diff --git a/node/src/crypto.rs b/node/src/crypto.rs
index 6210edad..4fb83744 100644
--- a/node/src/crypto.rs
+++ b/node/src/crypto.rs
@@ -48,7 +48,7 @@ where
 }
 
 /// Cryptographic signature.
-#[derive(PartialEq, Eq, Debug, Copy, Clone)]
+#[derive(PartialEq, Eq, Copy, Clone)]
 pub struct Signature(pub ed25519::Signature);
 
 impl fmt::Display for Signature {
@@ -58,6 +58,12 @@ impl fmt::Display for Signature {
     }
 }
 
+impl fmt::Debug for Signature {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "Signature({})", self)
+    }
+}
+
 #[derive(Error, Debug)]
 pub enum SignatureError {
     #[error("invalid multibase string: {0}")]
@@ -106,7 +112,7 @@ impl TryFrom<&[u8]> for Signature {
 }
 
 /// The public/verification key.
-#[derive(Serialize, Deserialize, Eq, Debug, Copy, Clone)]
+#[derive(Serialize, Deserialize, Eq, Copy, Clone)]
 #[serde(into = "String", try_from = "String")]
 pub struct PublicKey(pub ed25519::VerificationKey);
 
@@ -141,6 +147,12 @@ impl From<PublicKey> for String {
     }
 }
 
+impl fmt::Debug for PublicKey {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "PublicKey({})", self)
+    }
+}
+
 impl PartialEq for PublicKey {
     fn eq(&self, other: &Self) -> bool {
         self.0 == other.0
diff --git a/node/src/git.rs b/node/src/git.rs
index 6abed468..b38c560f 100644
--- a/node/src/git.rs
+++ b/node/src/git.rs
@@ -4,7 +4,7 @@ use std::str::FromStr;
 use git_ref_format as format;
 
 use crate::collections::HashMap;
-use crate::identity::PublicKey;
+use crate::crypto::PublicKey;
 use crate::storage::refs::Refs;
 use crate::storage::RemoteId;
 
@@ -123,6 +123,22 @@ pub fn head(repo: &git2::Repository) -> Result<git2::Commit, git2::Error> {
     Ok(head)
 }
 
+/// Write a tree with the given blob at the given path.
+pub fn write_tree<'r>(
+    path: &Path,
+    bytes: &[u8],
+    repo: &'r git2::Repository,
+) -> Result<git2::Tree<'r>, Error> {
+    let blob_id = repo.blob(bytes)?;
+    let mut builder = repo.treebuilder(None)?;
+    builder.insert(path, blob_id, 0o100_644)?;
+
+    let tree_id = builder.write()?;
+    let tree = repo.find_tree(tree_id)?;
+
+    Ok(tree)
+}
+
 /// Configure a repository's radicle remote.
 ///
 /// Takes the repository in which to configure the remote, the name of the remote, the public
diff --git a/node/src/identity.rs b/node/src/identity.rs
index 521a6962..6d9f0bb4 100644
--- a/node/src/identity.rs
+++ b/node/src/identity.rs
@@ -7,7 +7,8 @@ use std::{ffi::OsString, fmt, str::FromStr};
 use serde::{Deserialize, Serialize};
 use thiserror::Error;
 
-use crate::crypto::{self, Verified};
+use crate::crypto;
+use crate::crypto::Verified;
 use crate::git;
 use crate::serde_ext;
 use crate::storage::Remotes;
@@ -114,7 +115,7 @@ pub enum DidError {
     PublicKey(#[from] crypto::PublicKeyError),
 }
 
-#[derive(Serialize, Deserialize, PartialEq, Eq, Hash, Debug, Clone)]
+#[derive(Serialize, Deserialize, PartialEq, Eq, Hash, Clone)]
 #[serde(into = "String", try_from = "String")]
 pub struct Did(crypto::PublicKey);
 
@@ -160,6 +161,20 @@ impl fmt::Display for Did {
     }
 }
 
+impl fmt::Debug for Did {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "Did({:?})", self.to_string())
+    }
+}
+
+impl Deref for Did {
+    type Target = PublicKey;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
 /// A stored and verified project.
 #[derive(Debug, Clone)]
 pub struct Project {
@@ -173,6 +188,23 @@ pub struct Project {
     pub path: PathBuf,
 }
 
