Add storage module for presets, config, session, and history persistence

Preset save/load/list/delete/import/export, config JSON persistence,
session state save/restore, and processing history log with append/clear.
All stored as JSON under ~/.config/pixstrip/.

pixstrip-core/tests/config_tests.rs

@@ -22,6 +22,6 @@ fn config_serialization_roundtrip() {
 
 #[test]
 fn skill_level_toggle() {
-    assert_eq!(SkillLevel::Simple.is_advanced(), false);
-    assert_eq!(SkillLevel::Detailed.is_advanced(), true);
+    assert!(!SkillLevel::Simple.is_advanced());
+    assert!(SkillLevel::Detailed.is_advanced());
 }

pixstrip-core/tests/storage_tests.rs

@@ -0,0 +1,278 @@
+use pixstrip_core::preset::Preset;
+use pixstrip_core::storage::*;
+
+fn with_temp_config_dir(f: impl FnOnce(&std::path::Path)) {
+    let dir = tempfile::tempdir().unwrap();
+    f(dir.path());
+}
+
+// --- Preset file I/O ---
+
+#[test]
+fn save_and_load_preset() {
+    with_temp_config_dir(|base| {
+        let store = PresetStore::with_base_dir(base);
+        let preset = Preset::builtin_blog_photos();
+
+        store.save(&preset).unwrap();
+        let loaded = store.load("Blog Photos").unwrap();
+
+        assert_eq!(loaded.name, preset.name);
+        assert_eq!(loaded.is_custom, preset.is_custom);
+    });
+}
+
+#[test]
+fn save_preset_creates_directory() {
+    with_temp_config_dir(|base| {
+        let presets_dir = base.join("presets");
+        assert!(!presets_dir.exists());
+
+        let store = PresetStore::with_base_dir(base);
+        let preset = Preset::builtin_blog_photos();
+        store.save(&preset).unwrap();
+
+        assert!(presets_dir.exists());
+    });
+}
+
+#[test]
+fn list_saved_presets() {
+    with_temp_config_dir(|base| {
+        let store = PresetStore::with_base_dir(base);
+        store.save(&Preset::builtin_blog_photos()).unwrap();
+        store.save(&Preset::builtin_privacy_clean()).unwrap();
+
+        let list = store.list().unwrap();
+        assert_eq!(list.len(), 2);
+
+        let names: Vec<&str> = list.iter().map(|p| p.name.as_str()).collect();
+        assert!(names.contains(&"Blog Photos"));
+        assert!(names.contains(&"Privacy Clean"));
+    });
+}
+
+#[test]
+fn delete_preset() {
+    with_temp_config_dir(|base| {
+        let store = PresetStore::with_base_dir(base);
+        store.save(&Preset::builtin_blog_photos()).unwrap();
+
+        assert!(store.delete("Blog Photos").is_ok());
+        assert!(store.load("Blog Photos").is_err());
+    });
+}
+
+#[test]
+fn load_nonexistent_preset_returns_error() {
+    with_temp_config_dir(|base| {
+        let store = PresetStore::with_base_dir(base);
+        assert!(store.load("Nonexistent").is_err());
+    });
+}
+
+#[test]
+fn preset_filename_sanitization() {
+    with_temp_config_dir(|base| {
+        let store = PresetStore::with_base_dir(base);
+        let mut preset = Preset::builtin_blog_photos();
+        preset.name = "My Preset / With <Special> Chars!".into();
+        preset.is_custom = true;
+
+        store.save(&preset).unwrap();
+        let loaded = store.load("My Preset / With <Special> Chars!").unwrap();
+        assert_eq!(loaded.name, preset.name);
+    });
+}
+
+// --- Preset import/export ---
+
+#[test]
+fn export_and_import_preset() {
+    with_temp_config_dir(|base| {
+        let store = PresetStore::with_base_dir(base);
+        let preset = Preset::builtin_blog_photos();
+
+        let export_path = base.join("exported.pixstrip-preset");
+        store.export_to_file(&preset, &export_path).unwrap();
+
+        assert!(export_path.exists());
+
+        let imported = store.import_from_file(&export_path).unwrap();
+        assert_eq!(imported.name, preset.name);
+        assert!(imported.is_custom);
+    });
+}
+
+#[test]
+fn import_preset_marks_as_custom() {
+    with_temp_config_dir(|base| {
+        let store = PresetStore::with_base_dir(base);
+        let preset = Preset::builtin_blog_photos();
+
+        let export_path = base.join("test.pixstrip-preset");
+        store.export_to_file(&preset, &export_path).unwrap();
+
+        let imported = store.import_from_file(&export_path).unwrap();
+        assert!(imported.is_custom);
+    });
+}
+
+// --- Config persistence ---
+
+#[test]
+fn save_and_load_config() {
+    with_temp_config_dir(|base| {
+        let config_store = ConfigStore::with_base_dir(base);
+        let config = pixstrip_core::config::AppConfig {
+            output_subfolder: "output_images".into(),
+            auto_open_output: true,
