt::{Debug, Error, Formatter};
+use std::io::Read;
+use std::result::Result;
+use std::vec::Vec;
+
+use thiserror::Error;
+
+use crate::repo_path::{RepoPath, RepoPathComponent};
+
+#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Hash)]
+pub struct CommitId(pub Vec<u8>);
+
+impl Debug for CommitId {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
+        f.debug_tuple("CommitId").field(&self.hex()).finish()
+    }
+}
+
+impl CommitId {
+    pub fn from_hex(hex: &str) -> Self {
+        CommitId(hex::decode(hex).unwrap())
+    }
+
+    pub fn hex(&self) -> String {
+        hex::encode(&self.0)
+    }
+}
+
+#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Hash)]
+pub struct ChangeId(pub Vec<u8>);
+
+impl Debug for ChangeId {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
+        f.debug_tuple("ChangeId").field(&self.hex()).finish()
+    }
+}
+
+impl ChangeId {
+    pub fn from_hex(hex: &str) -> Self {
+        ChangeId(hex::decode(hex).unwrap())
+    }
+
+    pub fn hex(&self) -> String {
+        hex::encode(&self.0)
+    }
+}
+
+#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Hash)]
+pub struct TreeId(pub Vec<u8>);
+
+impl Debug for TreeId {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
+        f.debug_tuple("TreeId").field(&self.hex()).finish()
+    }
+}
+
+impl TreeId {
+    pub fn hex(&self) -> String {
+        hex::encode(&self.0)
+    }
+}
+
+#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Hash)]
+pub struct FileId(pub Vec<u8>);
+
+impl Debug for FileId {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
+        f.debug_tuple("FileId").field(&self.hex()).finish()
+    }
+}
+
+impl FileId {
+    pub fn hex(&self) -> String {
+        hex::encode(&self.0)
+    }
+}
+
+#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Hash)]
+pub struct SymlinkId(pub Vec<u8>);
+
+impl Debug for SymlinkId {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
+        f.debug_tuple("SymlinkId").field(&self.hex()).finish()
+    }
+}
+
+impl SymlinkId {
+    pub fn hex(&self) -> String {
+        hex::encode(&self.0)
+    }
+}
+
+#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Hash)]
+pub struct ConflictId(pub Vec<u8>);
+
+impl Debug for ConflictId {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
+        f.debug_tuple("ConflictId").field(&self.hex()).finish()
+    }
+}
+
+impl ConflictId {
+    pub fn hex(&self) -> String {
+        hex::encode(&self.0)
+    }
+}
+
+pub enum Phase {
+    Public,
+    Draft,
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, PartialOrd, Ord)]
+pub struct MillisSinceEpoch(pub u64);
+
+#[derive(Debug, PartialEq, Eq, Clone, PartialOrd, Ord)]
+pub struct Timestamp {
+    pub timestamp: MillisSinceEpoch,
+    // time zone offset in minutes
+    pub tz_offset: i32,
+}
+
+impl Timestamp {
+    pub fn now() -> Self {
+        let now = chrono::offset::Local::now();
+        Self {
+            timestamp: MillisSinceEpoch(now.timestamp_millis() as u64),
+            tz_offset: now.offset().local_minus_utc() / 60,
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub struct Signature {
+    pub name: String,
+    pub email: String,
+    pub timestamp: Timestamp,
+}
+
+#[derive(Debug, Clone)]
+pub struct Commit {
+    pub parents: Vec<CommitId>,
+    pub predecessors: Vec<CommitId>,
+    pub root_tree: TreeId,
+    pub change_id: ChangeId,
+    pub description: String,
+    pub author: Signature,
+    pub committer: Signature,
+    pub is_open: bool,
+    pub is_pruned: bool,
+}
+
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub struct ConflictPart {
+    // TODO: Store e.g. CommitId here too? Labels (theirs/ours/base)? Would those still be
+    //       useful e.g. after rebasing this conflict?
+    pub value: TreeValue,
+}
+
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub struct Conflict {
+    // A conflict is represented by a list of positive and negative states that need to be applied.
+    // In a simple 3-way merge of B and C with merge base A, the conflict will be { add: [B, C],
+    // remove: [A] }. Also note that a conflict of the form { add: [A], remove: [] } is the
+    // same as non-conflict A.
+    pub removes: Vec<ConflictPart>,
+    pub adds: Vec<ConflictPart>,
+}
+
+impl Default for Conflict {
+    fn default() -> Self {
+        Conflict {
+            removes: Default::default(),
+            adds: Default::default(),
+        }
+    }
+}
+
+#[derive(Debug, Error, PartialEq, Eq)]
+pub enum BackendError {
+    #[error("Object not found")]
+    NotFound,
+    #[error("Error: {0}")]
+    Other(String),
+}
+
+pub type BackendResult<T> = Result<T, BackendError>;
+
+#[derive(Debug, PartialEq, Eq, Clone, Hash)]
+pub enum TreeValue {
+    Normal { id: FileId, executable: bool },
+    Symlink(SymlinkId),
+    Tree(TreeId),
+    GitSubmodule(CommitId),
+    Conflict(ConflictId),
+}
+
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub struct TreeEntry<'a> {
+    name: &'a RepoPathComponent,
+    value: &'a TreeValue,
+}
+
+impl<'a> TreeEntry<'a> {
+    pub fn new(name: &'a RepoPathComponent, value: &'a TreeValue) -> Self {
+        TreeEntry { name, value }
+    }
+
+    pub fn name(&self) -> &'a RepoPathComponent {
+        self.name
+    }
+
+    pub fn value(&self) -> &'a TreeValue {
+        self.value
+    }
+}
+
+pub struct TreeEntriesNonRecursiveIter<'a> {
+    iter: std::collections::btree_map::Iter<'a, RepoPathComponent, TreeValue>,
+}
+
+impl<'a> Iterator for TreeEntriesNonRecursiveIter<'a> {
+    type Item = TreeEntry<'a>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.iter
+            .next()
+            .map(|(name, value)| TreeEntry { name, value })
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct Tree {
+    entries: BTreeMap<RepoPathComponent, TreeValue>,
+}
+
+impl Default for Tree {
+    fn default() -> Self {
+        Self {
+            entries: BTreeMap::new(),
+        }
+    }
+}
+
+impl Tree {
+    pub fn is_empty(&self) -> bool {
+        self.entries.is_empty()
+    }
+
+    pub fn entries(&self) -> TreeEntriesNonRecursiveIter {
+        TreeEntriesNonRecursiveIter {
+            iter: self.entries.iter(),
+        }
+    }
+
+    pub fn set(&mut self, name: RepoPathComponent, value: TreeValue) {
+        self.entries.insert(name, value);
+    }
+
+    pub fn remove(&mut self, name: &RepoPathComponent) {
+        self.entries.remove(name);
+    }
+
+    pub fn entry(&self, name: &RepoPathComponent) -> Option<TreeEntry> {
+        self.entries
+            .get_key_value(name)
+            .map(|(name, value)| TreeEntry { name, value })
+    }
+
+    pub fn value(&self, name: &RepoPathComponent) -> Option<&TreeValue> {
+        self.entries.get(name)
+    }
+}
+
+pub trait Backend: Send + Sync + Debug {
+    fn hash_length(&self) -> usize;
+
+    fn git_repo(&self) -> Option<git2::Repository>;
+
+    fn read_file(&self, path: &RepoPath, id: &FileId) -> BackendResult<Box<dyn Read>>;
+
+    fn write_file(&self, path: &RepoPath, contents: &mut dyn Read) -> BackendResult<FileId>;
+
+    fn read_symlink(&self, path: &RepoPath, id: &SymlinkId) -> BackendResult<String>;
+
+    fn write_symlink(&self, path: &RepoPath, target: &str) -> BackendResult<SymlinkId>;
+
+    fn empty_tree_id(&self) -> &TreeId;
+
+    fn read_tree(&self, path: &RepoPath, id: &TreeId) -> BackendResult<Tree>;
+
+    fn write_tree(&self, path: &RepoPath, contents: &Tree) -> BackendResult<TreeId>;
+
+    fn read_commit(&self, id: &CommitId) -> BackendResult<Commit>;
+
+    fn write_commit(&self, contents: &Commit) -> BackendResult<CommitId>;
+
+    // TODO: Pass in the paths here too even though they are unused, just like for
+    // files and trees?
+    fn read_conflict(&self, id: &ConflictId) -> BackendResult<Conflict>;
+
+    fn write_conflict(&self, contents: &Conflict) -> BackendResult<ConflictId>;
+}
diff --git a/lib/src/commit.rs b/lib/src/commit.rs
index 459d58753..c49479a7f 100644
--- a/lib/src/commit.rs
+++ b/lib/src/commit.rs
@@ -17,17 +17,17 @@ use std::fmt::{Debug, Error, Formatter};
 use std::hash::{Hash, Hasher};
 use std::sync::Arc;
 
+use crate::backend;
+use crate::backend::{ChangeId, CommitId, Signature};
 use crate::repo_path::RepoPath;
-use crate::store;
-use crate::store::{ChangeId, CommitId, Signature};
-use crate::store_wrapper::StoreWrapper;
+use crate::store::Store;
 use crate::tree::Tree;
 
 #[derive(Clone)]
 pub struct Commit {
-    store: Arc<StoreWrapper>,
+    store: Arc<Store>,
     id: CommitId,
-    data: Arc<store::Commit>,
+    data: Arc<backend::Commit>,
 }
 
 impl Debug for Commit {
@@ -63,11 +63,11 @@ impl Hash for Commit {
 }
 
 impl Commit {
-    pub fn new(store: Arc<StoreWrapper>, id: CommitId, data: Arc<store::Commit>) -> Self {
+    pub fn new(store: Arc<Store>, id: CommitId, data: Arc<backend::Commit>) -> Self {
         Commit { store, id, data }
     }
 
-    pub fn store(&self) -> &Arc<StoreWrapper> {
+    pub fn store(&self) -> &Arc<Store> {
         &self.store
     }
 
@@ -116,7 +116,7 @@ impl Commit {
         &self.data.change_id
     }
 
-    pub fn store_commit(&self) -> &store::Commit {
+    pub fn store_commit(&self) -> &backend::Commit {
         &self.data
     }
 
diff --git a/lib/src/commit_builder.rs b/lib/src/commit_builder.rs
index 2971c79df..9b1c1c174 100644
--- a/lib/src/commit_builder.rs
+++ b/lib/src/commit_builder.rs
@@ -16,17 +16,17 @@ use std::sync::Arc;
 
 use uuid::Uuid;
 
+use crate::backend;
+use crate::backend::{ChangeId, CommitId, Signature, Timestamp, TreeId};
 use crate::commit::Commit;
 use crate::repo::MutableRepo;
 use crate::settings::UserSettings;
-use crate::store;
-use crate::store::{ChangeId, CommitId, Signature, Timestamp, TreeId};
-use crate::store_wrapper::StoreWrapper;
+use crate::store::Store;
 
 #[derive(Debug)]
 pub struct CommitBuilder {
-    store: Arc<StoreWrapper>,
-    commit: store::Commit,
+    store: Arc<Store>,
+    commit: backend::Commit,
 }
 
 pub fn new_change_id() -> ChangeId {
@@ -45,11 +45,11 @@ pub fn signature(settings: &UserSettings) -> Signature {
 impl CommitBuilder {
     pub fn for_new_commit(
         settings: &UserSettings,
-        store: &Arc<StoreWrapper>,
+        store: &Arc<Store>,
         tree_id: TreeId,
     ) -> CommitBuilder {
         let signature = signature(settings);
-        let commit = store::Commit {
+        let commit = backend::Commit {
             parents: vec![],
             predecessors: vec![],
             root_tree: tree_id,
@@ -68,7 +68,7 @@ impl CommitBuilder {
 
     pub fn for_rewrite_from(
         settings: &UserSettings,
-        store: &Arc<StoreWrapper>,
+        store: &Arc<Store>,
         predecessor: &Commit,
     ) -> CommitBuilder {
         let mut commit = predecessor.store_commit().clone();
@@ -82,12 +82,12 @@ impl CommitBuilder {
 
     pub fn for_open_commit(
         settings: &UserSettings,
-        store: &Arc<StoreWrapper>,
+        store: &Arc<Store>,
         parent_id: CommitId,
         tree_id: TreeId,
     ) -> CommitBuilder {
         let signature = signature(settings);
-        let commit = store::Commit {
+        let commit = backend::Commit {
             parents: vec![parent_id],
             predecessors: vec![],
             root_tree: tree_id,
diff --git a/lib/src/conflicts.rs b/lib/src/conflicts.rs
index 5e932bfb8..06bb67fea 100644
--- a/lib/src/conflicts.rs
+++ b/lib/src/conflicts.rs
@@ -17,12 +17,12 @@ use std::io::{Cursor, Write};
 
 use itertools::Itertools;
 
+use crate::backend::{Conflict, ConflictPart, TreeValue};
 use crate::diff::{find_line_ranges, Diff, DiffHunk};
 use crate::files;
 use crate::files::{MergeHunk, MergeResult};
 use crate::repo_path::RepoPath;
-use crate::store::{Conflict, ConflictPart, TreeValue};
-use crate::store_wrapper::StoreWrapper;
+use crate::store::Store;
 
 fn describe_conflict_part(part: &ConflictPart) -> String {
     match &part.value {
@@ -79,7 +79,7 @@ fn file_parts(parts: &[ConflictPart]) -> Vec<&ConflictPart> {
         .collect_vec()
 }
 
-fn get_file_contents(store: &StoreWrapper, path: &RepoPath, part: &ConflictPart) -> Vec<u8> {
+fn get_file_contents(store: &Store, path: &RepoPath, part: &ConflictPart) -> Vec<u8> {
     if let TreeValue::Normal {
         id,
         executable: false,
@@ -123,7 +123,7 @@ fn write_diff_hunks(left: &[u8], right: &[u8], file: &mut dyn Write) -> std::io:
 }
 
 pub fn materialize_conflict(
-    store: &StoreWrapper,
+    store: &Store,
     path: &RepoPath,
     conflict: &Conflict,
     file: &mut dyn Write,
@@ -190,7 +190,7 @@ pub fn materialize_conflict(
 }
 
 pub fn conflict_to_materialized_value(
-    store: &StoreWrapper,
+    store: &Store,
     path: &RepoPath,
     conflict: &Conflict,
 ) -> TreeValue {
diff --git a/lib/src/evolution.rs b/lib/src/evolution.rs
index d646065f0..abebb7ec5 100644
--- a/lib/src/evolution.rs
+++ b/lib/src/evolution.rs
@@ -17,6 +17,7 @@ use std::sync::Arc;
 
 use itertools::Itertools;
 
+use crate::backend::{ChangeId, CommitId};
 use crate::commit::Commit;
 use crate::commit_builder::CommitBuilder;
 use crate::dag_walk::{bfs, closest_common_node, leaves};
@@ -25,8 +26,7 @@ use crate::repo::{MutableRepo, ReadonlyRepo, RepoRef};
 use crate::repo_path::RepoPath;
 use crate::rewrite::{merge_commit_trees, rebase_commit};
 use crate::settings::UserSettings;
-use crate::store::{ChangeId, CommitId};
-use crate::store_wrapper::StoreWrapper;
+use crate::store::Store;
 use crate::tree::merge_trees;
 
 // TODO: Combine some maps/sets and use a struct as value instead.
@@ -608,7 +608,7 @@ pub enum OrphanResolution {
 
 fn evolve_divergent_change(
     user_settings: &UserSettings,
-    store: &Arc<StoreWrapper>,
+    store: &Arc<Store>,
     mut_repo: &mut MutableRepo,
     commits: &HashSet<Commit>,
 ) -> DivergenceResolution {
@@ -657,7 +657,7 @@ fn evolve_divergent_change(
 
 fn evolve_two_divergent_commits(
     user_settings: &UserSettings,
-    store: &Arc<StoreWrapper>,
+    store: &Arc<Store>,
     mut_repo: &mut MutableRepo,
     common_predecessor: &Commit,
     commit1: &Commit,
diff --git a/lib/src/git.rs b/lib/src/git.rs
index 0a38fde15..075b6d8ce 100644
--- a/lib/src/git.rs
+++ b/lib/src/git.rs
@@ -18,10 +18,10 @@ use git2::FetchPrune;
 use itertools::Itertools;
 use thiserror::Error;
 