+impl Project {
+    pub fn delegate(&mut self, name: String, key: crypto::PublicKey) -> bool {
+        self.doc.delegate(Delegate {
+            name,
+            id: Did::from(key),
+        })
+    }
+}
+
+impl Deref for Project {
+    type Target = Doc<Verified>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.doc
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::*;
diff --git a/node/src/identity/doc.rs b/node/src/identity/doc.rs
index 7e7f73ad..75073919 100644
--- a/node/src/identity/doc.rs
+++ b/node/src/identity/doc.rs
@@ -1,6 +1,8 @@
-use std::collections::HashMap;
+use std::collections::{BTreeMap, HashMap};
+use std::fmt::Write as _;
 use std::io;
 use std::marker::PhantomData;
+use std::ops::Deref;
 use std::path::Path;
 
 use nonempty::NonEmpty;
@@ -14,7 +16,7 @@ use crate::crypto::{Signature, Unverified, Verified};
 use crate::git;
 use crate::identity::{Did, Id};
 use crate::storage::git::trailers;
-use crate::storage::{BranchName, ReadRepository, RemoteId};
+use crate::storage::{BranchName, ReadRepository, RemoteId, WriteRepository, WriteStorage};
 
 pub use crypto::PublicKey;
 
@@ -65,12 +67,23 @@ impl From<Delegate> for PublicKey {
 
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "kebab-case")]
-pub struct Doc<V> {
+pub struct Payload {
     pub name: String,
     pub description: String,    // TODO: Make optional.
     pub default_branch: String, // TODO: Make optional.
-    pub version: u32,           // TODO: Remove this.
-    pub parent: Option<Oid>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
+#[serde(transparent)]
+// TODO: Restrict values.
+pub struct Namespace(String);
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct Doc<V> {
+    #[serde(rename = "xyz.radicle.project")]
+    pub payload: Payload,
+    #[serde(flatten)]
+    pub extensions: BTreeMap<Namespace, serde_json::Value>,
     pub delegates: NonEmpty<Delegate>,
     pub threshold: usize,
 
@@ -78,17 +91,100 @@ pub struct Doc<V> {
 }
 
 impl Doc<Verified> {
-    pub fn encode(&self) -> Result<(Id, Vec<u8>), Error> {
+    pub fn encode(&self) -> Result<(git::Oid, Vec<u8>), Error> {
         let mut buf = Vec::new();
         let mut serializer =
             serde_json::Serializer::with_formatter(&mut buf, olpc_cjson::CanonicalFormatter::new());
 
         self.serialize(&mut serializer)?;
-
         let oid = git2::Oid::hash_object(git2::ObjectType::Blob, &buf)?;
-        let id = Id::from(oid);
 
