fix(invitations): guard the reverse disclosure direction

A will-join notice whose acceptance downgrades to no-join (stale
escalation denial, concurrent other-org membership) now fails with
disclosure-outdated instead of silently succeeding as an external grant —
the disclosure token binds the outcome in both directions.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: icecrasher321

apps/sim/lib/invitations/core.test.ts

@@ -737,6 +737,67 @@ describe('acceptInvitation', () => {
     expect(auditMock.recordAudit).not.toHaveBeenCalled()
   })
 
+  it('rejects a will-join disclosure when acceptance downgrades to external', async () => {
+    mockGetWorkspaceWithOwner.mockResolvedValue({
+      id: 'workspace-1',
+      name: 'Workspace',
+      ownerId: 'owner-1',
+      organizationId: 'org-1',
+      workspaceMode: 'organization',
+      billedAccountUserId: 'owner-1',
+    })
+    // Invitee joined a different organization after the preview rendered.
+    mockGetUserOrganization.mockImplementation(async (userId: string) =>
+      userId === 'invitee-user'
+        ? { organizationId: 'org-2', role: 'member', memberId: 'member-2' }
+        : null
+    )
+
+    queueWhereResponses([
+      [
+        {
+          id: 'inv-1',
+          kind: 'workspace',
+          email: 'invitee@example.com',
+          organizationId: 'org-1',
+          membershipIntent: 'internal',
+          inviterId: 'owner-1',
+          role: 'member',
+          status: 'pending',
+          token: 'tok-1',
+          expiresAt: new Date(Date.now() + 60_000),
+          createdAt: new Date(),
+          updatedAt: new Date(),
+        },
+      ],
+      [
+        {
+          id: 'grant-1',
+          workspaceId: 'workspace-1',
+          permission: 'write',
+          workspaceName: 'Workspace',
+        },
+      ],
+      [{ name: 'Acme' }],
+      [{ name: 'Owner', email: 'owner@example.com' }],
+      // Invitee-owned personal workspaces for the acceptance lock plan.
+      [{ id: 'joiner-ws-1' }],
+    ])
+
+    const result = await acceptInvitation({
+      userId: 'invitee-user',
+      userEmail: 'invitee@example.com',
+      invitationId: 'inv-1',
+      token: 'tok-1',
+      // The accept screen promised a membership migration of joiner-ws-1.
+      disclosedWorkspaceIds: ['joiner-ws-1'],
+    })
+
+    expect(result).toEqual({ success: false, kind: 'disclosure-outdated' })
+    expect(dbChainMockFns.values).not.toHaveBeenCalled()
+    expect(auditMock.recordAudit).not.toHaveBeenCalled()
+  })
+
   it('rolls back acceptance when the sweep set differs from the disclosed set', async () => {
     mockGetWorkspaceWithOwner.mockResolvedValue({
       id: 'workspace-1',

apps/sim/lib/invitations/core.ts

@@ -881,6 +881,21 @@ async function acceptLockedInvitation(
     }
   }
 
+  /**
+   * Reverse disclosure guard: a will-join notice (non-empty disclosed set)
+   * whose acceptance resolved to no-join must not silently succeed as an
+   * external grant — the user consented to membership plus a migration that
+   * will not happen. Nothing has been written on the no-join path, so a
+   * plain failure return suffices; retry renders the refreshed preview.
+   */
+  if (
+    !shouldJoinOrganization &&
+    input.disclosedWorkspaceIds !== undefined &&
+    input.disclosedWorkspaceIds.length > 0
+  ) {
+    return { success: false, kind: 'disclosure-outdated' }
+  }
+
   const acceptedWorkspaceIds: string[] = []
 
   try {