+use crate::backend::CommitId;
 use crate::commit::Commit;
 use crate::op_store::RefTarget;
 use crate::repo::MutableRepo;
-use crate::store::CommitId;
 use crate::view::RefName;
 
 #[derive(Error, Debug, PartialEq)]
diff --git a/lib/src/git_store.rs b/lib/src/git_backend.rs
similarity index 93%
rename from lib/src/git_store.rs
rename to lib/src/git_backend.rs
index a3b343845..003bd5a79 100644
--- a/lib/src/git_store.rs
+++ b/lib/src/git_backend.rs
@@ -25,11 +25,12 @@ use itertools::Itertools;
 use protobuf::Message;
 use uuid::Uuid;
 
-use crate::repo_path::{RepoPath, RepoPathComponent};
-use crate::store::{
-    ChangeId, Commit, CommitId, Conflict, ConflictId, ConflictPart, FileId, MillisSinceEpoch,
-    Signature, Store, StoreError, StoreResult, SymlinkId, Timestamp, Tree, TreeId, TreeValue,
+use crate::backend::{
+    Backend, BackendError, BackendResult, ChangeId, Commit, CommitId, Conflict, ConflictId,
+    ConflictPart, FileId, MillisSinceEpoch, Signature, SymlinkId, Timestamp, Tree, TreeId,
+    TreeValue,
 };
+use crate::repo_path::{RepoPath, RepoPathComponent};
 
 /// Ref namespace used only for preventing GC.
 const NO_GC_REF_NAMESPACE: &str = "refs/jj/keep/";
@@ -37,26 +38,26 @@ const NO_GC_REF_NAMESPACE: &str = "refs/jj/keep/";
 const COMMITS_NOTES_REF: &str = "refs/notes/jj/commits";
 const CONFLICT_SUFFIX: &str = ".jjconflict";
 
-impl From<git2::Error> for StoreError {
+impl From<git2::Error> for BackendError {
     fn from(err: git2::Error) -> Self {
         match err.code() {
-            git2::ErrorCode::NotFound => StoreError::NotFound,
-            _other => StoreError::Other(err.to_string()),
+            git2::ErrorCode::NotFound => BackendError::NotFound,
+            _other => BackendError::Other(err.to_string()),
         }
     }
 }
 
-pub struct GitStore {
+pub struct GitBackend {
     repo: Mutex<git2::Repository>,
     empty_tree_id: TreeId,
 }
 
-impl GitStore {
+impl GitBackend {
     pub fn load(path: &Path) -> Self {
         let repo = Mutex::new(git2::Repository::open(path).unwrap());
         let empty_tree_id =
             TreeId(hex::decode("4b825dc642cb6eb9a060e54bf8d69288fbee4904").unwrap());
-        GitStore {
+        GitBackend {
             repo,
             empty_tree_id,
         }
@@ -159,7 +160,7 @@ fn write_note(
     Ok(())
 }
 
-impl Debug for GitStore {
+impl Debug for GitBackend {
     fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
         f.debug_struct("GitStore")
             .field("path", &self.repo.lock().unwrap().path())
@@ -167,7 +168,7 @@ impl Debug for GitStore {
     }
 }
 
-impl Store for GitStore {
+impl Backend for GitBackend {
     fn hash_length(&self) -> usize {
         20
     }
@@ -177,9 +178,9 @@ impl Store for GitStore {
         Some(git2::Repository::open(&path).unwrap())
     }
 
-    fn read_file(&self, _path: &RepoPath, id: &FileId) -> StoreResult<Box<dyn Read>> {
+    fn read_file(&self, _path: &RepoPath, id: &FileId) -> BackendResult<Box<dyn Read>> {
         if id.0.len() != self.hash_length() {
-            return Err(StoreError::NotFound);
+            return Err(BackendError::NotFound);
         }
         let locked_repo = self.repo.lock().unwrap();
         let blob = locked_repo
@@ -189,7 +190,7 @@ impl Store for GitStore {
         Ok(Box::new(Cursor::new(content)))
     }
 
-    fn write_file(&self, _path: &RepoPath, contents: &mut dyn Read) -> StoreResult<FileId> {
+    fn write_file(&self, _path: &RepoPath, contents: &mut dyn Read) -> BackendResult<FileId> {
         let mut bytes = Vec::new();
         contents.read_to_end(&mut bytes).unwrap();
         let locked_repo = self.repo.lock().unwrap();
@@ -197,9 +198,9 @@ impl Store for GitStore {
         Ok(FileId(oid.as_bytes().to_vec()))
     }
 
-    fn read_symlink(&self, _path: &RepoPath, id: &SymlinkId) -> Result<String, StoreError> {
+    fn read_symlink(&self, _path: &RepoPath, id: &SymlinkId) -> Result<String, BackendError> {
         if id.0.len() != self.hash_length() {
-            return Err(StoreError::NotFound);
+            return Err(BackendError::NotFound);
         }
         let locked_repo = self.repo.lock().unwrap();
         let blob = locked_repo
@@ -209,7 +210,7 @@ impl Store for GitStore {
         Ok(target)
     }
 
-    fn write_symlink(&self, _path: &RepoPath, target: &str) -> Result<SymlinkId, StoreError> {
+    fn write_symlink(&self, _path: &RepoPath, target: &str) -> Result<SymlinkId, BackendError> {
         let locked_repo = self.repo.lock().unwrap();
         let oid = locked_repo.blob(target.as_bytes()).unwrap();
         Ok(SymlinkId(oid.as_bytes().to_vec()))
@@ -219,12 +220,12 @@ impl Store for GitStore {
         &self.empty_tree_id
     }
 
-    fn read_tree(&self, _path: &RepoPath, id: &TreeId) -> StoreResult<Tree> {
+    fn read_tree(&self, _path: &RepoPath, id: &TreeId) -> BackendResult<Tree> {
         if id == &self.empty_tree_id {
             return Ok(Tree::default());
         }
         if id.0.len() != self.hash_length() {
-            return Err(StoreError::NotFound);
+            return Err(BackendError::NotFound);
         }
 
         let locked_repo = self.repo.lock().unwrap();
@@ -284,7 +285,7 @@ impl Store for GitStore {
         Ok(tree)
     }
 
-    fn write_tree(&self, _path: &RepoPath, contents: &Tree) -> StoreResult<TreeId> {
+    fn write_tree(&self, _path: &RepoPath, contents: &Tree) -> BackendResult<TreeId> {
         let locked_repo = self.repo.lock().unwrap();
         let mut builder = locked_repo.treebuilder(None).unwrap();
         for entry in contents.entries() {
@@ -313,9 +314,9 @@ impl Store for GitStore {
         Ok(TreeId(oid.as_bytes().to_vec()))
     }
 
-    fn read_commit(&self, id: &CommitId) -> StoreResult<Commit> {
+    fn read_commit(&self, id: &CommitId) -> BackendResult<Commit> {
         if id.0.len() != self.hash_length() {
-            return Err(StoreError::NotFound);
+            return Err(BackendError::NotFound);
         }
 
         let locked_repo = self.repo.lock().unwrap();
@@ -365,7 +366,7 @@ impl Store for GitStore {
         Ok(commit)
     }
 
-    fn write_commit(&self, contents: &Commit) -> StoreResult<CommitId> {
+    fn write_commit(&self, contents: &Commit) -> BackendResult<CommitId> {
         // TODO: We shouldn't have to create an in-memory index just to write an
         // object...
         let locked_repo = self.repo.lock().unwrap();
@@ -405,7 +406,7 @@ impl Store for GitStore {
         Ok(id)
     }
 
-    fn read_conflict(&self, id: &ConflictId) -> StoreResult<Conflict> {
+    fn read_conflict(&self, id: &ConflictId) -> BackendResult<Conflict> {
         let mut file = self.read_file(
             &RepoPath::from_internal_string("unused"),
             &FileId(id.0.clone()),
@@ -419,7 +420,7 @@ impl Store for GitStore {
         })
     }
 
-    fn write_conflict(&self, conflict: &Conflict) -> StoreResult<ConflictId> {
+    fn write_conflict(&self, conflict: &Conflict) -> BackendResult<ConflictId> {
         let json = serde_json::json!({
             "removes": conflict_part_list_to_json(&conflict.removes),
             "adds": conflict_part_list_to_json(&conflict.adds),
@@ -507,7 +508,7 @@ fn bytes_vec_from_json(value: &serde_json::Value) -> Vec<u8> {
 mod tests {
 
     use super::*;
-    use crate::store::{FileId, MillisSinceEpoch};
+    use crate::backend::{FileId, MillisSinceEpoch};
 
     #[test]
     fn read_plain_git_commit() {
@@ -556,7 +557,7 @@ mod tests {
         // Check that the git commit above got the hash we expect
         assert_eq!(git_commit_id.as_bytes(), &commit_id.0);
 
-        let store = GitStore::load(git_repo_path);
+        let store = GitBackend::load(git_repo_path);
         let commit = store.read_commit(&commit_id).unwrap();
         assert_eq!(&commit.change_id, &change_id);
         assert_eq!(commit.parents, vec![]);
@@ -622,7 +623,7 @@ mod tests {
         let temp_dir = tempfile::tempdir().unwrap();
         let git_repo_path = temp_dir.path();
         let git_repo = git2::Repository::init(git_repo_path).unwrap();
-        let store = GitStore::load(git_repo_path);
+        let store = GitBackend::load(git_repo_path);
         let signature = Signature {
             name: "Someone".to_string(),
             email: "someone@example.com".to_string(),
@@ -656,7 +657,7 @@ mod tests {
         let temp_dir = tempfile::tempdir().unwrap();
         let git_repo_path = temp_dir.path();
         git2::Repository::init(git_repo_path).unwrap();
-        let store = GitStore::load(git_repo_path);
+        let store = GitBackend::load(git_repo_path);
         let signature = Signature {
             name: "Someone".to_string(),
             email: "someone@example.com".to_string(),
@@ -684,7 +685,7 @@ mod tests {
             Ok(_) => {
                 panic!("expectedly successfully wrote two commits with the same git commit object")
             }
-            Err(StoreError::Other(message)) if message.contains(&expected_error_message) => {}
+            Err(BackendError::Other(message)) if message.contains(&expected_error_message) => {}
             Err(err) => panic!("unexpected error: {:?}", err),
         };
     }
diff --git a/lib/src/index.rs b/lib/src/index.rs
index f8cad42e9..9299903b3 100644
--- a/lib/src/index.rs
+++ b/lib/src/index.rs
@@ -30,9 +30,9 @@ use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
 use itertools::Itertools;
 use tempfile::NamedTempFile;
 
+use crate::backend::{ChangeId, CommitId};
 use crate::commit::Commit;
 use crate::file_util::persist_content_addressed_temp_file;
-use crate::store::{ChangeId, CommitId};
 
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone, Copy, Hash)]
 pub struct IndexPosition(u32);
diff --git a/lib/src/index_store.rs b/lib/src/index_store.rs
index 836ad7292..e881f5bb0 100644
--- a/lib/src/index_store.rs
+++ b/lib/src/index_store.rs
@@ -22,14 +22,14 @@ use std::sync::Arc;
 use itertools::Itertools;
 use tempfile::NamedTempFile;
 
+use crate::backend::CommitId;
 use crate::commit::Commit;
 use crate::dag_walk;
 use crate::file_util::persist_content_addressed_temp_file;
 use crate::index::{MutableIndex, ReadonlyIndex};
 use crate::op_store::OperationId;
 use crate::operation::Operation;
-use crate::store::CommitId;
-use crate::store_wrapper::StoreWrapper;
+use crate::store::Store;
 
 pub struct IndexStore {
     dir: PathBuf,
@@ -50,7 +50,7 @@ impl IndexStore {
         IndexStore { dir }
     }
 
-    pub fn get_index_at_op(&self, op: &Operation, store: &StoreWrapper) -> Arc<ReadonlyIndex> {
+    pub fn get_index_at_op(&self, op: &Operation, store: &Store) -> Arc<ReadonlyIndex> {
         let op_id_hex = op.id().hex();
         let op_id_file = self.dir.join("operations").join(&op_id_hex);
         if op_id_file.exists() {
@@ -89,7 +89,7 @@ impl IndexStore {
 
     fn index_at_operation(
         &self,
-        store: &StoreWrapper,
+        store: &Store,
         operation: &Operation,
     ) -> io::Result<Arc<ReadonlyIndex>> {
         let view = operation.view();
@@ -163,7 +163,7 @@ impl IndexStore {
 // Returns the ancestors of heads with parents and predecessors come before the
 // commit itself
 fn topo_order_earlier_first(
-    store: &StoreWrapper,
+    store: &Store,
     heads: Vec<CommitId>,
     parent_file: Option<Arc<ReadonlyIndex>>,
 ) -> Vec<Commit> {
diff --git a/lib/src/lib.rs b/lib/src/lib.rs
index c1e1bd206..de81cf01c 100644
--- a/lib/src/lib.rs
+++ b/lib/src/lib.rs
@@ -24,6 +24,7 @@ extern crate pest_derive;
 #[macro_use]
 extern crate maplit;
 
+pub mod backend;
 pub mod commit;
 pub mod commit_builder;
 pub mod conflicts;
@@ -33,11 +34,11 @@ pub mod evolution;
 pub mod file_util;
 pub mod files;
 pub mod git;
-pub mod git_store;
+pub mod git_backend;
 pub mod gitignore;
 pub mod index;
 pub mod index_store;
-pub mod local_store;
+pub mod local_backend;
 pub mod lock;
 pub mod matchers;
 pub mod op_heads_store;
@@ -53,7 +54,6 @@ pub mod rewrite;
 pub mod settings;
 pub mod simple_op_store;
 pub mod store;
-pub mod store_wrapper;
 pub mod testutils;
 pub mod transaction;
 pub mod tree;
diff --git a/lib/src/local_store.rs b/lib/src/local_backend.rs
similarity index 86%
rename from lib/src/local_store.rs
rename to lib/src/local_backend.rs
index 3915b5860..01400f2d1 100644
--- a/lib/src/local_store.rs
+++ b/lib/src/local_backend.rs
@@ -22,55 +22,56 @@ use blake2::{Blake2b, Digest};
 use protobuf::{Message, ProtobufError};
 use tempfile::{NamedTempFile, PersistError};
 
+use crate::backend::{
+    Backend, BackendError, BackendResult, ChangeId, Commit, CommitId, Conflict, ConflictId,
+    ConflictPart, FileId, MillisSinceEpoch, Signature, SymlinkId, Timestamp, Tree, TreeId,
+    TreeValue,
+};
 use crate::file_util::persist_content_addressed_temp_file;
 use crate::repo_path::{RepoPath, RepoPathComponent};
-use crate::store::{
-    ChangeId, Commit, CommitId, Conflict, ConflictId, ConflictPart, FileId, MillisSinceEpoch,
-    Signature, Store, StoreError, StoreResult, SymlinkId, Timestamp, Tree, TreeId, TreeValue,
-};
 
-impl From<std::io::Error> for StoreError {
+impl From<std::io::Error> for BackendError {
     fn from(err: std::io::Error) -> Self {
-        StoreError::Other(err.to_string())
+        BackendError::Other(err.to_string())
     }
 }
 
-impl From<PersistError> for StoreError {
+impl From<PersistError> for BackendError {
     fn from(err: PersistError) -> Self {
-        StoreError::Other(err.to_string())
+        BackendError::Other(err.to_string())
     }
 }
 
