refactor(tvix/store): use strictly typed PathInfo struct r/8787

This switches the PathInfoService trait from using the proto-derived
PathInfo struct to a more restrictive struct, and updates all
implementations to use it.

It removes a lot of the previous conversion and checks, as invalid
states became nonrepresentable, and validations are expressed on the
type level.

PathInfoService implementations consuming protobuf need to convert and
do the verification internally, and can only return the strongly typed
variant.

The nix_compat::narinfo::NarInfo conversions for the proto PathInfo
are removed, we only keep a version showing a NarInfo representation for
the strong struct.

Converting back to a PathInfo requires the root node now, but is
otherwise trivial, so left to the users.

Co-Authored-By: Florian Klink <flokli@flokli.de>
Change-Id: I6fdfdb44063efebb44a8f0097b6b81a828717e03
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12588
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

19 files changed, 594 insertions, 874 deletions

diff --git a/tvix/store/src/bin/tvix-store.rs b/tvix/store/src/bin/tvix-store.rs
index b77a46dace7c..f39b73df2e0b 100644
--- a/tvix/store/src/bin/tvix-store.rs
+++ b/tvix/store/src/bin/tvix-store.rs
@@ -4,7 +4,7 @@ use clap::Subcommand;
 use futures::future::try_join_all;
 use futures::StreamExt;
 use futures::TryStreamExt;
-use nix_compat::path_info::ExportedPathInfo;
+use nix_compat::{path_info::ExportedPathInfo, store_path::StorePath};
 use serde::Deserialize;
 use serde::Serialize;
 use std::path::PathBuf;
@@ -16,15 +16,13 @@ use tracing::{info, info_span, instrument, Level, Span};
 use tracing_indicatif::span_ext::IndicatifSpanExt as _;
 use tvix_castore::import::fs::ingest_path;
 use tvix_store::nar::NarCalculationService;
-use tvix_store::proto::NarInfo;
-use tvix_store::proto::PathInfo;
 use tvix_store::utils::{ServiceUrls, ServiceUrlsGrpc};
 
 use tvix_castore::proto::blob_service_server::BlobServiceServer;
 use tvix_castore::proto::directory_service_server::DirectoryServiceServer;
 use tvix_castore::proto::GRPCBlobServiceWrapper;
 use tvix_castore::proto::GRPCDirectoryServiceWrapper;
-use tvix_store::pathinfoservice::PathInfoService;
+use tvix_store::pathinfoservice::{PathInfo, PathInfoService};
 use tvix_store::proto::path_info_service_server::PathInfoServiceServer;
 use tvix_store::proto::GRPCPathInfoServiceWrapper;
 
@@ -359,23 +357,14 @@ async fn run_cli(cli: Cli) -> Result<(), Box<dyn std::error::Error + Send + Sync
                 // Create and upload a PathInfo pointing to the root_node,
                 // annotated with information we have from the reference graph.
                 let path_info = PathInfo {
-                    node: Some(tvix_castore::proto::Node::from_name_and_node(
-                        elem.path.to_string().into(),
-                        root_node,
-                    )),
-                    references: Vec::from_iter(
-                        elem.references.iter().map(|e| e.digest().to_vec().into()),
-                    ),
-                    narinfo: Some(NarInfo {
-                        nar_size: elem.nar_size,
-                        nar_sha256: elem.nar_sha256.to_vec().into(),
-                        signatures: vec![],
-                        reference_names: Vec::from_iter(
-                            elem.references.iter().map(|e| e.to_string()),
-                        ),
-                        deriver: None,
-                        ca: None,
-                    }),
+                    store_path: elem.path.to_owned(),
+                    node: root_node,
+                    references: elem.references.iter().map(StorePath::to_owned).collect(),
+                    nar_size: elem.nar_size,
+                    nar_sha256: elem.nar_sha256,
+                    signatures: vec![],
+                    deriver: None,
+                    ca: None,
                 };
 
                 path_info_service.put(path_info).await?;
diff --git a/tvix/store/src/import.rs b/tvix/store/src/import.rs
index 2c2b205016a1..1e9fd060b492 100644
--- a/tvix/store/src/import.rs
+++ b/tvix/store/src/import.rs
@@ -3,18 +3,17 @@ use std::path::Path;
 use tracing::{debug, instrument};
 use tvix_castore::{
     blobservice::BlobService, directoryservice::DirectoryService, import::fs::ingest_path, Node,
-    PathComponent,
 };
 
 use nix_compat::{
     nixhash::{CAHash, NixHash},
-    store_path::{self, StorePathRef},
+    store_path::{self, StorePath, StorePathRef},
 };
 
 use crate::{
     nar::NarCalculationService,
-    pathinfoservice::PathInfoService,
-    proto::{nar_info, NarInfo, PathInfo},
+    pathinfoservice::{PathInfo, PathInfoService},
+    proto::nar_info,
 };
 
 impl From<CAHash> for nar_info::Ca {
@@ -74,33 +73,29 @@ pub fn path_to_name(path: &Path) -> std::io::Result<&str> {
 /// Takes the NAR size, SHA-256 of the NAR representation, the root node and optionally
 /// a CA hash information.
 ///
-/// Returns the path information object for a NAR-style object.
+/// Constructs a [PathInfo] for a NAR-style object.
 ///
-/// This [`PathInfo`] can be further filled for signatures, deriver or verified for the expected
-/// hashes.
+/// The user can then further fill the fields (like deriver, signatures), and/or
+/// verify to have the expected hashes.
 #[inline]
 pub fn derive_nar_ca_path_info(
     nar_size: u64,
     nar_sha256: [u8; 32],
-    ca: Option<&CAHash>,
-    name: bytes::Bytes,
+    ca: Option<CAHash>,
+    store_path: StorePath<String>,
     root_node: Node,
 ) -> PathInfo {
     // assemble the [crate::proto::PathInfo] object.
     PathInfo {
-        node: Some(tvix_castore::proto::Node::from_name_and_node(
-            name, root_node,
-        )),
+        store_path,
+        node: root_node,
         // There's no reference scanning on path contents ingested like this.
         references: vec![],
-        narinfo: Some(NarInfo {
-            nar_size,
-            nar_sha256: nar_sha256.to_vec().into(),
-            signatures: vec![],
-            reference_names: vec![],
-            deriver: None,
-            ca: ca.map(|ca_hash| ca_hash.into()),
-        }),
+        nar_size,
+        nar_sha256,
+        signatures: vec![],
+        deriver: None,
+        ca,
     }
 }
 
@@ -141,19 +136,13 @@ where
         )
     })?;
 
-    let name: PathComponent = output_path
-        .to_string()
-        .as_str()
-        .try_into()
-        .expect("Tvix bug: StorePath must be PathComponent");
-
     log_node(name.as_ref(), &root_node, path.as_ref());
 
     let path_info = derive_nar_ca_path_info(
         nar_size,
         nar_sha256,
-        Some(&CAHash::Nar(NixHash::Sha256(nar_sha256))),
-        name.into(),
+        Some(CAHash::Nar(NixHash::Sha256(nar_sha256))),
+        output_path.to_owned(),
         root_node,
     );
 
diff --git a/tvix/store/src/lib.rs b/tvix/store/src/lib.rs
index 81a77cd978a2..e1517609d51c 100644
--- a/tvix/store/src/lib.rs
+++ b/tvix/store/src/lib.rs
@@ -1,6 +1,7 @@
 pub mod composition;
 pub mod import;
 pub mod nar;
+pub mod path_info;
 pub mod pathinfoservice;
 pub mod proto;
 pub mod utils;
diff --git a/tvix/store/src/path_info.rs b/tvix/store/src/path_info.rs
new file mode 100644
index 000000000000..487261b4bdcb
--- /dev/null
+++ b/tvix/store/src/path_info.rs
@@ -0,0 +1,87 @@
+use nix_compat::{
+    narinfo::{Flags, Signature},
+    nixhash::CAHash,
+    store_path::StorePath,
+};
+
+/// Holds metadata about a store path, but not its contents.
+///
+/// This is somewhat equivalent to the information Nix holds in its SQLite
+/// database, or publishes as .narinfo files, except we also embed the
+/// [tvix_castore::Node] describing the contents in the castore model.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct PathInfo {
+    /// The store path this is about.
+    pub store_path: StorePath<String>,
+    /// The contents in the tvix-castore model.
+    //// Can be a directory, file or symlink.
+    pub node: tvix_castore::Node,
+    /// A list of references.
+    pub references: Vec<StorePath<String>>,
+    /// The size of the NAR representation of the contents, in bytes.
+    pub nar_size: u64,
+    /// The sha256 digest of the NAR representation of the contents.
+    pub nar_sha256: [u8; 32],
+    /// The signatures, usually shown in a .narinfo file.
+    pub signatures: Vec<Signature<String>>,
+    /// The StorePath of the .drv file producing this output.
+    /// The .drv suffix is omitted in its `name` field.
+    pub deriver: Option<StorePath<String>>,
+    /// The CA field in the .narinfo.
+    /// Its textual representations seen in the wild are one of the following:
+    ///
+    /// * `fixed:r:sha256:1gcky5hlf5vqfzpyhihydmm54grhc94mcs8w7xr8613qsqb1v2j6`
+    ///   fixed-output derivations using "recursive" `outputHashMode`.
+    /// * `fixed:sha256:19xqkh72crbcba7flwxyi3n293vav6d7qkzkh2v4zfyi4iia8vj8 fixed-output derivations using "flat" `outputHashMode\`
+    /// * `text:sha256:19xqkh72crbcba7flwxyi3n293vav6d7qkzkh2v4zfyi4iia8vj8`
+    ///   Text hashing, used for uploaded .drv files and outputs produced by
+    ///   builtins.toFile.
+    ///
+    /// Semantically, they can be split into the following components:
+    ///
+    /// * "content address prefix". Currently, "fixed" and "text" are supported.
+    /// * "hash mode". Currently, "flat" and "recursive" are supported.
+    /// * "hash type". The underlying hash function used.
+    ///   Currently, sha1, md5, sha256, sha512.
+    /// * "digest". The digest itself.
+    ///
+    /// There are some restrictions on the possible combinations.
+    /// For example, `text` and `fixed:recursive` always imply sha256.
+    pub ca: Option<CAHash>,
+}
+
+impl PathInfo {
+    /// Reconstructs a [nix_compat::narinfo::NarInfo<'_>].
+    ///
+    /// It does very little allocation (a Vec each for `signatures` and
+    /// `references`), the rest points to data owned elsewhere.
+    ///
+    /// It can be used to validate Signatures, or render a .narinfo file
+    /// (after some more fields are populated)
+    ///
+    /// Keep in mind this is not able to reconstruct all data present in the
+    /// NarInfo<'_>, as some of it is not stored at all:
+    /// - the `system`, `file_hash` and `file_size` fields are set to `None`.
+    /// - the URL is set to an empty string.
+    /// - Compression is set to "none"
+    ///
+    /// If you want to render it out to a string and be able to parse it back
+    /// in, at least URL *must* be set again.
+    pub fn to_narinfo(&self) -> nix_compat::narinfo::NarInfo<'_> {
+        nix_compat::narinfo::NarInfo {
+            flags: Flags::empty(),
+            store_path: self.store_path.as_ref(),
+            nar_hash: self.nar_sha256,
+            nar_size: self.nar_size,
+            references: self.references.iter().map(StorePath::as_ref).collect(),
+            signatures: self.signatures.iter().map(Signature::as_ref).collect(),
+            ca: self.ca.clone(),
+            system: None,
+            deriver: self.deriver.as_ref().map(StorePath::as_ref),
+            url: "",
+            compression: Some("none"),
+            file_hash: None,
+            file_size: None,
+        }
+    }
+}
diff --git a/tvix/store/src/pathinfoservice/bigtable.rs b/tvix/store/src/pathinfoservice/bigtable.rs
index 15128986ff56..3d8db8e5044a 100644
--- a/tvix/store/src/pathinfoservice/bigtable.rs
+++ b/tvix/store/src/pathinfoservice/bigtable.rs
@@ -1,6 +1,5 @@
-use super::PathInfoService;
+use super::{PathInfo, PathInfoService};
 use crate::proto;
-use crate::proto::PathInfo;
 use async_stream::try_stream;
 use bigtable_rs::{bigtable, google::bigtable::v2 as bigtable_v2};
 use bytes::Bytes;
@@ -232,14 +231,13 @@ impl PathInfoService for BigtablePathInfoService {
         }
 
