diff --git a/cli/src/commit_ref_list.rs b/cli/src/commit_ref_list.rs
index 9408f1d8e30..d2932c48501 100644
--- a/cli/src/commit_ref_list.rs
+++ b/cli/src/commit_ref_list.rs
@@ -313,9 +313,9 @@ mod tests {
         Arc::new(backend::Commit {
             parents: vec![],
             predecessors: vec![],
-            root_tree: Merge::resolved(TreeId::new(vec![])),
+            root_tree: Merge::resolved(TreeId::from_vec(vec![])),
             conflict_labels: Merge::resolved(String::new()),
-            change_id: ChangeId::new(vec![]),
+            change_id: ChangeId::from_vec(vec![]),
             description: String::new(),
             author,
             committer,
@@ -335,7 +335,7 @@ mod tests {
     }
 
     fn commit_id_generator() -> impl FnMut() -> CommitId {
-        let mut iter = (1_u128..).map(|n| CommitId::new(n.to_le_bytes().into()));
+        let mut iter = (1_u128..).map(|n| CommitId::from_vec(n.to_le_bytes().into()));
         move || iter.next().unwrap()
     }
 
diff --git a/lib/src/backend.rs b/lib/src/backend.rs
index 16bfd5e7c79..9e4933781d3 100644
--- a/lib/src/backend.rs
+++ b/lib/src/backend.rs
@@ -74,7 +74,7 @@ id_type!(
 impl ChangeId {
     /// Parses the given "reverse" hex string into a `ChangeId`.
     pub fn try_from_reverse_hex(hex: impl AsRef<[u8]>) -> Option<Self> {
-        hex_util::decode_reverse_hex(hex).map(Self)
+        hex_util::decode_reverse_hex(hex).map(Self::from_vec)
     }
 
     /// Returns the hex string representation of this ID, which uses `z-k`
@@ -89,7 +89,7 @@ impl CopyId {
     /// id yet.
     // TODO: Delete this
     pub fn placeholder() -> Self {
-        Self::new(vec![])
+        Self::from_vec(vec![])
     }
 }
 
diff --git a/lib/src/content_hash.rs b/lib/src/content_hash.rs
index ddacc23ce6a..132675eb342 100644
--- a/lib/src/content_hash.rs
+++ b/lib/src/content_hash.rs
@@ -104,6 +104,12 @@ impl<T: ContentHash> ContentHash for Vec<T> {
     }
 }
 
+impl<T: ContentHash + ?Sized> ContentHash for Box<T> {
+    fn hash(&self, state: &mut impl DigestUpdate) {
+        (**self).hash(state);
+    }
+}
+
 impl ContentHash for str {
     fn hash(&self, state: &mut impl DigestUpdate) {
         self.as_bytes().hash(state);
diff --git a/lib/src/default_index/bit_set.rs b/lib/src/default_index/bit_set.rs
index 17b86c30169..b284989eaf8 100644
--- a/lib/src/default_index/bit_set.rs
+++ b/lib/src/default_index/bit_set.rs
@@ -211,13 +211,13 @@ mod tests {
 
     /// Generator of unique 16-byte CommitId excluding root id
     fn commit_id_generator() -> impl FnMut() -> CommitId {
-        let mut iter = (1_u128..).map(|n| CommitId::new(n.to_le_bytes().into()));
+        let mut iter = (1_u128..).map(|n| CommitId::from_vec(n.to_le_bytes().into()));
         move || iter.next().unwrap()
     }
 
     /// Generator of unique 16-byte ChangeId excluding root id
     fn change_id_generator() -> impl FnMut() -> ChangeId {
-        let mut iter = (1_u128..).map(|n| ChangeId::new(n.to_le_bytes().into()));
+        let mut iter = (1_u128..).map(|n| ChangeId::from_vec(n.to_le_bytes().into()));
         move || iter.next().unwrap()
     }
 
diff --git a/lib/src/default_index/mod.rs b/lib/src/default_index/mod.rs
index 0c15ac80562..790b29112f5 100644
--- a/lib/src/default_index/mod.rs
+++ b/lib/src/default_index/mod.rs
@@ -89,13 +89,13 @@ mod tests {
 
     /// Generator of unique 16-byte CommitId excluding root id
     fn commit_id_generator() -> impl FnMut() -> CommitId {
-        let mut iter = (1_u128..).map(|n| CommitId::new(n.to_le_bytes().into()));
+        let mut iter = (1_u128..).map(|n| CommitId::from_vec(n.to_le_bytes().into()));
         move || iter.next().unwrap()
     }
 
