Address PR review feedback from JohnBaumb and Cin

Four fixes from the review:

**library.js — back button stack (JohnBaumb):**
Replace the single-slot `artistDetailPageState.originPage` with an origin
stack. Chained navigation like Search → Artist A → similar Artist B →
similar Artist C now walks back one step at a time (C → B → A → Search)
instead of jumping straight to Search and skipping A and B.

`navigateToArtistDetail` takes an optional `{skipOriginPush}` flag so the
back button can re-enter a prior artist without re-pushing onto the stack.
Fresh entries from a non-artist page clear any stale stack from a prior
chain. Duplicate-click detection avoids pushing the same target twice.
Label derivation (`_updateArtistDetailBackButtonLabel`) reads the stack top
so the button says "Back to <ArtistName>" mid-chain and "Back to Search"
at the root.

**library.js — checkArtistEnhanceEligibility after library upgrade (Cin):**
The quality-analysis endpoint only works on library PKs. After the
library-upgrade branch rewrites `currentArtistId` from the source ID to
the library PK, the check was still using the original closure arg, so
upgraded source artists never hit `/api/library/artist/<id>/quality-analysis`.
Use `artistDetailPageState.currentArtistId` so the call gets the resolved id.

**init.js — isPageAllowed + home page recursion (Cin):**
- artist-detail is reachable from both Library and Search results now, so
  permission check accepts either grant (plus legacy 'downloads'/'artists'
  aliases). Search-only profiles can open source artists; legacy artists-only
  profiles no longer recurse on the home redirect.
- `getProfileHomePage` rewrites 'artists' → 'search' (it already rewrote
  'downloads') so legacy home_page values resolve correctly.
- Legacy-compat expanded in isPageAllowed to treat 'artists' as equivalent
  to 'search' in both directions.

**init.js — profile edit forms dropping values on save (Cin):**
Both pageLabels maps (admin edit form + self-edit form) referenced the
legacy 'downloads'/'artists' keys. When editing a profile saved with
`home_page: 'search'` and `allowed_pages: ['search', 'library']`, the
home select didn't render a 'search' option, and the allowed_pages
checkboxes used 'downloads' as their value — so saving the form dropped
both values.

Update both maps to use 'search' as the canonical key. Add
`_normalizeLegacyAllowedPages` and `_normalizeLegacyHomePage` helpers that
migrate any legacy ids in allowed_pages/home_page on read, so a legacy
profile's first save upgrades its stored ids to the new canonical form.

webui/static/init.js

@@ -187,10 +187,28 @@ function applyReduceEffects(enabled) {
 // ── Profile System ─────────────────────────────────────────────
 let currentProfile = null;
 
+// Normalize legacy allowed_pages entries so the profile edit forms (which are
+// built from the new pageLabels map containing 'search') don't drop access
+// when saving a profile that was stored before the Search page rename.
+// 'downloads' was the old Search id, 'artists' was the retired inline page.
+function _normalizeLegacyAllowedPages(pages) {
+    if (!Array.isArray(pages)) return pages;
+    const mapped = pages.map(id => (id === 'downloads' || id === 'artists') ? 'search' : id);
+    return [...new Set(mapped)];
+}
+
+function _normalizeLegacyHomePage(homePage) {
+    if (homePage === 'downloads' || homePage === 'artists') return 'search';
+    return homePage;
+}
+
 function getProfileHomePage() {
     if (!currentProfile) return 'dashboard';
-    // Legacy profiles stored the Search page as 'downloads'.
+    // Legacy profiles stored the Search page as either 'downloads' (the old id
-    const home = currentProfile.home_page === 'downloads' ? 'search' : currentProfile.home_page;
+    // before the rename) or 'artists' (the retired inline Artists page).
+    // Both fold into the unified Search page now.
+    let home = currentProfile.home_page;
+    if (home === 'downloads' || home === 'artists') home = 'search';
     if (home) return home;
     return currentProfile.is_admin ? 'dashboard' : 'discover';
 }
@@ -199,19 +217,24 @@ function isPageAllowed(pageId) {
     if (!currentProfile) return true;
     if (currentProfile.id === 1) return true;
     if (pageId === 'help' || pageId === 'issues') return true;
+    if (pageId === 'settings') return currentProfile.is_admin;
     if (pageId === 'artist-detail') {
-        // artist-detail requires library access
+        // artist-detail is reachable from both Library and Search results, so
+        // either grant unlocks it. Without this, a Search-only profile couldn't
+        // open a source artist, and a legacy artists-only profile would hit the
+        // home-redirect recursion path below.
         const ap = currentProfile.allowed_pages;
         if (!ap) return true;
-        return ap.includes('library');
+        return ap.includes('library') || ap.includes('search')
+            || ap.includes('downloads') || ap.includes('artists');
     }
-    if (pageId === 'settings') return currentProfile.is_admin;
     const ap = currentProfile.allowed_pages;
     if (!ap) return true; // null = all pages
     if (ap.includes(pageId)) return true;
-    // Legacy compat: the Search page used to be saved as 'downloads'.
+    // Legacy compat: 'downloads' (old Search id) and 'artists' (retired inline
-    if (pageId === 'search' && ap.includes('downloads')) return true;
+    // Artists page) both fold into the unified 'search' page.
-    if (pageId === 'downloads' && ap.includes('search')) return true;
+    if (pageId === 'search' && (ap.includes('downloads') || ap.includes('artists'))) return true;
+    if ((pageId === 'downloads' || pageId === 'artists') && ap.includes('search')) return true;
     return false;
 }
 
