backend/WorkClub.Api/Services/MemberSyncService.cs

@@ -41,6 +41,20 @@ public class MemberSyncService
         }
 
         var email = httpContext.User.FindFirst("email")?.Value ?? httpContext.User.FindFirst("preferred_username")?.Value ?? "unknown@example.com";
+
+        // If not found by ExternalUserId, try to find by Email (for seeded users)
+        var memberByEmail = await _context.Members
+            .FirstOrDefaultAsync(m => m.Email == email && m.TenantId == tenantId);
+            
+        if (memberByEmail != null)
+        {
+            // Update the seeded user with the real ExternalUserId
+            memberByEmail.ExternalUserId = externalUserId;
+            memberByEmail.UpdatedAt = DateTimeOffset.UtcNow;
+            await _context.SaveChangesAsync();
+            return;
+        }
+
         var name = httpContext.User.FindFirst("name")?.Value ?? email.Split('@')[0];
 
         var roleClaim = httpContext.User.FindFirst(System.Security.Claims.ClaimTypes.Role)?.Value ?? "Member";

backend/WorkClub.Api/Services/ShiftService.cs

@@ -61,14 +61,17 @@ public class ShiftService
         if (shift == null)
             return null;
 
-        var signups = await _context.ShiftSignups
+        var signups = await (from ss in _context.ShiftSignups
-            .Where(ss => ss.ShiftId == id)
+                             where ss.ShiftId == id
-            .OrderBy(ss => ss.SignedUpAt)
+                             join m in _context.Members on ss.MemberId equals m.Id
-            .ToListAsync();
+                             orderby ss.SignedUpAt
+                             select new { ss.Id, ss.MemberId, m.ExternalUserId, ss.SignedUpAt })
+                            .ToListAsync();
 
         var signupDtos = signups.Select(ss => new ShiftSignupDto(
             ss.Id,
             ss.MemberId,
+            ss.ExternalUserId,
             ss.SignedUpAt
         )).ToList();
 
@@ -165,14 +168,17 @@ public class ShiftService
             return (null, "Shift was modified by another user. Please refresh and try again.", true);
         }
 
-        var signups = await _context.ShiftSignups
+        var signups = await (from ss in _context.ShiftSignups
-            .Where(ss => ss.ShiftId == id)
+                             where ss.ShiftId == id
-            .OrderBy(ss => ss.SignedUpAt)
+                             join m in _context.Members on ss.MemberId equals m.Id
-            .ToListAsync();
+                             orderby ss.SignedUpAt
+                             select new { ss.Id, ss.MemberId, m.ExternalUserId, ss.SignedUpAt })
+                            .ToListAsync();
 
         var signupDtos = signups.Select(ss => new ShiftSignupDto(
             ss.Id,
             ss.MemberId,
+            ss.ExternalUserId,
             ss.SignedUpAt
         )).ToList();
 

backend/WorkClub.Application/Shifts/DTOs/ShiftDetailDto.cs

@@ -17,6 +17,6 @@ public record ShiftDetailDto(
 
 public record ShiftSignupDto(
     Guid Id,
-    Guid MemberId,
+    Guid MemberId, string? ExternalUserId,
     DateTimeOffset SignedUpAt
 );

frontend/src/app/(protected)/shifts/[id]/page.tsx

@@ -23,7 +23,7 @@ export default function ShiftDetailPage({ params }: { params: Promise<{ id: stri
   const capacityPercentage = (shift.signups.length / shift.capacity) * 100;
   const isFull = shift.signups.length >= shift.capacity;
   const isPast = new Date(shift.startTime) < new Date();
-  const isSignedUp = shift.signups.some((s) => s.memberId === session?.user?.id);
+  const isSignedUp = shift.signups.some((s) => s.memberId === session?.user?.id || s.externalUserId === session?.user?.id);
 
   const handleSignUp = async () => {
     await signUpMutation.mutateAsync(shift.id);

frontend/src/hooks/useShifts.ts

@@ -36,6 +36,7 @@ export interface ShiftDetailDto {
 export interface ShiftSignupDto {
   id: string;
   memberId: string;
+  externalUserId?: string;
   signedUpAt: string;
 }