         // Try to parse the value into a PathInfo message
-        let path_info = proto::PathInfo::decode(Bytes::from(cell.value))
+        let path_info_proto = proto::PathInfo::decode(Bytes::from(cell.value))
             .map_err(|e| Error::StorageError(format!("unable to decode pathinfo proto: {}", e)))?;
 
-        let store_path = path_info
-            .validate()
-            .map_err(|e| Error::StorageError(format!("invalid PathInfo: {}", e)))?;
+        let path_info = PathInfo::try_from(path_info_proto)
+            .map_err(|e| Error::StorageError(format!("Invalid path info: {e}")))?;
 
-        if store_path.digest() != &digest {
+        if path_info.store_path.digest() != &digest {
             return Err(Error::StorageError("PathInfo has unexpected digest".into()));
         }
 
@@ -248,14 +246,10 @@ impl PathInfoService for BigtablePathInfoService {
 
     #[instrument(level = "trace", skip_all, fields(path_info.root_node = ?path_info.node))]
     async fn put(&self, path_info: PathInfo) -> Result<PathInfo, Error> {
-        let store_path = path_info
-            .validate()
-            .map_err(|e| Error::InvalidRequest(format!("pathinfo failed validation: {}", e)))?;
-
         let mut client = self.client.clone();
-        let path_info_key = derive_pathinfo_key(store_path.digest());
+        let path_info_key = derive_pathinfo_key(path_info.store_path.digest());
 
-        let data = path_info.encode_to_vec();
+        let data = proto::PathInfo::from(path_info.clone()).encode_to_vec();
         if data.len() as u64 > CELL_SIZE_LIMIT {
             return Err(Error::StorageError(
                 "PathInfo exceeds cell limit on Bigtable".into(),
@@ -340,16 +334,12 @@ impl PathInfoService for BigtablePathInfoService {
                 }
 
                 // Try to parse the value into a PathInfo message.
-                let path_info = proto::PathInfo::decode(Bytes::from(cell.value))
+                let path_info_proto = proto::PathInfo::decode(Bytes::from(cell.value))
                     .map_err(|e| Error::StorageError(format!("unable to decode pathinfo proto: {}", e)))?;
 
-                // Validate the containing PathInfo, ensure its StorePath digest
-                // matches row key.
-                let store_path = path_info
-                    .validate()
-                    .map_err(|e| Error::StorageError(format!("invalid PathInfo: {}", e)))?;
+                let path_info = PathInfo::try_from(path_info_proto).map_err(|e| Error::StorageError(format!("Invalid path info: {e}")))?;
 
-                let exp_path_info_key = derive_pathinfo_key(store_path.digest());
+                let exp_path_info_key = derive_pathinfo_key(path_info.store_path.digest());
 
                 if exp_path_info_key.as_bytes() != row_key.as_slice() {
                     Err(Error::StorageError("PathInfo has unexpected digest".into()))?
diff --git a/tvix/store/src/pathinfoservice/combinators.rs b/tvix/store/src/pathinfoservice/combinators.rs
index bb5595f72b10..1f413cf310a2 100644
--- a/tvix/store/src/pathinfoservice/combinators.rs
+++ b/tvix/store/src/pathinfoservice/combinators.rs
@@ -1,6 +1,5 @@
 use std::sync::Arc;
 
-use crate::proto::PathInfo;
 use futures::stream::BoxStream;
 use nix_compat::nixbase32;
 use tonic::async_trait;
@@ -8,7 +7,7 @@ use tracing::{debug, instrument};
 use tvix_castore::composition::{CompositionContext, ServiceBuilder};
 use tvix_castore::Error;
 
-use super::PathInfoService;
+use super::{PathInfo, PathInfoService};
 
 /// Asks near first, if not found, asks far.
 /// If found in there, returns it, and *inserts* it into
@@ -105,11 +104,9 @@ mod test {
 
     use crate::{
         pathinfoservice::{LruPathInfoService, MemoryPathInfoService, PathInfoService},
-        tests::fixtures::PATH_INFO_WITH_NARINFO,
+        tests::fixtures::PATH_INFO,
     };
 
-    const PATH_INFO_DIGEST: [u8; 20] = [0; 20];
-
     /// Helper function setting up an instance of a "far" and "near"
     /// PathInfoService.
     async fn create_pathinfoservice() -> super::Cache<LruPathInfoService, MemoryPathInfoService> {
@@ -129,21 +126,25 @@ mod test {
         let svc = create_pathinfoservice().await;
 
         // query the PathInfo, things should not be there.
-        assert!(svc.get(PATH_INFO_DIGEST).await.unwrap().is_none());
+        assert!(svc
+            .get(*PATH_INFO.store_path.digest())
+            .await
+            .unwrap()
+            .is_none());
 
         // insert it into the far one.
-        svc.far.put(PATH_INFO_WITH_NARINFO.clone()).await.unwrap();
+        svc.far.put(PATH_INFO.clone()).await.unwrap();
 
         // now try getting it again, it should succeed.
         assert_eq!(
-            Some(PATH_INFO_WITH_NARINFO.clone()),
-            svc.get(PATH_INFO_DIGEST).await.unwrap()
+            Some(PATH_INFO.clone()),
+            svc.get(*PATH_INFO.store_path.digest()).await.unwrap()
         );
 
         // peek near, it should now be there.
         assert_eq!(
-            Some(PATH_INFO_WITH_NARINFO.clone()),
-            svc.near.get(PATH_INFO_DIGEST).await.unwrap()
+            Some(PATH_INFO.clone()),
+            svc.near.get(*PATH_INFO.store_path.digest()).await.unwrap()
         );
     }
 }
diff --git a/tvix/store/src/pathinfoservice/fs/mod.rs b/tvix/store/src/pathinfoservice/fs/mod.rs
index 1f7fa8a8afce..d996ec9f6f76 100644
--- a/tvix/store/src/pathinfoservice/fs/mod.rs
+++ b/tvix/store/src/pathinfoservice/fs/mod.rs
@@ -58,32 +58,20 @@ where
             .as_ref()
             .get(*store_path.digest())
             .await?
-            .map(|path_info| {
-                let node = path_info
-                    .node
-                    .as_ref()
-                    .expect("missing root node")
-                    .to_owned();
-
-                match node.into_name_and_node() {
-                    Ok((_name, node)) => Ok(node),
-                    Err(e) => Err(Error::StorageError(e.to_string())),
-                }
-            })
-            .transpose()?)
+            .map(|path_info| path_info.node))
     }
 
     fn list(&self) -> BoxStream<Result<(PathComponent, Node), Error>> {
         Box::pin(self.0.as_ref().list().map(|result| {
-            result.and_then(|path_info| {
-                let node = path_info
-                    .node
-                    .as_ref()
-                    .expect("missing root node")
-                    .to_owned();
-
-                node.into_name_and_node()
-                    .map_err(|e| Error::StorageError(e.to_string()))
+            result.map(|path_info| {
+                let basename = path_info.store_path.to_string();
+                (
+                    basename
+                        .as_str()
+                        .try_into()
+                        .expect("Tvix bug: StorePath must be PathComponent"),
+                    path_info.node,
+                )
             })
         }))
     }
diff --git a/tvix/store/src/pathinfoservice/grpc.rs b/tvix/store/src/pathinfoservice/grpc.rs
index 7510ccd911f0..d292b2a784f6 100644
--- a/tvix/store/src/pathinfoservice/grpc.rs
+++ b/tvix/store/src/pathinfoservice/grpc.rs
@@ -1,7 +1,7 @@
-use super::PathInfoService;
+use super::{PathInfo, PathInfoService};
 use crate::{
     nar::NarCalculationService,
-    proto::{self, ListPathInfoRequest, PathInfo},
+    proto::{self, ListPathInfoRequest},
 };
 use async_stream::try_stream;
 use futures::stream::BoxStream;
@@ -53,15 +53,10 @@ where
             .await;
 
         match path_info {
-            Ok(path_info) => {
-                let path_info = path_info.into_inner();
-
-                path_info
-                    .validate()
-                    .map_err(|e| Error::StorageError(format!("invalid pathinfo: {}", e)))?;
-
-                Ok(Some(path_info))
-            }
+            Ok(path_info) => Ok(Some(
+                PathInfo::try_from(path_info.into_inner())
+                    .map_err(|e| Error::StorageError(format!("Invalid path info: {e}")))?,
+            )),
             Err(e) if e.code() == Code::NotFound => Ok(None),
             Err(e) => Err(Error::StorageError(e.to_string())),
         }
@@ -72,12 +67,12 @@ where
         let path_info = self
             .grpc_client
             .clone()
-            .put(path_info)
+            .put(proto::PathInfo::from(path_info))
             .await
             .map_err(|e| Error::StorageError(e.to_string()))?
             .into_inner();
-
-        Ok(path_info)
+        Ok(PathInfo::try_from(path_info)
+            .map_err(|e| Error::StorageError(format!("Invalid path info: {e}")))?)
     }
 
     #[instrument(level = "trace", skip_all)]
@@ -91,21 +86,8 @@ where
 
             loop {
                 match stream.message().await {
-                    Ok(o) => match o {
-                        Some(pathinfo) => {
-                            // validate the pathinfo
-                            if let Err(e) = pathinfo.validate() {
-                                Err(Error::StorageError(format!(
-                                    "pathinfo {:?} failed validation: {}",
-                                    pathinfo, e
-                                )))?;
-                            }
-                            yield pathinfo
-                        }
-                        None => {
-                            return;
-                        },
-                    },
+                    Ok(Some(path_info)) => yield PathInfo::try_from(path_info).map_err(|e| Error::StorageError(format!("Invalid path info: {e}")))?,
+                    Ok(None) => return,
                     Err(e) => Err(Error::StorageError(e.to_string()))?,
                 }
             }
diff --git a/tvix/store/src/pathinfoservice/lru.rs b/tvix/store/src/pathinfoservice/lru.rs
index 695c04636089..2d8d52e3c9f6 100644
--- a/tvix/store/src/pathinfoservice/lru.rs
+++ b/tvix/store/src/pathinfoservice/lru.rs
@@ -8,11 +8,10 @@ use tokio::sync::RwLock;
 use tonic::async_trait;
 use tracing::instrument;
 
-use crate::proto::PathInfo;
 use tvix_castore::composition::{CompositionContext, ServiceBuilder};
 use tvix_castore::Error;
 
-use super::PathInfoService;
+use super::{PathInfo, PathInfoService};
 
 pub struct LruPathInfoService {
     lru: Arc<RwLock<LruCache<[u8; 20], PathInfo>>>,
@@ -35,15 +34,10 @@ impl PathInfoService for LruPathInfoService {
 
