feat: complete task 3 - fix sync.go cache-hit path to use centralized filter

docs/plans/2026-07-21-fix-review-findings.md

@@ -33,8 +33,8 @@ Problem: Three separate filter implementations (`musicbrainz.FilterReleaseGroups
 
 ## Progress Tracking
 - Mark completed items with `[x]` immediately when done
-- Add newly discovered tasks with ➕ prefix
-- Document issues/blockers with ⚠️ prefix
+- Add newly discovered tasks with `➕` prefix
+- Document issues/blockers with `⚠️` prefix
 
 ## Implementation Steps
 
@@ -50,10 +50,10 @@ Problem: Three separate filter implementations (`musicbrainz.FilterReleaseGroups
 - [x] Run tests - must pass before task 3
 
 ### Task 3: Fix sync.go cache-hit path to use centralized filter
-- [ ] Update `SyncArtistDiscography` cache-hit branch (lines 93-115) to call the shared filter helper instead of inline logic
-- [ ] Ensure `opts` from `getArtistFilterOptions` is passed correctly
-- [ ] Write test in `sync_test.go` that verifies cache-hit path produces identical filter results as cache-miss path for same `FilterOptions` and release data
-- [ ] Run tests - must pass before task 4
+- [x] Update `SyncArtistDiscography` cache-hit branch to call the shared filter helper instead of inline logic
+- [x] Ensure `opts` from `getArtistFilterOptions` is passed correctly
+- [x] Write test in `sync_test.go` that verifies cache-hit path produces identical filter results as cache-miss path for same `FilterOptions` and release data
+- [x] Run tests - must pass before task 4
 
 ### Task 4: Fix scanner diff.go TypeFilter.suppressed to use centralized filter
 - [ ] Update `TypeFilter.suppressed` in `diff.go` to use the same logic as `ApplyTypeToggles` (i.e., treat `EP` in SecondaryTypes as a Single when `IgnoreSingles=true`)
@@ -104,33 +104,4 @@ Problem: Three separate filter implementations (`musicbrainz.FilterReleaseGroups
 
 ### Task 11: Update documentation
 - [ ] Update README.md if any new behavior or config documented
-- [ ] Note the filter centralization pattern in CLAUDE.md if new pattern established
-
-## Technical Details
-
-### Filter Logic Canonical Form
-```go
-// IgnoreSingles filters: Type == "Single" OR SecondaryTypes contains "Single" OR "EP"
-// IgnoreCompilations filters: Type == "Compilation" OR SecondaryTypes contains "Compilation"
-func matchesIgnoreSingles(r ExternalRelease) bool {
-    return r.Type == "Single" || hasSliceType(r.SecondaryTypes, "Single", "EP")
-}
-func matchesIgnoreCompilations(r ExternalRelease) bool {
-    return r.Type == "Compilation" || hasSliceType(r.SecondaryTypes, "Compilation")
-}
-```
-
-### Files to Modify
-1. `internal/musicbrainz/api.go` — export `hasSliceType`, `FilterOptions`; add `ApplyTypeToggles` or refactor `FilterReleaseGroups`
-2. `internal/musicbrainz/sync.go` — use shared filter in cache-hit path
-3. `internal/scanner/diff.go` — import and use shared filter
-4. `internal/database/external_releases.go` — migration + integer timestamp logic
-5. `internal/database/database.go` — add migration `006`
-6. `internal/musicbrainz/sync.go` — batch stale notification deletion
-7. `internal/scanner/scan.go` — handle `ErrArtistNotFound`
-8. `internal/notifier/scheduler.go` — composite map key
-9. `internal/database/artist_settings.go` — optimize upsert
-
-## Post-Completion
-- Manual verification: run against real Navidrome + MusicBrainz, confirm dashboard/notifications show consistent results regardless of cache state
-- No external system updates required
+- [ ] Note the filter centralization pattern in CLAUDE.md if new pattern established

internal/musicbrainz/sync.go

@@ -65,16 +65,7 @@ func SyncArtistDiscography(
 		if err != nil {
 			return nil, fmt.Errorf("sync artist discography: read artist filter options: %w", err)
 		}
-		filtered := make([]database.ExternalRelease, 0, len(cachedReleases))
-		for _, r := range cachedReleases {
-			if opts.IgnoreSingles && (r.Type == "Single" || hasSliceType(r.SecondaryTypes, "Single")) {
-				continue
-			}
-			if opts.IgnoreCompilations && (r.Type == "Compilation" || hasSliceType(r.SecondaryTypes, "Compilation")) {
-				continue
-			}
-			filtered = append(filtered, r)
-		}
+		filtered := ApplyTypeToggles(cachedReleases, opts)
 		return filtered, nil
 	}