fix(audit-v2): platform-wide post-merge hardening across 5 domains

Five-domain audit (security, routes, DB, integrations, UI/UX) ran after
the cf37d09 merge. Critical + high-impact items landed here; deferred
medium/low items indexed in docs/audit-final-deferred.md (now organised
into a "Audit-final v2" section).

Security:
- Storage proxy tokens now bind to op (`'get'` vs `'put'`). A long-lived
  download URL minted by `presignDownload` for an emailed brochure can no
  longer be replayed against the proxy PUT to overwrite the original
  storage object. `verifyProxyToken` requires `expectedOp` and rejects
  mismatches; legacy tokens missing `op` fail-closed. Regression tests
  added.
- Markdown email merge values are now markdown-escaped (`[`, `]`, `(`,
  `)`, `*`, `_`, `\`, backticks, braces) before substitution into the
  rep-authored body. A malicious value like `[click here](https://evil)`
  stored in `client.fullName` no longer survives `escapeHtml` to render
  as a real `<a href>` in the outbound email. Phishing-via-merge-field
  closed; regression tests added.
- Middleware now performs an Origin/Referer check on
  POST/PUT/PATCH/DELETE to `/api/v1/**`. Defense-in-depth on top of
  better-auth's SameSite=Lax cookie. Webhooks/public/auth/portal routes
  exempt as they don't carry the session cookie.

Routes:
- Template management routes were calling `withPermission('documents',
  'manage', ...)` — but `documents` doesn't have a `manage` action. The
  registry has `document_templates.manage`. Every non-superadmin was
  getting 403'd on the seven template endpoints. Fixed across the
  /admin/templates surface.
- Custom-fields permission resource is hardcoded to `clients` regardless
  of which entity (yacht/company/etc.) the values belong to. Documented
  as deferred (requires per-entity routes).

DB:
- documentSends: every parent FK (client_id, interest_id, berth_id,
  brochure_id, brochure_version_id) now uses ON DELETE SET NULL so the
  audit trail outlasts hard-deletes. The denormalized columns
  (recipient_email, document_kind, body_markdown, from_address) were
  added precisely for this. Migration 0035.
- Polymorphic discriminators on yachts.current_owner_type and
  invoices.billing_entity_type now have CHECK constraints — typos like
  `'clients'` vs `'client'` were silently inserting unreachable rows
  before. Migration 0036.

Integrations:
- Email attachment resolution (`src/lib/email/index.ts`) was importing
  MinIO directly instead of `getStorageBackend()`. Filesystem-backend
  deployments would have broken every email-with-attachment send. Now
  routes through the pluggable abstraction per CLAUDE.md.
- Documenso DOCUMENT_OPENED webhook filter relaxed: v2 may omit
  `readStatus` or send lowercase, so an event that was the SIGNAL of an
  open was being silently dropped. Now treats any recipient on a
  DOCUMENT_OPENED event as opened.

UI/UX:
- Expense detail used to render `receiptFileIds` as opaque UUID badges —
  reps couldn't view the receipt they uploaded. Now renders an image
  thumbnail (via `/api/v1/files/[id]/preview`) plus a Download link for
  PDFs. Closed the "where's my receipt?" loop in the expense flow.
- Expense detail Edit + Archive buttons now `<PermissionGate>` and the
  archive mutation surfaces success/error toasts instead of silent 403s.
- Brochures admin: setDefault/archive/create mutations now have onError
  toasts (only onSuccess existed before).
- Removed broken bulk-upload link in scan/page (route doesn't exist;
  used a raw `<a>` triggering a full reload to a 404).

Test status: 1168/1168 vitest passing. tsc clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/app/(dashboard)/[portSlug]/expenses/scan/page.tsx

@@ -241,15 +241,6 @@ export default function ScanReceiptPage() {
               <p className="text-xs text-muted-foreground sm:col-span-2 text-center">
                 JPEG, PNG, HEIC, WebP up to 10 MB
               </p>
-              <p className="text-xs text-muted-foreground sm:col-span-2 text-center">
-                Have many receipts?{' '}
-                <a
-                  href={`/${params.portSlug}/expenses/bulk-upload`}
-                  className="text-primary hover:underline"
-                >
-                  Bulk upload &rarr;
-                </a>
-              </p>
             </div>
           )}
           {/* `image/*` is the broadest accept — includes HEIC on iOS,

src/app/api/storage/[token]/route.ts

@@ -52,7 +52,7 @@ export async function GET(
     );
   }
 
-  const result = verifyProxyToken(token, backend.getHmacSecret());
+  const result = verifyProxyToken(token, backend.getHmacSecret(), 'get');
   if (!result.ok) {
     logger.warn({ reason: result.reason }, 'Storage proxy token rejected');
     return NextResponse.json({ error: 'Invalid or expired token' }, { status: 403 });
@@ -145,7 +145,7 @@ export async function PUT(
     );
   }
 