     /// Generator of unique 16-byte ChangeId excluding root id
     fn change_id_generator() -> impl FnMut() -> ChangeId {
-        let mut iter = (1_u128..).map(|n| ChangeId::new(n.to_le_bytes().into()));
+        let mut iter = (1_u128..).map(|n| ChangeId::from_vec(n.to_le_bytes().into()));
         move || iter.next().unwrap()
     }
 
diff --git a/lib/src/default_index/rev_walk.rs b/lib/src/default_index/rev_walk.rs
index 584f02dceaa..c75d46861f1 100644
--- a/lib/src/default_index/rev_walk.rs
+++ b/lib/src/default_index/rev_walk.rs
@@ -704,7 +704,7 @@ mod tests {
 
     /// Generator of unique 16-byte ChangeId excluding root id
     fn change_id_generator() -> impl FnMut() -> ChangeId {
-        let mut iter = (1_u128..).map(|n| ChangeId::new(n.to_le_bytes().into()));
+        let mut iter = (1_u128..).map(|n| ChangeId::from_vec(n.to_le_bytes().into()));
         move || iter.next().unwrap()
     }
 
diff --git a/lib/src/default_index/revset_engine.rs b/lib/src/default_index/revset_engine.rs
index 041e22bd735..f38b1677a59 100644
--- a/lib/src/default_index/revset_engine.rs
+++ b/lib/src/default_index/revset_engine.rs
@@ -1593,7 +1593,7 @@ mod tests {
 
     /// Generator of unique 16-byte ChangeId excluding root id
     fn change_id_generator() -> impl FnMut() -> ChangeId {
-        let mut iter = (1_u128..).map(|n| ChangeId::new(n.to_le_bytes().into()));
+        let mut iter = (1_u128..).map(|n| ChangeId::from_vec(n.to_le_bytes().into()));
         move || iter.next().unwrap()
     }
 
diff --git a/lib/src/default_index/store.rs b/lib/src/default_index/store.rs
index 07796c112ad..aee4d367fea 100644
--- a/lib/src/default_index/store.rs
+++ b/lib/src/default_index/store.rs
@@ -192,14 +192,14 @@ impl DefaultIndexStore {
             .map_err(|err| io::Error::new(io::ErrorKind::InvalidData, err))
             .context(&op_link_file)
             .map_err(DefaultIndexStoreError::LoadAssociation)?;
-        let commit_segment_id = CommitIndexSegmentId::new(proto.commit_segment_id);
+        let commit_segment_id = CommitIndexSegmentId::from_vec(proto.commit_segment_id);
         let changed_path_start_commit_pos = proto
             .changed_path_start_commit_pos
             .map(GlobalCommitPosition);
         let changed_path_segment_ids = proto
             .changed_path_segment_ids
             .into_iter()
-            .map(ChangedPathIndexSegmentId::new)
+            .map(ChangedPathIndexSegmentId::from_vec)
             .collect_vec();
 
         let commits = ReadonlyCommitIndexSegment::load(
diff --git a/lib/src/git_backend.rs b/lib/src/git_backend.rs
index d37b3200a32..8d6178f217e 100644
--- a/lib/src/git_backend.rs
+++ b/lib/src/git_backend.rs
@@ -729,7 +729,7 @@ pub fn synthetic_change_id_from_git_commit_id(id: &CommitId) -> ChangeId {
         .rev()
         .map(|b| b.reverse_bits())
         .collect();
-    ChangeId::new(bytes)
+    ChangeId::from_vec(bytes)
 }
 
 const EMPTY_STRING_PLACEHOLDER: &str = "JJ_EMPTY_STRING";
@@ -798,7 +798,7 @@ fn serialize_extras(commit: &Commit) -> Vec<u8> {
 fn deserialize_extras(commit: &mut Commit, bytes: &[u8]) {
     let proto = crate::protos::git_store::Commit::decode(bytes).unwrap();
     if !proto.change_id.is_empty() {
-        commit.change_id = ChangeId::new(proto.change_id);
+        commit.change_id = ChangeId::from_vec(proto.change_id);
     }
     if commit.root_tree.is_resolved()
         && proto.uses_tree_conflict_format
@@ -1074,7 +1074,7 @@ impl Backend for GitBackend {
         contents.read_to_end(&mut bytes).await.unwrap();
 
