diff --git a/backlog/tasks/task-048 - Version-History-&-CryptID-Registration-Enhancements.md b/backlog/tasks/task-048 - Version-History-&-CryptID-Registration-Enhancements.md
index f686806..cfcbec3 100644
--- a/backlog/tasks/task-048 - Version-History-&-CryptID-Registration-Enhancements.md	
+++ b/backlog/tasks/task-048 - Version-History-&-CryptID-Registration-Enhancements.md	
@@ -4,6 +4,7 @@ title: Version History & CryptID Registration Enhancements
 status: Done
 assignee: []
 created_date: '2025-12-10 22:22'
+updated_date: '2025-12-10 22:22'
 labels:
   - feature
   - auth
@@ -17,3 +18,41 @@ priority: high
 <!-- SECTION:DESCRIPTION:BEGIN -->
 Add version history feature with diff visualization and enhance CryptID registration flow with email backup
 <!-- SECTION:DESCRIPTION:END -->
+
+## Implementation Notes
+
+<!-- SECTION:NOTES:BEGIN -->
+## Implementation Summary
+
+### Email Service (SendGrid → Resend)
+- Updated `worker/types.ts` to use `RESEND_API_KEY`
+- Updated `worker/cryptidAuth.ts` sendEmail() to use Resend API
+
+### CryptID Registration Flow
+- Multi-step registration: welcome → username → email → success
+- Detailed explainer about passwordless authentication
+- Email backup for multi-device access
+- Added `email` field to Session type
+
+### Version History Feature
+
+**Backend API Endpoints:**
+- `GET /room/:roomId/history` - Get version history
+- `GET /room/:roomId/snapshot/:hash` - Get snapshot at version
+- `POST /room/:roomId/diff` - Compute diff between versions  
+- `POST /room/:roomId/revert` - Revert to a version
+
+**Frontend Components:**
+- `VersionHistoryPanel.tsx` - Timeline with diff visualization
+- `useVersionHistory.ts` - React hook for programmatic access
+- GREEN highlighting for added shapes
+- RED highlighting for removed shapes
+- PURPLE highlighting for modified shapes
+
+### Other Fixes
+- Network graph connect/trust buttons now work
+- CryptID dropdown integration buttons improved
+- Obsidian vault connection modal added
+
+Pushed to dev branch: commit 195cc7f
+<!-- SECTION:NOTES:END -->