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+# Database Consolidation Deployment Guide
+
+This document outlines the plan and checklist for consolidating the `openneo_id` database into the main `openneo_impress` database.
+
+## Current Status: BLOCKED
+
+**This migration cannot be deployed until Impress 2020 is retired.**
+
+## The Problem
+
+While the main DTI Rails app is ready to move to a single-database architecture, **Impress 2020 still directly accesses both databases**:
+
+- `openneo_impress` - For reading item, pet, and outfit data
+- `openneo_id` - For user authentication via GraphQL
+
+If we consolidate the databases now, Impress 2020's authentication will break immediately, causing login failures for users accessing DTI through the Impress 2020 GraphQL API.
+
+## Path Forward
+
+There are two options to unblock this migration:
+
+### Option A: Retire Impress 2020 First (Recommended)
+
+1. Complete the migration of remaining Impress 2020 dependencies back to the main Rails app
+   - See `docs/impress-2020-dependencies.md` for current status
+   - Primary remaining dependencies: GraphQL API for outfit data, image generation service
+2. Spin down the Impress 2020 service entirely
+3. Execute the database consolidation (steps below)
+
+### Option B: Coordinated Update (Complex)
+
+1. Update Impress 2020 to point to `openneo_impress.auth_users` instead of `openneo_id.users`
+2. Deploy both applications simultaneously during a maintenance window
+3. Execute the database consolidation
+
+**Recommendation:** Option A is simpler and aligns with our long-term goal of fully consolidating back into the Rails monolith.
+
+---
+
+## Deployment Checklist (When Ready)
+
+⚠️ **DO NOT EXECUTE UNTIL IMPRESS 2020 IS RETIRED**
+
+### Prerequisites
+
+- [ ] Impress 2020 service is spun down and no longer accessing databases
+- [ ] All Impress 2020 dependencies have been migrated to main Rails app
+- [ ] Database backups are current and tested
+- [ ] Maintenance window scheduled (estimate: 30-60 minutes)
+
+### Phase 1: Deploy Write Lock
+
+**Branch:** `feature/consolidate-auth-database` @ commit `604a8667`
+
+**Purpose:** Prevent writes to AuthUser table while keeping login/logout functional.
+
+**Steps:**
+
+1. Deploy Phase 1 to production
+2. Verify:
+   - [ ] Existing users can log in
+   - [ ] Existing users can log out
+   - [ ] Registration shows maintenance message
+   - [ ] Settings updates show maintenance message
+   - [ ] NeoPass connection shows maintenance message
+
+**Expected Downtime:** None (read-only mode for account changes only)
+
+### Phase 2: Copy Data
+
+**Purpose:** Copy auth data from `openneo_id` to `openneo_impress` while table is stable.
+
+**Steps:**
+
+1. **Backup openneo_id database:**
+   ```bash
+   mysqldump -h [host] -u [user] -p openneo_id > openneo_id_backup_$(date +%Y%m%d_%H%M%S).sql
+   ```
+
+2. **Verify backup:**
+   ```bash
+   # Check file size is reasonable
+   ls -lh openneo_id_backup_*.sql
+
+   # Spot-check contents
+   head -n 50 openneo_id_backup_*.sql
+   ```
+
+3. **Run the migration:**
+   ```bash
+   cd /var/www/impress
+   bundle exec rails db:migrate
+   ```
+
+4. **Verify data copy:**
+   ```sql
+   -- Connect to MySQL
+   mysql -h [host] -u [user] -p
+
+   -- Check row counts match
+   SELECT COUNT(*) AS openneo_id_count FROM openneo_id.users;
+   SELECT COUNT(*) AS auth_users_count FROM openneo_impress.auth_users;
+
+   -- Spot-check a few records
+   SELECT id, name, email FROM openneo_id.users LIMIT 5;
+   SELECT id, name, email FROM openneo_impress.auth_users WHERE id IN (1, 2, 3, 4, 5);
+
+   -- Verify indexes were created
+   SHOW INDEX FROM openneo_impress.auth_users;
+   ```
+
+5. **Verify results:**
+   - [ ] Row counts match exactly
+   - [ ] Sample records match (IDs, names, emails)
+   - [ ] All 4 indexes created (email, provider+uid, reset_password_token, unlock_token)
+
+**Expected Downtime:** None (still in write-lock mode)
+
+### Phase 3: Switch to New Table
+
+**Branch:** `feature/consolidate-auth-database` @ commit `2c21269a`
+
+**Purpose:** Point AuthUser at consolidated table, restore full functionality.