         let oid = self.write_blob(&bytes, "file")?;
-        Ok(FileId::new(oid.as_bytes().to_vec()))
+        Ok(FileId::from_vec(oid.as_bytes().to_vec()))
     }
 
     async fn read_symlink(&self, _path: &RepoPath, id: &SymlinkId) -> BackendResult<String> {
@@ -1092,7 +1092,7 @@ impl Backend for GitBackend {
 
     async fn write_symlink(&self, _path: &RepoPath, target: &str) -> BackendResult<SymlinkId> {
         let oid = self.write_blob(target.as_bytes(), "symlink")?;
-        Ok(SymlinkId::new(oid.as_bytes().to_vec()))
+        Ok(SymlinkId::from_vec(oid.as_bytes().to_vec()))
     }
 
     async fn read_copy(&self, _id: &CopyId) -> BackendResult<CopyHistory> {
@@ -2296,7 +2296,7 @@ mod tests {
             predecessors: vec![],
             root_tree: Merge::resolved(backend.empty_tree_id().clone()),
             conflict_labels: Merge::resolved(String::new()),
-            change_id: ChangeId::new(vec![42; 16]),
+            change_id: ChangeId::from_vec(vec![42; 16]),
             description: "initial".to_string(),
             author: signature.clone(),
             committer: signature,
@@ -2469,7 +2469,7 @@ mod tests {
             predecessors: vec![],
             root_tree: Merge::resolved(backend.empty_tree_id().clone()),
             conflict_labels: Merge::resolved(String::new()),
-            change_id: ChangeId::new(vec![42; 16]),
+            change_id: ChangeId::from_vec(vec![42; 16]),
             description: "initial".to_string(),
             author: create_signature(),
             committer: create_signature(),
diff --git a/lib/src/local_working_copy.rs b/lib/src/local_working_copy.rs
index 6b3896dc239..ff0037bbe9f 100644
--- a/lib/src/local_working_copy.rs
+++ b/lib/src/local_working_copy.rs
@@ -1154,13 +1154,13 @@ impl TreeState {
         if proto.tree_ids.is_empty() {
             self.tree = MergedTree::resolved(
                 self.store.clone(),
-                TreeId::new(proto.legacy_tree_id.clone()),
+                TreeId::from_vec(proto.legacy_tree_id.clone()),
             );
         } else {
             let tree_ids_builder: MergeBuilder<TreeId> = proto
                 .tree_ids
                 .iter()
-                .map(|id| TreeId::new(id.clone()))
+                .map(|id| TreeId::from_vec(id.clone()))
                 .collect();
             self.tree = MergedTree::new(
                 self.store.clone(),
@@ -2575,7 +2575,7 @@ impl CheckoutState {
         let proto = crate::protos::local_working_copy::Checkout::decode(&*buf)
             .map_err(|err| wrap_err(err.into()))?;
         Ok(Self {
-            operation_id: OperationId::new(proto.operation_id),
+            operation_id: OperationId::from_vec(proto.operation_id),
             workspace_name: if proto.workspace_name.is_empty() {
                 // For compatibility with old working copies.
                 // TODO: Delete in mid 2022 or so
diff --git a/lib/src/object_id.rs b/lib/src/object_id.rs
index 24e513e257b..b546290d9d5 100644
--- a/lib/src/object_id.rs
+++ b/lib/src/object_id.rs
@@ -27,9 +27,9 @@ pub trait ObjectId {
 }
 
 // Defines a new struct type with visibility `vis` and name `ident` containing
-// a single Vec<u8> used to store an identifier (typically the output of a hash
-// function) as bytes. Types defined using this macro automatically implement
-// the `ObjectId` and `ContentHash` traits.
+// a single Box<[u8]> used to store an identifier (typically the output of a
+// hash function) as bytes. Types defined using this macro automatically
+// implement the `ObjectId` and `ContentHash` traits.
 // Documentation comments written inside the macro definition will be captured
 // and associated with the type defined by the macro.
 //
@@ -46,7 +46,7 @@ macro_rules! id_type {
     ) => {
         $(#[$attr])*
         #[derive($crate::content_hash::ContentHash, PartialEq, Eq, PartialOrd, Ord, Clone, Hash)]
-        $vis struct $name(Vec<u8>);
+        $vis struct $name(Box<[u8]>);
         $crate::object_id::impl_id_type!($name, $hex_method);
     };
 }
@@ -56,13 +56,13 @@ macro_rules! impl_id_type {
         #[allow(dead_code)]
         impl $name {
             /// Creates a new instance of this id type from the given bytes.
-            pub fn new(value: Vec<u8>) -> Self {
-                Self(value)
+            pub fn from_vec(value: Vec<u8>) -> Self {
+                Self(value.into())
             }
 