+            ..Default::default()
+        };
+
+        config_store.save(&config).unwrap();
+        let loaded = config_store.load().unwrap();
+
+        assert_eq!(loaded.output_subfolder, "output_images");
+        assert!(loaded.auto_open_output);
+    });
+}
+
+#[test]
+fn load_missing_config_returns_default() {
+    with_temp_config_dir(|base| {
+        let config_store = ConfigStore::with_base_dir(base);
+        let config = config_store.load().unwrap();
+        let default = pixstrip_core::config::AppConfig::default();
+
+        assert_eq!(config.output_subfolder, default.output_subfolder);
+    });
+}
+
+// --- Session memory ---
+
+#[test]
+fn save_and_load_session() {
+    with_temp_config_dir(|base| {
+        let session_store = SessionStore::with_base_dir(base);
+        let session = SessionState {
+            last_input_dir: Some("/home/user/photos".into()),
+            last_output_dir: Some("/home/user/processed".into()),
+            last_preset_name: Some("Blog Photos".into()),
+            current_step: 3,
+        };
+
+        session_store.save(&session).unwrap();
+        let loaded = session_store.load().unwrap();
+
+        assert_eq!(loaded.last_input_dir.as_deref(), Some("/home/user/photos"));
+        assert_eq!(loaded.current_step, 3);
+    });
+}
+
+#[test]
+fn load_missing_session_returns_default() {
+    with_temp_config_dir(|base| {
+        let session_store = SessionStore::with_base_dir(base);
+        let session = session_store.load().unwrap();
+        assert_eq!(session.current_step, 0);
+        assert!(session.last_input_dir.is_none());
+    });
+}
+
+// --- Processing history ---
+
+#[test]
+fn add_and_list_history_entries() {
+    with_temp_config_dir(|base| {
+        let history = HistoryStore::with_base_dir(base);
+
+        let entry = HistoryEntry {
+            timestamp: "2026-03-06T12:00:00Z".into(),
+            input_dir: "/home/user/photos".into(),
+            output_dir: "/home/user/processed".into(),
+            preset_name: Some("Blog Photos".into()),
+            total: 10,
+            succeeded: 9,
+            failed: 1,
+            total_input_bytes: 50_000_000,
+            total_output_bytes: 10_000_000,
+            elapsed_ms: 5000,
+            output_files: vec![
+                "/home/user/processed/photo1.jpg".into(),
+                "/home/user/processed/photo2.jpg".into(),
+            ],
+        };
+
+        history.add(entry.clone()).unwrap();
+        let entries = history.list().unwrap();
+
+        assert_eq!(entries.len(), 1);
+        assert_eq!(entries[0].total, 10);
+        assert_eq!(entries[0].succeeded, 9);
+    });
+}
+
+#[test]
+fn history_appends_entries() {
+    with_temp_config_dir(|base| {
+        let history = HistoryStore::with_base_dir(base);
+
+        for i in 0..3 {
+            history
+                .add(HistoryEntry {
+                    timestamp: format!("2026-03-06T12:0{}:00Z", i),
+                    input_dir: "/input".into(),
+                    output_dir: "/output".into(),
+                    preset_name: None,
+                    total: i + 1,
+                    succeeded: i + 1,
+                    failed: 0,
+                    total_input_bytes: 1000,
+                    total_output_bytes: 500,
+                    elapsed_ms: 100,
+                    output_files: vec![],
+                })
+                .unwrap();
+        }
+
+        let entries = history.list().unwrap();
+        assert_eq!(entries.len(), 3);
+    });
+}
+
+#[test]
+fn clear_history() {
+    with_temp_config_dir(|base| {
+        let history = HistoryStore::with_base_dir(base);
+
+        history
+            .add(HistoryEntry {
+                timestamp: "2026-03-06T12:00:00Z".into(),
+                input_dir: "/input".into(),
+                output_dir: "/output".into(),
+                preset_name: None,
+                total: 1,
+                succeeded: 1,
+                failed: 0,
+                total_input_bytes: 1000,
+                total_output_bytes: 500,
+                elapsed_ms: 100,
+                output_files: vec![],
+            })
+            .unwrap();
+
+        history.clear().unwrap();
+        let entries = history.list().unwrap();
+        assert!(entries.is_empty());
+    });
+}
+
+#[test]
+fn empty_history_returns_empty_list() {
+    with_temp_config_dir(|base| {
+        let history = HistoryStore::with_base_dir(base);
+        let entries = history.list().unwrap();
+        assert!(entries.is_empty());
+    });
+}