     #[instrument(level = "trace", skip_all, fields(path_info.root_node = ?path_info.node))]
     async fn put(&self, path_info: PathInfo) -> Result<PathInfo, Error> {
-        // call validate
-        let store_path = path_info
-            .validate()
-            .map_err(|e| Error::InvalidRequest(format!("invalid PathInfo: {}", e)))?;
-
         self.lru
             .write()
             .await
-            .put(*store_path.digest(), path_info.clone());
+            .put(*path_info.store_path.digest(), path_info.clone());
 
         Ok(path_info)
     }
@@ -91,40 +85,22 @@ impl ServiceBuilder for LruPathInfoServiceConfig {
 
 #[cfg(test)]
 mod test {
+    use nix_compat::store_path::StorePath;
     use std::num::NonZeroUsize;
 
     use crate::{
-        pathinfoservice::{LruPathInfoService, PathInfoService},
-        proto::PathInfo,
-        tests::fixtures::PATH_INFO_WITH_NARINFO,
+        pathinfoservice::{LruPathInfoService, PathInfo, PathInfoService},
+        tests::fixtures::PATH_INFO,
     };
     use lazy_static::lazy_static;
-    use tvix_castore::proto as castorepb;
 
     lazy_static! {
-        static ref PATHINFO_1: PathInfo = PATH_INFO_WITH_NARINFO.clone();
-        static ref PATHINFO_1_DIGEST: [u8; 20] = [0; 20];
         static ref PATHINFO_2: PathInfo = {
-            let mut p = PATHINFO_1.clone();
-            let root_node = p.node.as_mut().unwrap();
-            if let castorepb::Node { node: Some(node) } = root_node {
-                match node {
-                    castorepb::node::Node::Directory(n) => {
-                        n.name = "11111111111111111111111111111111-dummy2".into()
-                    }
-                    castorepb::node::Node::File(n) => {
-                        n.name = "11111111111111111111111111111111-dummy2".into()
-                    }
-                    castorepb::node::Node::Symlink(n) => {
-                        n.name = "11111111111111111111111111111111-dummy2".into()
-                    }
-                }
-            } else {
-                unreachable!()
-            }
+            let mut p = PATH_INFO.clone();
+            p.store_path = StorePath::from_name_and_digest_fixed("dummy", [1; 20]).unwrap();
             p
         };
-        static ref PATHINFO_2_DIGEST: [u8; 20] = *(PATHINFO_2.validate().unwrap()).digest();
+        static ref PATHINFO_2_DIGEST: [u8; 20] = *PATHINFO_2.store_path.digest();
     }
 
     #[tokio::test]
@@ -133,18 +109,20 @@ mod test {
 
         // pathinfo_1 should not be there
         assert!(svc
-            .get(*PATHINFO_1_DIGEST)
+            .get(*PATH_INFO.store_path.digest())
             .await
             .expect("no error")
             .is_none());
 
         // insert it
-        svc.put(PATHINFO_1.clone()).await.expect("no error");
+        svc.put(PATH_INFO.clone()).await.expect("no error");
 
         // now it should be there.
         assert_eq!(
-            Some(PATHINFO_1.clone()),
-            svc.get(*PATHINFO_1_DIGEST).await.expect("no error")
+            Some(PATH_INFO.clone()),
+            svc.get(*PATH_INFO.store_path.digest())
+                .await
+                .expect("no error")
         );
 
         // insert pathinfo_2. This will evict pathinfo 1
@@ -158,7 +136,7 @@ mod test {
 
         // … but pathinfo 1 not anymore.
         assert!(svc
-            .get(*PATHINFO_1_DIGEST)
+            .get(*PATH_INFO.store_path.digest())
             .await
             .expect("no error")
             .is_none());
diff --git a/tvix/store/src/pathinfoservice/memory.rs b/tvix/store/src/pathinfoservice/memory.rs
index 3fabd239c7b1..fd013fe9a573 100644
--- a/tvix/store/src/pathinfoservice/memory.rs
+++ b/tvix/store/src/pathinfoservice/memory.rs
@@ -1,5 +1,4 @@
-use super::PathInfoService;
-use crate::proto::PathInfo;
+use super::{PathInfo, PathInfoService};
 use async_stream::try_stream;
 use futures::stream::BoxStream;
 use nix_compat::nixbase32;
@@ -29,22 +28,11 @@ impl PathInfoService for MemoryPathInfoService {
 
     #[instrument(level = "trace", skip_all, fields(path_info.root_node = ?path_info.node))]
     async fn put(&self, path_info: PathInfo) -> Result<PathInfo, Error> {
-        // Call validate on the received PathInfo message.
-        match path_info.validate() {
-            Err(e) => Err(Error::InvalidRequest(format!(
-                "failed to validate PathInfo: {}",
-                e
-            ))),
+        // This overwrites existing PathInfo objects with the same store path digest.
+        let mut db = self.db.write().await;
+        db.insert(*path_info.store_path.digest(), path_info.clone());
 
-            // In case the PathInfo is valid, and we were able to extract a NixPath, store it in the database.
-            // This overwrites existing PathInfo objects.
-            Ok(nix_path) => {
-                let mut db = self.db.write().await;
-                db.insert(*nix_path.digest(), path_info.clone());
-
-                Ok(path_info)
-            }
-        }
+        Ok(path_info)
     }
 
     fn list(&self) -> BoxStream<'static, Result<PathInfo, Error>> {
diff --git a/tvix/store/src/pathinfoservice/mod.rs b/tvix/store/src/pathinfoservice/mod.rs
index 8d60ff79a33b..0a91d6267260 100644
--- a/tvix/store/src/pathinfoservice/mod.rs
+++ b/tvix/store/src/pathinfoservice/mod.rs
@@ -19,7 +19,7 @@ use tvix_castore::composition::{Registry, ServiceBuilder};
 use tvix_castore::Error;
 
 use crate::nar::NarCalculationService;
-use crate::proto::PathInfo;
+pub use crate::path_info::PathInfo;
 
 pub use self::combinators::{
     Cache as CachePathInfoService, CacheConfig as CachePathInfoServiceConfig,
diff --git a/tvix/store/src/pathinfoservice/nix_http.rs b/tvix/store/src/pathinfoservice/nix_http.rs
index 2ff094858bc9..ed386f0e9d14 100644
--- a/tvix/store/src/pathinfoservice/nix_http.rs
+++ b/tvix/store/src/pathinfoservice/nix_http.rs
@@ -1,10 +1,11 @@
-use super::PathInfoService;
-use crate::{nar::ingest_nar_and_hash, proto::PathInfo};
+use super::{PathInfo, PathInfoService};
+use crate::nar::ingest_nar_and_hash;
 use futures::{stream::BoxStream, TryStreamExt};
 use nix_compat::{
-    narinfo::{self, NarInfo},
+    narinfo::{self, NarInfo, Signature},
     nixbase32,
     nixhash::NixHash,
+    store_path::StorePath,
 };
 use reqwest::StatusCode;
 use std::sync::Arc;
@@ -12,9 +13,7 @@ use tokio::io::{self, AsyncRead};
 use tonic::async_trait;
 use tracing::{debug, instrument, warn};
 use tvix_castore::composition::{CompositionContext, ServiceBuilder};
-use tvix_castore::{
-    blobservice::BlobService, directoryservice::DirectoryService, proto as castorepb, Error,
-};
+use tvix_castore::{blobservice::BlobService, directoryservice::DirectoryService, Error};
 use url::Url;
 
 /// NixHTTPPathInfoService acts as a bridge in between the Nix HTTP Binary cache
@@ -137,12 +136,11 @@ where
             }
         }
 
-        // Convert to a (sparse) PathInfo. We still need to populate the node field,
-        // and for this we need to download the NAR file.
+        // To construct the full PathInfo, we also need to populate the node field,
+        // and for this we need to download the NAR file and ingest it into castore.
         // FUTUREWORK: Keep some database around mapping from narsha256 to
         // (unnamed) rootnode, so we can use that (and the name from the
         // StorePath) and avoid downloading the same NAR a second time.
-        let pathinfo: PathInfo = (&narinfo).into();
 
         // create a request for the NAR file itself.
         let nar_url = self.base_url.join(narinfo.url).map_err(|e| {
@@ -228,12 +226,18 @@ where
         }
 
         Ok(Some(PathInfo {
-            node: Some(castorepb::Node::from_name_and_node(
-                narinfo.store_path.to_string().into(),
-                root_node,
-            )),
-            references: pathinfo.references,
-            narinfo: pathinfo.narinfo,
+            store_path: narinfo.store_path.to_owned(),
+            node: root_node,
+            references: narinfo.references.iter().map(StorePath::to_owned).collect(),
+            nar_size: narinfo.nar_size,
+            nar_sha256: narinfo.nar_hash,
+            deriver: narinfo.deriver.as_ref().map(StorePath::to_owned),
+            signatures: narinfo
+                .signatures
+                .into_iter()
+                .map(|s| Signature::<String>::new(s.name().to_string(), s.bytes().to_owned()))
+                .collect(),
+            ca: narinfo.ca,
         }))
     }
 
diff --git a/tvix/store/src/pathinfoservice/redb.rs b/tvix/store/src/pathinfoservice/redb.rs
index bd0e0fc2b686..6e794e1981f0 100644
--- a/tvix/store/src/pathinfoservice/redb.rs
+++ b/tvix/store/src/pathinfoservice/redb.rs
@@ -1,5 +1,5 @@
-use super::PathInfoService;
-use crate::proto::PathInfo;
+use super::{PathInfo, PathInfoService};
+use crate::proto;
 use data_encoding::BASE64;
 use futures::{stream::BoxStream, StreamExt};
 use prost::Message;
@@ -78,10 +78,13 @@ impl PathInfoService for RedbPathInfoService {
                 let table = txn.open_table(PATHINFO_TABLE)?;
                 match table.get(digest)? {
                     Some(pathinfo_bytes) => Ok(Some(
-                        PathInfo::decode(pathinfo_bytes.value().as_slice()).map_err(|e| {
-                            warn!(err=%e, "failed to decode stored PathInfo");
-                            Error::StorageError("failed to decode stored PathInfo".to_string())
-                        })?,
+                        proto::PathInfo::decode(pathinfo_bytes.value().as_slice())
+                            .map_err(|e| {
+                                warn!(err=%e, "failed to decode stored PathInfo");
+                                Error::StorageError("failed to decode stored PathInfo".to_string())
+                            })?
+                            .try_into()
+                            .map_err(|e| Error::StorageError(format!("Invalid path info: {e}")))?,
                     )),
                     None => Ok(None),
                 }
@@ -92,25 +95,19 @@ impl PathInfoService for RedbPathInfoService {
 