             /// Creates a new instance of this id type from the given byte slice.
             pub fn from_bytes(bytes: &[u8]) -> Self {
-                Self(bytes.to_vec())
+                Self(bytes.into())
             }
 
             /// Parses the given hex string into an ObjectId.
@@ -75,7 +75,7 @@ macro_rules! impl_id_type {
 
             /// Parses the given hex string into an ObjectId.
             pub fn try_from_hex(hex: impl AsRef<[u8]>) -> Option<Self> {
-                $crate::hex_util::decode_hex(hex).map(Self)
+                $crate::hex_util::decode_hex(hex).map(Self::from_vec)
             }
         }
 
@@ -119,7 +119,7 @@ macro_rules! impl_id_type {
             }
 
             fn to_bytes(&self) -> Vec<u8> {
-                self.0.clone()
+                self.0.to_vec()
             }
 
             fn hex(&self) -> String {
diff --git a/lib/src/rewrite.rs b/lib/src/rewrite.rs
index a94d7571932..e486b97afae 100644
--- a/lib/src/rewrite.rs
+++ b/lib/src/rewrite.rs
@@ -125,7 +125,7 @@ pub fn find_recursive_merge_commits(
         }
 
         fn merge_next(&mut self, ancestor: Merge<CommitId>) {
-            let dummy = Merge::resolved(CommitId::new(vec![]));
+            let dummy = Merge::resolved(CommitId::from_vec(vec![]));
             let result = mem::replace(&mut self.result, dummy);
             let other = Merge::resolved(self.commit_ids[self.pos].clone());
             self.result = Merge::from_vec(vec![result, ancestor, other]).flatten();
diff --git a/lib/src/settings.rs b/lib/src/settings.rs
index 1e35a892ba8..ac4dfacaf23 100644
--- a/lib/src/settings.rs
+++ b/lib/src/settings.rs
@@ -301,7 +301,7 @@ impl JJRng {
     pub fn new_change_id(&self, length: usize) -> ChangeId {
         let mut rng = self.0.lock().unwrap();
         let random_bytes = (0..length).map(|_| rng.random::<u8>()).collect();
-        ChangeId::new(random_bytes)
+        ChangeId::from_vec(random_bytes)
     }
 
     /// Creates a new RNGs. Could be made public, but we'd like to encourage all
diff --git a/lib/src/simple_backend.rs b/lib/src/simple_backend.rs
index c2767691446..30da9bd3427 100644
--- a/lib/src/simple_backend.rs
+++ b/lib/src/simple_backend.rs
@@ -217,7 +217,7 @@ impl Backend for SimpleBackend {
             hasher.update(bytes);
         }
         file.flush().map_err(to_other_err)?;
-        let id = FileId::new(hasher.finalize().to_vec());
+        let id = FileId::from_vec(hasher.finalize().to_vec());
 
         persist_content_addressed_temp_file(temp_file, self.file_path(&id))
             .map_err(to_other_err)?;
@@ -238,7 +238,7 @@ impl Backend for SimpleBackend {
             .map_err(to_other_err)?;
         let mut hasher = Blake2b512::new();
         hasher.update(target.as_bytes());
-        let id = SymlinkId::new(hasher.finalize().to_vec());
+        let id = SymlinkId::from_vec(hasher.finalize().to_vec());
 
         persist_content_addressed_temp_file(temp_file, self.symlink_path(&id))
             .map_err(to_other_err)?;
@@ -281,7 +281,7 @@ impl Backend for SimpleBackend {
             .write_all(&proto.encode_to_vec())
             .map_err(to_other_err)?;
 
-        let id = TreeId::new(blake2b_hash(tree).to_vec());
+        let id = TreeId::from_vec(blake2b_hash(tree).to_vec());
 
         persist_content_addressed_temp_file(temp_file, self.tree_path(&id))
             .map_err(to_other_err)?;
@@ -331,7 +331,7 @@ impl Backend for SimpleBackend {
             .write_all(&proto.encode_to_vec())
             .map_err(to_other_err)?;
 
