fix: address 4 P2 review issues from PR #8 round 6

db/commands: paginate tag search — add offset + COUNT query to
search_images_by_tag returning (images, total); TagSearchParams gains
offset field and command returns TagSearchPage; store handles both the
initial load and load-more path so results beyond PAGE_SIZE are reachable

commands: semantic search over-fetches by 4× when any post-query filter
(folder, media kind, favorites, rating) is active, then truncates to the
requested limit; previously well-rated matches ranked just beyond the bare
vector limit were silently omitted

db: wrap update_folder_path in a transaction so a path-rewrite failure
(e.g. uniqueness collision) rolls back the already-updated folder row
instead of leaving the DB in an inconsistent half-migrated state

store: invalidate exploreTagsFolderId when a tagging run completes so
Explore reflects the updated tag distribution without requiring a manual
folder switch; previously the cache was never busted by background tagging

src-tauri/src/commands.rs

@@ -151,6 +151,15 @@ pub struct TagSearchParams {
     pub favorites_only: Option<bool>,
     pub rating_min: Option<i64>,
     pub limit: Option<usize>,
+    pub offset: Option<usize>,
+}
+
+#[derive(Serialize)]
+pub struct TagSearchPage {
+    pub images: Vec<ImageRecord>,
+    pub total: usize,
+    pub offset: usize,
+    pub limit: usize,
 }
 
 #[derive(Deserialize)]
@@ -522,7 +531,17 @@ pub async fn semantic_search_images(
 
     let conn = db.get().map_err(|e| e.to_string())?;
     let limit = params.limit.unwrap_or(64);
-    let ids = vector::search_image_ids_by_embedding(&conn, &embedding, limit)
+
+    // When post-query filters are active the vector search may discard many
+    // candidates ranked just beyond the bare limit. Over-fetch by 4× so that
+    // well-rated or folder-scoped matches are not silently omitted.
+    let has_filters = params.folder_id.is_some()
+        || params.media_kind.is_some()
+        || params.favorites_only.unwrap_or(false)
+        || params.rating_min.map_or(false, |r| r > 0);
+    let fetch_limit = if has_filters { limit * 4 } else { limit };
+
+    let ids = vector::search_image_ids_by_embedding(&conn, &embedding, fetch_limit)
         .map_err(|e| e.to_string())?;
     let mut images = db::get_images_by_ids(&conn, &ids).map_err(|e| e.to_string())?;
 
@@ -538,6 +557,7 @@ pub async fn semantic_search_images(
     if let Some(rating_min) = params.rating_min {
         images.retain(|image| image.rating >= rating_min);
     }
+    images.truncate(limit);
 
     Ok(images)
 }
@@ -546,18 +566,22 @@ pub async fn semantic_search_images(
 pub async fn search_images_by_tag(
     db: State<'_, DbState>,
     params: TagSearchParams,
-) -> Result<Vec<ImageRecord>, String> {
+) -> Result<TagSearchPage, String> {
     let conn = db.get().map_err(|e| e.to_string())?;
-    db::search_images_by_tag(
+    let limit = params.limit.unwrap_or(64);
+    let offset = params.offset.unwrap_or(0);
+    let (images, total) = db::search_images_by_tag(
         &conn,
         &params.query,
         params.folder_id,
         params.media_kind.as_deref(),
         params.favorites_only.unwrap_or(false),
         params.rating_min.unwrap_or(0),
-        params.limit.unwrap_or(64),
+        limit,
+        offset,
     )
-    .map_err(|e| e.to_string())
+    .map_err(|e| e.to_string())?;
+    Ok(TagSearchPage { images, total, offset, limit })
 }
 
 #[tauri::command]

src-tauri/src/db.rs

@@ -1385,7 +1385,10 @@ pub fn rename_folder(conn: &Connection, folder_id: i64, new_name: &str) -> Resul
 }
 
 pub fn update_folder_path(conn: &Connection, folder_id: i64, old_path: &str, new_path: &str, new_name: &str) -> Result<()> {
-    conn.execute(
+    // Both updates must be atomic: if the image path rewrite fails (e.g. a
+    // uniqueness collision) the folder row must not remain at the new location.
+    let tx = conn.unchecked_transaction()?;
+    tx.execute(
         "UPDATE folders SET path = ?2, name = ?3, scan_error = NULL WHERE id = ?1",
         params![folder_id, new_path, new_name],
     )?;
@@ -1393,10 +1396,11 @@ pub fn update_folder_path(conn: &Connection, folder_id: i64, old_path: &str, new
     // re-generating thumbnails and embeddings for unchanged files.
     // Use SUBSTR to replace only the leading prefix; SQLite's replace()
     // would corrupt paths where the old folder name also appears deeper in the tree.
-    conn.execute(
+    tx.execute(
         "UPDATE images SET path = ?2 || SUBSTR(path, LENGTH(?1) + 1) WHERE folder_id = ?3",
         params![old_path, new_path, folder_id],
     )?;
+    tx.commit()?;
     Ok(())
 }
 