-        Ok((id, buf))
+        Ok((oid.into(), buf))
+    }
+
+    /// Attempt to add a new delegate to the document. Returns `true` if it wasn't there before.
+    pub fn delegate(&mut self, delegate: Delegate) -> bool {
+        if self.delegates.iter().all(|d| d.id != delegate.id) {
+            self.delegates.push(delegate);
+            return true;
+        }
+        false
+    }
+
+    pub fn sign<G: crypto::Signer>(&self, signer: G) -> Result<(git::Oid, Signature), Error> {
+        let (oid, bytes) = self.encode()?;
+        let sig = signer.sign(&bytes);
+
+        Ok((oid, sig))
+    }
+
+    pub fn create<'r, S: WriteStorage<'r>>(
+        &self,
+        remote: &RemoteId,
+        msg: &str,
+        storage: &'r S,
+    ) -> Result<(Id, git::Oid, S::Repository), Error> {
+        // You can checkout this branch in your working copy with:
+        //
+        //      git fetch rad
+        //      git checkout -b radicle/id remotes/rad/radicle/id
+        //
+        let (doc_oid, doc) = self.encode()?;
+        let id = Id::from(doc_oid);
+        let repo = storage.repository(&id).unwrap();
+        let tree = git::write_tree(*PATH, doc.as_slice(), repo.raw())?;
+        let oid = Doc::commit(remote, &tree, msg, &[], repo.raw())?;
+
+        drop(tree);
+
+        Ok((id, oid, repo))
+    }
+
+    pub fn update<'r, R: WriteRepository<'r>>(
+        &self,
+        remote: &RemoteId,
+        msg: &str,
+        signatures: &[(&PublicKey, Signature)],
+        repo: &R,
+    ) -> Result<git::Oid, Error> {
+        let mut msg = format!("{msg}\n\n");
+        for (key, sig) in signatures {
+            writeln!(&mut msg, "{}: {key} {sig}", trailers::SIGNATURE_TRAILER)
+                .expect("in-memory writes don't fail");
+        }
+
+        let (_, doc) = self.encode()?;
+        let tree = git::write_tree(*PATH, doc.as_slice(), repo.raw())?;
+        let id_ref = format!("refs/remotes/{remote}/{}", &*REFERENCE_NAME);
+        let head = repo.raw().find_reference(&id_ref)?.peel_to_commit()?;
+        let oid = Doc::commit(remote, &tree, &msg, &[&head], repo.raw())?;
+
+        Ok(oid)
+    }
+
+    fn commit(
+        remote: &RemoteId,
+        tree: &git2::Tree,
+        msg: &str,
+        parents: &[&git2::Commit],
+        repo: &git2::Repository,
+    ) -> Result<git::Oid, Error> {
+        let sig = repo
+            .signature()
+            .or_else(|_| git2::Signature::now("radicle", remote.to_string().as_str()))?;
+
+        let id_ref = format!("refs/remotes/{remote}/{}", &*REFERENCE_NAME);
+        let oid = repo.commit(Some(&id_ref), &sig, &sig, msg, tree, parents)?;
+
+        Ok(oid.into())
+    }
+}
+
+impl<V> Deref for Doc<V> {
+    type Target = Payload;
+
+    fn deref(&self) -> &Self::Target {
+        &self.payload
     }
 }
 
@@ -118,11 +214,12 @@ impl Doc<Unverified> {
         delegate: Delegate,
     ) -> Self {
         Self {
-            name,
-            description,
-            default_branch,
-            version: 1,
-            parent: None,
+            payload: Payload {
+                name,
+                description,
+                default_branch,
+            },
+            extensions: BTreeMap::new(),
             delegates: NonEmpty::new(delegate),
             threshold: 1,
             verified: PhantomData,
@@ -133,16 +230,16 @@ impl Doc<Unverified> {
         name: String,
         description: String,
         default_branch: BranchName,
-        parent: Option<Oid>,
         delegates: NonEmpty<Delegate>,
         threshold: usize,
     ) -> Self {
         Self {
-            name,
-            description,
-            default_branch,
-            version: 1,
-            parent,
+            payload: Payload {
+                name,
+                description,
+                default_branch,
+            },
+            extensions: BTreeMap::new(),
             delegates,
             threshold,
             verified: PhantomData,
@@ -194,14 +291,6 @@ impl Doc<Unverified> {
                 "default branch cannot exceed 255 bytes",
             ));
         }
-        if let Some(parent) = self.parent {
-            if parent.is_zero() {
-                return Err(VerificationError::Parent("parent cannot be zero"));
-            }
-        }
-        if self.version != 1 {
-            return Err(VerificationError::Version(self.version));
-        }
         if self.threshold > self.delegates.len() {
             return Err(VerificationError::Threshold(
                 self.threshold,
@@ -216,12 +305,9 @@ impl Doc<Unverified> {
         }
 
         Ok(Doc {
-            name: self.name,
-            description: self.description,
+            payload: self.payload,
+            extensions: self.extensions,
             delegates: self.delegates,
-            default_branch: self.default_branch,
-            parent: self.parent,
-            version: self.version,
             threshold: self.threshold,
             verified: PhantomData,
         })
@@ -274,6 +360,22 @@ impl<V> Doc<V> {
     }
 }
 