-        let id = CommitId::new(blake2b_hash(&commit).to_vec());
+        let id = CommitId::from_vec(blake2b_hash(&commit).to_vec());
 
         persist_content_addressed_temp_file(temp_file, self.commit_path(&id))
             .map_err(to_other_err)?;
@@ -380,12 +380,17 @@ fn commit_from_proto(mut proto: crate::protos::simple_store::Commit) -> Commit {
         sig,
     });
 
-    let parents = proto.parents.into_iter().map(CommitId::new).collect();
-    let predecessors = proto.predecessors.into_iter().map(CommitId::new).collect();
-    let merge_builder: MergeBuilder<_> = proto.root_tree.into_iter().map(TreeId::new).collect();
+    let parents = proto.parents.into_iter().map(CommitId::from_vec).collect();
+    let predecessors = proto
+        .predecessors
+        .into_iter()
+        .map(CommitId::from_vec)
+        .collect();
+    let merge_builder: MergeBuilder<_> =
+        proto.root_tree.into_iter().map(TreeId::from_vec).collect();
     let root_tree = merge_builder.build();
     let conflict_labels = ConflictLabels::from_vec(proto.conflict_labels);
-    let change_id = ChangeId::new(proto.change_id);
+    let change_id = ChangeId::from_vec(proto.change_id);
     Commit {
         parents,
         predecessors,
@@ -461,7 +466,7 @@ fn tree_value_to_proto(value: &TreeValue) -> crate::protos::simple_store::TreeVa
 fn tree_value_from_proto(proto: crate::protos::simple_store::TreeValue) -> TreeValue {
     match proto.value.unwrap() {
         crate::protos::simple_store::tree_value::Value::TreeId(id) => {
-            TreeValue::Tree(TreeId::new(id))
+            TreeValue::Tree(TreeId::from_vec(id))
         }
         crate::protos::simple_store::tree_value::Value::File(
             crate::protos::simple_store::tree_value::File {
@@ -470,12 +475,12 @@ fn tree_value_from_proto(proto: crate::protos::simple_store::TreeValue) -> TreeV
                 copy_id,
             },
         ) => TreeValue::File {
-            id: FileId::new(id),
+            id: FileId::from_vec(id),
             executable,
-            copy_id: CopyId::new(copy_id),
+            copy_id: CopyId::from_vec(copy_id),
         },
         crate::protos::simple_store::tree_value::Value::SymlinkId(id) => {
-            TreeValue::Symlink(SymlinkId::new(id))
+            TreeValue::Symlink(SymlinkId::from_vec(id))
         }
     }
 }
diff --git a/lib/src/simple_op_heads_store.rs b/lib/src/simple_op_heads_store.rs
index 560236de6aa..3b1e16a25c7 100644
--- a/lib/src/simple_op_heads_store.rs
+++ b/lib/src/simple_op_heads_store.rs
@@ -148,7 +148,7 @@ impl OpHeadsStore for SimpleOpHeadsStore {
                 )
             })?;
             if let Some(op_head) = hex_util::decode_hex(op_head_file_name) {
-                op_heads.push(OperationId::new(op_head));
+                op_heads.push(OperationId::from_vec(op_head));
             }
         }
         op_heads.sort();
diff --git a/lib/src/simple_op_store.rs b/lib/src/simple_op_store.rs
index 3dfaece4951..490108bc80f 100644
--- a/lib/src/simple_op_store.rs
+++ b/lib/src/simple_op_store.rs
@@ -174,7 +174,7 @@ impl OpStore for SimpleOpStore {
             .context(temp_file.path())
             .map_err(|err| io_to_write_error(err, "view"))?;
 
-        let id = ViewId::new(blake2b_hash(view).to_vec());
+        let id = ViewId::from_vec(blake2b_hash(view).to_vec());
 
         let new_path = dir.join(id.hex());
         persist_content_addressed_temp_file(temp_file, &new_path)
@@ -219,7 +219,7 @@ impl OpStore for SimpleOpStore {
             .context(temp_file.path())
             .map_err(|err| io_to_write_error(err, "operation"))?;
 
-        let id = OperationId::new(blake2b_hash(operation).to_vec());
+        let id = OperationId::from_vec(blake2b_hash(operation).to_vec());
 
         let new_path = dir.join(id.hex());
         persist_content_addressed_temp_file(temp_file, &new_path)
@@ -408,7 +408,7 @@ fn operation_id_from_proto(bytes: Vec<u8>) -> Result<OperationId, PostDecodeErro
             actual: bytes.len(),
         })
     } else {
-        Ok(OperationId::new(bytes))
+        Ok(OperationId::from_vec(bytes))
     }
 }
 
