add quick_discover startup check for common save paths

CHANGELOG.md

@@ -6,6 +6,12 @@ All notable changes to NotAlterra are documented in this file.
 
 ## [v0.3.2] — 2026-06-02
 
+### Added
+- **Lightweight startup check** — on launch, the app silently checks the
+  current user's default save locations (`%LOCALAPPDATA%` on Windows,
+  Proton + XDG data on Linux). No scanning of other profiles or system
+  drives. If nothing is found, use **Set save folder** as before.
+
 ### Removed
 - **`config.ini` eliminated entirely** — no save path, disclaimer flag, or
   scan timestamp is written to disk anymore. The save folder is session-only,

GOVERNANCE.md

@@ -84,7 +84,7 @@ Planned changes for upcoming releases, ordered by priority.
 
 | Target | Item |
 |--------|------|
-| v0.4.0 | Extract `validate_custom_path` and `derive_ini_path` from `discovery.rs`, then remove the module |
+| v0.4.0 | TBD — see GitHub issues for planned features |
 
 Items may shift between releases depending on feedback and urgency.
 

KNOWN_ISSUES.md

@@ -1,10 +1,3 @@
 # Known Issues
 
-## Discovery module is deprecated
-
-Auto-scan for save folders (`discovery.rs`) is deprecated in favor of the
-**Set save folder** menu option. The module remains for `validate_custom_path`
-and `derive_ini_path` utilities.
-
-**Planned**: Extract the two utility functions into `config.rs`, then remove
-`discovery.rs` entirely in v0.4.0.
+No known issues at this time.

src/discovery.rs

@@ -1,11 +1,8 @@
 //! Save-folder discovery.
 //!
-//! **Deprecated.** Auto-scanning user profiles and system directories for
-//! Subnautica 2 saves is a privacy concern. Scheduled for removal in v0.4.0.
-//! Use `Set save folder` from the main menu instead to enter paths manually.
-//!
-//! Traverses known path patterns across user profiles and common install
-//! locations to find Subnautica 2 save folders.
+//! Checks the current user's default save locations — no scanning of other
+//! profiles or system drives. Run at startup as a convenience; if nothing is
+//! found the user enters a path manually via `Set save folder`.
 
 use std::fs;
 use std::path::{Path, PathBuf};
@@ -340,6 +337,55 @@ fn fixed_drives() -> Vec<String> {
     drives
 }
 
+/// Quick check of the current user's default save locations.
+///
+/// No scanning of other profiles, no recursion into system directories.
+/// Returns the first valid path found, or `None`.
+///
+/// **Windows** (checked in order):
+/// 1. `%LOCALAPPDATA%\Subnautica2\Saved\SaveGames`
+///
+/// **Linux / Steam Deck** (checked in order):
+/// 1. `~/.steam/steam/steamapps/compatdata/1962700/pfx/drive_c/users/steamuser/AppData/Local/Subnautica2/Saved/SaveGames`
+/// 2. `~/.local/share/Steam/steamapps/compatdata/1962700/pfx/drive_c/users/steamuser/AppData/Local/Subnautica2/Saved/SaveGames`
+/// 3. `$XDG_DATA_HOME/Subnautica2/Saved/SaveGames` (typically `~/.local/share/Subnautica2/Saved/SaveGames`)
+pub fn quick_discover() -> Option<PathBuf> {
+    // Primary: %LOCALAPPDATA%\Subnautica2\Saved\SaveGames (Windows)
+    #[cfg(target_os = "windows")]
+    {
+        if let Some(local) = dirs::data_local_dir() {
+            let primary = local.join("Subnautica2").join("Saved").join("SaveGames");
+            if primary.exists() && has_save_files(&primary) {
+                return Some(primary);
+            }
+        }
+    }
+
+    // Primary: Proton paths + XDG data (Linux / Steam Deck)
+    #[cfg(not(target_os = "windows"))]
+    {
+        if let Some(home) = dirs::home_dir() {
+            for rel in &[
+                ".steam/steam/steamapps/compatdata/1962700/pfx/drive_c/users/steamuser/AppData/Local/Subnautica2/Saved/SaveGames",
+                ".local/share/Steam/steamapps/compatdata/1962700/pfx/drive_c/users/steamuser/AppData/Local/Subnautica2/Saved/SaveGames",
+            ] {
+                let candidate = home.join(rel);
+                if candidate.exists() && has_save_files(&candidate) {
+                    return Some(candidate);
+                }
+            }
+        }
+        if let Some(data) = dirs::data_local_dir() {
+            let primary = data.join("Subnautica2").join("Saved").join("SaveGames");
+            if primary.exists() && has_save_files(&primary) {
+                return Some(primary);
+            }
+        }
+    }
+
+    None
+}
+
 // ── helpers for the TUI ──────────────────────────────────────────────────
 
 /// Validate that a manually entered path exists and contains save files.

src/main.rs

@@ -144,6 +144,14 @@ fn run_app<B: Backend>(terminal: &mut Terminal<B>) -> Result<()> {
          result in incomplete, corrupt, or overwritten save files.",
     )?;
 
+    // Quick check of common save locations (current user only, no profile scans)
+    if app.save_folder.is_none() {
+        if let Some(path) = discovery::quick_discover() {
+            app.save_folder = Some(path);
+            refresh_stats(&mut app.tui_state, app.save_folder.as_deref());
+        }
+    }
+
     // Disclaimer flow
     if !crate::config::disclaimer_accepted() {
         match run_disclaimer(terminal, &mut app)? {