@@ -1574,9 +1597,11 @@ function showProfileEditForm(profileId, currentName, currentColor, currentAvatar
     const isAdmin = currentProfile && currentProfile.is_admin;
     const isEditingAdmin = profileSettings.is_admin;
     const editColors = ['#6366f1', '#ec4899', '#10b981', '#f59e0b', '#3b82f6', '#ef4444', '#8b5cf6', '#14b8a6'];
+    // 'search' replaces the legacy 'downloads'/'artists' ids; legacy values are
+    // normalized on read below so saving a legacy profile upgrades it.
     const pageLabels = {
-        dashboard: 'Dashboard', sync: 'Sync', downloads: 'Search', discover: 'Discover',
+        dashboard: 'Dashboard', sync: 'Sync', search: 'Search', discover: 'Discover',
-        artists: 'Artists', automations: 'Automations', library: 'Library', stats: 'Listening Stats',
+        automations: 'Automations', library: 'Library', stats: 'Listening Stats',
         'playlist-explorer': 'Playlist Explorer', import: 'Import', help: 'Help & Docs'
     };
 
@@ -1628,14 +1653,16 @@ function showProfileEditForm(profileId, currentName, currentColor, currentAvatar
     defaultOpt.value = '';
     defaultOpt.textContent = isEditingAdmin ? 'Default (Dashboard)' : 'Default (Discover)';
     homeSelect.appendChild(defaultOpt);
-    // Filter home page options to only allowed pages
+    // Normalize legacy ids so the form shows the right options/selection for
-    const allowedSet = profileSettings.allowed_pages;
+    // profiles saved before the Search page rename.
+    const allowedSet = _normalizeLegacyAllowedPages(profileSettings.allowed_pages);
+    const normalizedHome = _normalizeLegacyHomePage(profileSettings.home_page);
     Object.entries(pageLabels).forEach(([id, label]) => {
         if (allowedSet && !allowedSet.includes(id)) return; // Skip non-permitted
         const opt = document.createElement('option');
         opt.value = id;
         opt.textContent = label;
-        if (id === profileSettings.home_page) opt.selected = true;
+        if (id === normalizedHome) opt.selected = true;
         homeSelect.appendChild(opt);
     });
     form.appendChild(homeSelect);
@@ -1760,9 +1787,11 @@ function showSelfEditForm() {
     const existing = document.getElementById('self-edit-form');
     if (existing) existing.remove();
 
+    // 'search' replaces the legacy 'downloads'/'artists' ids; legacy values are
+    // normalized on read below so saving a legacy profile upgrades it.
     const pageLabels = {
-        dashboard: 'Dashboard', sync: 'Sync', downloads: 'Search', discover: 'Discover',
+        dashboard: 'Dashboard', sync: 'Sync', search: 'Search', discover: 'Discover',
-        artists: 'Artists', automations: 'Automations', library: 'Library', stats: 'Listening Stats',
+        automations: 'Automations', library: 'Library', stats: 'Listening Stats',
         'playlist-explorer': 'Playlist Explorer', import: 'Import', help: 'Help & Docs'
     };
 