-impl From<ProtobufError> for StoreError {
+impl From<ProtobufError> for BackendError {
     fn from(err: ProtobufError) -> Self {
-        StoreError::Other(err.to_string())
+        BackendError::Other(err.to_string())
     }
 }
 
 #[derive(Debug)]
-pub struct LocalStore {
+pub struct LocalBackend {
     path: PathBuf,
     empty_tree_id: TreeId,
 }
 
-impl LocalStore {
+impl LocalBackend {
     pub fn init(store_path: PathBuf) -> Self {
         fs::create_dir(store_path.join("commits")).unwrap();
         fs::create_dir(store_path.join("trees")).unwrap();
         fs::create_dir(store_path.join("files")).unwrap();
         fs::create_dir(store_path.join("symlinks")).unwrap();
         fs::create_dir(store_path.join("conflicts")).unwrap();
-        let store = Self::load(store_path);
-        let empty_tree_id = store
+        let backend = Self::load(store_path);
+        let empty_tree_id = backend
             .write_tree(&RepoPath::root(), &Tree::default())
             .unwrap();
-        assert_eq!(empty_tree_id, store.empty_tree_id);
-        store
+        assert_eq!(empty_tree_id, backend.empty_tree_id);
+        backend
     }
 
     pub fn load(store_path: PathBuf) -> Self {
         let empty_tree_id = TreeId(hex::decode("786a02f742015903c6c6fd852552d272912f4740e15847618a86e217f71f5419d25e1031afee585313896444934eb04b903a685b1448b755d56f701afe9be2ce").unwrap());
-        LocalStore {
+        LocalBackend {
             path: store_path,
             empty_tree_id,
         }
@@ -97,15 +98,15 @@ impl LocalStore {
     }
 }
 
-fn not_found_to_store_error(err: std::io::Error) -> StoreError {
+fn not_found_to_backend_error(err: std::io::Error) -> BackendError {
     if err.kind() == ErrorKind::NotFound {
-        StoreError::NotFound
+        BackendError::NotFound
     } else {
-        StoreError::from(err)
+        BackendError::from(err)
     }
 }
 
-impl Store for LocalStore {
+impl Backend for LocalBackend {
     fn hash_length(&self) -> usize {
         64
     }
@@ -114,13 +115,13 @@ impl Store for LocalStore {
         None
     }
 
-    fn read_file(&self, _path: &RepoPath, id: &FileId) -> StoreResult<Box<dyn Read>> {
+    fn read_file(&self, _path: &RepoPath, id: &FileId) -> BackendResult<Box<dyn Read>> {
         let path = self.file_path(id);
-        let file = File::open(path).map_err(not_found_to_store_error)?;
+        let file = File::open(path).map_err(not_found_to_backend_error)?;
         Ok(Box::new(zstd::Decoder::new(file)?))
     }
 
-    fn write_file(&self, _path: &RepoPath, contents: &mut dyn Read) -> StoreResult<FileId> {
+    fn write_file(&self, _path: &RepoPath, contents: &mut dyn Read) -> BackendResult<FileId> {
         let temp_file = NamedTempFile::new_in(&self.path)?;
         let mut encoder = zstd::Encoder::new(temp_file.as_file(), 0)?;
         let mut hasher = Blake2b::new();
@@ -145,15 +146,15 @@ impl Store for LocalStore {
         Ok(id)
     }
 
-    fn read_symlink(&self, _path: &RepoPath, id: &SymlinkId) -> Result<String, StoreError> {
+    fn read_symlink(&self, _path: &RepoPath, id: &SymlinkId) -> Result<String, BackendError> {
         let path = self.symlink_path(id);
-        let mut file = File::open(path).map_err(not_found_to_store_error)?;
+        let mut file = File::open(path).map_err(not_found_to_backend_error)?;
         let mut target = String::new();
         file.read_to_string(&mut target).unwrap();
         Ok(target)
     }
 
-    fn write_symlink(&self, _path: &RepoPath, target: &str) -> Result<SymlinkId, StoreError> {
+    fn write_symlink(&self, _path: &RepoPath, target: &str) -> Result<SymlinkId, BackendError> {
         let mut temp_file = NamedTempFile::new_in(&self.path)?;
         temp_file.write_all(target.as_bytes())?;
         let mut hasher = Blake2b::new();
@@ -168,15 +169,15 @@ impl Store for LocalStore {
         &self.empty_tree_id
     }
 
-    fn read_tree(&self, _path: &RepoPath, id: &TreeId) -> StoreResult<Tree> {
+    fn read_tree(&self, _path: &RepoPath, id: &TreeId) -> BackendResult<Tree> {
         let path = self.tree_path(id);
-        let mut file = File::open(path).map_err(not_found_to_store_error)?;
+        let mut file = File::open(path).map_err(not_found_to_backend_error)?;
 
         let proto: crate::protos::store::Tree = Message::parse_from_reader(&mut file)?;
         Ok(tree_from_proto(&proto))
     }
 
-    fn write_tree(&self, _path: &RepoPath, tree: &Tree) -> StoreResult<TreeId> {
+    fn write_tree(&self, _path: &RepoPath, tree: &Tree) -> BackendResult<TreeId> {
         let temp_file = NamedTempFile::new_in(&self.path)?;
 
         let proto = tree_to_proto(tree);
@@ -191,15 +192,15 @@ impl Store for LocalStore {
         Ok(id)
     }
 
-    fn read_commit(&self, id: &CommitId) -> StoreResult<Commit> {
+    fn read_commit(&self, id: &CommitId) -> BackendResult<Commit> {
         let path = self.commit_path(id);
-        let mut file = File::open(path).map_err(not_found_to_store_error)?;
+        let mut file = File::open(path).map_err(not_found_to_backend_error)?;
 
         let proto: crate::protos::store::Commit = Message::parse_from_reader(&mut file)?;
         Ok(commit_from_proto(&proto))
     }
 
-    fn write_commit(&self, commit: &Commit) -> StoreResult<CommitId> {
+    fn write_commit(&self, commit: &Commit) -> BackendResult<CommitId> {
         let temp_file = NamedTempFile::new_in(&self.path)?;
 
         let proto = commit_to_proto(commit);
@@ -214,15 +215,15 @@ impl Store for LocalStore {
         Ok(id)
     }
 
-    fn read_conflict(&self, id: &ConflictId) -> StoreResult<Conflict> {
+    fn read_conflict(&self, id: &ConflictId) -> BackendResult<Conflict> {
         let path = self.conflict_path(id);
-        let mut file = File::open(path).map_err(not_found_to_store_error)?;
+        let mut file = File::open(path).map_err(not_found_to_backend_error)?;
 
         let proto: crate::protos::store::Conflict = Message::parse_from_reader(&mut file)?;
         Ok(conflict_from_proto(&proto))
     }
 
-    fn write_conflict(&self, conflict: &Conflict) -> StoreResult<ConflictId> {
+    fn write_conflict(&self, conflict: &Conflict) -> BackendResult<ConflictId> {
         let temp_file = NamedTempFile::new_in(&self.path)?;
 
         let proto = conflict_to_proto(conflict);
diff --git a/lib/src/op_heads_store.rs b/lib/src/op_heads_store.rs
index 571b7cbb2..3d323bec0 100644
--- a/lib/src/op_heads_store.rs
+++ b/lib/src/op_heads_store.rs
@@ -19,11 +19,11 @@ use std::sync::Arc;
 use itertools::Itertools;
 use thiserror::Error;
 
+use crate::backend::Timestamp;
 use crate::lock::FileLock;
 use crate::op_store::{OpStore, OperationId, OperationMetadata};
 use crate::operation::Operation;
 use crate::repo::RepoLoader;
-use crate::store::Timestamp;
 use crate::transaction::UnpublishedOperation;
 use crate::{dag_walk, op_store};
 
diff --git a/lib/src/op_store.rs b/lib/src/op_store.rs
index 9160d3dfe..70c0f92f7 100644
--- a/lib/src/op_store.rs
+++ b/lib/src/op_store.rs
@@ -15,7 +15,7 @@
 use std::collections::{BTreeMap, HashMap, HashSet};
 use std::fmt::{Debug, Error, Formatter};
 
-use crate::store::{CommitId, Timestamp};
+use crate::backend::{CommitId, Timestamp};
 
 #[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Hash)]
 pub struct ViewId(pub Vec<u8>);
diff --git a/lib/src/operation.rs b/lib/src/operation.rs
index b481ae43f..23f15de2e 100644
--- a/lib/src/operation.rs
+++ b/lib/src/operation.rs
@@ -18,9 +18,9 @@ use std::fmt::{Debug, Error, Formatter};
 use std::hash::{Hash, Hasher};
 use std::sync::Arc;
 
+use crate::backend::CommitId;
 use crate::op_store;
 use crate::op_store::{OpStore, OperationId, ViewId};
-use crate::store::CommitId;
 
 #[derive(Clone)]
 pub struct Operation {
diff --git a/lib/src/refs.rs b/lib/src/refs.rs
index a5b7a0136..8c9834dc0 100644
--- a/lib/src/refs.rs
+++ b/lib/src/refs.rs
@@ -12,9 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+use crate::backend::CommitId;
 use crate::index::IndexRef;
 use crate::op_store::{BranchTarget, RefTarget};
-use crate::store::CommitId;
 
 pub fn merge_ref_targets(
     index: IndexRef,
diff --git a/lib/src/repo.rs b/lib/src/repo.rs
index bd8630f6c..131068fa8 100644
--- a/lib/src/repo.rs
+++ b/lib/src/repo.rs
@@ -21,25 +21,25 @@ use std::sync::{Arc, Mutex, MutexGuard};
 
 use thiserror::Error;
 
+use crate::backend::{Backend, BackendError, CommitId};
 use crate::commit::Commit;
 use crate::commit_builder::{new_change_id, signature, CommitBuilder};
 use crate::dag_walk::topo_order_reverse;
 use crate::evolution::{EvolutionRef, MutableEvolution, ReadonlyEvolution};
-use crate::git_store::GitStore;
+use crate::git_backend::GitBackend;
 use crate::index::{IndexRef, MutableIndex, ReadonlyIndex};
 use crate::index_store::IndexStore;
-use crate::local_store::LocalStore;
+use crate::local_backend::LocalBackend;
 use crate::op_heads_store::OpHeadsStore;
 use crate::op_store::{BranchTarget, OpStore, OperationId, RefTarget};
 use crate::operation::Operation;
 use crate::settings::{RepoSettings, UserSettings};
 use crate::simple_op_store::SimpleOpStore;
-use crate::store::{CommitId, Store, StoreError};
-use crate::store_wrapper::StoreWrapper;
+use crate::store::Store;
 use crate::transaction::Transaction;
 use crate::view::{RefName, View};
 use crate::working_copy::WorkingCopy;
-use crate::{conflicts, op_store, store};
+use crate::{backend, conflicts, op_store};
 
 #[derive(Debug, Error, PartialEq, Eq)]
 pub enum RepoError {
@@ -49,11 +49,11 @@ pub enum RepoError {
     Other(String),
 }
 
-impl From<StoreError> for RepoError {
-    fn from(err: StoreError) -> Self {
+impl From<BackendError> for RepoError {
+    fn from(err: BackendError) -> Self {
         match err {
-            StoreError::NotFound => RepoError::NotFound,
-            StoreError::Other(description) => RepoError::Other(description),
+            BackendError::NotFound => RepoError::NotFound,
+            BackendError::Other(description) => RepoError::Other(description),
         }
     }
 }
@@ -69,7 +69,7 @@ pub enum RepoRef<'a> {
 }
 
 impl<'a> RepoRef<'a> {
-    pub fn store(&self) -> &Arc<StoreWrapper> {
+    pub fn store(&self) -> &Arc<Store> {
         match self {
             RepoRef::Readonly(repo) => repo.store(),
             RepoRef::Mutable(repo) => repo.store(),
@@ -108,7 +108,7 @@ impl<'a> RepoRef<'a> {
 pub struct ReadonlyRepo {
     repo_path: PathBuf,
     wc_path: PathBuf,
-    store: Arc<StoreWrapper>,
+    store: Arc<Store>,
     op_store: Arc<dyn OpStore>,
     op_heads_store: Arc<OpHeadsStore>,
     operation: Operation,
@@ -150,11 +150,11 @@ impl ReadonlyRepo {
         let repo_path = ReadonlyRepo::init_repo_dir(&wc_path)?;
         let store_path = repo_path.join("store");
         fs::create_dir(&store_path).unwrap();
-        let store = Box::new(LocalStore::init(store_path));
-        Ok(ReadonlyRepo::init(settings, repo_path, wc_path, store))
+        let backend = Box::new(LocalBackend::init(store_path));
+        Ok(ReadonlyRepo::init(settings, repo_path, wc_path, backend))
     }
 
-    /// Initializes a repo with a new Git store in .jj/git/ (bare Git repo)
+    /// Initializes a repo with a new Git backend in .jj/git/ (bare Git repo)
     pub fn init_internal_git(
         settings: &UserSettings,
         wc_path: PathBuf,
@@ -166,11 +166,11 @@ impl ReadonlyRepo {
         let git_store_path = fs::canonicalize(git_store_path).unwrap();
         let mut store_file = File::create(store_path).unwrap();
         store_file.write_all(b"git: git").unwrap();
-        let store = Box::new(GitStore::load(&git_store_path));
-        Ok(ReadonlyRepo::init(settings, repo_path, wc_path, store))
+        let backend = Box::new(GitBackend::load(&git_store_path));
+        Ok(ReadonlyRepo::init(settings, repo_path, wc_path, backend))
     }
 
-    /// Initializes a repo with an existing Git store at the specified path
+    /// Initializes a repo with an existing Git backend at the specified path
     pub fn init_external_git(
         settings: &UserSettings,
         wc_path: PathBuf,
@@ -183,8 +183,8 @@ impl ReadonlyRepo {
         store_file
             .write_all(format!("git: {}", git_store_path.to_str().unwrap()).as_bytes())
             .unwrap();
-        let store = Box::new(GitStore::load(&git_store_path));
-        Ok(ReadonlyRepo::init(settings, repo_path, wc_path, store))
+        let backend = Box::new(GitBackend::load(&git_store_path));
+        Ok(ReadonlyRepo::init(settings, repo_path, wc_path, backend))
     }
 
     fn init_repo_dir(wc_path: &Path) -> Result<PathBuf, RepoInitError> {
@@ -201,10 +201,10 @@ impl ReadonlyRepo {
         user_settings: &UserSettings,
         repo_path: PathBuf,
         wc_path: PathBuf,
-        store: Box<dyn Store>,
+        backend: Box<dyn Backend>,
     ) -> Arc<ReadonlyRepo> {
         let repo_settings = user_settings.with_repo(&repo_path).unwrap();
-        let store = StoreWrapper::new(store);
+        let store = Store::new(backend);
 
         fs::create_dir(repo_path.join("working_copy")).unwrap();
         let working_copy = WorkingCopy::init(
@@ -215,7 +215,7 @@ impl ReadonlyRepo {
 
         fs::create_dir(repo_path.join("view")).unwrap();
         let signature = signature(user_settings);
-        let checkout_commit = store::Commit {
+        let checkout_commit = backend::Commit {
             parents: vec![],
             predecessors: vec![],
             root_tree: store.empty_tree_id().clone(),
@@ -352,7 +352,7 @@ impl ReadonlyRepo {
         self.working_copy.as_ref().lock().unwrap()
     }
 
-    pub fn store(&self) -> &Arc<StoreWrapper> {
+    pub fn store(&self) -> &Arc<Store> {
         &self.store
     }
 