@@ -419,7 +419,7 @@ fn view_id_from_proto(bytes: Vec<u8>) -> Result<ViewId, PostDecodeError> {
             actual: bytes.len(),
         })
     } else {
-        Ok(ViewId::new(bytes))
+        Ok(ViewId::from_vec(bytes))
     }
 }
 
@@ -494,11 +494,11 @@ fn commit_predecessors_map_from_proto(
     proto
         .into_iter()
         .map(|entry| {
-            let commit_id = CommitId::new(entry.commit_id);
+            let commit_id = CommitId::from_vec(entry.commit_id);
             let predecessor_ids = entry
                 .predecessor_ids
                 .into_iter()
-                .map(CommitId::new)
+                .map(CommitId::from_vec)
                 .collect();
             (commit_id, predecessor_ids)
         })
@@ -602,13 +602,13 @@ fn view_from_proto(proto: crate::protos::simple_op_store::View) -> Result<View,
     if !proto.wc_commit_id.is_empty() {
         wc_commit_ids.insert(
             WorkspaceName::DEFAULT.to_owned(),
-            CommitId::new(proto.wc_commit_id),
+            CommitId::from_vec(proto.wc_commit_id),
         );
     }
     for (name, commit_id) in proto.wc_commit_ids {
-        wc_commit_ids.insert(WorkspaceNameBuf::from(name), CommitId::new(commit_id));
+        wc_commit_ids.insert(WorkspaceNameBuf::from(name), CommitId::from_vec(commit_id));
     }
-    let head_ids = proto.head_ids.into_iter().map(CommitId::new).collect();
+    let head_ids = proto.head_ids.into_iter().map(CommitId::from_vec).collect();
 
     let (local_bookmarks, mut remote_views) = bookmark_views_from_proto_legacy(proto.bookmarks)?;
 
