diff --git a/tvix/shell.nix b/tvix/shell.nix
index 2da5b5f24..e8d1e5e38 100644
--- a/tvix/shell.nix
+++ b/tvix/shell.nix
@@ -6,10 +6,12 @@
 pkgs.mkShell {
   name = "tvix-eval-dev-env";
   packages = [
+    pkgs.buf-language-server
     pkgs.cargo
     pkgs.clippy
     pkgs.rust-analyzer
     pkgs.rustc
     pkgs.rustfmt
+    pkgs.protobuf
   ];
 }
diff --git a/tvix/store/Cargo.lock b/tvix/store/Cargo.lock
index dfe8db783..b5b2fb9e3 100644
--- a/tvix/store/Cargo.lock
+++ b/tvix/store/Cargo.lock
@@ -2,6 +2,324 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "anyhow"
+version = "1.0.66"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "216261ddc8289130e551ddcd5ce8a064710c0d064a4d2895c67151c92b5443f6"
+
+[[package]]
+name = "autocfg"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
+
+[[package]]
+name = "bitflags"
+version = "1.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
+
+[[package]]
+name = "bytes"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec8a7b6a70fde80372154c65702f00a0f56f3e1c36abbc6c440484be248856db"
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "either"
+version = "1.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "90e5c1c8368803113bf0c9584fc495a58b86dc8a29edbf8fe877d21d9507e797"
+
+[[package]]
+name = "fastrand"
+version = "1.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a7a407cfaa3385c4ae6b23e84623d48c2798d06e3e6a1878f7f59f17b3f86499"
+dependencies = [
+ "instant",
+]
+
+[[package]]
+name = "fixedbitset"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0ce7134b9999ecaf8bcd65542e436736ef32ddca1b3e06094cb6ec5755203b80"
+
+[[package]]
+name = "hashbrown"
+version = "0.12.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8a9ee70c43aaf417c914396645a0fa852624801b24ebb7ae78fe8272889ac888"
+
+[[package]]
+name = "heck"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2540771e65fc8cb83cd6e8a237f70c319bd5c29f78ed1084ba5d50eeac86f7f9"
+
+[[package]]
+name = "indexmap"
+version = "1.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "10a35a97730320ffe8e2d410b5d3b69279b98d2c14bdb8b70ea89ecf7888d41e"
+dependencies = [
+ "autocfg",
+ "hashbrown",
+]
+
+[[package]]
+name = "instant"
+version = "0.1.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7a5bbe824c507c5da5956355e86a746d82e0e1464f65d862cc5e71da70e94b2c"
+dependencies = [
+ "cfg-if",
+]
+
+[[package]]
+name = "itertools"
+version = "0.10.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b0fd2260e829bddf4cb6ea802289de2f86d6a7a690192fbe91b3f46e0f2c8473"
+dependencies = [
+ "either",
+]
+
+[[package]]
+name = "lazy_static"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
+
+[[package]]
+name = "libc"
+version = "0.2.137"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fc7fcc620a3bff7cdd7a365be3376c97191aeaccc2a603e600951e452615bf89"
+
+[[package]]
+name = "log"
+version = "0.4.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "abb12e687cfb44aa40f41fc3978ef76448f9b6038cad6aef4259d3c095a2382e"
+dependencies = [
+ "cfg-if",
+]
+
+[[package]]
+name = "multimap"
+version = "0.8.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e5ce46fe64a9d73be07dcbe690a38ce1b293be448fd8ce1e6c1b8062c9f72c6a"
+
+[[package]]
+name = "once_cell"
+version = "1.16.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "86f0b0d4bf799edbc74508c1e8bf170ff5f41238e5f8225603ca7caaae2b7860"
+
+[[package]]
+name = "petgraph"
+version = "0.6.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6d5014253a1331579ce62aa67443b4a658c5e7dd03d4bc6d302b94474888143"
+dependencies = [
+ "fixedbitset",
+ "indexmap",
+]
+
+[[package]]
+name = "prettyplease"
+version = "0.1.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c142c0e46b57171fe0c528bee8c5b7569e80f0c17e377cd0e30ea57dbc11bb51"
+dependencies = [
+ "proc-macro2",
+ "syn",
+]
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.47"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5ea3d908b0e36316caf9e9e2c4625cdde190a7e6f440d794667ed17a1855e725"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "prost"
+version = "0.11.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a0841812012b2d4a6145fae9a6af1534873c32aa67fff26bd09f8fa42c83f95a"
+dependencies = [
+ "bytes",
+ "prost-derive",
+]
+
+[[package]]
+name = "prost-build"
+version = "0.11.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1d8b442418ea0822409d9e7d047cbf1e7e9e1760b172bf9982cf29d517c93511"
