issue: update 3ca0 - Phase 3 should implement SyncLevel per design, not full confirmation

3ca0-announcements-purgatory.md

@@ -45,15 +45,23 @@ This prevents serving announcements for repositories that may never receive stat
   - Cleanup task handles announcement expiry
   - Updated count()/cleanup() to 3-tuples
 
-- [ ] Phase 3: Fix sync integration (ROOT CAUSE of test failure)
-  - Sync module treats purgatory announcements as "not confirmed" so
-    per-repo sync (state events, PRs) never triggers for them
-  - Partial fix in commit 1d09e4b: ProcessResult::Purgatory now counts
-    as confirmed for pending_sync_index, and announcements going to
-    purgatory invalidate rejected state events from hot cache
-  - Still failing: test_archive_read_only_creates_bare_repo (30s timeout)
-  - Need to verify the partial fix is correct and sufficient, or if
-    additional sync plumbing is needed
+- [ ] Phase 3: Implement SyncLevel and fix sync integration (ROOT CAUSE of test failure)
+  - The sync module doesn't fetch state events for purgatory announcements
+    because they're not saved to DB and thus never "confirmed" as repos
+  - The fix per design doc (decision #6) is SyncLevel, NOT treating
+    purgatory as fully confirmed. Full confirmation would over-fetch
+    L2/L3 events (PRs, issues) that get rejected anyway.
+  - Add SyncLevel enum (StateOnly vs Full) to RepoSyncNeeds
+  - When announcement enters purgatory, register in sync index with
+    SyncLevel::StateOnly (only fetches kind 30618 state events)
+  - On promotion, upgrade sync level to Full
+  - Modify filter building in src/sync/filters.rs to partition repos
+    by sync level and build appropriate filters
+  - Revert the partial fix in commit 1d09e4b that treats
+    ProcessResult::Purgatory as confirmed in pending_sync_index
+    (wrong approach - would trigger full L2/L3 sync)
+  - Keep the hot cache invalidation for rejected state events (correct)
+  - This should fix test_archive_read_only_creates_bare_repo
 
 - [ ] Phase 4: Announcement persistence (save/restore)
   - save_to_disk() and restore_from_disk() skip announcement_purgatory
@@ -63,8 +71,6 @@ This prevents serving announcements for repositories that may never receive stat
   - Need persistence tests (purgatory_persistence.rs currently asserts 0)
 
 - [ ] Phase 5: Remaining design features
-  - SyncLevel (StateOnly vs Full) - purgatory announcements should only
-    sync state events, not L2/L3 events
   - Soft expiry two-phase - delete bare repo but retain event for 24h,
     allow revival on state event arrival
   - Expiry extension - extend_announcement_expiry() exists but is never