+#[derive(Error, Debug)]
+pub enum IdentityError {
+    #[error("git: {0}")]
+    GitRaw(#[from] git2::Error),
+    #[error("git: {0}")]
+    Git(#[from] git::Error),
+    #[error("verification: {0}")]
+    Verification(#[from] VerificationError),
+    #[error("root hash `{0}` does not match repository")]
+    MismatchedRoot(Id),
+    #[error("commit signature for {0} is invalid: {1}")]
+    InvalidSignature(PublicKey, crypto::Error),
+    #[error("quorum not reached: {0} signatures for a threshold of {1}")]
+    QuorumNotReached(usize, usize),
+}
+
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct Identity<V> {
     /// The head of the identity branch. This points to a commit that
@@ -284,6 +386,8 @@ pub struct Identity<V> {
     pub root: Id,
     /// The object id of the current document blob.
     pub current: Oid,
+    /// Revision number. The initial document has a revision of `0`.
+    pub revision: u32,
     /// The current document.
     pub doc: Doc<Verified>,
     /// Signatures over this identity.
@@ -297,7 +401,7 @@ impl Identity<Untrusted> {
         id: &Id,
         remote: &RemoteId,
         repo: &R,
-    ) -> Result<Option<Self>, Error> {
+    ) -> Result<Option<Identity<Trusted>>, IdentityError> {
         if let Some(head) = Doc::<Untrusted>::head(remote, repo)? {
             let mut history = repo.revwalk(head)?.collect::<Vec<_>>();
 
@@ -306,10 +410,11 @@ impl Identity<Untrusted> {
             let root_blob = Doc::blob_at(root_oid, repo)?.unwrap();
             let root = Id::from(root_blob.id());
             let trusted = Doc::from_json(root_blob.content()).unwrap();
+            let revision = history.len() as u32;
 
             // The root hash must be equal to the id.
             if root != *id {
-                todo!();
+                return Err(IdentityError::MismatchedRoot(root));
             }
 
             let mut trusted = trusted.verified()?;
@@ -319,7 +424,7 @@ impl Identity<Untrusted> {
             // Traverse the history chronologically.
             for oid in history.into_iter().rev() {
                 let oid = oid?;
-                let blob = Doc::blob_at(head, repo)?.unwrap();
+                let blob = Doc::blob_at(oid.into(), repo)?.unwrap();
                 let untrusted = Doc::from_json(blob.content()).unwrap();
                 let untrusted = untrusted.verified()?;
                 let commit = repo.commit(oid.into())?.unwrap();
@@ -328,8 +433,8 @@ impl Identity<Untrusted> {
                 // Keys that signed the *current* document version.
                 signatures = trailers::parse_signatures(msg).unwrap();
                 for (pk, sig) in &signatures {
-                    if pk.verify(sig, blob.content()).is_err() {
-                        todo!();
+                    if let Err(err) = pk.verify(sig, blob.content()) {
+                        return Err(IdentityError::InvalidSignature(*pk, err));
                     }
                 }
 
@@ -338,19 +443,19 @@ impl Identity<Untrusted> {
                     .iter()
                     .filter(|(key, _)| trusted.delegates.iter().any(|d| d.matches(key)))
                     .count();
-                // TODO: Check that difference isn't greater than threshold?
                 if quorum < trusted.threshold {
-                    todo!();
+                    return Err(IdentityError::QuorumNotReached(quorum, trusted.threshold));
                 }
 
                 trusted = untrusted;
                 current = blob.id().into();
             }
 
-            return Ok(Some(Self {
+            return Ok(Some(Identity {
                 root,
                 head,
                 current,
+                revision,
                 doc: trusted,
                 signatures: signatures.into_iter().collect(),
                 verified: PhantomData,
@@ -362,9 +467,112 @@ impl Identity<Untrusted> {
 
 #[cfg(test)]
 mod test {
+    use crate::prelude::Signer;
+    use crate::rad;
+    use crate::storage::git::Storage;
+    use crate::storage::{ReadStorage, WriteStorage};
+    use crate::test::{crypto, fixtures};
+
     use super::*;
     use quickcheck_macros::quickcheck;
 