@@ -631,7 +631,7 @@ fn view_from_proto(proto: crate::protos::simple_op_store::View) -> Result<View,
             } else {
                 // Legacy format
                 #[expect(deprecated)]
-                RefTarget::normal(CommitId::new(git_ref.commit_id))
+                RefTarget::normal(CommitId::from_vec(git_ref.commit_id))
             };
             (name, target)
         })
@@ -671,7 +671,7 @@ fn view_from_proto(proto: crate::protos::simple_op_store::View) -> Result<View,
     let git_head = if proto.git_head.is_some() {
         ref_target_from_proto(proto.git_head)
     } else if !proto.git_head_legacy.is_empty() {
-        RefTarget::normal(CommitId::new(proto.git_head_legacy))
+        RefTarget::normal(CommitId::from_vec(proto.git_head_legacy))
     } else {
         RefTarget::absent()
     };
@@ -832,7 +832,9 @@ fn ref_target_from_terms_proto(
 ) -> Result<RefTarget, PostDecodeError> {
     let terms: SmallVec<[_; 1]> = proto
         .into_iter()
-        .map(|crate::protos::simple_op_store::RefTargetTerm { value }| value.map(CommitId::new))
+        .map(|crate::protos::simple_op_store::RefTargetTerm { value }| {
+            value.map(CommitId::from_vec)
+        })
         .collect();
     if terms.len().is_multiple_of(2) {
         Err(PostDecodeError::EvenNumberOfRefTargetTerms(terms.len()))
@@ -903,18 +905,18 @@ fn ref_target_from_proto(
         #[expect(deprecated)]
         crate::protos::simple_op_store::ref_target::Value::CommitId(id) => {
             // Legacy non-conflicting id
-            RefTarget::normal(CommitId::new(id))
+            RefTarget::normal(CommitId::from_vec(id))
         }
         #[expect(deprecated)]
         crate::protos::simple_op_store::ref_target::Value::ConflictLegacy(conflict) => {
             // Legacy conflicting ids
-            let removes = conflict.removes.into_iter().map(CommitId::new);
-            let adds = conflict.adds.into_iter().map(CommitId::new);
+            let removes = conflict.removes.into_iter().map(CommitId::from_vec);
+            let adds = conflict.adds.into_iter().map(CommitId::from_vec);
             RefTarget::from_legacy_form(removes, adds)
         }
         crate::protos::simple_op_store::ref_target::Value::Conflict(conflict) => {
             let term_from_proto = |term: crate::protos::simple_op_store::ref_conflict::Term| {
-                term.value.map(CommitId::new)
+                term.value.map(CommitId::from_vec)
             };
             let removes = conflict.removes.into_iter().map(term_from_proto);
             let adds = conflict.adds.into_iter().map(term_from_proto);
@@ -1017,10 +1019,10 @@ mod tests {
             bytes
         };
         Operation {
-            view_id: ViewId::new(pad_id_bytes("aaa111", VIEW_ID_LENGTH)),
+            view_id: ViewId::from_vec(pad_id_bytes("aaa111", VIEW_ID_LENGTH)),
             parents: vec![
-                OperationId::new(pad_id_bytes("bbb111", OPERATION_ID_LENGTH)),
-                OperationId::new(pad_id_bytes("bbb222", OPERATION_ID_LENGTH)),
+                OperationId::from_vec(pad_id_bytes("bbb111", OPERATION_ID_LENGTH)),
+                OperationId::from_vec(pad_id_bytes("bbb222", OPERATION_ID_LENGTH)),
             ],
             metadata: OperationMetadata {
                 time: TimestampRange {
@@ -1057,7 +1059,7 @@ mod tests {
     fn test_hash_view() {
         // Test exact output so we detect regressions in compatibility
         assert_snapshot!(
-            ViewId::new(blake2b_hash(&create_view()).to_vec()).hex(),
+            ViewId::from_vec(blake2b_hash(&create_view()).to_vec()).hex(),
             @"2c0b174d117ca85e7faa96f6d997362403105e8eb31e7f82ac9abd3dc48ae62683e9a76ef5d117ebc8a743d17e1945236df9ccefd7574f7e4b5336a63796b967"
         );
     }
@@ -1066,7 +1068,7 @@ mod tests {
     fn test_hash_operation() {
         // Test exact output so we detect regressions in compatibility
         assert_snapshot!(
-            OperationId::new(blake2b_hash(&create_operation()).to_vec()).hex(),
+            OperationId::from_vec(blake2b_hash(&create_operation()).to_vec()).hex(),
             @"f5963c593a63bb852061a86ad919c12c6ba1940eeef30a832524c39ccea6a9f768aa2aa53becec34d379eb291ec6726837c4113857849cb9dcc62dbe0a517176"
         );
     }
diff --git a/lib/tests/test_commit_builder.rs b/lib/tests/test_commit_builder.rs
index a2f50703c18..52d1bb27d31 100644
--- a/lib/tests/test_commit_builder.rs
+++ b/lib/tests/test_commit_builder.rs
@@ -103,7 +103,7 @@ fn test_initial(backend: TestRepoBackend) -> TestResult {
             tz_offset: -60,
         },
     };
-    let change_id = ChangeId::new(vec![100u8; 16]);
+    let change_id = ChangeId::from_vec(vec![100u8; 16]);
     let builder = tx
         .repo_mut()
         .new_commit(vec![store.root_commit_id().clone()], tree.clone())
diff --git a/lib/tests/test_converge.rs b/lib/tests/test_converge.rs
index aa0bda10384..36a02c00955 100644
--- a/lib/tests/test_converge.rs
+++ b/lib/tests/test_converge.rs
@@ -60,7 +60,7 @@ use testutils::write_random_commit;
 use testutils::write_random_commit_with_parents;
 
 fn make_change_id(repo: &TestRepo, byte: u8) -> ChangeId {
-    ChangeId::new(vec![byte; repo.repo.store().change_id_length()])
+    ChangeId::from_vec(vec![byte; repo.repo.store().change_id_length()])
 }
 
 fn get_merged_tree_value(tree: &MergedTree, path: &str) -> TestResult<Option<TreeValue>> {
diff --git a/lib/tests/test_local_working_copy.rs b/lib/tests/test_local_working_copy.rs
index a689d6eef90..72d1b35c5d5 100644
--- a/lib/tests/test_local_working_copy.rs
+++ b/lib/tests/test_local_working_copy.rs
@@ -1875,7 +1875,7 @@ fn test_git_submodule(gitignore_content: &str) -> TestResult {
         Merge::normal(TreeValue::File {
             id: testutils::write_file(repo.store(), added_path, "added\n"),
             executable: false,
-            copy_id: CopyId::new(vec![]),
+            copy_id: CopyId::from_vec(vec![]),
         }),
     );
 
