feat(settings): add Windows toggle to disable WebView2 hardware acceleration

src-tauri/src/preferences.rs

@@ -0,0 +1,56 @@
+//! User-scoped preferences stored at `~/.codeg/preferences.json`.
+//!
+//! These are settings that must be readable **before** the Tauri builder and
+//! tokio runtime start (e.g. WebView2 rendering flags applied via
+//! `WEBVIEW2_ADDITIONAL_BROWSER_ARGUMENTS`). All access is synchronous I/O so
+//! the data must stay tiny.
+
+use std::fs;
+use std::io;
+use std::path::PathBuf;
+
+use serde::{Deserialize, Serialize};
+
+const PREFERENCES_FILE_NAME: &str = "preferences.json";
+const CODEG_DIR_NAME: &str = ".codeg";
+
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+#[serde(default)]
+pub struct AppPreferences {
+    pub disable_hardware_acceleration: bool,
+}
+
+pub fn preferences_file_path() -> Option<PathBuf> {
+    dirs::home_dir().map(|h| h.join(CODEG_DIR_NAME).join(PREFERENCES_FILE_NAME))
+}
+
+/// Read preferences synchronously. Missing / unreadable / malformed file
+/// returns `Default::default()`. Errors are intentionally swallowed because
+/// this is called on the startup hot-path; callers log if needed.
+pub fn load() -> AppPreferences {
+    let Some(path) = preferences_file_path() else {
+        return AppPreferences::default();
+    };
+    match fs::read_to_string(&path) {
+        Ok(raw) => serde_json::from_str(&raw).unwrap_or_default(),
+        Err(err) if err.kind() == io::ErrorKind::NotFound => AppPreferences::default(),
+        Err(err) => {
+            eprintln!(
+                "[Preferences] failed to read {}: {err}",
+                path.display()
+            );
+            AppPreferences::default()
+        }
+    }
+}
+
+pub fn save(prefs: &AppPreferences) -> io::Result<()> {
+    let path = preferences_file_path()
+        .ok_or_else(|| io::Error::new(io::ErrorKind::NotFound, "home directory unavailable"))?;
+    if let Some(parent) = path.parent() {
+        fs::create_dir_all(parent)?;
+    }
+    let serialized = serde_json::to_string_pretty(prefs)
+        .map_err(|err| io::Error::new(io::ErrorKind::InvalidData, err.to_string()))?;
+    fs::write(&path, serialized)
+}