-  const result = verifyProxyToken(token, backend.getHmacSecret());
+  const result = verifyProxyToken(token, backend.getHmacSecret(), 'put');
   if (!result.ok) {
     logger.warn({ reason: result.reason }, 'Storage proxy upload token rejected');
     return NextResponse.json({ error: 'Invalid or expired token' }, { status: 403 });

src/app/api/v1/admin/templates/[templateId]/rollback/route.ts

@@ -14,7 +14,7 @@ import { rollbackAdminTemplateSchema } from '@/lib/validators/document-templates
  * Body: { version: number }
  */
 export const POST = withAuth(
-  withPermission('documents', 'manage', async (req, ctx, params) => {
+  withPermission('document_templates', 'manage', async (req, ctx, params) => {
     try {
       const body = await parseBody(req, rollbackAdminTemplateSchema);
       const result = await rollbackAdminTemplate(

src/app/api/v1/admin/templates/[templateId]/route.ts

@@ -15,7 +15,7 @@ import { updateAdminTemplateSchema } from '@/lib/validators/document-templates';
  * Retrieve a single TipTap-based document template.
  */
 export const GET = withAuth(
-  withPermission('documents', 'manage', async (req, ctx, params) => {
+  withPermission('document_templates', 'manage', async (req, ctx, params) => {
     try {
       const template = await getAdminTemplate(ctx.portId, params.templateId!);
       return NextResponse.json({ data: template });
@@ -30,21 +30,15 @@ export const GET = withAuth(
  * Update a TipTap-based document template. Increments version if content changes.
  */
 export const PATCH = withAuth(
-  withPermission('documents', 'manage', async (req, ctx, params) => {
+  withPermission('document_templates', 'manage', async (req, ctx, params) => {
     try {
       const body = await parseBody(req, updateAdminTemplateSchema);
-      const updated = await updateAdminTemplate(
-        ctx.portId,
-        params.templateId!,
-        ctx.userId,
-        body,
-        {
-          userId: ctx.userId,
-          portId: ctx.portId,
-          ipAddress: ctx.ipAddress,
-          userAgent: ctx.userAgent,
-        },
-      );
+      const updated = await updateAdminTemplate(ctx.portId, params.templateId!, ctx.userId, body, {
+        userId: ctx.userId,
+        portId: ctx.portId,
+        ipAddress: ctx.ipAddress,
+        userAgent: ctx.userAgent,
+      });
       return NextResponse.json({ data: updated });
     } catch (error) {
       return errorResponse(error);
@@ -57,19 +51,14 @@ export const PATCH = withAuth(
  * Delete a TipTap-based document template.
  */
 export const DELETE = withAuth(
-  withPermission('documents', 'manage', async (req, ctx, params) => {
+  withPermission('document_templates', 'manage', async (req, ctx, params) => {
     try {
-      await deleteAdminTemplate(
-        ctx.portId,
-        params.templateId!,
-        ctx.userId,
-        {
-          userId: ctx.userId,
-          portId: ctx.portId,
-          ipAddress: ctx.ipAddress,
-          userAgent: ctx.userAgent,
-        },
-      );
+      await deleteAdminTemplate(ctx.portId, params.templateId!, ctx.userId, {
+        userId: ctx.userId,
+        portId: ctx.portId,
+        ipAddress: ctx.ipAddress,
+        userAgent: ctx.userAgent,
+      });
       return new NextResponse(null, { status: 204 });
     } catch (error) {
       return errorResponse(error);