     #[instrument(level = "trace", skip_all, fields(path_info.root_node = ?path_info.node))]
     async fn put(&self, path_info: PathInfo) -> Result<PathInfo, Error> {
-        // Call validate on the received PathInfo message.
-        let store_path = path_info
-            .validate()
-            .map_err(|e| {
-                warn!(err=%e, "failed to validate PathInfo");
-                Error::StorageError("failed to validate PathInfo".to_string())
-            })?
-            .to_owned();
-
-        let path_info_encoded = path_info.encode_to_vec();
         let db = self.db.clone();
 
         tokio::task::spawn_blocking({
+            let path_info = path_info.clone();
             move || -> Result<(), Error> {
                 let txn = db.begin_write()?;
                 {
                     let mut table = txn.open_table(PATHINFO_TABLE)?;
                     table
-                        .insert(store_path.digest(), path_info_encoded)
+                        .insert(
+                            *path_info.store_path.digest(),
+                            proto::PathInfo::from(path_info).encode_to_vec(),
+                        )
                         .map_err(|e| {
                             warn!(err=%e, "failed to insert PathInfo");
                             Error::StorageError("failed to insert PathInfo".to_string())
@@ -137,12 +134,18 @@ impl PathInfoService for RedbPathInfoService {
                 for elem in table.iter()? {
                     let elem = elem?;
                     tokio::runtime::Handle::current()
-                        .block_on(tx.send(Ok(
-                            PathInfo::decode(elem.1.value().as_slice()).map_err(|e| {
+                        .block_on(tx.send(Ok({
+                            let path_info_proto = proto::PathInfo::decode(
+                                elem.1.value().as_slice(),
+                            )
+                            .map_err(|e| {
                                 warn!(err=%e, "invalid PathInfo");
                                 Error::StorageError("invalid PathInfo".to_string())
-                            })?,
-                        )))
+                            })?;
+                            PathInfo::try_from(path_info_proto).map_err(|e| {
+                                Error::StorageError(format!("Invalid path info: {e}"))
+                            })?
+                        })))
                         .map_err(|e| Error::StorageError(e.to_string()))?;
                 }
 
diff --git a/tvix/store/src/pathinfoservice/signing_wrapper.rs b/tvix/store/src/pathinfoservice/signing_wrapper.rs
index 7f754ec49849..3230e000ab96 100644
--- a/tvix/store/src/pathinfoservice/signing_wrapper.rs
+++ b/tvix/store/src/pathinfoservice/signing_wrapper.rs
@@ -1,7 +1,6 @@
 //! This module provides a [PathInfoService] implementation that signs narinfos
 
-use super::PathInfoService;
-use crate::proto::PathInfo;
+use super::{PathInfo, PathInfoService};
 use futures::stream::BoxStream;
 use std::path::PathBuf;
 use std::sync::Arc;
@@ -11,9 +10,9 @@ use tvix_castore::composition::{CompositionContext, ServiceBuilder};
 
 use tvix_castore::Error;
 
-use nix_compat::narinfo::{parse_keypair, SigningKey};
+use nix_compat::narinfo::{parse_keypair, Signature, SigningKey};
 use nix_compat::nixbase32;
-use tracing::{instrument, warn};
+use tracing::instrument;
 
 #[cfg(test)]
 use super::MemoryPathInfoService;
@@ -52,22 +51,15 @@ where
     }
 
     async fn put(&self, path_info: PathInfo) -> Result<PathInfo, Error> {
-        let store_path = path_info.validate().map_err(|e| {
-            warn!(err=%e, "invalid PathInfo");
-            Error::StorageError(e.to_string())
-        })?;
-        let root_node = path_info.node.clone();
-        // If we have narinfo then sign it, else passthrough to the upper pathinfoservice
-        let path_info_to_put = match path_info.to_narinfo(store_path.as_ref()) {
-            Some(mut nar_info) => {
-                nar_info.add_signature(self.signing_key.as_ref());
-                let mut signed_path_info = PathInfo::from(&nar_info);
-                signed_path_info.node = root_node;
-                signed_path_info
-            }
-            None => path_info,
-        };
-        self.inner.put(path_info_to_put).await
+        let mut path_info = path_info.clone();
+        let mut nar_info = path_info.to_narinfo();
+        nar_info.add_signature(self.signing_key.as_ref());
+        path_info.signatures = nar_info
+            .signatures
+            .into_iter()
+            .map(|s| Signature::<String>::new(s.name().to_string(), s.bytes().to_owned()))
+            .collect();
+        self.inner.put(path_info).await
     }
 
     fn list(&self) -> BoxStream<'static, Result<PathInfo, Error>> {
@@ -134,51 +126,35 @@ pub const DUMMY_VERIFYING_KEY: &str = "do.not.use:cuXqnuzlWfGTKmfzBPx2kXShjRryZM
 
 #[cfg(test)]
 mod test {
-    use crate::{
-        pathinfoservice::PathInfoService,
-        proto::PathInfo,
-        tests::fixtures::{DUMMY_PATH, PATH_INFO_WITH_NARINFO},
-    };
+    use crate::{pathinfoservice::PathInfoService, tests::fixtures::PATH_INFO};
     use nix_compat::narinfo::VerifyingKey;
 
-    use lazy_static::lazy_static;
-    use nix_compat::store_path::StorePath;
-
-    lazy_static! {
-        static ref PATHINFO_1: PathInfo = PATH_INFO_WITH_NARINFO.clone();
-        static ref PATHINFO_1_DIGEST: [u8; 20] = [0; 20];
-    }
-
     #[tokio::test]
     async fn put_and_verify_signature() {
         let svc = super::test_signing_service();
 
         // pathinfo_1 should not be there ...
         assert!(svc
-            .get(*PATHINFO_1_DIGEST)
+            .get(*PATH_INFO.store_path.digest())
             .await
             .expect("no error")
             .is_none());
 
         // ... and not be signed
-        assert!(PATHINFO_1.narinfo.clone().unwrap().signatures.is_empty());
+        assert!(PATH_INFO.signatures.is_empty());
 
         // insert it
-        svc.put(PATHINFO_1.clone()).await.expect("no error");
+        svc.put(PATH_INFO.clone()).await.expect("no error");
 
         // now it should be there ...
         let signed = svc
-            .get(*PATHINFO_1_DIGEST)
+            .get(*PATH_INFO.store_path.digest())
             .await
             .expect("no error")
             .unwrap();
 
         // and signed
-        let narinfo = signed
-            .to_narinfo(
-                StorePath::from_bytes(DUMMY_PATH.as_bytes()).expect("DUMMY_PATH to be parsed"),
-            )
-            .expect("no error");
+        let narinfo = signed.to_narinfo();
         let fp = narinfo.fingerprint();
 
         // load our keypair from the fixtures
diff --git a/tvix/store/src/pathinfoservice/tests/mod.rs b/tvix/store/src/pathinfoservice/tests/mod.rs
index 028fa5af57fc..12c685c80fad 100644
--- a/tvix/store/src/pathinfoservice/tests/mod.rs
+++ b/tvix/store/src/pathinfoservice/tests/mod.rs
@@ -6,12 +6,10 @@ use futures::TryStreamExt;
 use rstest::*;
 use rstest_reuse::{self, *};
 
-use super::PathInfoService;
+use super::{PathInfo, PathInfoService};
 use crate::pathinfoservice::redb::RedbPathInfoService;
 use crate::pathinfoservice::MemoryPathInfoService;
-use crate::proto::PathInfo;
-use crate::tests::fixtures::DUMMY_PATH_DIGEST;
-use tvix_castore::proto as castorepb;
+use crate::tests::fixtures::{DUMMY_PATH_DIGEST, PATH_INFO};
 
 use crate::pathinfoservice::test_signing_service;
 
@@ -52,32 +50,35 @@ async fn not_found(svc: impl PathInfoService) {
 #[apply(path_info_services)]
 #[tokio::test]
 async fn put_get(svc: impl PathInfoService) {
-    let path_info = PathInfo {
-        node: Some(castorepb::Node {
-            node: Some(castorepb::node::Node::Symlink(castorepb::SymlinkNode {
-                name: "00000000000000000000000000000000-foo".into(),
-                target: "doesntmatter".into(),
-            })),
-        }),
-        ..Default::default()
-    };
-
     // insert
-    let resp = svc.put(path_info.clone()).await.expect("must succeed");
+    let resp = svc.put(PATH_INFO.clone()).await.expect("must succeed");
 
-    // expect the returned PathInfo to be equal (for now)
-    // in the future, some stores might add additional fields/signatures.
-    assert_eq!(path_info, resp);
+    // expect the returned PathInfo to be equal,
+    // remove the signatures as the SigningPathInfoService adds them
+    assert_eq!(*PATH_INFO, strip_signatures(resp));
 
     // get it back
     let resp = svc.get(DUMMY_PATH_DIGEST).await.expect("must succeed");
 
-    assert_eq!(Some(path_info.clone()), resp);
+    assert_eq!(Some(PATH_INFO.clone()), resp.map(strip_signatures));
 
     // Ensure the listing endpoint works, and returns the same path_info.
     // FUTUREWORK: split this, some impls might (rightfully) not support listing
     let pathinfos: Vec<PathInfo> = svc.list().try_collect().await.expect("must succeed");
 
     // We should get a single pathinfo back, the one we inserted.
-    assert_eq!(vec![path_info], pathinfos);
+    assert_eq!(
+        vec![PATH_INFO.clone()],
+        pathinfos
+            .into_iter()
+            .map(strip_signatures)
+            .collect::<Vec<_>>()
+    );
+}
+
+fn strip_signatures(path_info: PathInfo) -> PathInfo {
+    PathInfo {
+        signatures: vec![],
+        ..path_info
+    }
 }
diff --git a/tvix/store/src/proto/grpc_pathinfoservice_wrapper.rs b/tvix/store/src/proto/grpc_pathinfoservice_wrapper.rs
index 60da73012df7..5da3b23c269c 100644
--- a/tvix/store/src/proto/grpc_pathinfoservice_wrapper.rs
+++ b/tvix/store/src/proto/grpc_pathinfoservice_wrapper.rs
@@ -1,5 +1,5 @@
 use crate::nar::{NarCalculationService, RenderError};
-use crate::pathinfoservice::PathInfoService;
+use crate::pathinfoservice::{PathInfo, PathInfoService};
 use crate::proto;
 use futures::{stream::BoxStream, TryStreamExt};
 use std::ops::Deref;
@@ -44,7 +44,7 @@ where
                     .map_err(|_e| Status::invalid_argument("invalid output digest length"))?;
                 match self.path_info_service.get(digest).await {
                     Ok(None) => Err(Status::not_found("PathInfo not found")),
-                    Ok(Some(path_info)) => Ok(Response::new(path_info)),
+                    Ok(Some(path_info)) => Ok(Response::new(proto::PathInfo::from(path_info))),
                     Err(e) => {
                         warn!(err = %e, "failed to get PathInfo");
                         Err(e.into())
@@ -56,12 +56,15 @@ where
 
     #[instrument(skip_all)]
     async fn put(&self, request: Request<proto::PathInfo>) -> Result<Response<proto::PathInfo>> {
-        let path_info = request.into_inner();
+        let path_info_proto = request.into_inner();
+
+        let path_info = PathInfo::try_from(path_info_proto)
+            .map_err(|e| Status::invalid_argument(format!("Invalid path info: {e}")))?;
 
         // Store the PathInfo in the client. Clients MUST validate the data
         // they receive, so we don't validate additionally here.
         match self.path_info_service.put(path_info).await {
-            Ok(path_info_new) => Ok(Response::new(path_info_new)),
+            Ok(path_info_new) => Ok(Response::new(proto::PathInfo::from(path_info_new))),
             Err(e) => {
                 warn!(err = %e, "failed to put PathInfo");
                 Err(e.into())
@@ -99,6 +102,7 @@ where
         let stream = Box::pin(
             self.path_info_service
                 .list()
+                .map_ok(proto::PathInfo::from)
                 .map_err(|e| Status::internal(e.to_string())),
         );
 
diff --git a/tvix/store/src/proto/mod.rs b/tvix/store/src/proto/mod.rs
index f3ea4b196946..807f03854ddc 100644
--- a/tvix/store/src/proto/mod.rs
+++ b/tvix/store/src/proto/mod.rs
@@ -4,7 +4,7 @@ use bytes::Bytes;
 use data_encoding::BASE64;
 // https://github.com/hyperium/tonic/issues/1056
 use nix_compat::{
-    narinfo::Flags,
+    narinfo::{Signature, SignatureError},
     nixhash::{CAHash, NixHash},
     store_path::{self, StorePathRef},
 };
@@ -17,6 +17,8 @@ pub use grpc_pathinfoservice_wrapper::GRPCPathInfoServiceWrapper;
 
 tonic::include_proto!("tvix.store.v1");
 