@@ -1797,13 +1826,16 @@ function showSelfEditForm() {
     defaultOpt.value = '';
     defaultOpt.textContent = 'Default (Discover)';
     homeSelect.appendChild(defaultOpt);
-    const ap = currentProfile.allowed_pages;
+    // Normalize legacy ids so the form shows the right options/selection for
+    // profiles saved before the Search page rename.
+    const ap = _normalizeLegacyAllowedPages(currentProfile.allowed_pages);
+    const normalizedHome = _normalizeLegacyHomePage(currentProfile.home_page);
     Object.entries(pageLabels).forEach(([id, label]) => {
         if (ap && !ap.includes(id)) return;
         const opt = document.createElement('option');
         opt.value = id;
         opt.textContent = label;
-        if (id === currentProfile.home_page) opt.selected = true;
+        if (id === normalizedHome) opt.selected = true;
         homeSelect.appendChild(opt);
     });
     form.appendChild(homeSelect);

webui/static/library.js

@@ -640,7 +640,11 @@ let artistDetailPageState = {
     currentArtistId: null,
     currentArtistName: null,
     currentArtistSource: null,
-    originPage: null,  // page id captured by navigateToArtistDetail for the back button
+    // Stack of origins captured by navigateToArtistDetail for the back button.
+    // Each entry is either {type:'page', pageId} or {type:'artist', id, name, source}
+    // so chained navigation (Search → A → similar B → similar C) walks back one
+    // step at a time instead of jumping straight to Search.
+    originStack: [],
     enhancedView: false,
     enhancedData: null,
     expandedAlbums: new Set(),
@@ -672,19 +676,45 @@ const _ARTIST_DETAIL_BACK_LABELS = {
     'active-downloads': 'Back to Downloads',
 };
 
-function navigateToArtistDetail(artistId, artistName, sourceOverride = null) {
+function navigateToArtistDetail(artistId, artistName, sourceOverride = null, options = {}) {
     console.log(`🎵 Navigating to artist detail: ${artistName} (ID: ${artistId}${sourceOverride ? `, source: ${sourceOverride}` : ''})`);
 
-    // Capture where the user is coming from BEFORE navigateToPage flips
+    // Capture the current location on the origin stack BEFORE navigateToPage
-    // currentPage. The back button on the artist-detail page reads this so it
+    // flips currentPage. The back button walks this stack one step at a time,
-    // can say "Back to Search" / "Back to Discover" / etc. instead of the
+    // so a chain like Search → A → similar B → similar C steps back through
-    // hardcoded "Back to Library". Falls back to library when origin is
+    // C → B → A → Search instead of jumping straight home. `skipOriginPush`
-    // unknown or when chaining from one artist-detail page to another.
+    // lets the back button re-enter a prior artist without re-pushing.
-    let origin = (typeof currentPage === 'string' && currentPage) ? currentPage : null;
+    if (!options.skipOriginPush) {
-    if (!origin || origin === 'artist-detail') {
+        // Fresh entry (from a non-artist page) starts a new chain; any stale
-        origin = artistDetailPageState.originPage || 'library';
+        // entries from a prior artist-detail visit are dropped.
+        if (currentPage !== 'artist-detail') {
+            artistDetailPageState.originStack = [];
+        }
+
+        let entry;
+        if (currentPage === 'artist-detail' && artistDetailPageState.currentArtistId) {
+            entry = {
+                type: 'artist',
+                id: artistDetailPageState.currentArtistId,
+                name: artistDetailPageState.currentArtistName,
+                source: artistDetailPageState.currentArtistSource,
+            };
+        } else {
+            const pageId = (typeof currentPage === 'string' && currentPage && currentPage !== 'artist-detail')
+                ? currentPage : 'library';
+            entry = { type: 'page', pageId };
+        }
+
+        // Avoid pushing a duplicate top entry on repeated clicks of the same target.
+        const top = artistDetailPageState.originStack[artistDetailPageState.originStack.length - 1];
+        const isDuplicate = top && top.type === entry.type && (
+            (entry.type === 'page' && top.pageId === entry.pageId) ||
+            (entry.type === 'artist' && String(top.id) === String(entry.id))
+        );
+        if (!isDuplicate) {
+            artistDetailPageState.originStack.push(entry);
+        }
     }
-    artistDetailPageState.originPage = origin;
 
