diff --git a/testing/tests/client_main_process_contract.rs b/testing/tests/client_main_process_contract.rs
new file mode 100644
index 0000000..371f65e
--- /dev/null
+++ b/testing/tests/client_main_process_contract.rs
@@ -0,0 +1,48 @@
+//! Integration coverage for client process startup behavior.
+//!
+//! Scope: launch the real `lesavka-client` binary and validate guarded startup
+//! behavior when desktop runtime prerequisites are missing.
+//! Targets: `client/src/main.rs`.
+//! Why: process-level startup failures should stay deterministic and
+//! user-readable.
+
+use serial_test::serial;
+use std::path::{Path, PathBuf};
+use std::process::Command;
+
+fn candidate_dirs() -> Vec<PathBuf> {
+    let exe = std::env::current_exe().expect("current exe path");
+    let mut dirs = Vec::new();
+    if let Some(parent) = exe.parent() {
+        dirs.push(parent.to_path_buf());
+        if let Some(grand) = parent.parent() {
+            dirs.push(grand.to_path_buf());
+        }
+    }
+    dirs.push(PathBuf::from("target/debug"));
+    dirs.push(PathBuf::from("target/llvm-cov-target/debug"));
+    dirs
+}
+
+fn find_binary(name: &str) -> Option<PathBuf> {
+    candidate_dirs()
+        .into_iter()
+        .map(|dir| dir.join(name))
+        .find(|path| path.exists() && path.is_file())
+}
+
+#[test]
+#[serial]
+fn client_binary_fails_fast_without_runtime_dir() {
+    let Some(bin) = find_binary("lesavka-client") else {
+        return;
+    };
+
+    let status = Command::new(Path::new(&bin))
+        .env_remove("XDG_RUNTIME_DIR")
+        .env_remove("LESAVKA_HEADLESS")
+        .status()
+        .expect("spawn lesavka-client");
+
+    assert!(!status.success(), "startup should fail without runtime dir");
+}
diff --git a/testing/tests/server_main_process_contract.rs b/testing/tests/server_main_process_contract.rs
new file mode 100644
index 0000000..95ebf94
--- /dev/null
+++ b/testing/tests/server_main_process_contract.rs
@@ -0,0 +1,62 @@
+//! Integration coverage for server process startup behavior.
+//!
+//! Scope: launch the real `lesavka-server` binary and assert startup reaches a
+//! terminal state quickly in this non-gadget test environment.
+//! Targets: `server/src/main.rs`.
+//! Why: process-level boot behavior should remain deterministic when required
+//! gadget endpoints are unavailable.
+
+use serial_test::serial;
+use std::path::PathBuf;
+use std::process::Command;
+use std::time::{Duration, Instant};
+
+fn candidate_dirs() -> Vec<PathBuf> {
+    let exe = std::env::current_exe().expect("current exe path");
+    let mut dirs = Vec::new();
+    if let Some(parent) = exe.parent() {
+        dirs.push(parent.to_path_buf());
+        if let Some(grand) = parent.parent() {
+            dirs.push(grand.to_path_buf());
+        }
+    }
+    dirs.push(PathBuf::from("target/debug"));
+    dirs.push(PathBuf::from("target/llvm-cov-target/debug"));
+    dirs
+}
+
+fn find_binary(name: &str) -> Option<PathBuf> {
+    candidate_dirs()
+        .into_iter()
+        .map(|dir| dir.join(name))
+        .find(|path| path.exists() && path.is_file())
+}
+
+#[test]
+#[serial]
+fn server_binary_exits_quickly_without_hid_nodes() {
+    let Some(bin) = find_binary("lesavka-server") else {
+        return;
+    };
+
+    let mut child = Command::new(bin)
+        .env("LESAVKA_DISABLE_UVC", "1")
+        .spawn()
+        .expect("spawn lesavka-server");
+
+    let deadline = Instant::now() + Duration::from_secs(3);
+    loop {
+        if let Some(status) = child.try_wait().expect("poll child") {
+            assert!(
+                !status.success(),
+                "server unexpectedly succeeded in test environment"
+            );
+            break;
+        }
+        if Instant::now() >= deadline {
+            let _ = child.kill();
+            panic!("server did not terminate within startup timeout");
+        }
+        std::thread::sleep(Duration::from_millis(50));
+    }
+}