diff --git a/socktop/build.rs b/socktop/build.rs
index 0cf4635..a79719b 100644
--- a/socktop/build.rs
+++ b/socktop/build.rs
@@ -1,8 +1,14 @@
 fn main() {
+    // Vendored protoc for reproducible builds (works on crates.io build machines)
     let protoc = protoc_bin_vendored::protoc_bin_path().expect("protoc");
-    std::env::set_var("PROTOC", protoc);
+    std::env::set_var("PROTOC", &protoc);
+
+    // Tell Cargo when to re-run
+    println!("cargo:rerun-if-changed=proto/processes.proto");
+
     let mut cfg = prost_build::Config::new();
     cfg.out_dir(std::env::var("OUT_DIR").unwrap());
-    cfg.compile_protos(&["../proto/processes.proto"], &["../proto"])
+    // Use in-crate relative path so `cargo package` includes the file
+    cfg.compile_protos(&["proto/processes.proto"], &["proto"]) // paths relative to CARGO_MANIFEST_DIR
         .expect("compile protos");
 }
diff --git a/socktop/proto/processes.proto b/socktop/proto/processes.proto
new file mode 100644
index 0000000..631e162
--- /dev/null
+++ b/socktop/proto/processes.proto
@@ -0,0 +1,15 @@
+syntax = "proto3";
+package socktop;
+
+// All running processes. Sorting is done client-side.
+message Processes {
+  uint64 process_count = 1;           // total processes in the system
+  repeated Process rows = 2;          // all processes
+}
+
+message Process {
+  uint32 pid = 1;
+  string name = 2;
+  float cpu_usage = 3;                // 0..100
+  uint64 mem_bytes = 4;               // RSS bytes
+}
diff --git a/socktop_agent/build.rs b/socktop_agent/build.rs
index 366d490..f931d80 100644
--- a/socktop_agent/build.rs
+++ b/socktop_agent/build.rs
@@ -1,11 +1,14 @@
 fn main() {
-    // Ensure protoc exists (vendored for reproducible builds)
+    // Vendored protoc for reproducible builds
     let protoc = protoc_bin_vendored::protoc_bin_path().expect("protoc");
-    std::env::set_var("PROTOC", protoc);
+    std::env::set_var("PROTOC", &protoc);
+
+    println!("cargo:rerun-if-changed=proto/processes.proto");
 
     // Compile protobuf definitions for processes
     let mut cfg = prost_build::Config::new();
     cfg.out_dir(std::env::var("OUT_DIR").unwrap());
-    cfg.compile_protos(&["../proto/processes.proto"], &["../proto"])
+    // Use local path (ensures file is inside published crate tarball)
+    cfg.compile_protos(&["proto/processes.proto"], &["proto"]) // relative to CARGO_MANIFEST_DIR
         .expect("compile protos");
 }
diff --git a/socktop_agent/proto/processes.proto b/socktop_agent/proto/processes.proto
new file mode 100644
index 0000000..631e162
--- /dev/null
+++ b/socktop_agent/proto/processes.proto
@@ -0,0 +1,15 @@
+syntax = "proto3";
+package socktop;
+
+// All running processes. Sorting is done client-side.
+message Processes {
+  uint64 process_count = 1;           // total processes in the system
+  repeated Process rows = 2;          // all processes
+}
+
+message Process {
+  uint32 pid = 1;
+  string name = 2;
+  float cpu_usage = 3;                // 0..100
+  uint64 mem_bytes = 4;               // RSS bytes
+}