@@ -396,7 +396,7 @@ pub struct RepoLoader {
     wc_path: PathBuf,
     repo_path: PathBuf,
     repo_settings: RepoSettings,
-    store: Arc<StoreWrapper>,
+    store: Arc<Store>,
     op_store: Arc<dyn OpStore>,
     op_heads_store: Arc<OpHeadsStore>,
     index_store: Arc<IndexStore>,
@@ -423,7 +423,7 @@ impl RepoLoader {
     ) -> Result<RepoLoader, RepoLoadError> {
         let repo_path = find_repo_dir(&wc_path).ok_or(RepoLoadError::NoRepoHere(wc_path))?;
         let wc_path = repo_path.parent().unwrap().to_owned();
-        let store = StoreWrapper::load_store(&repo_path);
+        let store = Store::load_store(&repo_path);
         let repo_settings = user_settings.with_repo(&repo_path).unwrap();
         let op_store: Arc<dyn OpStore> = Arc::new(SimpleOpStore::load(repo_path.join("op_store")));
         let op_heads_store = Arc::new(OpHeadsStore::load(repo_path.join("op_heads")));
@@ -439,7 +439,7 @@ impl RepoLoader {
         })
     }
 
-    pub fn store(&self) -> &Arc<StoreWrapper> {
+    pub fn store(&self) -> &Arc<Store> {
         &self.store
     }
 
@@ -548,7 +548,7 @@ impl MutableRepo {
         &self.base_repo
     }
 
-    pub fn store(&self) -> &Arc<StoreWrapper> {
+    pub fn store(&self) -> &Arc<Store> {
         self.base_repo.store()
     }
 
@@ -593,7 +593,7 @@ impl MutableRepo {
         self.evolution.lock().unwrap().take();
     }
 
-    pub fn write_commit(&mut self, commit: store::Commit) -> Commit {
+    pub fn write_commit(&mut self, commit: backend::Commit) -> Commit {
         let commit = self.store().write_commit(commit);
         self.add_head(&commit);
         commit
diff --git a/lib/src/revset.rs b/lib/src/revset.rs
index fd2db852f..383d48e30 100644
--- a/lib/src/revset.rs
+++ b/lib/src/revset.rs
@@ -23,11 +23,11 @@ use pest::iterators::Pairs;
 use pest::Parser;
 use thiserror::Error;
 
+use crate::backend::{BackendError, CommitId};
 use crate::commit::Commit;
 use crate::index::{HexPrefix, IndexEntry, IndexPosition, PrefixResolution, RevWalk};
 use crate::repo::RepoRef;
 use crate::revset_graph_iterator::RevsetGraphIterator;
-use crate::store::{CommitId, StoreError};
 
 #[derive(Debug, Error, PartialEq, Eq)]
 pub enum RevsetError {
@@ -38,7 +38,7 @@ pub enum RevsetError {
     #[error("Change id prefix \"{0}\" is ambiguous")]
     AmbiguousChangeIdPrefix(String),
     #[error("Unexpected error from store: {0}")]
-    StoreError(#[from] StoreError),
+    StoreError(#[from] BackendError),
 }
 
 fn resolve_git_ref(repo: RepoRef, symbol: &str) -> Result<Vec<CommitId>, RevsetError> {
@@ -75,7 +75,7 @@ fn resolve_commit_id(repo: RepoRef, symbol: &str) -> Result<Vec<CommitId>, Revse
         let commit_id = CommitId(binary_commit_id);
         match repo.store().get_commit(&commit_id) {
             Ok(_) => return Ok(vec![commit_id]),
-            Err(StoreError::NotFound) => {} // fall through
+            Err(BackendError::NotFound) => {} // fall through
             Err(err) => return Err(RevsetError::StoreError(err)),
         }
     }
diff --git a/lib/src/rewrite.rs b/lib/src/rewrite.rs
index c83cc971d..69bd7ef79 100644
--- a/lib/src/rewrite.rs
+++ b/lib/src/rewrite.rs
@@ -16,13 +16,13 @@ use std::collections::{HashMap, HashSet};
 
 use itertools::Itertools;
 
+use crate::backend::CommitId;
 use crate::commit::Commit;
 use crate::commit_builder::CommitBuilder;
 use crate::repo::{MutableRepo, RepoRef};
 use crate::repo_path::RepoPath;
 use crate::revset::RevsetExpression;
 use crate::settings::UserSettings;
-use crate::store::CommitId;
 use crate::tree::{merge_trees, Tree};
 
 pub fn merge_commit_trees(repo: RepoRef, commits: &[Commit]) -> Tree {
diff --git a/lib/src/simple_op_store.rs b/lib/src/simple_op_store.rs
index 8e751dcc9..4bb1d379f 100644
--- a/lib/src/simple_op_store.rs
+++ b/lib/src/simple_op_store.rs
@@ -24,12 +24,12 @@ use itertools::Itertools;
 use protobuf::{Message, ProtobufError};
 use tempfile::{NamedTempFile, PersistError};
 
+use crate::backend::{CommitId, MillisSinceEpoch, Timestamp};
 use crate::file_util::persist_content_addressed_temp_file;
 use crate::op_store::{
     BranchTarget, OpStore, OpStoreError, OpStoreResult, Operation, OperationId, OperationMetadata,
     RefTarget, View, ViewId,
 };
-use crate::store::{CommitId, MillisSinceEpoch, Timestamp};
 
 impl From<std::io::Error> for OpStoreError {
     fn from(err: std::io::Error) -> Self {
diff --git a/lib/src/store.rs b/lib/src/store.rs
index e208b29f3..63b3d51da 100644
--- a/lib/src/store.rs
+++ b/lib/src/store.rs
@@ -12,307 +12,217 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use std::collections::BTreeMap;
-use std::fmt::{Debug, Error, Formatter};
+use std::collections::HashMap;
+use std::fs::File;
 use std::io::Read;
-use std::result::Result;
-use std::vec::Vec;
+use std::path::{Path, PathBuf};
+use std::sync::{Arc, RwLock, Weak};
 
-use thiserror::Error;
+use crate::backend;
+use crate::backend::{
+    Backend, BackendResult, ChangeId, CommitId, Conflict, ConflictId, FileId, MillisSinceEpoch,
+    Signature, SymlinkId, Timestamp, TreeId,
+};
+use crate::commit::Commit;
+use crate::git_backend::GitBackend;
+use crate::local_backend::LocalBackend;
+use crate::repo_path::RepoPath;
+use crate::tree::Tree;
+use crate::tree_builder::TreeBuilder;
 
-use crate::repo_path::{RepoPath, RepoPathComponent};
-
-#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Hash)]
-pub struct CommitId(pub Vec<u8>);
-
-impl Debug for CommitId {
-    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
-        f.debug_tuple("CommitId").field(&self.hex()).finish()
-    }
+/// Wraps the low-level backend and makes it return more convenient types. Also
+/// adds the root commit and adds caching.
+#[derive(Debug)]
+pub struct Store {
+    weak_self: Option<Weak<Store>>,
+    backend: Box<dyn Backend>,
+    root_commit_id: CommitId,
+    commit_cache: RwLock<HashMap<CommitId, Arc<backend::Commit>>>,
+    tree_cache: RwLock<HashMap<(RepoPath, TreeId), Arc<backend::Tree>>>,
 }
 
-impl CommitId {
-    pub fn from_hex(hex: &str) -> Self {
-        CommitId(hex::decode(hex).unwrap())
+impl Store {
+    pub fn new(backend: Box<dyn Backend>) -> Arc<Self> {
+        let root_commit_id = CommitId(vec![0; backend.hash_length()]);
+        let mut wrapper = Arc::new(Store {
+            weak_self: None,
+            backend,
+            root_commit_id,
+            commit_cache: Default::default(),
+            tree_cache: Default::default(),
+        });
+        let weak_self = Arc::downgrade(&wrapper);
+        let mut ref_mut = unsafe { Arc::get_mut_unchecked(&mut wrapper) };
+        ref_mut.weak_self = Some(weak_self);
+        wrapper
     }
 
-    pub fn hex(&self) -> String {
-        hex::encode(&self.0)
-    }
-}
-
-#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Hash)]
-pub struct ChangeId(pub Vec<u8>);
-
-impl Debug for ChangeId {
-    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
-        f.debug_tuple("ChangeId").field(&self.hex()).finish()
-    }
-}
-
-impl ChangeId {
-    pub fn from_hex(hex: &str) -> Self {
-        ChangeId(hex::decode(hex).unwrap())
-    }
-
-    pub fn hex(&self) -> String {
-        hex::encode(&self.0)
-    }
-}
-
-#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Hash)]
-pub struct TreeId(pub Vec<u8>);
-
-impl Debug for TreeId {
-    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
-        f.debug_tuple("TreeId").field(&self.hex()).finish()
-    }
-}
-
-impl TreeId {
-    pub fn hex(&self) -> String {
-        hex::encode(&self.0)
-    }
-}
-
-#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Hash)]
-pub struct FileId(pub Vec<u8>);
-
-impl Debug for FileId {
-    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
-        f.debug_tuple("FileId").field(&self.hex()).finish()
-    }
-}
-
-impl FileId {
-    pub fn hex(&self) -> String {
-        hex::encode(&self.0)
-    }
-}
-
-#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Hash)]
-pub struct SymlinkId(pub Vec<u8>);
-
-impl Debug for SymlinkId {
-    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
-        f.debug_tuple("SymlinkId").field(&self.hex()).finish()
-    }
-}
-
-impl SymlinkId {
-    pub fn hex(&self) -> String {
-        hex::encode(&self.0)
-    }
-}
-
-#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Hash)]
-pub struct ConflictId(pub Vec<u8>);
-
-impl Debug for ConflictId {
-    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
-        f.debug_tuple("ConflictId").field(&self.hex()).finish()
-    }
-}
-
-impl ConflictId {
-    pub fn hex(&self) -> String {
-        hex::encode(&self.0)
-    }
-}
-
-pub enum Phase {
-    Public,
-    Draft,
-}
-
-#[derive(Debug, PartialEq, Eq, Clone, PartialOrd, Ord)]
-pub struct MillisSinceEpoch(pub u64);
-
-#[derive(Debug, PartialEq, Eq, Clone, PartialOrd, Ord)]
-pub struct Timestamp {
-    pub timestamp: MillisSinceEpoch,
-    // time zone offset in minutes
-    pub tz_offset: i32,
-}
-
-impl Timestamp {
-    pub fn now() -> Self {
-        let now = chrono::offset::Local::now();
-        Self {
-            timestamp: MillisSinceEpoch(now.timestamp_millis() as u64),
-            tz_offset: now.offset().local_minus_utc() / 60,
+    pub fn load_store(repo_path: &Path) -> Arc<Store> {
+        let store_path = repo_path.join("store");
+        let backend: Box<dyn Backend>;
+        // TODO: Perhaps .jj/store should always be a directory. Then .jj/git would live
+        // inside that directory and this function would not need to know the repo path
+        // (only the store path). Maybe there would be a .jj/store/format file
+        // indicating which kind of store it is?
+        if store_path.is_dir() {
+            backend = Box::new(LocalBackend::load(store_path));
+        } else {
+            let mut store_file = File::open(store_path).unwrap();
+            let mut buf = Vec::new();
+            store_file.read_to_end(&mut buf).unwrap();
+            let contents = String::from_utf8(buf).unwrap();
+            assert!(contents.starts_with("git: "));
+            let git_backend_path_str = contents[5..].to_string();
+            let git_backend_path =
+                std::fs::canonicalize(repo_path.join(PathBuf::from(git_backend_path_str))).unwrap();
+            backend = Box::new(GitBackend::load(&git_backend_path));
         }
-    }
-}
-
-#[derive(Debug, PartialEq, Eq, Clone)]
-pub struct Signature {
-    pub name: String,
-    pub email: String,
-    pub timestamp: Timestamp,
-}
-
-#[derive(Debug, Clone)]
-pub struct Commit {
-    pub parents: Vec<CommitId>,
-    pub predecessors: Vec<CommitId>,
-    pub root_tree: TreeId,
-    pub change_id: ChangeId,
-    pub description: String,
-    pub author: Signature,
-    pub committer: Signature,
-    pub is_open: bool,
-    pub is_pruned: bool,
-}
-
-#[derive(Debug, PartialEq, Eq, Clone)]
-pub struct ConflictPart {
-    // TODO: Store e.g. CommitId here too? Labels (theirs/ours/base)? Would those still be
-    //       useful e.g. after rebasing this conflict?
-    pub value: TreeValue,
-}
-
-#[derive(Debug, PartialEq, Eq, Clone)]
-pub struct Conflict {
-    // A conflict is represented by a list of positive and negative states that need to be applied.
-    // In a simple 3-way merge of B and C with merge base A, the conflict will be { add: [B, C],
-    // remove: [A] }. Also note that a conflict of the form { add: [A], remove: [] } is the
-    // same as non-conflict A.
-    pub removes: Vec<ConflictPart>,
-    pub adds: Vec<ConflictPart>,
-}
-
-impl Default for Conflict {
-    fn default() -> Self {
-        Conflict {
-            removes: Default::default(),
-            adds: Default::default(),
-        }
-    }
-}
-
-#[derive(Debug, Error, PartialEq, Eq)]
-pub enum StoreError {
-    #[error("Object not found")]
-    NotFound,
-    #[error("Error: {0}")]
-    Other(String),
-}
-
-pub type StoreResult<T> = Result<T, StoreError>;
-
-#[derive(Debug, PartialEq, Eq, Clone, Hash)]
-pub enum TreeValue {
-    Normal { id: FileId, executable: bool },
-    Symlink(SymlinkId),
-    Tree(TreeId),
-    GitSubmodule(CommitId),
-    Conflict(ConflictId),
-}
-
-#[derive(Debug, PartialEq, Eq, Clone)]
-pub struct TreeEntry<'a> {
-    name: &'a RepoPathComponent,
-    value: &'a TreeValue,
-}
-
-impl<'a> TreeEntry<'a> {
-    pub fn new(name: &'a RepoPathComponent, value: &'a TreeValue) -> Self {
-        TreeEntry { name, value }
+        Store::new(backend)
     }
 
-    pub fn name(&self) -> &'a RepoPathComponent {
-        self.name
+    pub fn hash_length(&self) -> usize {
+        self.backend.hash_length()
     }
 
-    pub fn value(&self) -> &'a TreeValue {
-        self.value
-    }
-}
-
-pub struct TreeEntriesNonRecursiveIter<'a> {
-    iter: std::collections::btree_map::Iter<'a, RepoPathComponent, TreeValue>,
-}
-
-impl<'a> Iterator for TreeEntriesNonRecursiveIter<'a> {
-    type Item = TreeEntry<'a>;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        self.iter
-            .next()
-            .map(|(name, value)| TreeEntry { name, value })
-    }
-}
-
-#[derive(Debug, Clone)]
-pub struct Tree {
-    entries: BTreeMap<RepoPathComponent, TreeValue>,
-}
-
-impl Default for Tree {
-    fn default() -> Self {
-        Self {
-            entries: BTreeMap::new(),
-        }
-    }
-}
-
-impl Tree {
-    pub fn is_empty(&self) -> bool {
-        self.entries.is_empty()
+    pub fn git_repo(&self) -> Option<git2::Repository> {
+        self.backend.git_repo()
     }
 