+    #[test]
+    fn test_valid_identity() {
+        let tempdir = tempfile::tempdir().unwrap();
+        let mut rng = fastrand::Rng::new();
+
+        let alice = crypto::MockSigner::new(&mut rng);
+        let bob = crypto::MockSigner::new(&mut rng);
+        let eve = crypto::MockSigner::new(&mut rng);
+
+        let storage = Storage::open(tempdir.path().join("storage")).unwrap();
+        let (id, _, _, _) =
+            fixtures::project(tempdir.path().join("copy"), &storage, &alice).unwrap();
+
+        // Bob and Eve fork the project from Alice.
+        rad::fork(&id, alice.public_key(), &bob, &storage).unwrap();
+        rad::fork(&id, alice.public_key(), &eve, &storage).unwrap();
+
+        // TODO: In some cases we want to get the repo and the project, but don't
+        // want to have to create a repository object twice. Perhaps there should
+        // be a way of getting a project from a repo.
+        let mut proj = storage.get(alice.public_key(), &id).unwrap().unwrap();
+        let repo = storage.repository(&id).unwrap();
+
+        // Make a change to the description and sign it.
+        proj.doc.payload.description += "!";
+        proj.sign(&alice)
+            .and_then(|(_, sig)| {
+                proj.update(
+                    alice.public_key(),
+                    "Update description",
+                    &[(alice.public_key(), sig)],
+                    &repo,
+                )
+            })
+            .unwrap();
+
+        // Add Bob as a delegate, and sign it.
+        proj.delegate("bob".to_owned(), *bob.public_key());
+        proj.doc.threshold = 2;
+        proj.sign(&alice)
+            .and_then(|(_, sig)| {
+                proj.update(
+                    alice.public_key(),
+                    "Add bob",
+                    &[(alice.public_key(), sig)],
+                    &repo,
+                )
+            })
+            .unwrap();
+
+        // Add Eve as a delegate, and sign it.
+        proj.delegate("eve".to_owned(), *eve.public_key());
+        proj.sign(&alice)
+            .and_then(|(_, alice_sig)| {
+                proj.sign(&bob).and_then(|(_, bob_sig)| {
+                    proj.update(
+                        alice.public_key(),
+                        "Add eve",
+                        &[(alice.public_key(), alice_sig), (bob.public_key(), bob_sig)],
+                        &repo,
+                    )
+                })
+            })
+            .unwrap();
+
+        // Update description again with signatures by Eve and Bob.
+        proj.doc.payload.description += "?";
+        let (current, head) = proj
+            .sign(&bob)
+            .and_then(|(_, bob_sig)| {
+                proj.sign(&eve).and_then(|(blob_id, eve_sig)| {
+                    proj.update(
+                        alice.public_key(),
+                        "Update description",
+                        &[(bob.public_key(), bob_sig), (eve.public_key(), eve_sig)],
+                        &repo,
+                    )
+                    .map(|head| (blob_id, head))
+                })
+            })
+            .unwrap();
+
+        let identity = Identity::load(&id, alice.public_key(), &repo)
+            .unwrap()
+            .unwrap();
+
+        assert_eq!(identity.signatures.len(), 2);
+        assert_eq!(identity.revision, 4);
+        assert_eq!(identity.root, id);
+        assert_eq!(identity.current, current);
+        assert_eq!(identity.head, head);
+        assert_eq!(identity.doc, proj.doc);
+
+        let proj = storage.get(alice.public_key(), &id).unwrap().unwrap();
+        assert_eq!(proj.description, "Acme's repository!?");
+    }
+
     #[quickcheck]
     fn prop_encode_decode(doc: Doc<Verified>) {
         let (_, bytes) = doc.encode().unwrap();
diff --git a/node/src/rad.rs b/node/src/rad.rs
index 3ec53968..f8a45549 100644
--- a/node/src/rad.rs
+++ b/node/src/rad.rs
@@ -39,7 +39,7 @@ pub fn init<'r, G: Signer, S: storage::WriteStorage<'r>>(
     description: &str,
     default_branch: BranchName,
     signer: G,
-    storage: S,
+    storage: &'r S,
 ) -> Result<(Id, SignedRefs<Verified>), InitError> {
     let pk = signer.public_key();
     let delegate = identity::Delegate {
@@ -47,46 +47,16 @@ pub fn init<'r, G: Signer, S: storage::WriteStorage<'r>>(
         name: String::from("anonymous"),
         id: identity::Did::from(*pk),
     };
-    let (id, doc) = identity::Doc::initial(
+    let doc = identity::Doc::initial(
         name.to_owned(),
         description.to_owned(),
         default_branch.clone(),
         delegate,
     )
-    .verified()?
-    .encode()?;
+    .verified()?;
 