+dependencies = [
+ "bytes",
+ "heck",
+ "itertools",
+ "lazy_static",
+ "log",
+ "multimap",
+ "petgraph",
+ "prettyplease",
+ "prost",
+ "prost-types",
+ "regex",
+ "syn",
+ "tempfile",
+ "which",
+]
+
+[[package]]
+name = "prost-derive"
+version = "0.11.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "164ae68b6587001ca506d3bf7f1000bfa248d0e1217b618108fba4ec1d0cc306"
+dependencies = [
+ "anyhow",
+ "itertools",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "prost-types"
+version = "0.11.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "747761bc3dc48f9a34553bf65605cf6cb6288ba219f3450b4275dbd81539551a"
+dependencies = [
+ "bytes",
+ "prost",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbe448f377a7d6961e30f5955f9b8d106c3f5e449d493ee1b125c1d43c2b5179"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "redox_syscall"
+version = "0.2.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fb5a58c1855b4b6819d59012155603f0b22ad30cad752600aadfcb695265519a"
+dependencies = [
+ "bitflags",
+]
+
+[[package]]
+name = "regex"
+version = "1.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e076559ef8e241f2ae3479e36f97bd5741c0330689e217ad51ce2c76808b868a"
+dependencies = [
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-syntax"
+version = "0.6.28"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "456c603be3e8d448b072f410900c09faf164fbce2d480456f50eea6e25f9c848"
+
+[[package]]
+name = "remove_dir_all"
+version = "0.5.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3acd125665422973a33ac9d3dd2df85edad0f4ae9b00dafb1a05e43a9f5ef8e7"
+dependencies = [
+ "winapi",
+]
+
+[[package]]
+name = "syn"
+version = "1.0.103"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a864042229133ada95abf3b54fdc62ef5ccabe9515b64717bcb9a1919e59445d"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "tempfile"
+version = "3.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5cdb1ef4eaeeaddc8fbd371e5017057064af0911902ef36b39801f67cc6d79e4"
+dependencies = [
+ "cfg-if",
+ "fastrand",
+ "libc",
+ "redox_syscall",
+ "remove_dir_all",
+ "winapi",
+]
+
 [[package]]
 name = "tvix-store"
 version = "0.1.0"
+dependencies = [
+ "prost",
+ "prost-build",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6ceab39d59e4c9499d4e5a8ee0e2735b891bb7308ac83dfb4e80cad195c9f6f3"
+
+[[package]]
+name = "which"
+version = "4.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1c831fbbee9e129a8cf93e7747a82da9d95ba8e16621cae60ec2cdc849bacb7b"
+dependencies = [
+ "either",
+ "libc",
+ "once_cell",
+]
+
+[[package]]
+name = "winapi"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c839a674fcd7a98952e593242ea400abe93992746761e38641405d28b00f419"
+dependencies = [
+ "winapi-i686-pc-windows-gnu",
+ "winapi-x86_64-pc-windows-gnu",
+]
+
+[[package]]
+name = "winapi-i686-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
+
+[[package]]
+name = "winapi-x86_64-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
diff --git a/tvix/store/Cargo.toml b/tvix/store/Cargo.toml
index 83e2de8d4..1b758be64 100644
--- a/tvix/store/Cargo.toml
+++ b/tvix/store/Cargo.toml
@@ -4,3 +4,7 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+prost = "0.11.2"
+
+[build-dependencies]
+prost-build = "0.11.2"
diff --git a/tvix/store/build.rs b/tvix/store/build.rs
new file mode 100644
index 000000000..cc0bf2293
--- /dev/null
+++ b/tvix/store/build.rs
@@ -0,0 +1,18 @@
+use std::io::Result;
+
+fn main() -> Result<()> {
+    prost_build::compile_protos(
+        &[
+            "tvix/store/protos/castore.proto",
+            "tvix/store/protos/pathinfo.proto",
+        ],
+        // If we are in running `cargo build` manually, using `../..` works fine,
+        // but in case we run inside a nix build, we need to instead point PROTO_ROOT
+        // to a sparseTree containing that structure.
+        &[match std::env::var_os(&"PROTO_ROOT") {
+            Some(proto_root) => proto_root.to_str().unwrap().to_owned(),
+            None => "../..".to_string(),
+        }],
+    )?;
+    Ok(())
+}
diff --git a/tvix/store/src/lib.rs b/tvix/store/src/lib.rs
new file mode 100644
index 000000000..0d8c560e2
--- /dev/null
+++ b/tvix/store/src/lib.rs
@@ -0,0 +1,3 @@
+pub mod protos {
+    include!(concat!(env!("OUT_DIR"), "/tvix.store.v1.rs"));
+}