-    pub fn entries(&self) -> TreeEntriesNonRecursiveIter {
-        TreeEntriesNonRecursiveIter {
-            iter: self.entries.iter(),
+    pub fn empty_tree_id(&self) -> &TreeId {
+        self.backend.empty_tree_id()
+    }
+
+    pub fn root_commit_id(&self) -> &CommitId {
+        &self.root_commit_id
+    }
+
+    pub fn root_commit(&self) -> Commit {
+        self.get_commit(&self.root_commit_id).unwrap()
+    }
+
+    pub fn get_commit(&self, id: &CommitId) -> BackendResult<Commit> {
+        let data = self.get_backend_commit(id)?;
+        Ok(Commit::new(
+            self.weak_self.as_ref().unwrap().upgrade().unwrap(),
+            id.clone(),
+            data,
+        ))
+    }
+
+    fn make_root_commit(&self) -> backend::Commit {
+        let timestamp = Timestamp {
+            timestamp: MillisSinceEpoch(0),
+            tz_offset: 0,
+        };
+        let signature = Signature {
+            name: String::new(),
+            email: String::new(),
+            timestamp,
+        };
+        let change_id = ChangeId(vec![0; 16]);
+        backend::Commit {
+            parents: vec![],
+            predecessors: vec![],
+            root_tree: self.backend.empty_tree_id().clone(),
+            change_id,
+            description: String::new(),
+            author: signature.clone(),
+            committer: signature,
+            is_open: false,
+            is_pruned: false,
         }
     }
 
-    pub fn set(&mut self, name: RepoPathComponent, value: TreeValue) {
-        self.entries.insert(name, value);
+    fn get_backend_commit(&self, id: &CommitId) -> BackendResult<Arc<backend::Commit>> {
+        {
+            let read_locked_cached = self.commit_cache.read().unwrap();
+            if let Some(data) = read_locked_cached.get(id).cloned() {
+                return Ok(data);
+            }
+        }
+        let commit = if id == self.root_commit_id() {
+            self.make_root_commit()
+        } else {
+            self.backend.read_commit(id)?
+        };
+        let data = Arc::new(commit);
+        let mut write_locked_cache = self.commit_cache.write().unwrap();
+        write_locked_cache.insert(id.clone(), data.clone());
+        Ok(data)
     }
 
-    pub fn remove(&mut self, name: &RepoPathComponent) {
-        self.entries.remove(name);
+    pub fn write_commit(&self, commit: backend::Commit) -> Commit {
+        let commit_id = self.backend.write_commit(&commit).unwrap();
+        let data = Arc::new(commit);
+        {
+            let mut write_locked_cache = self.commit_cache.write().unwrap();
+            write_locked_cache.insert(commit_id.clone(), data.clone());
+        }
+        let commit = Commit::new(
+            self.weak_self.as_ref().unwrap().upgrade().unwrap(),
+            commit_id,
+            data,
+        );
+        commit
     }
 
-    pub fn entry(&self, name: &RepoPathComponent) -> Option<TreeEntry> {
-        self.entries
-            .get_key_value(name)
-            .map(|(name, value)| TreeEntry { name, value })
+    pub fn get_tree(&self, dir: &RepoPath, id: &TreeId) -> BackendResult<Tree> {
+        let data = self.get_backend_tree(dir, id)?;
+        Ok(Tree::new(
+            self.weak_self.as_ref().unwrap().upgrade().unwrap(),
+            dir.clone(),
+            id.clone(),
+            data,
+        ))
     }
 
-    pub fn value(&self, name: &RepoPathComponent) -> Option<&TreeValue> {
-        self.entries.get(name)
+    fn get_backend_tree(&self, dir: &RepoPath, id: &TreeId) -> BackendResult<Arc<backend::Tree>> {
+        let key = (dir.clone(), id.clone());
+        {
+            let read_locked_cache = self.tree_cache.read().unwrap();
+            if let Some(data) = read_locked_cache.get(&key).cloned() {
+                return Ok(data);
+            }
+        }
+        let data = Arc::new(self.backend.read_tree(dir, id)?);
+        let mut write_locked_cache = self.tree_cache.write().unwrap();
+        write_locked_cache.insert(key, data.clone());
+        Ok(data)
+    }
+
+    pub fn write_tree(&self, path: &RepoPath, contents: &backend::Tree) -> BackendResult<TreeId> {
+        // TODO: This should also do caching like write_commit does.
+        self.backend.write_tree(path, contents)
+    }
+
+    pub fn read_file(&self, path: &RepoPath, id: &FileId) -> BackendResult<Box<dyn Read>> {
+        self.backend.read_file(path, id)
+    }
+
+    pub fn write_file(&self, path: &RepoPath, contents: &mut dyn Read) -> BackendResult<FileId> {
+        self.backend.write_file(path, contents)
+    }
+
+    pub fn read_symlink(&self, path: &RepoPath, id: &SymlinkId) -> BackendResult<String> {
+        self.backend.read_symlink(path, id)
+    }
+
+    pub fn write_symlink(&self, path: &RepoPath, contents: &str) -> BackendResult<SymlinkId> {
+        self.backend.write_symlink(path, contents)
+    }
+
+    pub fn read_conflict(&self, id: &ConflictId) -> BackendResult<Conflict> {
+        self.backend.read_conflict(id)
+    }
+
+    pub fn write_conflict(&self, contents: &Conflict) -> BackendResult<ConflictId> {
+        self.backend.write_conflict(contents)
+    }
+
+    pub fn tree_builder(&self, base_tree_id: TreeId) -> TreeBuilder {
+        TreeBuilder::new(
+            self.weak_self.as_ref().unwrap().upgrade().unwrap(),
+            base_tree_id,
+        )
     }
 }
-
-pub trait Store: Send + Sync + Debug {
-    fn hash_length(&self) -> usize;
-
-    fn git_repo(&self) -> Option<git2::Repository>;
-
-    fn read_file(&self, path: &RepoPath, id: &FileId) -> StoreResult<Box<dyn Read>>;
-
-    fn write_file(&self, path: &RepoPath, contents: &mut dyn Read) -> StoreResult<FileId>;
-
-    fn read_symlink(&self, path: &RepoPath, id: &SymlinkId) -> StoreResult<String>;
-
-    fn write_symlink(&self, path: &RepoPath, target: &str) -> StoreResult<SymlinkId>;
-
-    fn empty_tree_id(&self) -> &TreeId;
-
-    fn read_tree(&self, path: &RepoPath, id: &TreeId) -> StoreResult<Tree>;
-
-    fn write_tree(&self, path: &RepoPath, contents: &Tree) -> StoreResult<TreeId>;
-
-    fn read_commit(&self, id: &CommitId) -> StoreResult<Commit>;
-
-    fn write_commit(&self, contents: &Commit) -> StoreResult<CommitId>;
-
-    // TODO: Pass in the paths here too even though they are unused, just like for
-    // files and trees?
-    fn read_conflict(&self, id: &ConflictId) -> StoreResult<Conflict>;
-
-    fn write_conflict(&self, contents: &Conflict) -> StoreResult<ConflictId>;
-}
diff --git a/lib/src/store_wrapper.rs b/lib/src/store_wrapper.rs
deleted file mode 100644
index 1f48dd22f..000000000
--- a/lib/src/store_wrapper.rs
+++ /dev/null
@@ -1,230 +0,0 @@
-// Copyright 2020 Google LLC
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-use std::collections::HashMap;
-use std::fs::File;
-use std::io::Read;
-use std::path::{Path, PathBuf};
-use std::sync::{Arc, RwLock, Weak};
-
-use crate::commit::Commit;
-use crate::git_store::GitStore;
-use crate::local_store::LocalStore;
-use crate::repo_path::RepoPath;
-use crate::store;
-use crate::store::{
-    ChangeId, CommitId, Conflict, ConflictId, FileId, MillisSinceEpoch, Signature, Store,
-    StoreResult, SymlinkId, Timestamp, TreeId,
-};
-use crate::tree::Tree;
-use crate::tree_builder::TreeBuilder;
-
-/// Wraps the low-level store and makes it return more convenient types. Also
-/// adds the root commit and adds caching.
-/// TODO: Come up with a better name, possibly by renaming the current Store
-/// trait to something else.
-#[derive(Debug)]
-pub struct StoreWrapper {
-    weak_self: Option<Weak<StoreWrapper>>,
-    store: Box<dyn Store>,
-    root_commit_id: CommitId,
-    commit_cache: RwLock<HashMap<CommitId, Arc<store::Commit>>>,
-    tree_cache: RwLock<HashMap<(RepoPath, TreeId), Arc<store::Tree>>>,
-}
-
-impl StoreWrapper {
-    pub fn new(store: Box<dyn Store>) -> Arc<Self> {
-        let root_commit_id = CommitId(vec![0; store.hash_length()]);
-        let mut wrapper = Arc::new(StoreWrapper {
-            weak_self: None,
-            store,
-            root_commit_id,
-            commit_cache: Default::default(),
-            tree_cache: Default::default(),
-        });
-        let weak_self = Arc::downgrade(&wrapper);
-        let mut ref_mut = unsafe { Arc::get_mut_unchecked(&mut wrapper) };
-        ref_mut.weak_self = Some(weak_self);
-        wrapper
-    }
-
-    pub fn load_store(repo_path: &Path) -> Arc<StoreWrapper> {
-        let store_path = repo_path.join("store");
-        let store: Box<dyn Store>;
-        // TODO: Perhaps .jj/store should always be a directory. Then .jj/git would live
-        // inside that directory and this function would not need to know the repo path
-        // (only the store path). Maybe there would be a .jj/store/format file
-        // indicating which kind of store it is?
-        if store_path.is_dir() {
-            store = Box::new(LocalStore::load(store_path));
-        } else {
-            let mut store_file = File::open(store_path).unwrap();
-            let mut buf = Vec::new();
-            store_file.read_to_end(&mut buf).unwrap();
-            let contents = String::from_utf8(buf).unwrap();
-            assert!(contents.starts_with("git: "));
-            let git_store_path_str = contents[5..].to_string();
-            let git_store_path =
-                std::fs::canonicalize(repo_path.join(PathBuf::from(git_store_path_str))).unwrap();
-            store = Box::new(GitStore::load(&git_store_path));
-        }
-        StoreWrapper::new(store)
-    }
-
-    pub fn hash_length(&self) -> usize {
-        self.store.hash_length()
-    }
-
-    pub fn git_repo(&self) -> Option<git2::Repository> {
-        self.store.git_repo()
-    }
-
-    pub fn empty_tree_id(&self) -> &TreeId {
-        self.store.empty_tree_id()
-    }
-
-    pub fn root_commit_id(&self) -> &CommitId {
-        &self.root_commit_id
-    }
-
-    pub fn root_commit(&self) -> Commit {
-        self.get_commit(&self.root_commit_id).unwrap()
-    }
-
-    pub fn get_commit(&self, id: &CommitId) -> StoreResult<Commit> {
-        let data = self.get_store_commit(id)?;
-        Ok(Commit::new(
-            self.weak_self.as_ref().unwrap().upgrade().unwrap(),
-            id.clone(),
-            data,
-        ))
-    }
-
-    fn make_root_commit(&self) -> store::Commit {
-        let timestamp = Timestamp {
-            timestamp: MillisSinceEpoch(0),
-            tz_offset: 0,
-        };
-        let signature = Signature {
-            name: String::new(),
-            email: String::new(),
-            timestamp,
-        };
-        let change_id = ChangeId(vec![0; 16]);
-        store::Commit {
-            parents: vec![],
-            predecessors: vec![],
-            root_tree: self.store.empty_tree_id().clone(),
-            change_id,
-            description: String::new(),
-            author: signature.clone(),
-            committer: signature,
-            is_open: false,
-            is_pruned: false,
-        }
-    }
-
-    fn get_store_commit(&self, id: &CommitId) -> StoreResult<Arc<store::Commit>> {
-        {
-            let read_locked_cached = self.commit_cache.read().unwrap();
-            if let Some(data) = read_locked_cached.get(id).cloned() {
-                return Ok(data);
-            }
-        }
-        let commit = if id == self.root_commit_id() {
-            self.make_root_commit()
-        } else {
-            self.store.read_commit(id)?
-        };
-        let data = Arc::new(commit);
-        let mut write_locked_cache = self.commit_cache.write().unwrap();
-        write_locked_cache.insert(id.clone(), data.clone());
-        Ok(data)
-    }
-
-    pub fn write_commit(&self, commit: store::Commit) -> Commit {
-        let commit_id = self.store.write_commit(&commit).unwrap();
-        let data = Arc::new(commit);
-        {
-            let mut write_locked_cache = self.commit_cache.write().unwrap();
-            write_locked_cache.insert(commit_id.clone(), data.clone());
-        }
-        let commit = Commit::new(
-            self.weak_self.as_ref().unwrap().upgrade().unwrap(),
-            commit_id,
-            data,
-        );
-        commit
-    }
-
-    pub fn get_tree(&self, dir: &RepoPath, id: &TreeId) -> StoreResult<Tree> {
-        let data = self.get_store_tree(dir, id)?;
-        Ok(Tree::new(
-            self.weak_self.as_ref().unwrap().upgrade().unwrap(),
-            dir.clone(),
-            id.clone(),
-            data,
-        ))
-    }
-
-    fn get_store_tree(&self, dir: &RepoPath, id: &TreeId) -> StoreResult<Arc<store::Tree>> {
-        let key = (dir.clone(), id.clone());
-        {
-            let read_locked_cache = self.tree_cache.read().unwrap();
-            if let Some(data) = read_locked_cache.get(&key).cloned() {
-                return Ok(data);
-            }
-        }
-        let data = Arc::new(self.store.read_tree(dir, id)?);
-        let mut write_locked_cache = self.tree_cache.write().unwrap();
-        write_locked_cache.insert(key, data.clone());
-        Ok(data)
-    }
-
-    pub fn write_tree(&self, path: &RepoPath, contents: &store::Tree) -> StoreResult<TreeId> {
-        // TODO: This should also do caching like write_commit does.
-        self.store.write_tree(path, contents)
-    }
-
-    pub fn read_file(&self, path: &RepoPath, id: &FileId) -> StoreResult<Box<dyn Read>> {
-        self.store.read_file(path, id)
-    }
-
-    pub fn write_file(&self, path: &RepoPath, contents: &mut dyn Read) -> StoreResult<FileId> {
-        self.store.write_file(path, contents)
-    }
-
-    pub fn read_symlink(&self, path: &RepoPath, id: &SymlinkId) -> StoreResult<String> {
-        self.store.read_symlink(path, id)
-    }
-
-    pub fn write_symlink(&self, path: &RepoPath, contents: &str) -> StoreResult<SymlinkId> {
-        self.store.write_symlink(path, contents)
-    }
-
-    pub fn read_conflict(&self, id: &ConflictId) -> StoreResult<Conflict> {
-        self.store.read_conflict(id)
-    }
-
-    pub fn write_conflict(&self, contents: &Conflict) -> StoreResult<ConflictId> {
-        self.store.write_conflict(contents)
-    }
-
-    pub fn tree_builder(&self, base_tree_id: TreeId) -> TreeBuilder {
-        TreeBuilder::new(
-            self.weak_self.as_ref().unwrap().upgrade().unwrap(),
-            base_tree_id,
-        )
-    }
-}
diff --git a/lib/src/testutils.rs b/lib/src/testutils.rs
index 4a94cf6e6..876c64bba 100644
--- a/lib/src/testutils.rs
+++ b/lib/src/testutils.rs
@@ -20,13 +20,13 @@ use std::sync::Arc;
 use itertools::Itertools;
 use tempfile::TempDir;
 
+use crate::backend::{FileId, TreeId, TreeValue};
 use crate::commit::Commit;
 use crate::commit_builder::CommitBuilder;
 use crate::repo::{MutableRepo, ReadonlyRepo};
 use crate::repo_path::RepoPath;
 use crate::settings::UserSettings;
-use crate::store::{FileId, TreeId, TreeValue};
-use crate::store_wrapper::StoreWrapper;
+use crate::store::Store;
 use crate::tree::Tree;
 use crate::tree_builder::TreeBuilder;
 
@@ -62,7 +62,7 @@ pub fn init_repo(settings: &UserSettings, use_git: bool) -> (TempDir, Arc<Readon
     (temp_dir, repo)
 }
 