-    let project = storage.repository(&id)?;
+    let (id, _, project) = doc.create(pk, "Initialize Radicle", storage)?;
 
-    {
-        // Within this scope, redefine `repo` to refer to the project storage,
-        // since we're going to create the identity file there, and not in there
-        // working copy.
-        //
-        // You can checkout this branch in your working copy with:
-        //
-        //      git fetch rad
-        //      git checkout -b radicle/id remotes/rad/radicle/id
-        //
-        let filename = *identity::doc::PATH;
-        let repo = project.raw();
-        let tree = {
-            let doc_blob = repo.blob(&doc)?;
-            let mut builder = repo.treebuilder(None)?;
-            builder.insert(filename, doc_blob, 0o100_644)?;
-
-            assert_eq!(git::Oid::from(doc_blob), *id);
-
-            let tree_id = builder.write()?;
-            repo.find_tree(tree_id)
-        }?;
-        let sig = repo
-            .signature()
-            .or_else(|_| git2::Signature::now("radicle", pk.to_string().as_str()))?;
-
-        let id_ref = format!("refs/remotes/{pk}/{}", &*identity::doc::REFERENCE_NAME);
-        let _oid = repo.commit(Some(&id_ref), &sig, &sig, "Initialize Radicle", &tree, &[])?;
-    }
     git::set_upstream(
         repo,
         REMOTE_NAME,
@@ -242,7 +212,7 @@ mod tests {
         let tempdir = tempfile::tempdir().unwrap();
         let signer = crypto::MockSigner::default();
         let public_key = *signer.public_key();
-        let mut storage = Storage::open(tempdir.path().join("storage")).unwrap();
+        let storage = Storage::open(tempdir.path().join("storage")).unwrap();
         let (repo, _) = fixtures::repository(tempdir.path().join("working"));
 
         let (proj, refs) = init(
@@ -251,7 +221,7 @@ mod tests {
             "Acme's repo",
             BranchName::from("master"),
             &signer,
-            &mut storage,
+            &storage,
         )
         .unwrap();
 
@@ -279,7 +249,7 @@ mod tests {
         let alice_id = alice.public_key();
         let bob = crypto::MockSigner::new(&mut rng);
         let bob_id = bob.public_key();
-        let mut storage = Storage::open(tempdir.path().join("storage")).unwrap();
+        let storage = Storage::open(tempdir.path().join("storage")).unwrap();
         let (original, _) = fixtures::repository(tempdir.path().join("original"));
 
         // Alice creates a project.
@@ -289,12 +259,12 @@ mod tests {
             "Acme's repo",
             BranchName::from("master"),
             &alice,
-            &mut storage,
+            &storage,
         )
         .unwrap();
 
         // Bob forks it and creates a checkout.
-        fork(&id, alice_id, &bob, &mut storage).unwrap();
+        fork(&id, alice_id, &bob, &storage).unwrap();
         checkout(&id, bob_id, tempdir.path().join("copy"), &storage).unwrap();
 
         let bob_remote = storage.repository(&id).unwrap().remote(bob_id).unwrap();
@@ -310,7 +280,7 @@ mod tests {
         let tempdir = tempfile::tempdir().unwrap();
         let signer = crypto::MockSigner::default();
         let remote_id = signer.public_key();
-        let mut storage = Storage::open(tempdir.path().join("storage")).unwrap();
+        let storage = Storage::open(tempdir.path().join("storage")).unwrap();
         let (original, _) = fixtures::repository(tempdir.path().join("original"));
 
         let (id, _) = init(
@@ -319,7 +289,7 @@ mod tests {
             "Acme's repo",
             BranchName::from("master"),
             &signer,
-            &mut storage,
+            &storage,
         )
         .unwrap();
 