+use tvix_castore::proto as castorepb;
+
 #[cfg(feature = "tonic-reflection")]
 /// Compiled file descriptors for implementing [gRPC
 /// reflection](https://github.com/grpc/grpc/blob/master/doc/server-reflection.md) with e.g.
@@ -70,183 +72,18 @@ pub enum ValidatePathInfoError {
     /// The deriver field is invalid.
     #[error("deriver field is invalid: {0}")]
     InvalidDeriverField(store_path::Error),
-}
 
-/// Parses a root node name.
-///
-/// On success, this returns the parsed [store_path::StorePathRef].
-/// On error, it returns an error generated from the supplied constructor.
-fn parse_node_name_root<E>(
-    name: &[u8],
-    err: fn(Vec<u8>, store_path::Error) -> E,
-) -> Result<store_path::StorePathRef<'_>, E> {
-    store_path::StorePathRef::from_bytes(name).map_err(|e| err(name.to_vec(), e))
-}
+    /// The narinfo field is missing
+    #[error("The narinfo field is missing")]
+    NarInfoFieldMissing,
 
-impl PathInfo {
-    /// validate performs some checks on the PathInfo struct,
-    /// Returning either a [store_path::StorePath] of the root node, or a
-    /// [ValidatePathInfoError].
-    pub fn validate(&self) -> Result<store_path::StorePath<String>, ValidatePathInfoError> {
-        // ensure the references have the right number of bytes.
-        for (i, reference) in self.references.iter().enumerate() {
-            if reference.len() != store_path::DIGEST_SIZE {
-                return Err(ValidatePathInfoError::InvalidReferenceDigestLen(
-                    i,
-                    reference.len(),
-                ));
-            }
-        }
+    /// The ca field is invalid
+    #[error("The ca field is invalid: {0}")]
+    InvalidCaField(ConvertCAError),
 
-        // If there is a narinfo field populated…
-        if let Some(narinfo) = &self.narinfo {
-            // ensure the nar_sha256 digest has the correct length.
-            if narinfo.nar_sha256.len() != 32 {
-                return Err(ValidatePathInfoError::InvalidNarSha256DigestLen(
-                    narinfo.nar_sha256.len(),
-                ));
-            }
-
-            // ensure the number of references there matches PathInfo.references count.
-            if narinfo.reference_names.len() != self.references.len() {
-                return Err(ValidatePathInfoError::InconsistentNumberOfReferences(
-                    self.references.len(),
-                    narinfo.reference_names.len(),
-                ));
-            }
-
-            // parse references in reference_names.
-            for (i, reference_name_str) in narinfo.reference_names.iter().enumerate() {
-                // ensure thy parse as (non-absolute) store path
-                let reference_names_store_path = store_path::StorePathRef::from_bytes(
-                    reference_name_str.as_bytes(),
-                )
-                .map_err(|_| {
-                    ValidatePathInfoError::InvalidNarinfoReferenceName(
-                        i,
-                        reference_name_str.to_owned(),
-                    )
-                })?;
-
-                // ensure their digest matches the one at self.references[i].
-                {
-                    // This is safe, because we ensured the proper length earlier already.
-                    let reference_digest = self.references[i].to_vec().try_into().unwrap();
-
-                    if reference_names_store_path.digest() != &reference_digest {
-                        return Err(
-                            ValidatePathInfoError::InconsistentNarinfoReferenceNameDigest(
-                                i,
-                                reference_digest,
-                                *reference_names_store_path.digest(),
-                            ),
-                        );
-                    }
-                }
-
-                // If the Deriver field is populated, ensure it parses to a
-                // [store_path::StorePath].
-                // We can't check for it to *not* end with .drv, as the .drv files produced by
-                // recursive Nix end with multiple .drv suffixes, and only one is popped when
-                // converting to this field.
-                if let Some(deriver) = &narinfo.deriver {
-                    store_path::StorePathRef::from_name_and_digest(&deriver.name, &deriver.digest)
-                        .map_err(ValidatePathInfoError::InvalidDeriverField)?;
-                }
-            }
-        }
-
-        // Ensure there is a (root) node present, and it properly parses to a [store_path::StorePath].
-        let root_nix_path = match &self.node {
-            None => Err(ValidatePathInfoError::NoNodePresent)?,
-            Some(node) => {
-                // NOTE: We could have some PathComponent not allocating here,
-                // so this can return StorePathRef.
-                // However, as this will get refactored away to stricter types
-                // soon anyways, there's no point.
-                let (name, _node) = node
-                    .clone()
-                    .into_name_and_node()
-                    .map_err(ValidatePathInfoError::InvalidRootNode)?;
-
-                // parse the name of the node itself and return
-                parse_node_name_root(name.as_ref(), ValidatePathInfoError::InvalidNodeName)?
-                    .to_owned()
-            }
-        };
-
-        // return the root nix path
-        Ok(root_nix_path)
-    }
-
-    /// With self and its store path name, this reconstructs a
-    /// [nix_compat::narinfo::NarInfo<'_>].
-    /// It can be used to validate Signatures, or get back a (sparse) NarInfo
-    /// struct to prepare writing it out.
-    ///
-    /// It assumes self to be validated first, and will only return None if the
-    /// `narinfo` field is unpopulated.
-    ///
-    /// It does very little allocation (a Vec each for `signatures` and
-    /// `references`), the rest points to data owned elsewhere.
-    ///
-    /// Keep in mind this is not able to reconstruct all data present in the
-    /// NarInfo<'_>, as some of it is not stored at all:
-    /// - the `system`, `file_hash` and `file_size` fields are set to `None`.
-    /// - the URL is set to an empty string.
-    /// - Compression is set to "none"
-    ///
-    /// If you want to render it out to a string and be able to parse it back
-    /// in, at least URL *must* be set again.
-    pub fn to_narinfo<'a>(
-        &'a self,
-        store_path: store_path::StorePathRef<'a>,
-    ) -> Option<nix_compat::narinfo::NarInfo<'_>> {
-        let narinfo = &self.narinfo.as_ref()?;
-
-        Some(nix_compat::narinfo::NarInfo {
-            flags: Flags::empty(),
-            store_path,
-            nar_hash: narinfo
-                .nar_sha256
-                .as_ref()
-                .try_into()
-                .expect("invalid narhash"),
-            nar_size: narinfo.nar_size,
-            references: narinfo
-                .reference_names
-                .iter()
-                .map(|ref_name| {
-                    // This shouldn't pass validation
-                    StorePathRef::from_bytes(ref_name.as_bytes()).expect("invalid reference")
-                })
-                .collect(),
-            signatures: narinfo
-                .signatures
-                .iter()
-                .map(|sig| {
-                    nix_compat::narinfo::SignatureRef::new(
-                        &sig.name,
-                        // This shouldn't pass validation
-                        sig.data[..].try_into().expect("invalid signature len"),
-                    )
-                })
-                .collect(),
-            ca: narinfo
-                .ca
-                .as_ref()
-                .map(|ca| ca.try_into().expect("invalid ca")),
-            system: None,
-            deriver: narinfo.deriver.as_ref().map(|deriver| {
-                StorePathRef::from_name_and_digest(&deriver.name, &deriver.digest)
-                    .expect("invalid deriver")
-            }),
-            url: "",
-            compression: Some("none"),
-            file_hash: None,
-            file_size: None,
-        })
-    }
+    /// The signature at position is invalid
+    #[error("The signature at position {0} is invalid: {1}")]
+    InvalidSignature(usize, SignatureError),
 }
 
 /// Errors that can occur when converting from a [nar_info::Ca] to a (stricter)
@@ -341,45 +178,154 @@ impl From<&nix_compat::nixhash::CAHash> for nar_info::Ca {
     }
 }
 