@@ -1909,7 +1909,7 @@ fn test_git_submodule(gitignore_content: &str) -> TestResult {
                 "file with same path as submodule\n",
             ),
             executable: false,
-            copy_id: CopyId::new(vec![]),
+            copy_id: CopyId::from_vec(vec![]),
         }),
     );
     let tree_id3 = tree_builder.write_tree().block_on()?;
diff --git a/lib/tests/test_merged_tree.rs b/lib/tests/test_merged_tree.rs
index aab711847d4..fcf8de68a14 100644
--- a/lib/tests/test_merged_tree.rs
+++ b/lib/tests/test_merged_tree.rs
@@ -739,9 +739,9 @@ fn create_copy_records(paths: &[(&RepoPath, &RepoPath)]) -> CopyRecords {
     copy_records.add_records(paths.iter().map(|&(source, target)| CopyRecord {
         source: source.to_owned(),
         target: target.to_owned(),
-        target_commit: CommitId::new(vec![]),
-        source_commit: CommitId::new(vec![]),
-        source_file: FileId::new(vec![]),
+        target_commit: CommitId::from_vec(vec![]),
+        source_commit: CommitId::from_vec(vec![]),
+        source_file: FileId::from_vec(vec![]),
     }));
     copy_records
 }
diff --git a/lib/tests/test_rewrite.rs b/lib/tests/test_rewrite.rs
index 7cdaff97a71..28192ca0791 100644
--- a/lib/tests/test_rewrite.rs
+++ b/lib/tests/test_rewrite.rs
@@ -2427,7 +2427,7 @@ fn test_find_duplicate_divergent_commits() -> TestResult {
     let mut make_commit = |change_id_byte, tree, parents| {
         tx.repo_mut()
             .new_commit(parents, tree)
-            .set_change_id(ChangeId::new(vec![
+            .set_change_id(ChangeId::from_vec(vec![
                 change_id_byte;
                 store.change_id_length()
             ]))
diff --git a/lib/testutils/src/test_backend.rs b/lib/testutils/src/test_backend.rs
index 87bb36bc30e..6d468c9fa8a 100644
--- a/lib/testutils/src/test_backend.rs
+++ b/lib/testutils/src/test_backend.rs
@@ -131,7 +131,7 @@ impl TestBackend {
     pub fn with_data(data: Arc<Mutex<TestBackendData>>) -> Self {
         let root_commit_id = CommitId::from_bytes(&[0; HASH_LENGTH]);
         let root_change_id = ChangeId::from_bytes(&[0; CHANGE_ID_LENGTH]);
-        let empty_tree_id = TreeId::new(get_hash(&Tree::default()));
+        let empty_tree_id = TreeId::from_vec(get_hash(&Tree::default()));
         let runtime = Runtime::new().unwrap();
 
         Self {
@@ -237,7 +237,7 @@ impl Backend for TestBackend {
         let mut bytes = Vec::new();
         contents.read_to_end(&mut bytes).await.unwrap();
         self.run_async(move |mut data| {
-            let id = FileId::new(get_hash(&bytes));
+            let id = FileId::from_vec(get_hash(&bytes));
             data.files
                 .entry(path.clone())
                 .or_default()
@@ -269,7 +269,7 @@ impl Backend for TestBackend {
     }
 
     async fn write_symlink(&self, path: &RepoPath, target: &str) -> BackendResult<SymlinkId> {
-        let id = SymlinkId::new(get_hash(target.as_bytes()));
+        let id = SymlinkId::from_vec(get_hash(target.as_bytes()));
         let path = path.to_owned();
         let target = target.to_owned();
         self.run_async(move |mut data| {
@@ -302,7 +302,7 @@ impl Backend for TestBackend {
     async fn write_copy(&self, contents: &CopyHistory) -> BackendResult<CopyId> {
         let contents = contents.clone();
         self.run_async(move |mut data| {
-            let id = CopyId::new(get_hash(&contents));
+            let id = CopyId::from_vec(get_hash(&contents));
             data.copies.insert(id.clone(), contents);
             Ok(id)
         })
@@ -369,7 +369,7 @@ impl Backend for TestBackend {
         let path = path.to_owned();
         let contents = contents.clone();
         self.run_async(move |mut data| {
-            let id = TreeId::new(get_hash(&contents));
+            let id = TreeId::from_vec(get_hash(&contents));
             data.trees
                 .entry(path.clone())
                 .or_default()
@@ -412,7 +412,7 @@ impl Backend for TestBackend {
         }
 
         self.run_async(move |mut data| {
-            let id = CommitId::new(get_hash(&contents));
+            let id = CommitId::from_vec(get_hash(&contents));
             data.commits.insert(id.clone(), contents.clone());
             Ok((id, contents))
         })