-pub fn write_file(store: &StoreWrapper, path: &RepoPath, contents: &str) -> FileId {
+pub fn write_file(store: &Store, path: &RepoPath, contents: &str) -> FileId {
     store.write_file(path, &mut contents.as_bytes()).unwrap()
 }
 
diff --git a/lib/src/transaction.rs b/lib/src/transaction.rs
index 459269425..a4cc92c61 100644
--- a/lib/src/transaction.rs
+++ b/lib/src/transaction.rs
@@ -15,13 +15,13 @@
 use std::collections::HashMap;
 use std::sync::{Arc, Mutex};
 
+use crate::backend::Timestamp;
 use crate::evolution::ReadonlyEvolution;
 use crate::index::ReadonlyIndex;
 use crate::op_store;
 use crate::op_store::{OperationId, OperationMetadata};
 use crate::operation::Operation;
 use crate::repo::{MutableRepo, ReadonlyRepo, RepoLoader};
-use crate::store::Timestamp;
 use crate::view::View;
 use crate::working_copy::WorkingCopy;
 
diff --git a/lib/src/tree.rs b/lib/src/tree.rs
index e60a3a1fd..dcfd53873 100644
--- a/lib/src/tree.rs
+++ b/lib/src/tree.rs
@@ -19,22 +19,22 @@ use std::iter::Peekable;
 use std::pin::Pin;
 use std::sync::Arc;
 
+use crate::backend::{
+    BackendError, Conflict, ConflictId, ConflictPart, TreeEntriesNonRecursiveIter, TreeEntry,
+    TreeId, TreeValue,
+};
 use crate::files::MergeResult;
 use crate::matchers::{EverythingMatcher, Matcher};
 use crate::repo_path::{RepoPath, RepoPathComponent, RepoPathJoin};
-use crate::store::{
-    Conflict, ConflictId, ConflictPart, StoreError, TreeEntriesNonRecursiveIter, TreeEntry, TreeId,
-    TreeValue,
-};
-use crate::store_wrapper::StoreWrapper;
-use crate::{files, store};
+use crate::store::Store;
+use crate::{backend, files};
 
 #[derive(Clone)]
 pub struct Tree {
-    store: Arc<StoreWrapper>,
+    store: Arc<Store>,
     dir: RepoPath,
     id: TreeId,
-    data: Arc<store::Tree>,
+    data: Arc<backend::Tree>,
 }
 
 impl Debug for Tree {
@@ -60,12 +60,7 @@ impl DiffSummary {
 }
 
 impl Tree {
-    pub fn new(
-        store: Arc<StoreWrapper>,
-        dir: RepoPath,
-        id: TreeId,
-        data: Arc<store::Tree>,
-    ) -> Self {
+    pub fn new(store: Arc<Store>, dir: RepoPath, id: TreeId, data: Arc<backend::Tree>) -> Self {
         Tree {
             store,
             dir,
@@ -74,16 +69,16 @@ impl Tree {
         }
     }
 
-    pub fn null(store: Arc<StoreWrapper>, dir: RepoPath) -> Self {
+    pub fn null(store: Arc<Store>, dir: RepoPath) -> Self {
         Tree {
             store,
             dir,
             id: TreeId(vec![]),
-            data: Arc::new(store::Tree::default()),
+            data: Arc::new(backend::Tree::default()),
         }
     }
 
-    pub fn store(&self) -> &Arc<StoreWrapper> {
+    pub fn store(&self) -> &Arc<Store> {
         &self.store
     }
 
@@ -95,7 +90,7 @@ impl Tree {
         &self.id
     }
 
-    pub fn data(&self) -> &store::Tree {
+    pub fn data(&self) -> &backend::Tree {
         &self.data
     }
 
@@ -496,7 +491,7 @@ pub fn merge_trees(
     side1_tree: &Tree,
     base_tree: &Tree,
     side2_tree: &Tree,
-) -> Result<TreeId, StoreError> {
+) -> Result<TreeId, BackendError> {
     let store = base_tree.store().as_ref();
     let dir = base_tree.dir();
     assert_eq!(side1_tree.dir(), dir);
@@ -539,13 +534,13 @@ pub fn merge_trees(
 }
 
 fn merge_tree_value(
-    store: &StoreWrapper,
+    store: &Store,
     dir: &RepoPath,
     basename: &RepoPathComponent,
     maybe_base: Option<&TreeValue>,
     maybe_side1: Option<&TreeValue>,
     maybe_side2: Option<&TreeValue>,
-) -> Result<Option<TreeValue>, StoreError> {
+) -> Result<Option<TreeValue>, BackendError> {
     // Resolve non-trivial conflicts:
     //   * resolve tree conflicts by recursing
     //   * try to resolve file conflicts by merging the file contents
@@ -646,10 +641,7 @@ fn merge_tree_value(
     })
 }
 
-fn conflict_part_to_conflict(
-    store: &StoreWrapper,
-    part: &ConflictPart,
-) -> Result<Conflict, StoreError> {
+fn conflict_part_to_conflict(store: &Store, part: &ConflictPart) -> Result<Conflict, BackendError> {
     match &part.value {
         TreeValue::Conflict(id) => {
             let conflict = store.read_conflict(id)?;
@@ -665,9 +657,9 @@ fn conflict_part_to_conflict(
 }
 
 fn simplify_conflict(
-    store: &StoreWrapper,
+    store: &Store,
     conflict: &Conflict,
-) -> Result<Option<TreeValue>, StoreError> {
+) -> Result<Option<TreeValue>, BackendError> {
     // Important cases to simplify:
     //
     // D
diff --git a/lib/src/tree_builder.rs b/lib/src/tree_builder.rs
index 342e09b5d..f0920deeb 100644
--- a/lib/src/tree_builder.rs
+++ b/lib/src/tree_builder.rs
@@ -15,10 +15,10 @@
 use std::collections::{BTreeMap, HashSet};
 use std::sync::Arc;
 
+use crate::backend;
+use crate::backend::{TreeId, TreeValue};
 use crate::repo_path::{RepoPath, RepoPathJoin};
-use crate::store;
-use crate::store::{TreeId, TreeValue};
-use crate::store_wrapper::StoreWrapper;
+use crate::store::Store;
 use crate::tree::Tree;
 
 #[derive(Debug)]
@@ -29,13 +29,13 @@ enum Override {
 
 #[derive(Debug)]
 pub struct TreeBuilder {
-    store: Arc<StoreWrapper>,
+    store: Arc<Store>,
     base_tree_id: TreeId,
     overrides: BTreeMap<RepoPath, Override>,
 }
 
 impl TreeBuilder {
-    pub fn new(store: Arc<StoreWrapper>, base_tree_id: TreeId) -> TreeBuilder {
+    pub fn new(store: Arc<Store>, base_tree_id: TreeId) -> TreeBuilder {
         let overrides = BTreeMap::new();
         TreeBuilder {
             store,
@@ -44,7 +44,7 @@ impl TreeBuilder {
         }
     }
 
-    pub fn repo(&self) -> &StoreWrapper {
+    pub fn repo(&self) -> &Store {
         self.store.as_ref()
     }
 
@@ -108,7 +108,7 @@ impl TreeBuilder {
         }
     }
 
-    fn get_base_trees(&mut self) -> BTreeMap<RepoPath, store::Tree> {
+    fn get_base_trees(&mut self) -> BTreeMap<RepoPath, backend::Tree> {
         let mut tree_cache = BTreeMap::new();
         let mut base_trees = BTreeMap::new();
         let store = self.store.clone();
diff --git a/lib/src/view.rs b/lib/src/view.rs
index f596c4e9b..a613202a2 100644
--- a/lib/src/view.rs
+++ b/lib/src/view.rs
@@ -14,11 +14,11 @@
 
 use std::collections::{BTreeMap, HashSet};
 
+use crate::backend::CommitId;
 use crate::index::IndexRef;
 use crate::op_store;
 use crate::op_store::{BranchTarget, RefTarget};
 use crate::refs::merge_ref_targets;
-use crate::store::CommitId;
 
 #[derive(PartialEq, Eq, Clone, Hash, Debug)]
 pub enum RefName {
diff --git a/lib/src/working_copy.rs b/lib/src/working_copy.rs
index f2337b9b3..9344aebf8 100644
--- a/lib/src/working_copy.rs
+++ b/lib/src/working_copy.rs
@@ -31,13 +31,15 @@ use protobuf::Message;
 use tempfile::NamedTempFile;
 use thiserror::Error;
 
+use crate::backend::{
+    BackendError, CommitId, FileId, MillisSinceEpoch, SymlinkId, TreeId, TreeValue,
+};
 use crate::commit::Commit;
 use crate::gitignore::GitIgnoreFile;
 use crate::lock::FileLock;
 use crate::matchers::EverythingMatcher;
 use crate::repo_path::{RepoPath, RepoPathComponent, RepoPathJoin};
-use crate::store::{CommitId, FileId, MillisSinceEpoch, StoreError, SymlinkId, TreeId, TreeValue};
-use crate::store_wrapper::StoreWrapper;
+use crate::store::Store;
 use crate::tree::Diff;
 
 #[derive(Debug, PartialEq, Eq, Clone)]
@@ -76,7 +78,7 @@ impl FileState {
 }
 
 pub struct TreeState {
-    store: Arc<StoreWrapper>,
+    store: Arc<Store>,
     working_copy_path: PathBuf,
     state_path: PathBuf,
     tree_id: TreeId,
@@ -146,7 +148,7 @@ pub enum CheckoutError {
     #[error("Concurrent checkout")]
     ConcurrentCheckout,
     #[error("Internal error: {0:?}")]
-    InternalStoreError(StoreError),
+    InternalBackendError(BackendError),
 }
 
 impl TreeState {
@@ -158,21 +160,13 @@ impl TreeState {
         &self.file_states
     }
 
-    pub fn init(
-        store: Arc<StoreWrapper>,
-        working_copy_path: PathBuf,
-        state_path: PathBuf,
-    ) -> TreeState {
+    pub fn init(store: Arc<Store>, working_copy_path: PathBuf, state_path: PathBuf) -> TreeState {
         let mut wc = TreeState::empty(store, working_copy_path, state_path);
         wc.save();
         wc
     }
 
-    fn empty(
-        store: Arc<StoreWrapper>,
-        working_copy_path: PathBuf,
-        state_path: PathBuf,
-    ) -> TreeState {
+    fn empty(store: Arc<Store>, working_copy_path: PathBuf, state_path: PathBuf) -> TreeState {
         let tree_id = store.empty_tree_id().clone();
         // Canonicalize the working copy path because "repo/." makes libgit2 think that
         // everything should be ignored
@@ -186,11 +180,7 @@ impl TreeState {
         }
     }
 
-    pub fn load(
-        store: Arc<StoreWrapper>,
-        working_copy_path: PathBuf,
-        state_path: PathBuf,
-    ) -> TreeState {
+    pub fn load(store: Arc<Store>, working_copy_path: PathBuf, state_path: PathBuf) -> TreeState {
         let maybe_file = File::open(state_path.join("tree_state"));
         let file = match maybe_file {
             Err(ref err) if err.kind() == std::io::ErrorKind::NotFound => {
@@ -481,15 +471,15 @@ impl TreeState {
             .store
             .get_tree(&RepoPath::root(), &self.tree_id)
             .map_err(|err| match err {
-                StoreError::NotFound => CheckoutError::SourceNotFound,
-                other => CheckoutError::InternalStoreError(other),
+                BackendError::NotFound => CheckoutError::SourceNotFound,
+                other => CheckoutError::InternalBackendError(other),
             })?;
         let new_tree =
             self.store
                 .get_tree(&RepoPath::root(), &tree_id)
                 .map_err(|err| match err {
-                    StoreError::NotFound => CheckoutError::TargetNotFound,
-                    other => CheckoutError::InternalStoreError(other),
+                    BackendError::NotFound => CheckoutError::TargetNotFound,
+                    other => CheckoutError::InternalBackendError(other),
                 })?;
 
         let mut stats = CheckoutStats {
@@ -587,7 +577,7 @@ impl TreeState {
 }
 
 pub struct WorkingCopy {
-    store: Arc<StoreWrapper>,
+    store: Arc<Store>,
     working_copy_path: PathBuf,
     state_path: PathBuf,
     commit_id: RefCell<Option<CommitId>>,
@@ -597,11 +587,7 @@ pub struct WorkingCopy {
 }
 
 impl WorkingCopy {
-    pub fn init(
-        store: Arc<StoreWrapper>,
-        working_copy_path: PathBuf,
-        state_path: PathBuf,
-    ) -> WorkingCopy {
+    pub fn init(store: Arc<Store>, working_copy_path: PathBuf, state_path: PathBuf) -> WorkingCopy {
         // Leave the commit_id empty so a subsequent call to check out the root revision
         // will have an effect.
         let proto = crate::protos::working_copy::Checkout::new();
@@ -621,11 +607,7 @@ impl WorkingCopy {
         }
     }
 
-    pub fn load(
-        store: Arc<StoreWrapper>,
-        working_copy_path: PathBuf,
-        state_path: PathBuf,
-    ) -> WorkingCopy {
+    pub fn load(store: Arc<Store>, working_copy_path: PathBuf, state_path: PathBuf) -> WorkingCopy {
         WorkingCopy {
             store,
             working_copy_path,
diff --git a/lib/tests/test_bad_locking.rs b/lib/tests/test_bad_locking.rs
index ae8c7c04e..5a04aed03 100644
--- a/lib/tests/test_bad_locking.rs
+++ b/lib/tests/test_bad_locking.rs
@@ -88,8 +88,8 @@ fn merge_directories(left: &Path, base: &Path, right: &Path, output: &Path) {
     }
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_bad_locking_children(use_git: bool) {
     // Test that two new commits created on separate machines are both visible (not
     // lost due to lack of locking)
@@ -139,8 +139,8 @@ fn test_bad_locking_children(use_git: bool) {
     assert_eq!(op.parents.len(), 2);
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_bad_locking_interrupted(use_git: bool) {
     // Test that an interrupted update of the op-heads resulting in on op-head
     // that's a descendant of the other is resolved without creating a new
diff --git a/lib/tests/test_commit_builder.rs b/lib/tests/test_commit_builder.rs
index 266daa7ee..9e6f84637 100644
--- a/lib/tests/test_commit_builder.rs
+++ b/lib/tests/test_commit_builder.rs
@@ -20,8 +20,8 @@ use jujutsu_lib::testutils;
 use jujutsu_lib::tree::DiffSummary;
 use test_case::test_case;
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_initial(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -64,8 +64,8 @@ fn test_initial(use_git: bool) {
     );
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_rewrite(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
diff --git a/lib/tests/test_commit_concurrent.rs b/lib/tests/test_commit_concurrent.rs
index e7e225033..30bb3fec6 100644
--- a/lib/tests/test_commit_concurrent.rs
+++ b/lib/tests/test_commit_concurrent.rs
@@ -36,8 +36,8 @@ fn count_non_merge_operations(repo: &ReadonlyRepo) -> usize {
     num_ops
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_commit_parallel(use_git: bool) {
     // This loads a Repo instance and creates and commits many concurrent
     // transactions from it. It then reloads the repo. That should merge all the
@@ -70,8 +70,8 @@ fn test_commit_parallel(use_git: bool) {
     assert_eq!(count_non_merge_operations(&repo), num_threads + 1);
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_commit_parallel_instances(use_git: bool) {
     // Like the test above but creates a new repo instance for every thread, which
     // makes it behave very similar to separate processes.
diff --git a/lib/tests/test_diff_summary.rs b/lib/tests/test_diff_summary.rs
index 7e8d671f2..ce6285737 100644
--- a/lib/tests/test_diff_summary.rs
+++ b/lib/tests/test_diff_summary.rs
@@ -19,8 +19,8 @@ use jujutsu_lib::tree::DiffSummary;
 use maplit::hashset;
 use test_case::test_case;
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_types(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -58,8 +58,8 @@ fn test_types(use_git: bool) {
     );
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_tree_file_transition(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -88,8 +88,8 @@ fn test_tree_file_transition(use_git: bool) {
     );
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_sorting(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -153,8 +153,8 @@ fn test_sorting(use_git: bool) {
     );
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_matcher_dir_file_transition(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -220,8 +220,8 @@ fn test_matcher_dir_file_transition(use_git: bool) {
     );
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_matcher_normal_cases(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
diff --git a/lib/tests/test_evolution.rs b/lib/tests/test_evolution.rs
index a29bc973e..3258495ef 100644
--- a/lib/tests/test_evolution.rs
+++ b/lib/tests/test_evolution.rs
@@ -33,8 +33,8 @@ fn child_commit(settings: &UserSettings, repo: &ReadonlyRepo, commit: &Commit) -
     testutils::create_random_commit(settings, repo).set_parents(vec![commit.id().clone()])
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_obsolete_and_orphan(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -80,8 +80,8 @@ fn test_obsolete_and_orphan(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_divergent(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -107,8 +107,8 @@ fn test_divergent(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_divergent_pruned(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -134,8 +134,8 @@ fn test_divergent_pruned(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_divergent_duplicate(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -163,8 +163,8 @@ fn test_divergent_duplicate(use_git: bool) {
 