-impl From<&nix_compat::narinfo::NarInfo<'_>> for NarInfo {
-    /// Converts from a NarInfo (returned from the NARInfo parser) to the proto-
-    /// level NarInfo struct.
-    fn from(value: &nix_compat::narinfo::NarInfo<'_>) -> Self {
-        let signatures = value
-            .signatures
-            .iter()
-            .map(|sig| nar_info::Signature {
-                name: sig.name().to_string(),
-                data: Bytes::copy_from_slice(sig.bytes()),
-            })
-            .collect();
-
-        NarInfo {
-            nar_size: value.nar_size,
-            nar_sha256: Bytes::copy_from_slice(&value.nar_hash),
-            signatures,
-            reference_names: value.references.iter().map(|r| r.to_string()).collect(),
-            deriver: value.deriver.as_ref().map(|sp| StorePath {
-                name: (*sp.name()).to_owned(),
-                digest: Bytes::copy_from_slice(sp.digest()),
-            }),
-            ca: value.ca.as_ref().map(|ca| ca.into()),
-        }
-    }
-}
-
-impl From<&nix_compat::narinfo::NarInfo<'_>> for PathInfo {
-    /// Converts from a NarInfo (returned from the NARInfo parser) to a PathInfo
-    /// struct with the node set to None.
-    fn from(value: &nix_compat::narinfo::NarInfo<'_>) -> Self {
+impl From<crate::pathinfoservice::PathInfo> for PathInfo {
+    fn from(value: crate::pathinfoservice::PathInfo) -> Self {
         Self {
-            node: None,
+            node: Some(castorepb::Node::from_name_and_node(
+                value.store_path.to_string().into_bytes().into(),
+                value.node,
+            )),
             references: value
                 .references
                 .iter()
-                .map(|x| Bytes::copy_from_slice(x.digest()))
+                .map(|reference| Bytes::copy_from_slice(reference.digest()))
                 .collect(),
-            narinfo: Some(value.into()),
+            narinfo: Some(NarInfo {
+                nar_size: value.nar_size,
+                nar_sha256: Bytes::copy_from_slice(&value.nar_sha256),
+                signatures: value
+                    .signatures
+                    .iter()
+                    .map(|sig| nar_info::Signature {
+                        name: sig.name().to_string(),
+                        data: Bytes::copy_from_slice(sig.bytes()),
+                    })
+                    .collect(),
+                reference_names: value.references.iter().map(|r| r.to_string()).collect(),
+                deriver: value.deriver.as_ref().map(|sp| StorePath {
+                    name: (*sp.name()).to_owned(),
+                    digest: Bytes::copy_from_slice(sp.digest()),
+                }),
+                ca: value.ca.as_ref().map(|ca| ca.into()),
+            }),
+        }
+    }
+}
+
+impl TryFrom<PathInfo> for crate::pathinfoservice::PathInfo {
+    type Error = ValidatePathInfoError;
+    fn try_from(value: PathInfo) -> Result<Self, Self::Error> {
+        let narinfo = value
+            .narinfo
+            .ok_or_else(|| ValidatePathInfoError::NarInfoFieldMissing)?;
+
+        // ensure the references have the right number of bytes.
+        for (i, reference) in value.references.iter().enumerate() {
+            if reference.len() != store_path::DIGEST_SIZE {
+                return Err(ValidatePathInfoError::InvalidReferenceDigestLen(
+                    i,
+                    reference.len(),
+                ));
+            }
+        }
+
+        // ensure the number of references there matches PathInfo.references count.
+        if narinfo.reference_names.len() != value.references.len() {
+            return Err(ValidatePathInfoError::InconsistentNumberOfReferences(
+                value.references.len(),
+                narinfo.reference_names.len(),
+            ));
+        }
+
+        // parse references in reference_names.
+        let mut references = vec![];
+        for (i, reference_name_str) in narinfo.reference_names.iter().enumerate() {
+            // ensure thy parse as (non-absolute) store path
+            let reference_names_store_path =
+                StorePathRef::from_bytes(reference_name_str.as_bytes()).map_err(|_| {
+                    ValidatePathInfoError::InvalidNarinfoReferenceName(
+                        i,
+                        reference_name_str.to_owned(),
+                    )
+                })?;
+
+            // ensure their digest matches the one at self.references[i].
+            {
+                // This is safe, because we ensured the proper length earlier already.
+                let reference_digest = value.references[i].to_vec().try_into().unwrap();
+
+                if reference_names_store_path.digest() != &reference_digest {
+                    return Err(
+                        ValidatePathInfoError::InconsistentNarinfoReferenceNameDigest(
+                            i,
+                            reference_digest,
+                            *reference_names_store_path.digest(),
+                        ),
+                    );
+                } else {
+                    references.push(reference_names_store_path.to_owned());
+                }
+            }
         }
+
+        let nar_sha256_length = narinfo.nar_sha256.len();
+
+        // split value.node into the name and node components
+        let (name, node) = value
+            .node
+            .ok_or_else(|| ValidatePathInfoError::NoNodePresent)?
+            .into_name_and_node()
+            .map_err(ValidatePathInfoError::InvalidRootNode)?;
+
+        Ok(Self {
+            // value.node has a valid name according to the castore model but might not parse to a
+            // [StorePath]
+            store_path: nix_compat::store_path::StorePath::from_bytes(name.as_ref()).map_err(
+                |err| ValidatePathInfoError::InvalidNodeName(name.as_ref().to_vec(), err),
+            )?,
+            node,
+            references,
+            nar_size: narinfo.nar_size,
+            nar_sha256: narinfo.nar_sha256.to_vec()[..]
+                .try_into()
+                .map_err(|_| ValidatePathInfoError::InvalidNarSha256DigestLen(nar_sha256_length))?,
+            // If the Deriver field is populated, ensure it parses to a
+            // [StorePath].
+            // We can't check for it to *not* end with .drv, as the .drv files produced by
+            // recursive Nix end with multiple .drv suffixes, and only one is popped when
+            // converting to this field.
+            deriver: narinfo
+                .deriver
+                .map(|deriver| {
+                    nix_compat::store_path::StorePath::from_name_and_digest(
+                        &deriver.name,
+                        &deriver.digest,
+                    )
+                    .map_err(ValidatePathInfoError::InvalidDeriverField)
+                })
+                .transpose()?,
+            signatures: narinfo
+                .signatures
+                .into_iter()
+                .enumerate()
+                .map(|(i, signature)| {
+                    signature.data.to_vec()[..]
+                        .try_into()
+                        .map_err(|_| {
+                            ValidatePathInfoError::InvalidSignature(
+                                i,
+                                SignatureError::InvalidSignatureLen(signature.data.len()),
+                            )
+                        })
+                        .map(|signature_data| Signature::new(signature.name, signature_data))
+                })
+                .collect::<Result<Vec<_>, ValidatePathInfoError>>()?,
+            ca: narinfo
+                .ca
+                .as_ref()
+                .map(TryFrom::try_from)
+                .transpose()
+                .map_err(ValidatePathInfoError::InvalidCaField)?,
+        })
     }
 }
diff --git a/tvix/store/src/proto/tests/pathinfo.rs b/tvix/store/src/proto/tests/pathinfo.rs
index f5ecc798bbfb..320f419b6c59 100644
--- a/tvix/store/src/proto/tests/pathinfo.rs
+++ b/tvix/store/src/proto/tests/pathinfo.rs
@@ -1,274 +1,226 @@
-use crate::proto::{nar_info::Signature, NarInfo, PathInfo, ValidatePathInfoError};
-use crate::tests::fixtures::*;
+use crate::pathinfoservice::PathInfo;
+use crate::proto::{self, ValidatePathInfoError};
+use crate::tests::fixtures::{DUMMY_PATH, DUMMY_PATH_DIGEST, DUMMY_PATH_STR};
 use bytes::Bytes;
-use data_encoding::BASE64;
-use nix_compat::nixbase32;
-use nix_compat::store_path::{self, StorePath, StorePathRef};
+use lazy_static::lazy_static;
+use nix_compat::store_path;
 use rstest::rstest;
+use tvix_castore::fixtures::DUMMY_DIGEST;
 use tvix_castore::proto as castorepb;
 use tvix_castore::{DirectoryError, ValidateNodeError};
 
-#[rstest]
-#[case::no_node(None, Err(ValidatePathInfoError::NoNodePresent))]
-#[case::no_node_2(Some(castorepb::Node { node: None}), Err(ValidatePathInfoError::InvalidRootNode(DirectoryError::NoNodeSet)))]
+lazy_static! {
+    /// A valid PathInfo message
+    /// The references in `narinfo.reference_names` aligns with what's in
+    /// `references`.
+    static ref PROTO_PATH_INFO : proto::PathInfo = proto::PathInfo {
+        node: Some(castorepb::Node {
+            node: Some(castorepb::node::Node::Directory(castorepb::DirectoryNode {
+                name: DUMMY_PATH_STR.into(),
+                digest: DUMMY_DIGEST.clone().into(),
+                size: 0,
+            })),
+        }),
+        references: vec![DUMMY_PATH_DIGEST.as_slice().into()],
+        narinfo: Some(proto::NarInfo {
+            nar_size: 0,
+            nar_sha256: DUMMY_DIGEST.clone().into(),
+            signatures: vec![],
+            reference_names: vec![DUMMY_PATH_STR.to_string()],
+            deriver: None,
+            ca: Some(proto::nar_info::Ca { r#type: proto::nar_info::ca::Hash::NarSha256.into(), digest:  DUMMY_DIGEST.clone().into() })
+        }),
+    };
+}
+
+#[test]
+fn convert_valid() {
+    let path_info = PROTO_PATH_INFO.clone();
+    PathInfo::try_from(path_info).expect("must succeed");
+}
+
+/// Create a PathInfo with a correct deriver field and ensure it succeeds.
+#[test]
+fn convert_valid_deriver() {
+    let mut path_info = PROTO_PATH_INFO.clone();
+
+    // add a valid deriver
+    let narinfo = path_info.narinfo.as_mut().unwrap();
+    narinfo.deriver = Some(crate::proto::StorePath {
+        name: DUMMY_PATH.name().to_string(),
+        digest: Bytes::from(DUMMY_PATH_DIGEST.as_slice()),
+    });
 
-fn validate_pathinfo(
+    let path_info = PathInfo::try_from(path_info).expect("must succeed");
+    assert_eq!(DUMMY_PATH.clone(), path_info.deriver.unwrap())
+}
+
+#[rstest]
+#[case::no_node(None, ValidatePathInfoError::NoNodePresent)]
+#[case::no_node_2(Some(castorepb::Node { node: None}), ValidatePathInfoError::InvalidRootNode(DirectoryError::NoNodeSet))]
+fn convert_pathinfo_wrong_nodes(
     #[case] node: Option<castorepb::Node>,
-    #[case] exp_result: Result<StorePath<String>, ValidatePathInfoError>,
+    #[case] exp_err: ValidatePathInfoError,
 ) {
     // construct the PathInfo object
-    let p = PathInfo {
-        node,
-        ..Default::default()
-    };
+    let mut path_info = PROTO_PATH_INFO.clone();
+    path_info.node = node;
 
-    assert_eq!(exp_result, p.validate());
+    assert_eq!(
+        exp_err,
+        PathInfo::try_from(path_info).expect_err("must fail")
+    );
 }
 
+/// Constructs a [proto::PathInfo] with root nodes that have wrong data in
+/// various places, causing the conversion to [PathInfo] to fail.
 #[rstest]
-#[case::ok(castorepb::DirectoryNode {
-        name: DUMMY_PATH.into(),
-        digest: DUMMY_DIGEST.clone().into(),
-        size: 0,
-}, Ok(StorePath::from_bytes(DUMMY_PATH.as_bytes()).unwrap()))]
-#[case::invalid_digest_length(castorepb::DirectoryNode {
-        name: DUMMY_PATH.into(),
+#[case::directory_invalid_digest_length(
+    castorepb::node::Node::Directory(castorepb::DirectoryNode {
+        name: DUMMY_PATH_STR.into(),
         digest: Bytes::new(),
         size: 0,
-}, Err(ValidatePathInfoError::InvalidRootNode(DirectoryError::InvalidNode(DUMMY_PATH.into(), ValidateNodeError::InvalidDigestLen(0)))))]
-#[case::invalid_node_name_no_storepath(castorepb::DirectoryNode {
+    }),
+    ValidatePathInfoError::InvalidRootNode(DirectoryError::InvalidNode(DUMMY_PATH_STR.into(), ValidateNodeError::InvalidDigestLen(0)))
+)]
+#[case::directory_invalid_node_name_no_storepath(
+    castorepb::node::Node::Directory(castorepb::DirectoryNode {
         name: "invalid".into(),
         digest: DUMMY_DIGEST.clone().into(),
         size: 0,
-}, Err(ValidatePathInfoError::InvalidNodeName(
-        "invalid".into(),
-        store_path::Error::InvalidLength
-)))]
-fn validate_directory(
-    #[case] directory_node: castorepb::DirectoryNode,
-    #[case] exp_result: Result<StorePath<String>, ValidatePathInfoError>,
-) {
-    // construct the PathInfo object
-    let p = PathInfo {
-        node: Some(castorepb::Node {
-            node: Some(castorepb::node::Node::Directory(directory_node)),
-        }),
-        ..Default::default()
-    };
-    assert_eq!(exp_result, p.validate());
-}
-
-#[rstest]
-#[case::ok(
-    castorepb::FileNode {
-        name: DUMMY_PATH.into(),
-        digest: DUMMY_DIGEST.clone().into(),
-        size: 0,
-        executable: false,
-    },
-    Ok(StorePath::from_bytes(DUMMY_PATH.as_bytes()).unwrap())
+    }),
+    ValidatePathInfoError::InvalidNodeName("invalid".into(), store_path::Error::InvalidLength)
 )]
-#[case::invalid_digest_len(
-    castorepb::FileNode {
-        name: DUMMY_PATH.into(),
+#[case::file_invalid_digest_len(
+    castorepb::node::Node::File(castorepb::FileNode {
+        name: DUMMY_PATH_STR.into(),
         digest: Bytes::new(),
         ..Default::default()
-    },
-    Err(ValidatePathInfoError::InvalidRootNode(DirectoryError::InvalidNode(DUMMY_PATH.into(), ValidateNodeError::InvalidDigestLen(0))))
+    }),
+    ValidatePathInfoError::InvalidRootNode(DirectoryError::InvalidNode(DUMMY_PATH_STR.into(), ValidateNodeError::InvalidDigestLen(0)))
 )]
-#[case::invalid_node_name(
-    castorepb::FileNode {
+#[case::file_invalid_node_name(
+    castorepb::node::Node::File(castorepb::FileNode {
         name: "invalid".into(),
         digest: DUMMY_DIGEST.clone().into(),
         ..Default::default()
-    },
-    Err(ValidatePathInfoError::InvalidNodeName(
+    }),
+    ValidatePathInfoError::InvalidNodeName(
         "invalid".into(),
         store_path::Error::InvalidLength
-    ))
-)]
-fn validate_file(
-    #[case] file_node: castorepb::FileNode,
-    #[case] exp_result: Result<StorePath<String>, ValidatePathInfoError>,
-) {
-    // construct the PathInfo object
-    let p = PathInfo {
-        node: Some(castorepb::Node {
-            node: Some(castorepb::node::Node::File(file_node)),
-        }),
-        ..Default::default()
-    };
-    assert_eq!(exp_result, p.validate());
-}
-
-#[rstest]
-#[case::ok(
-    castorepb::SymlinkNode {
-        name: DUMMY_PATH.into(),
-        target: "foo".into(),
-    },
-    Ok(StorePath::from_bytes(DUMMY_PATH.as_bytes()).unwrap())
+    )
 )]
-#[case::invalid_node_name(
-    castorepb::SymlinkNode {
+#[case::symlink_invalid_node_name(
+    castorepb::node::Node::Symlink(castorepb::SymlinkNode {
         name: "invalid".into(),
         target: "foo".into(),
-    },
-    Err(ValidatePathInfoError::InvalidNodeName(
+    }),
+    ValidatePathInfoError::InvalidNodeName(
         "invalid".into(),
         store_path::Error::InvalidLength
-    ))
+    )
 )]
-fn validate_symlink(
-    #[case] symlink_node: castorepb::SymlinkNode,
-    #[case] exp_result: Result<StorePath<String>, ValidatePathInfoError>,
-) {
-    // construct the PathInfo object
-    let p = PathInfo {
-        node: Some(castorepb::Node {
-            node: Some(castorepb::node::Node::Symlink(symlink_node)),
-        }),
-        ..Default::default()
-    };
-    assert_eq!(exp_result, p.validate());
-}
+fn convert_fail_node(#[case] node: castorepb::node::Node, #[case] exp_err: ValidatePathInfoError) {
+    // construct the proto::PathInfo object
+    let mut p = PROTO_PATH_INFO.clone();
+    p.node = Some(castorepb::Node { node: Some(node) });
 