+
+**Steps:**
+
+1. Deploy Phase 2 to production
+2. **Immediately test critical paths:**
+   - [ ] Login with existing account
+   - [ ] Logout
+   - [ ] Register new account
+   - [ ] Update account settings (email, password)
+   - [ ] Connect NeoPass (if available)
+   - [ ] Disconnect NeoPass (if available)
+
+3. **Monitor error logs:**
+   ```bash
+   tail -f /var/www/impress/log/production.log | grep -i error
+   ```
+
+4. **Verify database queries are using auth_users:**
+   ```bash
+   # Check recent queries in logs
+   grep "auth_users" /var/www/impress/log/production.log | tail -n 20
+
+   # Should see SELECT/INSERT/UPDATE on auth_users, NOT openneo_id.users
+   ```
+
+**Expected Downtime:** Brief (< 1 minute for deployment)
+
+**Rollback Plan:** If critical issues found, revert to Phase 1 commit and restore openneo_id from backup.
+
+### Phase 4: Documentation Update
+
+**Branch:** `feature/consolidate-auth-database` @ commit `9ba94f9f`
+
+**Purpose:** Update documentation to reflect single-database architecture.
+
+**Steps:**
+
+1. Deploy Phase 3 to production
+2. Verify no errors
+
+**Expected Downtime:** None
+
+### Phase 5: Database Teardown
+
+**Purpose:** Remove the now-unused `openneo_id` database.
+
+**Steps:**
+
+1. **Wait 7 days** to ensure no issues found in production
+
+2. **Final backup:**
+   ```bash
+   mysqldump -h [host] -u [user] -p openneo_id > openneo_id_final_backup_$(date +%Y%m%d_%H%M%S).sql
+   ```
+
+3. **Store backup offsite:**
+   - Upload to secure backup storage
+   - Keep for at least 90 days
+
+4. **Drop the database:**
+   ```sql
+   DROP DATABASE openneo_id;
+   ```
+
+5. **Remove environment variable:**
+   - Delete `DATABASE_URL_OPENNEO_ID` from production environment config
+   - Restart app to ensure it doesn't try to connect
+
+6. **Update MySQL users:**
+   ```sql
+   -- Remove openneo_id privileges from users
+   -- (Already done in deploy/setup.yml for new deployments)
+   ```
+
+**Expected Downtime:** None
+
+---
+
+## Rollback Procedures
+
+### If Issues Found After Phase 3
+
+1. **Immediate rollback:**
+   ```bash
+   # Revert to Phase 1 commit
+   git checkout 604a8667
+   bundle exec rails db:migrate:down VERSION=20251102064247
+   # Deploy
+   ```
+
+2. **Restore openneo_id (if needed):**
+   ```bash
+   mysql -h [host] -u [user] -p openneo_id < openneo_id_backup_[timestamp].sql
+   ```
+
+3. **Investigate issues before reattempting**
+
+### If Data Corruption Detected
+
+1. **Immediately restore from backup:**
+   ```bash
+   # Drop corrupted auth_users table
+   mysql -h [host] -u [user] -p -e "DROP TABLE openneo_impress.auth_users;"
+
+   # Restore openneo_id if needed
+   mysql -h [host] -u [user] -p openneo_id < openneo_id_backup_[timestamp].sql
+   ```
+
+2. **Revert to pre-migration code**
+3. **Review migration SQL before reattempting**
+
+---
+
+## Key Risks & Mitigations
+
+| Risk | Impact | Mitigation | Status |
+|------|--------|------------|--------|
+| Impress 2020 auth breaks | HIGH - Users can't log in via I2020 | Block deployment until I2020 retired | ⚠️ BLOCKING |
+| Data copy fails mid-migration | HIGH - Incomplete auth data | Wrapped in transaction, can rollback | ✅ Mitigated |
+| Production traffic during copy | MEDIUM - Stale data | Write lock prevents changes | ✅ Mitigated |
+| Schema mismatch between DBs | MEDIUM - Migration fails | Migration matches exact schema | ✅ Mitigated |
+| Indexes not created | MEDIUM - Slow queries | Verification step checks indexes | ✅ Mitigated |
+| Login tracking data loss | LOW - Missing login stats | Acceptable trade-off | ✅ Accepted |
+
+---
+
+## Success Criteria
+
+- [ ] All existing users can log in
+- [ ] New user registration works
+- [ ] Settings updates work
+- [ ] NeoPass connection/disconnection works
+- [ ] No errors in production logs
+- [ ] Query performance unchanged
+- [ ] Database row counts match
+- [ ] All auth_users indexes present
+
+---
+
+## Timeline Estimate
+
+**Total time:** 30-60 minutes (after Impress 2020 retired)
+
+- Phase 1 deployment: 5 min
+- Phase 2 data copy: 5-10 min (depending on user count)
+- Phase 3 deployment + testing: 15-30 min
+- Phase 4 deployment: 5 min
+- Phase 5 teardown: 7+ days later, 10 min
+
+---
+
+## Questions Before Proceeding
+
+1. **Is Impress 2020 fully retired?** If not, STOP.
+2. Do we have recent database backups? (< 24 hours old)
+3. Do we have a maintenance window scheduled?
+4. Have we announced the maintenance to users?
+5. Do we have rollback access ready?
+
+---
+
+**Last Updated:** November 2025
+**Status:** Blocked on Impress 2020 retirement
+**Branch:** `feature/consolidate-auth-database`