 // TODO: Create a #[repo_test] proc macro that injects the `settings` and `repo`
 // variables into the test function
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_new_parent_rewritten(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -187,8 +187,8 @@ fn test_new_parent_rewritten(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_new_parent_cherry_picked(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -210,8 +210,8 @@ fn test_new_parent_cherry_picked(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_new_parent_is_pruned(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -237,8 +237,8 @@ fn test_new_parent_is_pruned(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_new_parent_divergent(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -275,8 +275,8 @@ fn test_new_parent_divergent(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_new_parent_divergent_one_not_pruned(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -319,8 +319,8 @@ fn test_new_parent_divergent_one_not_pruned(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_new_parent_divergent_all_pruned(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -365,8 +365,8 @@ fn test_new_parent_divergent_all_pruned(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_new_parent_split(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -398,8 +398,8 @@ fn test_new_parent_split(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_new_parent_split_pruned_descendant(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -435,8 +435,8 @@ fn test_new_parent_split_pruned_descendant(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_new_parent_split_forked(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -474,8 +474,8 @@ fn test_new_parent_split_forked(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_new_parent_split_forked_pruned(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -511,8 +511,8 @@ fn test_new_parent_split_forked_pruned(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 fn test_evolve_orphan(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -554,8 +554,8 @@ fn test_evolve_orphan(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 /// When evolving a merge commit, the new commit should not have a parent that
 /// is an ancestor of another parent.
 fn test_evolve_orphan_merge_ancestor_of_other_parent(use_git: bool) {
@@ -589,8 +589,8 @@ fn test_evolve_orphan_merge_ancestor_of_other_parent(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_evolve_pruned_orphan(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -625,8 +625,8 @@ fn test_evolve_pruned_orphan(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 fn test_evolve_multiple_orphans(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -679,8 +679,8 @@ fn test_evolve_multiple_orphans(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 fn test_evolve_divergent(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
diff --git a/lib/tests/test_git.rs b/lib/tests/test_git.rs
index 4be0f9cc9..9246e50b5 100644
--- a/lib/tests/test_git.rs
+++ b/lib/tests/test_git.rs
@@ -16,12 +16,12 @@ use std::path::PathBuf;
 use std::sync::Arc;
 
 use git2::Oid;
+use jujutsu_lib::backend::CommitId;
 use jujutsu_lib::commit::Commit;
 use jujutsu_lib::git::{GitFetchError, GitPushError, GitRefUpdate};
 use jujutsu_lib::op_store::{BranchTarget, RefTarget};
 use jujutsu_lib::repo::ReadonlyRepo;
 use jujutsu_lib::settings::UserSettings;
-use jujutsu_lib::store::CommitId;
 use jujutsu_lib::testutils::create_random_commit;
 use jujutsu_lib::{git, testutils};
 use maplit::{btreemap, hashset};
diff --git a/lib/tests/test_index.rs b/lib/tests/test_index.rs
index cae5b5009..be287aba6 100644
--- a/lib/tests/test_index.rs
+++ b/lib/tests/test_index.rs
@@ -14,12 +14,12 @@
 
 use std::sync::Arc;
 
+use jujutsu_lib::backend::CommitId;
 use jujutsu_lib::commit::Commit;
 use jujutsu_lib::commit_builder::CommitBuilder;
 use jujutsu_lib::index::IndexRef;
 use jujutsu_lib::repo::ReadonlyRepo;
 use jujutsu_lib::settings::UserSettings;
-use jujutsu_lib::store::CommitId;
 use jujutsu_lib::testutils;
 use jujutsu_lib::testutils::{create_random_commit, CommitGraphBuilder};
 use test_case::test_case;
@@ -38,8 +38,8 @@ fn generation_number<'a>(index: impl Into<IndexRef<'a>>, commit_id: &CommitId) -
         .generation_number()
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_index_commits_empty_repo(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -62,8 +62,8 @@ fn test_index_commits_empty_repo(use_git: bool) {
     );
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_index_commits_standard_cases(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -132,8 +132,8 @@ fn test_index_commits_standard_cases(use_git: bool) {
     assert!(index.is_ancestor(commit_a.id(), commit_h.id()));
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_index_commits_criss_cross(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -231,8 +231,8 @@ fn test_index_commits_criss_cross(use_git: bool) {
     );
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_index_commits_previous_operations(use_git: bool) {
     // Test that commits visible only in previous operations are indexed.
     let settings = testutils::user_settings();
@@ -284,8 +284,8 @@ fn test_index_commits_previous_operations(use_git: bool) {
     assert_eq!(generation_number(index.as_ref(), commit_c.id()), 3);
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_index_commits_incremental(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, mut repo) = testutils::init_repo(&settings, use_git);
@@ -333,8 +333,8 @@ fn test_index_commits_incremental(use_git: bool) {
     assert_eq!(generation_number(index.as_ref(), commit_c.id()), 3);
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_index_commits_incremental_empty_transaction(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, mut repo) = testutils::init_repo(&settings, use_git);
@@ -375,8 +375,8 @@ fn test_index_commits_incremental_empty_transaction(use_git: bool) {
     assert_eq!(generation_number(index.as_ref(), commit_a.id()), 1);
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_index_commits_incremental_already_indexed(use_git: bool) {
     // Tests that trying to add a commit that's already been added is a no-op.
     let settings = testutils::user_settings();
@@ -424,8 +424,8 @@ fn commits_by_level(repo: &ReadonlyRepo) -> Vec<u32> {
         .collect()
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_index_commits_incremental_squashed(use_git: bool) {
     let settings = testutils::user_settings();
 
diff --git a/lib/tests/test_init.rs b/lib/tests/test_init.rs
index 897e067cb..234f3a742 100644
--- a/lib/tests/test_init.rs
+++ b/lib/tests/test_init.rs
@@ -68,8 +68,8 @@ fn test_init_external_git() {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_init_no_config_set(use_git: bool) {
     // Test that we can create a repo without setting any config
     let settings = UserSettings::from_config(config::Config::new());
@@ -90,8 +90,8 @@ fn test_init_no_config_set(use_git: bool) {
     );
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_init_checkout(use_git: bool) {
     // Test the contents of the checkout after init
     let settings = testutils::user_settings();
diff --git a/lib/tests/test_load_repo.rs b/lib/tests/test_load_repo.rs
index 44636a81f..953a9ccb5 100644
--- a/lib/tests/test_load_repo.rs
+++ b/lib/tests/test_load_repo.rs
@@ -26,8 +26,8 @@ fn test_load_bad_path() {
     assert_eq!(result.err(), Some(RepoLoadError::NoRepoHere(wc_path)));
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_load_from_subdir(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -41,8 +41,8 @@ fn test_load_from_subdir(use_git: bool) {
     assert_eq!(same_repo.working_copy_path(), repo.working_copy_path());
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_load_at_operation(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
diff --git a/lib/tests/test_merge_trees.rs b/lib/tests/test_merge_trees.rs
index 7999233b4..8f3c78c77 100644
--- a/lib/tests/test_merge_trees.rs
+++ b/lib/tests/test_merge_trees.rs
@@ -13,14 +13,14 @@
 // limitations under the License.
 
 use itertools::Itertools;
+use jujutsu_lib::backend::{ConflictPart, TreeValue};
 use jujutsu_lib::repo_path::{RepoPath, RepoPathComponent};
-use jujutsu_lib::store::{ConflictPart, TreeValue};
 use jujutsu_lib::tree::Tree;
 use jujutsu_lib::{testutils, tree};
 use test_case::test_case;
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_same_type(use_git: bool) {
     // Tests all possible cases where the entry type is unchanged, specifically
     // using only normal files in all trees (no symlinks, no trees, etc.).
@@ -219,8 +219,8 @@ fn test_same_type(use_git: bool) {
     };
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_subtrees(use_git: bool) {
     // Tests that subtrees are merged.
 
@@ -275,8 +275,8 @@ fn test_subtrees(use_git: bool) {
     assert_eq!(entries, expected_entries);
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_subtree_becomes_empty(use_git: bool) {
     // Tests that subtrees that become empty are removed from the parent tree.
 
@@ -306,8 +306,8 @@ fn test_subtree_becomes_empty(use_git: bool) {
     assert_eq!(merged_tree.id(), store.empty_tree_id());
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_types(use_git: bool) {
     // Tests conflicts between different types. This is mostly to test that the
     // conflicts survive the roundtrip to the store.
@@ -433,8 +433,8 @@ fn test_types(use_git: bool) {
     };
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_simplify_conflict(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
diff --git a/lib/tests/test_mut_repo.rs b/lib/tests/test_mut_repo.rs
index babe8d6b5..f827503c8 100644
--- a/lib/tests/test_mut_repo.rs
+++ b/lib/tests/test_mut_repo.rs
@@ -14,11 +14,11 @@
 
 use std::sync::Arc;
 
+use jujutsu_lib::backend::{Conflict, ConflictId, ConflictPart, TreeValue};
 use jujutsu_lib::commit_builder::CommitBuilder;
 use jujutsu_lib::op_store::RefTarget;
 use jujutsu_lib::repo_path::RepoPath;
-use jujutsu_lib::store::{Conflict, ConflictId, ConflictPart, TreeValue};
-use jujutsu_lib::store_wrapper::StoreWrapper;
+use jujutsu_lib::store::Store;
 use jujutsu_lib::testutils;
 use jujutsu_lib::testutils::CommitGraphBuilder;
 use test_case::test_case;
@@ -26,8 +26,8 @@ use test_case::test_case;
 // TODO Many of the tests here are not run with Git because they end up creating
 // two commits with the same contents.
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 fn test_checkout_open(use_git: bool) {
     // Test that MutableRepo::check_out() uses the requested commit if it's open
     let settings = testutils::user_settings();
@@ -46,8 +46,8 @@ fn test_checkout_open(use_git: bool) {
     assert_eq!(repo.view().checkout(), actual_checkout.id());
 }
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 fn test_checkout_closed(use_git: bool) {
     // Test that MutableRepo::check_out() creates a child if the requested commit is
     // closed
@@ -69,8 +69,8 @@ fn test_checkout_closed(use_git: bool) {
     assert_eq!(repo.view().checkout(), actual_checkout.id());
 }
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 fn test_checkout_open_with_conflict(use_git: bool) {
     // Test that MutableRepo::check_out() creates a child if the requested
     // commit is open and has conflicts
@@ -108,8 +108,8 @@ fn test_checkout_open_with_conflict(use_git: bool) {
     assert_eq!(repo.view().checkout(), actual_checkout.id());
 }
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 fn test_checkout_closed_with_conflict(use_git: bool) {
     // Test that MutableRepo::check_out() creates a child if the requested commit is
     // closed and has conflicts
@@ -147,7 +147,7 @@ fn test_checkout_closed_with_conflict(use_git: bool) {
     assert_eq!(repo.view().checkout(), actual_checkout.id());
 }
 
-fn write_conflict(store: &Arc<StoreWrapper>, file_path: &RepoPath) -> ConflictId {
+fn write_conflict(store: &Arc<Store>, file_path: &RepoPath) -> ConflictId {
     let file_id1 = testutils::write_file(store, file_path, "a\n");
     let file_id2 = testutils::write_file(store, file_path, "b\n");
     let file_id3 = testutils::write_file(store, file_path, "c\n");
@@ -176,8 +176,8 @@ fn write_conflict(store: &Arc<StoreWrapper>, file_path: &RepoPath) -> ConflictId
     store.write_conflict(&conflict).unwrap()
 }
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 fn test_checkout_previous_not_empty(use_git: bool) {
     // Test that MutableRepo::check_out() does not usually prune the previous
     // commit.
@@ -202,8 +202,8 @@ fn test_checkout_previous_not_empty(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 fn test_checkout_previous_empty(use_git: bool) {
     // Test that MutableRepo::check_out() prunes the previous commit if it was
     // empty.
@@ -232,8 +232,8 @@ fn test_checkout_previous_empty(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 fn test_checkout_previous_empty_and_obsolete(use_git: bool) {
     // Test that MutableRepo::check_out() does not unnecessarily prune the previous
     // commit if it was empty but already obsolete.
@@ -266,8 +266,8 @@ fn test_checkout_previous_empty_and_obsolete(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 fn test_checkout_previous_empty_and_pruned(use_git: bool) {
     // Test that MutableRepo::check_out() does not unnecessarily prune the previous
     // commit if it was empty but already obsolete.
@@ -296,8 +296,8 @@ fn test_checkout_previous_empty_and_pruned(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 fn test_add_head_success(use_git: bool) {
     // Test that MutableRepo::add_head() adds the head, and that it's still there
     // after commit. It should also be indexed.
@@ -330,8 +330,8 @@ fn test_add_head_success(use_git: bool) {
     assert_eq!(index_stats.max_generation_number, 1);
 }
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 fn test_add_head_ancestor(use_git: bool) {
     // Test that MutableRepo::add_head() does not add a head if it's an ancestor of
     // an existing head.
@@ -360,8 +360,8 @@ fn test_add_head_ancestor(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 fn test_add_head_not_immediate_child(use_git: bool) {
     // Test that MutableRepo::add_head() can be used for adding a head that is not
     // an immediate child of a current head.
@@ -405,8 +405,8 @@ fn test_add_head_not_immediate_child(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 fn test_remove_head(use_git: bool) {
     // Test that MutableRepo::remove_head() removes the head, and that it's still
     // removed after commit. It should remain in the index, since we otherwise would
@@ -446,8 +446,8 @@ fn test_remove_head(use_git: bool) {
     assert!(repo.index().has_id(commit3.id()));
 }
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 fn test_remove_head_ancestor_git_ref(use_git: bool) {
     // Test that MutableRepo::remove_head() does not leave the view with a git ref
     // pointing to a commit that's not reachable by any head.
@@ -490,8 +490,8 @@ fn test_remove_head_ancestor_git_ref(use_git: bool) {
     assert!(!heads.contains(commit1.id()));
 }
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 fn test_add_public_head(use_git: bool) {
     // Test that MutableRepo::add_public_head() adds the head, and that it's still
     // there after commit.
@@ -511,8 +511,8 @@ fn test_add_public_head(use_git: bool) {
     assert!(repo.view().public_heads().contains(commit1.id()));
 }
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 fn test_add_public_head_ancestor(use_git: bool) {
     // Test that MutableRepo::add_public_head() does not add a public head if it's
     // an ancestor of an existing public head.
@@ -535,8 +535,8 @@ fn test_add_public_head_ancestor(use_git: bool) {
     assert!(!repo.view().public_heads().contains(commit1.id()));
 }
 
