ubiquitous-invention/plans/Plan-multitenant-saas-hardening/Epic-tenant-lifecycle/Task-account-merge.md

---
kind: task
slug: account-merge
title: Merge two existing user accounts that turn out to share an email
plan_slug: multitenant-saas-hardening
epic_slug: tenant-lifecycle
status: draft
priority: P2
tenant_id: global
owner: unassigned
cursor_todo_id: null
updated_at: "2026-06-02"
---

# Task summary

Handle the case where a user has, historically, created two separate `users` rows (one via GitHub OAuth, one via Credentials, etc.) and now wants them merged into a single identity. The current behavior in `Task-multi-email-identity` is to *reject* the OAuth sign-in when the email collides with another user — this task is the operator-facing fix.

## Why deferred from the invites convoy

Account merge is security-sensitive and has cascading data implications:

- Both users may have authored `objects`, posted comments, owned workspaces, accepted invites.
- After merge, all FKs on the losing user's id need to point to the winning user's id, in one transaction.
- Some FKs have unique constraints (e.g., `workspace_members(workspace_id, user_id)`) — merging two users who are both in the same workspace creates a conflict that has to be resolved by keeping the higher-role row.
- Requires both accounts to prove ownership (re-sign-in to the losing account, then OAuth-verify the winning account's email).

This is its own multi-day effort. Out of scope for the invites convoy.

## Scope (sketch — refine when scheduled)

- Detection: when `ensureUserIdByVerifiedEmail` would reject an OAuth sign-in because the email is verified on another user, instead surface a "we found another account with this email — merge?" affordance.
- Merge procedure: a transactional operator that rewires FKs from the losing user to the winning user, handles unique-constraint collisions per table, and writes a comprehensive audit-log entry.
- UI: profile-side "Merge another account into this one" flow that requires authenticating to both.

## Acceptance criteria (draft)

- [ ] All FKs that referenced the losing user now reference the winning user; no orphans.
- [ ] Workspace-membership conflicts resolved with the higher-role row kept.
- [ ] Audit-log entry includes a snapshot of every rewired FK count.
- [ ] Losing user row is hard-deleted only after a 30-day window during which the merge can be reverted (soft-delete first; reuses `Task-workspace-soft-delete-and-audit` semantics).

## Links

- Epic: `./Epic-tenant-lifecycle.md`
- Depends on: `./Task-multi-email-identity.md`, `./Task-workspace-soft-delete-and-audit.md`.
docs(plans): split workspace-invites convoy into identity + invites + autocomplete User pushed back on "strict email match in v1" — the right architectural answer is multi-email identity (one users row owning multiple verified emails), not a stopgap. Scaling the convoy accordingly: 1. Task-multi-email-identity (NEW, P1, foundation) - user_email_identities table (user_id, email lowercased, verified_at, source: primary \| oauth:<provider> \| manual) - Refactor ensureUserIdByEmail -> ensureUserIdByVerifiedEmail against the new table. - OAuth callback writes a source='oauth:<provider>' identity when the provider returns email_verified=true. Cross-user conflict rejects. - Profile UI: "Linked emails" section, read-only in v1. - Exports userOwnsEmail(userId, emailLower) for invite accept to call. 2. Task-workspace-invites-and-roles (existing, narrowed) - All the original spec. - Accept procedure calls userOwnsEmail() instead of comparing users.email directly. Mismatch renders an explainer page, not a silent accept. 3. Task-invite-recipient-autocomplete (NEW, P1, polish) - invites.suggestRecipient returns typed suggestions across four kinds: member / pending_invite / known_user / new_email. - Tenancy fence on known_user is the security-relevant assertion; test for it explicitly. - Combobox UI renders each kind with its own affordance. Three follow-ups filed explicitly to keep this convoy PR-sized: - Task-manual-email-verification (add an email outside OAuth) - Task-disconnect-linked-email (destructive, needs last-verified guard) - Task-account-merge (handle the legacy duplicate-users case) Epic file refreshed with the new task table, follow-up table, and a phase ordering note. Identity lands first because it touches the sign-in path; invites and autocomplete can ship in their own PRs. Co-authored-by: Cursor <cursoragent@cursor.com> 2026-06-02 11:02:38 -04:00			`---`
			`kind: task`
			`slug: account-merge`
			`title: Merge two existing user accounts that turn out to share an email`
			`plan_slug: multitenant-saas-hardening`
			`epic_slug: tenant-lifecycle`
			`status: draft`
			`priority: P2`
			`tenant_id: global`
			`owner: unassigned`
			`cursor_todo_id: null`
			`updated_at: "2026-06-02"`
			`---`

			`# Task summary`

			Handle the case where a user has, historically, created two separate `users` rows (one via GitHub OAuth, one via Credentials, etc.) and now wants them merged into a single identity. The current behavior in `Task-multi-email-identity` is to reject the OAuth sign-in when the email collides with another user — this task is the operator-facing fix.

			`## Why deferred from the invites convoy`

			`Account merge is security-sensitive and has cascading data implications:`

			- Both users may have authored `objects`, posted comments, owned workspaces, accepted invites.
			`- After merge, all FKs on the losing user's id need to point to the winning user's id, in one transaction.`
			- Some FKs have unique constraints (e.g., `workspace_members(workspace_id, user_id)`) — merging two users who are both in the same workspace creates a conflict that has to be resolved by keeping the higher-role row.
			`- Requires both accounts to prove ownership (re-sign-in to the losing account, then OAuth-verify the winning account's email).`

			`This is its own multi-day effort. Out of scope for the invites convoy.`

			`## Scope (sketch — refine when scheduled)`

			- Detection: when `ensureUserIdByVerifiedEmail` would reject an OAuth sign-in because the email is verified on another user, instead surface a "we found another account with this email — merge?" affordance.
			`- Merge procedure: a transactional operator that rewires FKs from the losing user to the winning user, handles unique-constraint collisions per table, and writes a comprehensive audit-log entry.`
			`- UI: profile-side "Merge another account into this one" flow that requires authenticating to both.`

			`## Acceptance criteria (draft)`

			`- [ ] All FKs that referenced the losing user now reference the winning user; no orphans.`
			`- [ ] Workspace-membership conflicts resolved with the higher-role row kept.`
			`- [ ] Audit-log entry includes a snapshot of every rewired FK count.`
			- [ ] Losing user row is hard-deleted only after a 30-day window during which the merge can be reverted (soft-delete first; reuses `Task-workspace-soft-delete-and-audit` semantics).

			`## Links`

			- Epic: `./Epic-tenant-lifecycle.md`
			- Depends on: `./Task-multi-email-identity.md`, `./Task-workspace-soft-delete-and-audit.md`.