-/// Ensure parsing a correct PathInfo without narinfo populated succeeds.
-#[test]
-fn validate_references_without_narinfo_ok() {
-    assert!(PATH_INFO_WITHOUT_NARINFO.validate().is_ok());
+    assert_eq!(exp_err, PathInfo::try_from(p).expect_err("must fail"));
 }
 
-/// Ensure parsing a correct PathInfo with narinfo populated succeeds.
+/// Ensure a PathInfo without narinfo populated fails converting!
 #[test]
-fn validate_references_with_narinfo_ok() {
-    assert!(PATH_INFO_WITH_NARINFO.validate().is_ok());
+fn convert_without_narinfo_fail() {
+    let mut path_info = PROTO_PATH_INFO.clone();
+    path_info.narinfo = None;
+
+    assert_eq!(
+        ValidatePathInfoError::NarInfoFieldMissing,
+        PathInfo::try_from(path_info).expect_err("must fail"),
+    );
 }
 
 /// Create a PathInfo with a wrong digest length in narinfo.nar_sha256, and
-/// ensure validation fails.
+/// ensure conversion fails.
 #[test]
-fn validate_wrong_nar_sha256() {
-    let mut path_info = PATH_INFO_WITH_NARINFO.clone();
+fn convert_wrong_nar_sha256() {
+    let mut path_info = PROTO_PATH_INFO.clone();
     path_info.narinfo.as_mut().unwrap().nar_sha256 = vec![0xbe, 0xef].into();
 
-    match path_info.validate().expect_err("must_fail") {
-        ValidatePathInfoError::InvalidNarSha256DigestLen(2) => {}
-        e => panic!("unexpected error: {:?}", e),
-    };
+    assert_eq!(
+        ValidatePathInfoError::InvalidNarSha256DigestLen(2),
+        PathInfo::try_from(path_info).expect_err("must fail")
+    );
 }
 
 /// Create a PathInfo with a wrong count of narinfo.reference_names,
 /// and ensure validation fails.
 #[test]
-fn validate_inconsistent_num_refs_fail() {
-    let mut path_info = PATH_INFO_WITH_NARINFO.clone();
+fn convert_inconsistent_num_refs_fail() {
+    let mut path_info = PROTO_PATH_INFO.clone();
     path_info.narinfo.as_mut().unwrap().reference_names = vec![];
 
-    match path_info.validate().expect_err("must_fail") {
-        ValidatePathInfoError::InconsistentNumberOfReferences(1, 0) => {}
-        e => panic!("unexpected error: {:?}", e),
-    };
+    assert_eq!(
+        ValidatePathInfoError::InconsistentNumberOfReferences(1, 0),
+        PathInfo::try_from(path_info).expect_err("must fail")
+    );
 }
 
 /// Create a PathInfo with a wrong digest length in references.
 #[test]
-fn validate_invalid_reference_digest_len() {
-    let mut path_info = PATH_INFO_WITHOUT_NARINFO.clone();
+fn convert_invalid_reference_digest_len() {
+    let mut path_info = PROTO_PATH_INFO.clone();
     path_info.references.push(vec![0xff, 0xff].into());
 
-    match path_info.validate().expect_err("must fail") {
+    assert_eq!(
         ValidatePathInfoError::InvalidReferenceDigestLen(
             1, // position
             2, // unexpected digest len
-        ) => {}
-        e => panic!("unexpected error: {:?}", e),
-    };
+        ),
+        PathInfo::try_from(path_info).expect_err("must fail")
+    );
 }
 
 /// Create a PathInfo with a narinfo.reference_name[1] that is no valid store path.
 #[test]
-fn validate_invalid_narinfo_reference_name() {
-    let mut path_info = PATH_INFO_WITH_NARINFO.clone();
+fn convert_invalid_narinfo_reference_name() {
+    let mut path_info = PROTO_PATH_INFO.clone();
 
     // This is invalid, as the store prefix is not part of reference_names.
     path_info.narinfo.as_mut().unwrap().reference_names[0] =
         "/nix/store/00000000000000000000000000000000-dummy".to_string();
 
-    match path_info.validate().expect_err("must fail") {
-        ValidatePathInfoError::InvalidNarinfoReferenceName(0, reference_name) => {
-            assert_eq!(
-                "/nix/store/00000000000000000000000000000000-dummy",
-                reference_name
-            );
-        }
-        e => panic!("unexpected error: {:?}", e),
-    }
+    assert_eq!(
+        ValidatePathInfoError::InvalidNarinfoReferenceName(
+            0,
+            "/nix/store/00000000000000000000000000000000-dummy".to_string()
+        ),
+        PathInfo::try_from(path_info).expect_err("must fail")
+    );
 }
 
 /// Create a PathInfo with a narinfo.reference_name[0] that doesn't match references[0].
 #[test]
-fn validate_inconsistent_narinfo_reference_name_digest() {
-    let mut path_info = PATH_INFO_WITH_NARINFO.clone();
+fn convert_inconsistent_narinfo_reference_name_digest() {
+    let mut path_info = PROTO_PATH_INFO.clone();
 
     // mutate the first reference, they were all zeroes before
     path_info.references[0] = vec![0xff; store_path::DIGEST_SIZE].into();
 
-    match path_info.validate().expect_err("must fail") {
-        ValidatePathInfoError::InconsistentNarinfoReferenceNameDigest(0, e_expected, e_actual) => {
-            assert_eq!(path_info.references[0][..], e_expected[..]);
-            assert_eq!(DUMMY_PATH_DIGEST, e_actual);
-        }
-        e => panic!("unexpected error: {:?}", e),
-    }
-}
-
-/// Create a node with an empty symlink target, and ensure it fails validation.
-#[test]
-fn validate_symlink_empty_target_invalid() {
-    castorepb::Node {
-        node: Some(castorepb::node::Node::Symlink(castorepb::SymlinkNode {
-            name: "foo".into(),
-            target: "".into(),
-        })),
-    }
-    .into_name_and_node()
-    .expect_err("must fail validation");
-}
-
-/// Create a node with a symlink target including null bytes, and ensure it
-/// fails validation.
-#[test]
-fn validate_symlink_target_null_byte_invalid() {
-    castorepb::Node {
-        node: Some(castorepb::node::Node::Symlink(castorepb::SymlinkNode {
-            name: "foo".into(),
-            target: "foo\0".into(),
-        })),
-    }
-    .into_name_and_node()
-    .expect_err("must fail validation");
-}
-
-/// Create a PathInfo with a correct deriver field and ensure it succeeds.
-#[test]
-fn validate_valid_deriver() {
-    let mut path_info = PATH_INFO_WITH_NARINFO.clone();
-
-    // add a valid deriver
-    let narinfo = path_info.narinfo.as_mut().unwrap();
-    narinfo.deriver = Some(crate::proto::StorePath {
-        name: "foo".to_string(),
-        digest: Bytes::from(DUMMY_PATH_DIGEST.as_slice()),
-    });
-
-    path_info.validate().expect("must validate");
+    assert_eq!(
+        ValidatePathInfoError::InconsistentNarinfoReferenceNameDigest(
+            0,
+            path_info.references[0][..].try_into().unwrap(),
+            DUMMY_PATH_DIGEST
+        ),
+        PathInfo::try_from(path_info).expect_err("must fail")
+    )
 }
 
 /// Create a PathInfo with a broken deriver field and ensure it fails.
 #[test]
-fn validate_invalid_deriver() {
-    let mut path_info = PATH_INFO_WITH_NARINFO.clone();
+fn convert_invalid_deriver() {
+    let mut path_info = PROTO_PATH_INFO.clone();
 
     // add a broken deriver (invalid digest)
     let narinfo = path_info.narinfo.as_mut().unwrap();
@@ -277,157 +229,8 @@ fn validate_invalid_deriver() {
         digest: vec![].into(),
     });
 
