feat(15-02): rewrite send route with multi-signer token loop and legacy fallback

- Loop over doc.signers when populated: one createSigningToken per signer with signerEmail
- Dispatch all signing emails in parallel via Promise.all
- Preserve legacy single-signer path unchanged when signers is null/empty
- Replace NEXT_PUBLIC_BASE_URL with APP_BASE_URL for signing URLs
- Add audit event with metadata.signerEmail for each signer in multi-signer path
- Import DocumentSigner from schema for type casting

teressa-copeland-homes/src/app/api/documents/[id]/send/route.ts

@@ -1,7 +1,7 @@
 import { NextResponse } from 'next/server';
 import { auth } from '@/lib/auth';
 import { db } from '@/lib/db';
-import { documents, clients } from '@/lib/db/schema';
+import { documents, clients, DocumentSigner } from '@/lib/db/schema';
 import { eq } from 'drizzle-orm';
 import { createSigningToken } from '@/lib/signing/token';
 import { sendSigningRequestEmail } from '@/lib/signing/signing-mailer';
@@ -26,24 +26,45 @@ export async function POST(
     if (doc.status === 'Signed')
       return NextResponse.json({ error: 'Already signed' }, { status: 409 });
 
-    // Resolve recipient: prefer assignedClientId, fall back to clientId
-    const clientId = doc.assignedClientId ?? doc.clientId;
-    const client = await db.query.clients.findFirst({ where: eq(clients.id, clientId) });
-    if (!client) return NextResponse.json({ error: 'Client not found' }, { status: 422 });
+    const baseUrl = process.env.APP_BASE_URL ?? 'http://localhost:3000';
 
-    const { token, expiresAt } = await createSigningToken(doc.id);
-    const baseUrl = process.env.NEXT_PUBLIC_BASE_URL ?? 'http://localhost:3000';
-    const signingUrl = `${baseUrl}/sign/${token}`;
+    if (doc.signers && (doc.signers as DocumentSigner[]).length > 0) {
+      // ── Multi-signer path (D-02) ──
+      const signers = doc.signers as DocumentSigner[];
+      await Promise.all(
+        signers.map(async (signer) => {
+          const { token, expiresAt } = await createSigningToken(doc.id, signer.email);
+          const signingUrl = `${baseUrl}/sign/${token}`;
+          await sendSigningRequestEmail({
+            to: signer.email,
+            documentName: doc.name,
+            signingUrl,
+            expiresAt,
+          });
+          await logAuditEvent({
+            documentId: doc.id,
+            eventType: 'email_sent',
+            metadata: { signerEmail: signer.email },
+          });
+        })
+      );
+    } else {
+      // ── Legacy single-signer path (D-01) ──
+      const clientId = doc.assignedClientId ?? doc.clientId;
+      const client = await db.query.clients.findFirst({ where: eq(clients.id, clientId) });
+      if (!client) return NextResponse.json({ error: 'Client not found' }, { status: 422 });
 
-    await sendSigningRequestEmail({
-      to: client.email,
-      clientName: client.name,
-      documentName: doc.name,
-      signingUrl,
-      expiresAt,
-    });
-
-    await logAuditEvent({ documentId: doc.id, eventType: 'email_sent' });
+      const { token, expiresAt } = await createSigningToken(doc.id);
+      const signingUrl = `${baseUrl}/sign/${token}`;
+      await sendSigningRequestEmail({
+        to: client.email,
+        clientName: client.name,
+        documentName: doc.name,
+        signingUrl,
+        expiresAt,
+      });
+      await logAuditEvent({ documentId: doc.id, eventType: 'email_sent' });
+    }
 
     // Update status to Sent (skip if already Sent or Signed to avoid downgrade)
     if (doc.status === 'Draft') {
@@ -53,7 +74,7 @@ export async function POST(
         .where(eq(documents.id, id));
     }
 
-    return NextResponse.json({ ok: true, expiresAt: expiresAt.toISOString() });
+    return NextResponse.json({ ok: true });
   } catch (err) {
     console.error('[send] error:', err);
     return NextResponse.json({ error: 'Failed to send signing email' }, { status: 502 });