feat: add waitlist entry timestamp tracking for applicants

- Add waitlist_entered_at column to applicant table
- Update TypeScript schema to include new field
- Automatically save timestamp when applicant transitions from onboarding to waitlist
- Add new Waitlist column in applicants page to display entry timestamp
- Column shows date and time when applicant moved to waitlist status

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: Zeff01

apps/codebility/app/applicant/onboarding/_service/action.ts

@@ -201,6 +201,30 @@ export async function completeOnboarding(codevId: string, newStatus: string = "w
       return { success: false, error };
     }
 
+    // If transitioning to waitlist, save the timestamp in applicant table
+    if (newStatus === "waitlist") {
+      const { data: applicantData } = await supabase
+        .from("applicant")
+        .select("id")
+        .eq("codev_id", codevId)
+        .single();
+
+      if (applicantData) {
+        const { error: applicantError } = await supabase
+          .from("applicant")
+          .update({
+            waitlist_entered_at: new Date().toISOString(),
+            updated_at: new Date().toISOString(),
+          })
+          .eq("id", applicantData.id);
+
+        if (applicantError) {
+          console.error("Error updating applicant waitlist timestamp:", applicantError);
+          // Don't fail the whole operation if this fails
+        }
+      }
+    }
+
     revalidatePath("/applicant/onboarding");
     revalidatePath("/applicant/waiting");
     return { success: true };

apps/codebility/app/home/applicants/_components/_table/applicantColumns.tsx

@@ -455,6 +455,48 @@ const waitlistColumns: ColumnDef<NewApplicantType>[] = [
       className: "w-28 text-center",
     },
   },
+  {
+    id: "waitlist_entered",
+    accessorKey: "applicant.waitlist_entered_at",
+    header: ({ column }) => {
+      return (
+        <Button
+          variant="ghost"
+          onClick={() => column.toggleSorting(column.getIsSorted() === "asc")}
+          className="flex h-8 items-center justify-center gap-1 px-2 py-1 text-xs font-semibold text-gray-800 hover:bg-gray-50 hover:text-gray-900 dark:text-gray-100 dark:hover:bg-gray-800 dark:hover:text-white"
+        >
+          Waitlist
+          <ArrowUpDown className="h-3 w-3" />
+        </Button>
+      );
+    },
+    cell: ({ row }) => {
+      const applicant = row.original;
+      const waitlistEntered = applicant.applicant?.waitlist_entered_at;
+
+      return (
+        <div className="flex items-center justify-center px-2 py-2">
+          {waitlistEntered ? (
+            <div className="flex flex-col items-center gap-0.5">
+              <span className="text-xs font-medium text-gray-900 dark:text-gray-100">
+                {new Date(waitlistEntered).toLocaleDateString('en-US', { month: 'short', day: 'numeric', year: '2-digit' })}
+              </span>
+              <span className="text-[10px] text-gray-500 dark:text-gray-400">
+                {new Date(waitlistEntered).toLocaleTimeString('en-US', { hour: '2-digit', minute: '2-digit' })}
+              </span>
+            </div>
+          ) : (
+            <span className="text-xs text-gray-500 dark:text-gray-500">
+              N/A
+            </span>
+          )}
+        </div>
+      );
+    },
+    meta: {
+      className: "w-28 text-center",
+    },
+  },
 ];
 
 /**

apps/codebility/app/home/applicants/_service/types.ts

@@ -44,6 +44,7 @@ export const newApplicantsSchema = z.object({
         quiz_completed_at: z.string().datetime({ offset: true }).nullable(),
         can_do_mobile: z.boolean().nullable(),
         commitment_signed_at: z.string().datetime({ offset: true }).nullable(),
+        waitlist_entered_at: z.string().datetime({ offset: true }).nullable(),
         signature_data: z.string().nullable(),
         created_at: z.string().datetime({ offset: true }),
         updated_at: z.string().datetime({ offset: true }),

apps/codebility/supabase/migrations/20260223_add_waitlist_entered_at.sql

@@ -0,0 +1,13 @@
+-- Add waitlist_entered_at timestamp to applicant table
+-- This tracks when an applicant transitions from onboarding to waitlist status
+
+ALTER TABLE public.applicant
+ADD COLUMN IF NOT EXISTS waitlist_entered_at TIMESTAMPTZ;
+
+-- Add comment for documentation
+COMMENT ON COLUMN public.applicant.waitlist_entered_at IS 'Timestamp when the applicant moved from onboarding to waitlist status';
+
+-- Add index for querying applicants by waitlist entry date
+CREATE INDEX IF NOT EXISTS idx_applicant_waitlist_entered
+    ON public.applicant(waitlist_entered_at)
+    WHERE waitlist_entered_at IS NOT NULL;