     // Abort any in-progress completion stream
     if (artistDetailPageState.completionController) {
@@ -731,12 +761,8 @@ function navigateToArtistDetail(artistId, artistName, sourceOverride = null) {
     // Navigate to artist detail page
     navigateToPage('artist-detail');
 
-    // Update back-button label for the captured origin.
+    // Update back-button label to reflect where the next pop will land.
-    const backBtnLabel = document.querySelector('#artist-detail-back-btn span');
+    _updateArtistDetailBackButtonLabel();
-    if (backBtnLabel) {
-        const friendly = _ARTIST_DETAIL_BACK_LABELS[origin] || _ARTIST_DETAIL_BACK_LABELS.library;
-        backBtnLabel.textContent = `← ${friendly}`;
-    }
 
     // Initialize if needed and load data
     if (!artistDetailPageState.isInitialized) {
@@ -747,27 +773,58 @@ function navigateToArtistDetail(artistId, artistName, sourceOverride = null) {
     loadArtistDetailData(artistId, artistName);
 }
 
+function _updateArtistDetailBackButtonLabel() {
+    const backBtnLabel = document.querySelector('#artist-detail-back-btn span');
+    if (!backBtnLabel) return;
+    const stack = artistDetailPageState.originStack || [];
+    const top = stack[stack.length - 1];
+    if (!top) {
+        backBtnLabel.textContent = `← ${_ARTIST_DETAIL_BACK_LABELS.library}`;
+    } else if (top.type === 'artist') {
+        backBtnLabel.textContent = `← Back to ${top.name}`;
+    } else {
+        const friendly = _ARTIST_DETAIL_BACK_LABELS[top.pageId] || _ARTIST_DETAIL_BACK_LABELS.library;
+        backBtnLabel.textContent = `← ${friendly}`;
+    }
+}
+
 function initializeArtistDetailPage() {
     console.log("🔧 Initializing Artist Detail page...");
 
-    // Initialize back button — navigates back to whichever page initiated the
+    // Initialize back button — pops the origin stack one step at a time so a
-    // current artist-detail view (Search, Discover, Watchlist, Library, etc.),
+    // chain like Search → A → B → C walks back through C → B → A → Search
-    // captured by navigateToArtistDetail before the page swap.
+    // instead of jumping straight to the original entry page.
     const backBtn = document.getElementById("artist-detail-back-btn");
     if (backBtn) {
         backBtn.addEventListener("click", () => {
-            const dest = artistDetailPageState.originPage || 'library';
+            // Abort any in-progress completion stream regardless of destination
-            console.log(`🔙 Returning to ${dest}`);
-            // Abort any in-progress completion stream
             if (artistDetailPageState.completionController) {
                 artistDetailPageState.completionController.abort();
                 artistDetailPageState.completionController = null;
             }
-            // Clear artist detail state so we go back to the list view
+
+            const stack = artistDetailPageState.originStack || [];
+            if (stack.length > 0) {
+                const target = stack.pop();
+                if (target.type === 'artist') {
+                    // Re-enter a prior artist in the chain without re-pushing,
+                    // so the stack keeps shrinking as the user steps back.
+                    navigateToArtistDetail(target.id, target.name, target.source, { skipOriginPush: true });
+                    return;
+                }
+                // target.type === 'page' — fully exit the artist-detail chain
+                artistDetailPageState.currentArtistId = null;
+                artistDetailPageState.currentArtistName = null;
+                artistDetailPageState.originStack = [];
+                navigateToPage(target.pageId);
+                return;
+            }
+
+            // No history — default to library
             artistDetailPageState.currentArtistId = null;
             artistDetailPageState.currentArtistName = null;
-            artistDetailPageState.originPage = null;
+            artistDetailPageState.originStack = [];
-            navigateToPage(dest);
+            navigateToPage('library');
         });
     }
 
@@ -874,8 +931,11 @@ async function loadArtistDetailData(artistId, artistName) {
             }
         }
 
-        // Check if artist has tracks eligible for quality enhancement
+        // Check if artist has tracks eligible for quality enhancement.
-        checkArtistEnhanceEligibility(artistId);
+        // Use currentArtistId (not the closure arg) because the library-upgrade
+        // branch above may have rewritten it from the source ID to the library PK,
+        // and /api/library/artist/<id>/quality-analysis only works on library PKs.
+        checkArtistEnhanceEligibility(artistDetailPageState.currentArtistId);
 
     } catch (error) {
         console.error(`❌ Error loading artist detail data:`, error);