-    match path_info.validate().expect_err("must fail validation") {
-        ValidatePathInfoError::InvalidDeriverField(_) => {}
-        e => panic!("unexpected error: {:?}", e),
-    }
-}
-
-#[test]
-fn from_nixcompat_narinfo() {
-    let narinfo_parsed = nix_compat::narinfo::NarInfo::parse(
-        r#"StorePath: /nix/store/s66mzxpvicwk07gjbjfw9izjfa797vsw-hello-2.12.1
-URL: nar/1nhgq6wcggx0plpy4991h3ginj6hipsdslv4fd4zml1n707j26yq.nar.xz
-Compression: xz
-FileHash: sha256:1nhgq6wcggx0plpy4991h3ginj6hipsdslv4fd4zml1n707j26yq
-FileSize: 50088
-NarHash: sha256:0yzhigwjl6bws649vcs2asa4lbs8hg93hyix187gc7s7a74w5h80
-NarSize: 226488
-References: 3n58xw4373jp0ljirf06d8077j15pc4j-glibc-2.37-8 s66mzxpvicwk07gjbjfw9izjfa797vsw-hello-2.12.1
-Deriver: ib3sh3pcz10wsmavxvkdbayhqivbghlq-hello-2.12.1.drv
-Sig: cache.nixos.org-1:8ijECciSFzWHwwGVOIVYdp2fOIOJAfmzGHPQVwpktfTQJF6kMPPDre7UtFw3o+VqenC5P8RikKOAAfN7CvPEAg=="#).expect("must parse");
-
-    assert_eq!(
-        PathInfo {
-            node: None,
-            references: vec![
-                Bytes::copy_from_slice(&nixbase32::decode_fixed::<20>("3n58xw4373jp0ljirf06d8077j15pc4j").unwrap()),
-                Bytes::copy_from_slice(&nixbase32::decode_fixed::<20>("s66mzxpvicwk07gjbjfw9izjfa797vsw").unwrap()),
-            ],
-            narinfo: Some(
-                NarInfo {
-                    nar_size: 226488,
-                    nar_sha256: Bytes::copy_from_slice(
-                        &nixbase32::decode_fixed::<32>("0yzhigwjl6bws649vcs2asa4lbs8hg93hyix187gc7s7a74w5h80".as_bytes())
-                            .unwrap()
-                    ),
-                    signatures: vec![Signature {
-                        name: "cache.nixos.org-1".to_string(),
-                        data: BASE64.decode("8ijECciSFzWHwwGVOIVYdp2fOIOJAfmzGHPQVwpktfTQJF6kMPPDre7UtFw3o+VqenC5P8RikKOAAfN7CvPEAg==".as_bytes()).unwrap().into(),
-                    }],
-                    reference_names: vec![
-                        "3n58xw4373jp0ljirf06d8077j15pc4j-glibc-2.37-8".to_string(),
-                        "s66mzxpvicwk07gjbjfw9izjfa797vsw-hello-2.12.1".to_string()
-                    ],
-                    deriver: Some(crate::proto::StorePath {
-                        digest: Bytes::copy_from_slice(&nixbase32::decode_fixed::<20>("ib3sh3pcz10wsmavxvkdbayhqivbghlq").unwrap()),
-                        name: "hello-2.12.1".to_string(),
-                     }),
-                    ca: None,
-                }
-            )
-        },
-        (&narinfo_parsed).into(),
-    );
-}
-
-#[test]
-fn from_nixcompat_narinfo_fod() {
-    let narinfo_parsed = nix_compat::narinfo::NarInfo::parse(
-        r#"StorePath: /nix/store/pa10z4ngm0g83kx9mssrqzz30s84vq7k-hello-2.12.1.tar.gz
-URL: nar/1zjrhzhaizsrlsvdkqfl073vivmxcqnzkff4s50i0cdf541ary1r.nar.xz
-Compression: xz
-FileHash: sha256:1zjrhzhaizsrlsvdkqfl073vivmxcqnzkff4s50i0cdf541ary1r
-FileSize: 1033524
-NarHash: sha256:1lvqpbk2k1sb39z8jfxixf7p7v8sj4z6mmpa44nnmff3w1y6h8lh
-NarSize: 1033416
-References: 
-Deriver: dyivpmlaq2km6c11i0s6bi6mbsx0ylqf-hello-2.12.1.tar.gz.drv
-Sig: cache.nixos.org-1:ywnIG629nQZQhEr6/HLDrLT/mUEp5J1LC6NmWSlJRWL/nM7oGItJQUYWGLvYGhSQvHrhIuvMpjNmBNh/WWqCDg==
-CA: fixed:sha256:086vqwk2wl8zfs47sq2xpjc9k066ilmb8z6dn0q6ymwjzlm196cd"#
-    ).expect("must parse");
-
-    assert_eq!(
-        PathInfo {
-            node: None,
-            references: vec![],
-            narinfo: Some(
-                NarInfo {
-                    nar_size: 1033416,
-                    nar_sha256: Bytes::copy_from_slice(
-                        &nixbase32::decode_fixed::<32>(
-                            "1lvqpbk2k1sb39z8jfxixf7p7v8sj4z6mmpa44nnmff3w1y6h8lh"
-                        )
-                        .unwrap()
-                    ),
-                    signatures: vec![Signature {
-                        name: "cache.nixos.org-1".to_string(),
-                        data: BASE64
-                            .decode("ywnIG629nQZQhEr6/HLDrLT/mUEp5J1LC6NmWSlJRWL/nM7oGItJQUYWGLvYGhSQvHrhIuvMpjNmBNh/WWqCDg==".as_bytes())
-                            .unwrap()
-                            .into(),
-                    }],
-                    reference_names: vec![],
-                    deriver: Some(crate::proto::StorePath {
-                        digest: Bytes::copy_from_slice(
-                            &nixbase32::decode_fixed::<20>("dyivpmlaq2km6c11i0s6bi6mbsx0ylqf").unwrap()
-                        ),
-                        name: "hello-2.12.1.tar.gz".to_string(),
-                    }),
-                    ca: Some(crate::proto::nar_info::Ca {
-                        r#type: crate::proto::nar_info::ca::Hash::FlatSha256.into(),
-                        digest: Bytes::copy_from_slice(
-                            &nixbase32::decode_fixed::<32>(
-                                "086vqwk2wl8zfs47sq2xpjc9k066ilmb8z6dn0q6ymwjzlm196cd"
-                            )
-                            .unwrap()
-                        )
-                    }),
-                }
-            ),
-        },
-        (&narinfo_parsed).into()
-    );
-}
-
-/// Exercise .as_narinfo() on a PathInfo and ensure important fields are preserved..
-#[test]
-fn as_narinfo() {
-    let narinfo_parsed = nix_compat::narinfo::NarInfo::parse(
-        r#"StorePath: /nix/store/pa10z4ngm0g83kx9mssrqzz30s84vq7k-hello-2.12.1.tar.gz
-URL: nar/1zjrhzhaizsrlsvdkqfl073vivmxcqnzkff4s50i0cdf541ary1r.nar.xz
-Compression: xz
-FileHash: sha256:1zjrhzhaizsrlsvdkqfl073vivmxcqnzkff4s50i0cdf541ary1r
-FileSize: 1033524
-NarHash: sha256:1lvqpbk2k1sb39z8jfxixf7p7v8sj4z6mmpa44nnmff3w1y6h8lh
-NarSize: 1033416
-References: 
-Deriver: dyivpmlaq2km6c11i0s6bi6mbsx0ylqf-hello-2.12.1.tar.gz.drv
-Sig: cache.nixos.org-1:ywnIG629nQZQhEr6/HLDrLT/mUEp5J1LC6NmWSlJRWL/nM7oGItJQUYWGLvYGhSQvHrhIuvMpjNmBNh/WWqCDg==
-CA: fixed:sha256:086vqwk2wl8zfs47sq2xpjc9k066ilmb8z6dn0q6ymwjzlm196cd"#
-    ).expect("must parse");
-
-    let path_info: PathInfo = (&narinfo_parsed).into();
-
-    let mut narinfo_returned = path_info
-        .to_narinfo(
-            StorePathRef::from_bytes(b"pa10z4ngm0g83kx9mssrqzz30s84vq7k-hello-2.12.1.tar.gz")
-                .expect("invalid storepath"),
-        )
-        .expect("must be some");
-    narinfo_returned.url = "some.nar";
-
     assert_eq!(
-        r#"StorePath: /nix/store/pa10z4ngm0g83kx9mssrqzz30s84vq7k-hello-2.12.1.tar.gz
-URL: some.nar
-Compression: none
-NarHash: sha256:1lvqpbk2k1sb39z8jfxixf7p7v8sj4z6mmpa44nnmff3w1y6h8lh
-NarSize: 1033416
-References: 
-Deriver: dyivpmlaq2km6c11i0s6bi6mbsx0ylqf-hello-2.12.1.tar.gz.drv
-Sig: cache.nixos.org-1:ywnIG629nQZQhEr6/HLDrLT/mUEp5J1LC6NmWSlJRWL/nM7oGItJQUYWGLvYGhSQvHrhIuvMpjNmBNh/WWqCDg==
-CA: fixed:sha256:086vqwk2wl8zfs47sq2xpjc9k066ilmb8z6dn0q6ymwjzlm196cd
-"#,
-        narinfo_returned.to_string(),
-    );
+        ValidatePathInfoError::InvalidDeriverField(store_path::Error::InvalidLength),
+        PathInfo::try_from(path_info).expect_err("must fail")
+    )
 }
diff --git a/tvix/store/src/tests/fixtures.rs b/tvix/store/src/tests/fixtures.rs
index 48cc365365a9..91628f2fee79 100644
--- a/tvix/store/src/tests/fixtures.rs
+++ b/tvix/store/src/tests/fixtures.rs
@@ -1,24 +1,27 @@
+use crate::pathinfoservice::PathInfo;
 use lazy_static::lazy_static;
+use nix_compat::nixhash::{CAHash, NixHash};
+use nix_compat::store_path::StorePath;
 use rstest::{self, *};
 use rstest_reuse::*;
 use std::io;
 use std::sync::Arc;
-pub use tvix_castore::fixtures::*;
+use tvix_castore::fixtures::{
+    DIRECTORY_COMPLICATED, DIRECTORY_WITH_KEEP, DUMMY_DIGEST, EMPTY_BLOB_CONTENTS,
+    EMPTY_BLOB_DIGEST, HELLOWORLD_BLOB_CONTENTS, HELLOWORLD_BLOB_DIGEST,
+};
 use tvix_castore::{
     blobservice::{BlobService, MemoryBlobService},
     directoryservice::{DirectoryService, MemoryDirectoryService},
-    proto as castorepb, Node,
-};
-
-use crate::proto::{
-    nar_info::{ca, Ca},
-    NarInfo, PathInfo,
+    Node,
 };
 
-pub const DUMMY_PATH: &str = "00000000000000000000000000000000-dummy";
+pub const DUMMY_PATH_STR: &str = "00000000000000000000000000000000-dummy";
 pub const DUMMY_PATH_DIGEST: [u8; 20] = [0; 20];
 
 lazy_static! {
+    pub static ref DUMMY_PATH: StorePath<String> = StorePath::from_name_and_digest_fixed("dummy", DUMMY_PATH_DIGEST).unwrap();
+
     pub static ref CASTORE_NODE_SYMLINK: Node = Node::Symlink {
         target: "/nix/store/somewhereelse".try_into().unwrap(),
     };
@@ -130,32 +133,19 @@ lazy_static! {
         1, 0, 0, 0, 0, 0, 0, 0, b')', 0, 0, 0, 0, 0, 0, 0, // ")"
     ];
 
-    /// A PathInfo message without .narinfo populated.
-    pub static ref PATH_INFO_WITHOUT_NARINFO : PathInfo = PathInfo {
-        node: Some(castorepb::Node {
-            node: Some(castorepb::node::Node::Directory(castorepb::DirectoryNode {
-                name: DUMMY_PATH.into(),
-                digest: DUMMY_DIGEST.clone().into(),
-                size: 0,
-            })),
-        }),
-        references: vec![DUMMY_PATH_DIGEST.as_slice().into()],
-        narinfo: None,
-    };
-
-    /// A PathInfo message with .narinfo populated.
-    /// The references in `narinfo.reference_names` aligns with what's in
-    /// `references`.
-    pub static ref PATH_INFO_WITH_NARINFO : PathInfo = PathInfo {
-        narinfo: Some(NarInfo {
-            nar_size: 0,
-            nar_sha256: DUMMY_DIGEST.clone().into(),
-            signatures: vec![],
-            reference_names: vec![DUMMY_PATH.to_string()],
-            deriver: None,
-            ca: Some(Ca { r#type: ca::Hash::NarSha256.into(), digest:  DUMMY_DIGEST.clone().into() })
-        }),
-      ..PATH_INFO_WITHOUT_NARINFO.clone()
+    /// A PathInfo message
+    pub static ref PATH_INFO: PathInfo = PathInfo {
+        store_path: DUMMY_PATH.clone(),
+        node: tvix_castore::Node::Directory {
+            digest: DUMMY_DIGEST.clone(),
+            size: 0,
+        },
+        references: vec![DUMMY_PATH.clone()],
+        nar_sha256: [0; 32],
+        nar_size: 0,
+        signatures: vec![],
+        deriver: None,
+        ca: Some(CAHash::Nar(NixHash::Sha256([0; 32]))),
     };
 }