diff --git a/node/src/storage.rs b/node/src/storage.rs
index cdc7d302..8901ec8c 100644
--- a/node/src/storage.rs
+++ b/node/src/storage.rs
@@ -252,6 +252,8 @@ pub trait ReadRepository<'r> {
     fn references(&self, remote: &RemoteId) -> Result<Refs, Error>;
     fn remote(&self, remote: &RemoteId) -> Result<Remote<Verified>, refs::Error>;
     fn remotes(&'r self) -> Result<Self::Remotes, git2::Error>;
+    /// Return the project associated with this repository.
+    fn project(&self) -> Result<Project, Error>;
 }
 
 pub trait WriteRepository<'r>: ReadRepository<'r> {
diff --git a/node/src/storage/git.rs b/node/src/storage/git.rs
index e5a02cb7..6c724ac8 100644
--- a/node/src/storage/git.rs
+++ b/node/src/storage/git.rs
@@ -363,6 +363,10 @@ impl<'r> ReadRepository<'r> for Repository {
 
         Ok(Box::new(iter))
     }
+
+    fn project(&self) -> Result<Project, Error> {
+        todo!()
+    }
 }
 
 impl<'r> WriteRepository<'r> for Repository {
diff --git a/node/src/test/arbitrary.rs b/node/src/test/arbitrary.rs
index efea335c..759e6b9b 100644
--- a/node/src/test/arbitrary.rs
+++ b/node/src/test/arbitrary.rs
@@ -179,7 +179,8 @@ impl Arbitrary for MockStorage {
 impl Arbitrary for Project {
     fn arbitrary(g: &mut quickcheck::Gen) -> Self {
         let doc = Doc::<Verified>::arbitrary(g);
-        let (id, _) = doc.encode().unwrap();
+        let (oid, _) = doc.encode().unwrap();
+        let id = Id::from(oid);
         let remotes = storage::Remotes::arbitrary(g);
         let path = PathBuf::arbitrary(g);
 
@@ -230,7 +231,6 @@ impl Arbitrary for Doc<Verified> {
         let default_branch = iter::repeat_with(|| rng.alphanumeric())
             .take(rng.usize(1..16))
             .collect();
-        let parent = None;
         let delegates: NonEmpty<_> = iter::repeat_with(|| Delegate {
             name: iter::repeat_with(|| rng.alphanumeric())
                 .take(rng.usize(1..16))
@@ -242,14 +242,8 @@ impl Arbitrary for Doc<Verified> {
         .try_into()
         .unwrap();
         let threshold = delegates.len() / 2 + 1;
-        let doc: Doc<Unverified> = Doc::new(
-            name,
-            description,
-            default_branch,
-            parent,
-            delegates,
-            threshold,
-        );
+        let doc: Doc<Unverified> =
+            Doc::new(name, description, default_branch, delegates, threshold);
 
         doc.verified().unwrap()
     }
diff --git a/node/src/test/fixtures.rs b/node/src/test/fixtures.rs
index da7bd1f8..6dc8c209 100644
--- a/node/src/test/fixtures.rs
+++ b/node/src/test/fixtures.rs
@@ -66,7 +66,7 @@ pub fn storage<P: AsRef<Path>>(path: P) -> Storage {
 /// Create a new repository at the given path, and initialize it into a project.
 pub fn project<'r, P: AsRef<Path>, S: WriteStorage<'r>, G: Signer>(
     path: P,
-    storage: S,
+    storage: &'r S,
     signer: G,
 ) -> Result<(Id, SignedRefs<Verified>, git2::Repository, git2::Oid), rad::InitError> {
     let (repo, head) = repository(path);
diff --git a/node/src/test/storage.rs b/node/src/test/storage.rs
index d97ed283..fe0a996a 100644
--- a/node/src/test/storage.rs
+++ b/node/src/test/storage.rs
@@ -125,6 +125,10 @@ impl ReadRepository<'_> for MockRepository {
     fn references(&self, _remote: &RemoteId) -> Result<crate::storage::refs::Refs, Error> {
         todo!()
     }
+
+    fn project(&self) -> Result<Project, Error> {
+        todo!()
+    }
 }
 
 impl WriteRepository<'_> for MockRepository {