diff --git a/packages/desktop/src-tauri/build.rs b/packages/desktop/src-tauri/build.rs
index f6a8b9be..cb770638 100644
--- a/packages/desktop/src-tauri/build.rs
+++ b/packages/desktop/src-tauri/build.rs
@@ -6,17 +6,22 @@ use std::path::PathBuf;
 use std::os::unix::fs::PermissionsExt;
 
 fn main() {
-  ensure_opencode_sidecar();
+  // Ensure sidecar exists in all builds (debug and release)
+  if let Err(e) = ensure_opencode_sidecar() {
+    eprintln!("Error: {}", e);
+    eprintln!("Install OpenCode or set OPENCODE_BIN_PATH.");
+    std::process::exit(1);
+  }
   tauri_build::build();
 }
 
-fn ensure_opencode_sidecar() {
+fn ensure_opencode_sidecar() -> Result<(), String> {
   let target = env::var("CARGO_CFG_TARGET_TRIPLE")
     .or_else(|_| env::var("TARGET"))
     .or_else(|_| env::var("TAURI_ENV_TARGET_TRIPLE"))
     .unwrap_or_default();
   if target.is_empty() {
-    return;
+    return Ok(());
   }
 
   let manifest_dir = env::var("CARGO_MANIFEST_DIR")
@@ -31,7 +36,7 @@ fn ensure_opencode_sidecar() {
   let dest_path = sidecar_dir.join(file_name);
 
   if dest_path.exists() {
-    return;
+    return Ok(());
   }
 
   let source_path = env::var("OPENCODE_BIN_PATH")
@@ -40,20 +45,14 @@ fn ensure_opencode_sidecar() {
     .filter(|path| path.is_file())
     .or_else(|| find_in_path(if target.contains("windows") { "opencode.exe" } else { "opencode" }));
 
-  let profile = env::var("PROFILE").unwrap_or_default();
-
   let Some(source_path) = source_path else {
-    println!(
-      "cargo:warning=OpenCode sidecar missing at {} (set OPENCODE_BIN_PATH or install OpenCode)",
-      dest_path.display()
-    );
-
-    create_debug_stub(&dest_path, &sidecar_dir, &profile, &target);
-    return;
+    return Err(format!(
+      "OpenCode not found. Install OpenCode or set OPENCODE_BIN_PATH."
+    ));
   };
 
   if fs::create_dir_all(&sidecar_dir).is_err() {
-    return;
+    return Err(format!("Failed to create directory: {}", sidecar_dir.display()));
   }
 
   let mut copied = fs::copy(&source_path, &dest_path).is_ok();
@@ -77,13 +76,13 @@ fn ensure_opencode_sidecar() {
     {
       let _ = fs::set_permissions(&dest_path, fs::Permissions::from_mode(0o755));
     }
+    Ok(())
   } else {
-    println!(
-      "cargo:warning=Failed to copy OpenCode sidecar from {} to {}",
+    Err(format!(
+      "Failed to copy OpenCode from {} to {}",
       source_path.display(),
       dest_path.display()
-    );
-    create_debug_stub(&dest_path, &sidecar_dir, &profile, &target);
+    ))
   }
 }
 
@@ -98,21 +97,3 @@ fn find_in_path(binary: &str) -> Option<PathBuf> {
     }
   })
 }
-
-fn create_debug_stub(dest_path: &PathBuf, sidecar_dir: &PathBuf, profile: &str, target: &str) {
-  if profile != "debug" || target.contains("windows") {
-    return;
-  }
-
-  if fs::create_dir_all(sidecar_dir).is_err() {
-    return;
-  }
-
-  let stub = "#!/usr/bin/env bash\n\
-echo 'OpenCode sidecar missing. Install OpenCode or set OPENCODE_BIN_PATH.'\n\
-exit 1\n";
-  if fs::write(dest_path, stub).is_ok() {
-    #[cfg(unix)]
-    let _ = fs::set_permissions(dest_path, fs::Permissions::from_mode(0o755));
-  }
-}
diff --git a/packages/desktop/src/app/app.tsx b/packages/desktop/src/app/app.tsx
index e13f4212..45337f80 100644
--- a/packages/desktop/src/app/app.tsx
+++ b/packages/desktop/src/app/app.tsx
@@ -129,7 +129,8 @@ export default function App() {
   const [themeMode, setThemeMode] = createSignal<ThemeMode>(getInitialThemeMode());
 
   const [engineSource, setEngineSource] = createSignal<"path" | "sidecar">(
-    isTauriRuntime() ? "sidecar" : "path"
+    // Use PATH in development, sidecar in production (when bundled)
+    isTauriRuntime() && import.meta.env.PROD ? "sidecar" : "path"
   );
 
   const [baseUrl, setBaseUrl] = createSignal("http://127.0.0.1:4096");