-#[test_case(false ; "local store")]
-// #[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+// #[test_case(true ; "git backend")]
 fn test_remove_public_head(use_git: bool) {
     // Test that MutableRepo::remove_public_head() removes the head, and that it's
     // still removed after commit.
diff --git a/lib/tests/test_operations.rs b/lib/tests/test_operations.rs
index 9d9ea38b0..ae4147d7c 100644
--- a/lib/tests/test_operations.rs
+++ b/lib/tests/test_operations.rs
@@ -14,9 +14,9 @@
 
 use std::path::Path;
 
+use jujutsu_lib::backend::CommitId;
 use jujutsu_lib::commit_builder::CommitBuilder;
 use jujutsu_lib::repo::RepoRef;
-use jujutsu_lib::store::CommitId;
 use jujutsu_lib::testutils;
 use test_case::test_case;
 
@@ -27,8 +27,8 @@ fn list_dir(dir: &Path) -> Vec<String> {
         .collect()
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_unpublished_operation(use_git: bool) {
     // Test that the operation doesn't get published until that's requested.
     let settings = testutils::user_settings();
@@ -48,8 +48,8 @@ fn test_unpublished_operation(use_git: bool) {
     assert_eq!(list_dir(&op_heads_dir), vec![op_id1.hex()]);
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_consecutive_operations(use_git: bool) {
     // Test that consecutive operations result in a single op-head on disk after
     // each operation
@@ -80,8 +80,8 @@ fn test_consecutive_operations(use_git: bool) {
     assert_eq!(list_dir(&op_heads_dir), vec![op_id2.hex()]);
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_concurrent_operations(use_git: bool) {
     // Test that consecutive operations result in multiple op-heads on disk until
     // the repo has been reloaded (which currently happens right away).
@@ -125,8 +125,8 @@ fn assert_heads(repo: RepoRef, expected: Vec<&CommitId>) {
     assert_eq!(*repo.view().heads(), expected);
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_isolation(use_git: bool) {
     // Test that two concurrent transactions don't see each other's changes.
     let settings = testutils::user_settings();
diff --git a/lib/tests/test_revset.rs b/lib/tests/test_revset.rs
index c916a74a1..74418bbae 100644
--- a/lib/tests/test_revset.rs
+++ b/lib/tests/test_revset.rs
@@ -12,17 +12,17 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+use jujutsu_lib::backend::{CommitId, MillisSinceEpoch, Signature, Timestamp};
 use jujutsu_lib::commit_builder::CommitBuilder;
 use jujutsu_lib::op_store::RefTarget;
 use jujutsu_lib::repo::RepoRef;
 use jujutsu_lib::revset::{parse, resolve_symbol, RevsetError};
-use jujutsu_lib::store::{CommitId, MillisSinceEpoch, Signature, Timestamp};
 use jujutsu_lib::testutils::CommitGraphBuilder;
 use jujutsu_lib::{git, testutils};
 use test_case::test_case;
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_resolve_symbol_root(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -232,8 +232,8 @@ fn test_resolve_symbol_change_id() {
     );
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_resolve_symbol_checkout(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -391,8 +391,8 @@ fn resolve_commit_ids(repo: RepoRef, revset_str: &str) -> Vec<CommitId> {
         .collect()
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_evaluate_expression_root_and_checkout(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -419,8 +419,8 @@ fn test_evaluate_expression_root_and_checkout(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_evaluate_expression_parents(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -481,8 +481,8 @@ fn test_evaluate_expression_parents(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_evaluate_expression_children(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -548,8 +548,8 @@ fn test_evaluate_expression_children(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_evaluate_expression_ancestors(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -585,8 +585,8 @@ fn test_evaluate_expression_ancestors(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_evaluate_expression_range(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -649,8 +649,8 @@ fn test_evaluate_expression_range(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_evaluate_expression_dag_range(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -724,8 +724,8 @@ fn test_evaluate_expression_dag_range(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_evaluate_expression_descendants(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -782,8 +782,8 @@ fn test_evaluate_expression_descendants(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_evaluate_expression_all_heads(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -803,8 +803,8 @@ fn test_evaluate_expression_all_heads(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_evaluate_expression_public_heads(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -837,8 +837,8 @@ fn test_evaluate_expression_public_heads(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_evaluate_expression_git_refs(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -907,8 +907,8 @@ fn test_evaluate_expression_git_refs(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_evaluate_expression_obsolete(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -954,8 +954,8 @@ fn test_evaluate_expression_obsolete(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_evaluate_expression_merges(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -986,8 +986,8 @@ fn test_evaluate_expression_merges(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_evaluate_expression_description(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -1033,8 +1033,8 @@ fn test_evaluate_expression_description(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_evaluate_expression_union(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -1107,8 +1107,8 @@ fn test_evaluate_expression_union(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_evaluate_expression_intersection(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -1148,8 +1148,8 @@ fn test_evaluate_expression_intersection(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_evaluate_expression_difference(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
diff --git a/lib/tests/test_rewrite.rs b/lib/tests/test_rewrite.rs
index f3d3741e5..5773c0e7b 100644
--- a/lib/tests/test_rewrite.rs
+++ b/lib/tests/test_rewrite.rs
@@ -19,8 +19,8 @@ use jujutsu_lib::testutils;
 use jujutsu_lib::testutils::CommitGraphBuilder;
 use test_case::test_case;
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_rebase_descendants_sideways(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -74,8 +74,8 @@ fn test_rebase_descendants_sideways(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_rebase_descendants_forward(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -115,8 +115,8 @@ fn test_rebase_descendants_forward(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_rebase_descendants_backward(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -153,8 +153,8 @@ fn test_rebase_descendants_backward(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_rebase_descendants_internal_merge(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -212,8 +212,8 @@ fn test_rebase_descendants_internal_merge(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_rebase_descendants_external_merge(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -260,8 +260,8 @@ fn test_rebase_descendants_external_merge(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_rebase_descendants_degenerate_merge(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -300,8 +300,8 @@ fn test_rebase_descendants_degenerate_merge(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_rebase_descendants_widen_merge(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -351,8 +351,8 @@ fn test_rebase_descendants_widen_merge(use_git: bool) {
     tx.discard();
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_rebase_descendants_contents(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
diff --git a/lib/tests/test_view.rs b/lib/tests/test_view.rs
index 64c380c18..c171faee3 100644
--- a/lib/tests/test_view.rs
+++ b/lib/tests/test_view.rs
@@ -18,8 +18,8 @@ use jujutsu_lib::testutils::CommitGraphBuilder;
 use maplit::{btreemap, hashset};
 use test_case::test_case;
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_heads_empty(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -32,8 +32,8 @@ fn test_heads_empty(use_git: bool) {
     );
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_heads_fork(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
@@ -56,8 +56,8 @@ fn test_heads_fork(use_git: bool) {
     );
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_heads_merge(use_git: bool) {
     let settings = testutils::user_settings();
     let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
diff --git a/lib/tests/test_working_copy.rs b/lib/tests/test_working_copy.rs
index 08d651175..cf10227fe 100644
--- a/lib/tests/test_working_copy.rs
+++ b/lib/tests/test_working_copy.rs
@@ -19,17 +19,17 @@ use std::os::unix::fs::PermissionsExt;
 use std::sync::Arc;
 
 use itertools::Itertools;
+use jujutsu_lib::backend::TreeValue;
 use jujutsu_lib::commit_builder::CommitBuilder;
 use jujutsu_lib::repo::ReadonlyRepo;
 use jujutsu_lib::repo_path::{RepoPath, RepoPathComponent};
 use jujutsu_lib::settings::UserSettings;
-use jujutsu_lib::store::TreeValue;
 use jujutsu_lib::testutils;
 use jujutsu_lib::tree_builder::TreeBuilder;
 use test_case::test_case;
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_root(use_git: bool) {
     // Test that the working copy is clean and empty after init.
     let settings = testutils::user_settings();
@@ -45,8 +45,8 @@ fn test_root(use_git: bool) {
     assert_eq!(&new_tree_id, repo.store().empty_tree_id());
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_checkout_file_transitions(use_git: bool) {
     // Tests switching between commits where a certain path is of one type in one
     // commit and another type in the other. Includes a "missing" type, so we cover
@@ -234,8 +234,8 @@ fn test_checkout_file_transitions(use_git: bool) {
     }
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_commit_racy_timestamps(use_git: bool) {
     // Tests that file modifications are detected even if they happen the same
     // millisecond as the updated working copy state.
@@ -265,8 +265,8 @@ fn test_commit_racy_timestamps(use_git: bool) {
     }
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_gitignores(use_git: bool) {
     // Tests that .gitignore files are respected.
 
@@ -335,8 +335,8 @@ fn test_gitignores(use_git: bool) {
     );
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_gitignores_checkout_overwrites_ignored(use_git: bool) {
     // Tests that a .gitignore'd file gets overwritten if check out a commit where
     // the file is tracked.
@@ -391,8 +391,8 @@ fn test_gitignores_checkout_overwrites_ignored(use_git: bool) {
         .is_some());
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_gitignores_ignored_directory_already_tracked(use_git: bool) {
     // Tests that a .gitignore'd directory that already has a tracked file in it
     // does not get removed when committing the working directory.
@@ -435,8 +435,8 @@ fn test_gitignores_ignored_directory_already_tracked(use_git: bool) {
     assert!(new_tree.path_value(&file_path).is_some());
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_dotgit_ignored(use_git: bool) {
     // Tests that .git directories and files are always ignored (we could accept
     // them if the backend is not git).
diff --git a/lib/tests/test_working_copy_concurrent.rs b/lib/tests/test_working_copy_concurrent.rs
index b19c2aa36..5716e98cc 100644
--- a/lib/tests/test_working_copy_concurrent.rs
+++ b/lib/tests/test_working_copy_concurrent.rs
@@ -23,8 +23,8 @@ use jujutsu_lib::testutils;
 use jujutsu_lib::working_copy::CheckoutError;
 use test_case::test_case;
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_concurrent_checkout(use_git: bool) {
     // Test that we error out if a concurrent checkout is detected (i.e. if the
     // current checkout changed on disk after we read it).
@@ -68,8 +68,8 @@ fn test_concurrent_checkout(use_git: bool) {
     );
 }
 
-#[test_case(false ; "local store")]
-#[test_case(true ; "git store")]
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
 fn test_checkout_parallel(use_git: bool) {
     // Test that concurrent checkouts by different processes (simulated by using
     // different repo instances) is safe.
diff --git a/src/commands.rs b/src/commands.rs
index 0a774addb..71efbfdbb 100644
--- a/src/commands.rs
+++ b/src/commands.rs
@@ -31,6 +31,7 @@ use std::{fs, io};
 use clap::{crate_version, App, Arg, ArgMatches, SubCommand};
 use criterion::Criterion;
 use itertools::Itertools;
+use jujutsu_lib::backend::{BackendError, CommitId, Timestamp, TreeValue};
 use jujutsu_lib::commit::Commit;
 use jujutsu_lib::commit_builder::CommitBuilder;
 use jujutsu_lib::dag_walk::topo_order_reverse;
@@ -53,8 +54,7 @@ use jujutsu_lib::revset::{RevsetError, RevsetExpression, RevsetParseError};
 use jujutsu_lib::revset_graph_iterator::RevsetGraphEdgeType;
 use jujutsu_lib::rewrite::{back_out_commit, merge_commit_trees, rebase_commit, DescendantRebaser};
 use jujutsu_lib::settings::UserSettings;
-use jujutsu_lib::store::{CommitId, StoreError, Timestamp, TreeValue};
-use jujutsu_lib::store_wrapper::StoreWrapper;
+use jujutsu_lib::store::Store;
 use jujutsu_lib::transaction::Transaction;
 use jujutsu_lib::tree::{Diff, DiffSummary};
 use jujutsu_lib::working_copy::{CheckoutStats, WorkingCopy};
@@ -87,8 +87,8 @@ impl From<std::io::Error> for CommandError {
     }
 }
 
-impl From<StoreError> for CommandError {
-    fn from(err: StoreError) -> Self {
+impl From<BackendError> for CommandError {
+    fn from(err: BackendError) -> Self {
         CommandError::UserError(format!("Unexpected error from store: {}", err))
     }
 }
@@ -3205,7 +3205,7 @@ fn cmd_operation(
     Ok(())
 }
 
-fn get_git_repo(store: &StoreWrapper) -> Result<git2::Repository, CommandError> {
+fn get_git_repo(store: &Store) -> Result<git2::Repository, CommandError> {
     match store.git_repo() {
         None => Err(CommandError::UserError(
             "The repo is not backed by a git repo".to_string(),
diff --git a/src/diff_edit.rs b/src/diff_edit.rs
index 928930f4e..046cb3f71 100644
--- a/src/diff_edit.rs
+++ b/src/diff_edit.rs
@@ -18,10 +18,10 @@ use std::path::{Path, PathBuf};
 use std::process::Command;
 use std::sync::Arc;
 
+use jujutsu_lib::backend::{BackendError, TreeId, TreeValue};
 use jujutsu_lib::matchers::EverythingMatcher;
 use jujutsu_lib::repo_path::RepoPath;
-use jujutsu_lib::store::{StoreError, TreeId, TreeValue};
-use jujutsu_lib::store_wrapper::StoreWrapper;
+use jujutsu_lib::store::Store;
 use jujutsu_lib::tree::{merge_trees, Tree};
 use jujutsu_lib::tree_builder::TreeBuilder;
 use jujutsu_lib::working_copy::{CheckoutError, TreeState};
@@ -37,7 +37,7 @@ pub enum DiffEditError {
     #[error("Failed to write directories to diff: {0:?}")]
     CheckoutError(CheckoutError),
     #[error("Internal error: {0:?}")]
-    InternalStoreError(StoreError),
+    InternalBackendError(BackendError),
 }
 
 impl From<CheckoutError> for DiffEditError {
@@ -46,18 +46,18 @@ impl From<CheckoutError> for DiffEditError {
     }
 }
 
-impl From<StoreError> for DiffEditError {
-    fn from(err: StoreError) -> Self {
-        DiffEditError::InternalStoreError(err)
+impl From<BackendError> for DiffEditError {
+    fn from(err: BackendError) -> Self {
+        DiffEditError::InternalBackendError(err)
     }
 }
 
 fn add_to_tree(
-    store: &StoreWrapper,
+    store: &Store,
     tree_builder: &mut TreeBuilder,
     repo_path: &RepoPath,
     value: &TreeValue,
-) -> Result<(), StoreError> {
+) -> Result<(), BackendError> {
     match value {
         TreeValue::Conflict(conflict_id) => {
             let conflict = store.read_conflict(conflict_id)?;
@@ -73,7 +73,7 @@ fn add_to_tree(
 }
 
 fn check_out(
-    store: Arc<StoreWrapper>,
+    store: Arc<Store>,
     wc_dir: PathBuf,
     state_dir: PathBuf,
     tree_id: TreeId,
diff --git a/src/template_parser.rs b/src/template_parser.rs
index f24b59d66..39d5be1d4 100644
--- a/src/template_parser.rs
+++ b/src/template_parser.rs
@@ -15,9 +15,9 @@
 extern crate pest;
 
 use chrono::{FixedOffset, TimeZone, Utc};
+use jujutsu_lib::backend::{CommitId, Signature};
 use jujutsu_lib::commit::Commit;
 use jujutsu_lib::repo::RepoRef;
-use jujutsu_lib::store::{CommitId, Signature};
 use pest::iterators::{Pair, Pairs};
 use pest::Parser;
 
diff --git a/src/templater.rs b/src/templater.rs
index 9d19ec738..8e54920f7 100644
--- a/src/templater.rs
+++ b/src/templater.rs
@@ -17,9 +17,9 @@ use std::io;
 use std::ops::Add;
 
 use itertools::Itertools;
+use jujutsu_lib::backend::{CommitId, Signature};
 use jujutsu_lib::commit::Commit;
 use jujutsu_lib::repo::RepoRef;
-use jujutsu_lib::store::{CommitId, Signature};
 
 use crate::formatter::Formatter;