@@ -1522,13 +1526,28 @@ pub fn search_images_by_tag(
     favorites_only: bool,
     rating_min: i64,
     limit: usize,
-) -> Result<Vec<ImageRecord>> {
+    offset: usize,
+) -> Result<(Vec<ImageRecord>, usize)> {
     let normalized_query = query.trim().to_ascii_lowercase();
     if normalized_query.is_empty() {
-        return Ok(Vec::new());
+        return Ok((Vec::new(), 0));
     }
     let favorites_flag = i64::from(favorites_only);
 
+    // Total count (for pagination)
+    let total: usize = conn.query_row(
+        "SELECT COUNT(DISTINCT i.id)
+         FROM images i
+         JOIN image_tags t ON t.image_id = i.id
+         WHERE (?1 IS NULL OR i.folder_id = ?1)
+           AND (?2 IS NULL OR i.media_kind = ?2)
+           AND (?3 = 0 OR i.favorite = 1)
+           AND i.rating >= ?4
+           AND LOWER(TRIM(t.tag)) = ?5",
+        params![folder_id, media_kind, favorites_flag, rating_min, normalized_query],
+        |row| row.get::<_, i64>(0),
+    )? as usize;
+
     let mut stmt = conn.prepare(
         "SELECT DISTINCT i.id
          FROM images i
@@ -1539,7 +1558,7 @@ pub fn search_images_by_tag(
            AND i.rating >= ?4
            AND LOWER(TRIM(t.tag)) = ?5
          ORDER BY i.rating DESC, i.modified_at DESC NULLS LAST, i.filename ASC
-         LIMIT ?6",
+         LIMIT ?6 OFFSET ?7",
     )?;
 
     let image_ids = stmt
@@ -1550,13 +1569,14 @@ pub fn search_images_by_tag(
                 favorites_flag,
                 rating_min,
                 normalized_query,
-                limit as i64
+                limit as i64,
+                offset as i64
             ],
             |row| row.get::<_, i64>(0),
         )?
         .collect::<rusqlite::Result<Vec<_>>>()?;
 
-    get_images_by_ids(conn, &image_ids)
+    Ok((get_images_by_ids(conn, &image_ids)?, total))
 }
 
 pub fn search_tags_autocomplete(

src/store.ts

@@ -725,7 +725,8 @@ export const useGalleryStore = create<GalleryState>((set, get) => ({
       }
 
       if (parsedSearch.mode === "tag" && parsedSearch.query) {
-        const images = await invoke<ImageRecord[]>("search_images_by_tag", {
+        const offset = reset ? 0 : loadedCount;
+        const result = await invoke<{ images: ImageRecord[]; total: number; offset: number; limit: number }>("search_images_by_tag", {
           params: {
             query: parsedSearch.query,
             folder_id: selectedFolderId,
@@ -733,14 +734,16 @@ export const useGalleryStore = create<GalleryState>((set, get) => ({
             favorites_only: favoritesOnly,
             rating_min: minimumRating > 0 ? minimumRating : null,
             limit: PAGE_SIZE,
+            offset,
           },
         });
 
         if (requestToken !== galleryRequestToken) return;
+        if (reset) {
           set({
-          images,
+            images: result.images,
-          totalImages: images.length,
+            totalImages: result.total,
-          loadedCount: images.length,
+            loadedCount: result.images.length,
             loadingImages: false,
             collectionTitle: `Tag search: ${parsedSearch.query}`,
             selectedFolderId,
@@ -749,6 +752,14 @@ export const useGalleryStore = create<GalleryState>((set, get) => ({
             similarHasMore: false,
             similarFolderId: null,
           });
+        } else {
+          set((state) => ({
+            images: [...state.images, ...result.images],
+            loadedCount: state.loadedCount + result.images.length,
+            totalImages: result.total,
+            loadingImages: false,
+          }));
+        }
         return;
       }
 
@@ -1608,6 +1619,9 @@ export const useGalleryStore = create<GalleryState>((set, get) => ({
             "AI tagging complete",
             `${folderName} finished generating tags.${failureDetail}`,
           );
+          // New tags are now in the DB — invalidate the Explore tag cache so
+          // reopening Explore reflects the updated tag distribution.
+          set({ exploreTagsFolderId: undefined });
         }
       }