fix(tauri): rename misleading ci feature and fail loudly without it…

.github/workflows/build-and-release.yml

@@ -280,16 +280,16 @@ jobs:
       matrix:
         include:
           - platform: "macos-latest"
-            # Enable CI feature so prod() spawns backend + sync in release builds
-            args: "--target aarch64-apple-darwin --features ci"
+            # Enable bundled-sidecars feature so prod() spawns backend + sync in release builds
+            args: "--target aarch64-apple-darwin --features bundled-sidecars"
             server-artifact: "PictoPy-MacOS"
             sync-artifact: "PictoPy-Sync-MacOS"
           - platform: "ubuntu-22.04"
-            args: "--features ci"
+            args: "--features bundled-sidecars"
             server-artifact: "PictoPy-Ubuntu"
             sync-artifact: "PictoPy-Sync-Ubuntu"
           - platform: "windows-latest"
-            args: "--features ci"
+            args: "--features bundled-sidecars"
             server-artifact: "PictoPy-Windows"
             sync-artifact: "PictoPy-Sync-Windows"
     runs-on: ${{ matrix.platform }}

.github/workflows/pr-check-build.yml

@@ -14,11 +14,11 @@ jobs:
       matrix:
         include:
           - platform: "macos-latest"
-            args: "--target aarch64-apple-darwin --features ci"
+            args: "--target aarch64-apple-darwin --features bundled-sidecars"
           - platform: "ubuntu-22.04"
-            args: "--features ci"
+            args: "--features bundled-sidecars"
           - platform: "windows-latest"
-            args: "--features ci"
+            args: "--features bundled-sidecars"
     runs-on: ${{ matrix.platform }}
     steps:
       - uses: actions/checkout@v4

frontend/src-tauri/Cargo.toml

@@ -41,6 +41,9 @@ tauri-plugin-opener = "2.5.2"
 [features]
 # This feature is used for production builds or when a dev server is not specified, DO NOT REMOVE!!
 custom-protocol = ["tauri/custom-protocol"]
-ci = []
+# Enables spawning the bundled Python backend/sync sidecars. Required for
+# release builds (see frontend/src-tauri/src/main.rs); without it `prod()`
+# fails loudly in release builds instead of silently launching a backend-less app.
+bundled-sidecars = []
 
 [target.'cfg(not(any(target_os = "android", target_os = "ios")))'.dependencies]

frontend/src-tauri/src/main.rs

@@ -21,7 +21,7 @@ const ENDPOINTS: [(&str, &str, &str); 2] = [
     ),
 ];
 
-#[cfg(feature = "ci")]
+#[cfg(feature = "bundled-sidecars")]
 fn is_process_alive() -> bool {
     use reqwest::blocking::Client;
 
@@ -102,9 +102,9 @@ fn kill_process_tree() -> Result<(), String> {
     Ok(())
 }
 
-#[cfg(feature = "ci")]
+#[cfg(feature = "bundled-sidecars")]
 fn prod(app: &tauri::AppHandle, resource_path: &std::path::Path) -> Result<(), String> {
-    println!("`ci` feature enabled");
+    println!("`bundled-sidecars` feature enabled");
     let backend_path = resource_path.join("backend");
     let backend_executable = backend_path.join("PictoPy_Server");
 
@@ -183,9 +183,43 @@ fn prod(app: &tauri::AppHandle, resource_path: &std::path::Path) -> Result<(), S
     Ok(())
 }
 
-#[cfg(not(feature = "ci"))]
+#[cfg(not(feature = "bundled-sidecars"))]
 fn prod(_app: &tauri::AppHandle, _resource_path: &std::path::Path) -> Result<(), String> {
-    Ok(())
+    prod_without_bundled_sidecars()
+}
+
+#[cfg(not(feature = "bundled-sidecars"))]
+fn prod_without_bundled_sidecars() -> Result<(), String> {
+    // `cargo tauri dev` intentionally omits this feature; the backend/sync
+    // services are run separately during local development.
+    if cfg!(debug_assertions) {
+        return Ok(());
+    }
+
+    // A release build without this feature would otherwise launch with no
+    // backend and no indication anything is wrong (see issue #1347).
+    Err(
+        "Release build is missing the `bundled-sidecars` feature: the bundled \
+        backend/sync services will never be started. Rebuild with \
+        `--features bundled-sidecars`."
+            .to_string(),
+    )
+}
+
+#[cfg(all(test, not(feature = "bundled-sidecars")))]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn no_op_in_debug_builds_fails_loudly_in_release_builds() {
+        let result = prod_without_bundled_sidecars();
+
+        if cfg!(debug_assertions) {
+            assert_eq!(result, Ok(()));
+        } else {
+            assert!(result.is_err());
+        }
+    }
 }
 
 fn main() {