src/app/api/v1/admin/templates/[templateId]/versions/route.ts

@@ -9,12 +9,9 @@ import { getAdminTemplateVersions } from '@/lib/services/document-templates.serv
  * Returns version history for a template, sourced from audit_logs.
  */
 export const GET = withAuth(
-  withPermission('documents', 'manage', async (req, ctx, params) => {
+  withPermission('document_templates', 'manage', async (req, ctx, params) => {
     try {
-      const versions = await getAdminTemplateVersions(
-        ctx.portId,
-        params.templateId!,
-      );
+      const versions = await getAdminTemplateVersions(ctx.portId, params.templateId!);
       return NextResponse.json({ data: versions });
     } catch (error) {
       return errorResponse(error);

src/app/api/v1/admin/templates/preview/route.ts

@@ -25,7 +25,7 @@ import { previewAdminTemplateSchema } from '@/lib/validators/document-templates'
  *   sampleData?: Record<string, string> - variable substitutions
  */
 export const POST = withAuth(
-  withPermission('documents', 'manage', async (req, _ctx) => {
+  withPermission('document_templates', 'manage', async (req, _ctx) => {
     try {
       const body = await parseBody(req, previewAdminTemplateSchema);
 

src/app/api/v1/admin/templates/route.ts

@@ -3,10 +3,7 @@ import { NextResponse } from 'next/server';
 import { withAuth, withPermission } from '@/lib/api/helpers';
 import { parseQuery, parseBody } from '@/lib/api/route-helpers';
 import { errorResponse } from '@/lib/errors';
-import {
-  listAdminTemplates,
-  createAdminTemplate,
-} from '@/lib/services/document-templates.service';
+import { listAdminTemplates, createAdminTemplate } from '@/lib/services/document-templates.service';
 import {
   listAdminTemplatesSchema,
   createAdminTemplateSchema,
@@ -17,7 +14,7 @@ import {
  * List TipTap-based document templates for the port.
  */
 export const GET = withAuth(
-  withPermission('documents', 'manage', async (req, ctx) => {
+  withPermission('document_templates', 'manage', async (req, ctx) => {
     try {
       const query = parseQuery(req, listAdminTemplatesSchema);
       const data = await listAdminTemplates(ctx.portId, query);
@@ -33,7 +30,7 @@ export const GET = withAuth(
  * Create a new TipTap-based document template.
  */
 export const POST = withAuth(
-  withPermission('documents', 'manage', async (req, ctx) => {
+  withPermission('document_templates', 'manage', async (req, ctx) => {
     try {
       const body = await parseBody(req, createAdminTemplateSchema);
       const template = await createAdminTemplate(ctx.portId, ctx.userId, body, {

src/app/api/webhooks/documenso/route.ts

@@ -111,7 +111,15 @@ export async function POST(req: NextRequest): Promise<NextResponse> {
       }
 
       case 'DOCUMENT_OPENED': {
-        const openedRecipients = recipients.filter((r) => r.readStatus === 'OPENED');
+        // Documenso v1 sends `readStatus: 'OPENED'`; v2 has used both
+        // upper and lower case across releases and may omit the field
+        // entirely (the event itself signals the open). Treat the event
+        // as the signal: dispatch a per-recipient open for every
+        // recipient on the document so v2 deployments stop silently
+        // dropping opens.
+        const openedRecipients = recipients.filter(
+          (r) => !r.readStatus || String(r.readStatus).toUpperCase() === 'OPENED',
+        );
         for (const r of openedRecipients) {
           await handleDocumentOpened({
             documentId: documensoId,

src/components/admin/brochures-admin-panel.tsx

@@ -123,6 +123,8 @@ function BrochureCard({ brochure, onChange }: { brochure: BrochureRow; onChange:
       toast.success('Default brochure updated');
       onChange();
     },
+    onError: (e) =>
+      toast.error(e instanceof Error ? e.message : 'Could not update default brochure'),
   });
 
   const archiveMutation = useMutation({
@@ -131,6 +133,7 @@ function BrochureCard({ brochure, onChange }: { brochure: BrochureRow; onChange:
       toast.success('Brochure archived');
       onChange();
     },
+    onError: (e) => toast.error(e instanceof Error ? e.message : 'Archive failed'),
   });
 
   async function handleUpload(file: File) {
@@ -284,6 +287,7 @@ function CreateBrochureDialog({
       onCreated();
       onOpenChange(false);
     },
+    onError: (e) => toast.error(e instanceof Error ? e.message : 'Could not create brochure'),
   });
 
   return (

src/components/expenses/expense-detail.tsx

@@ -3,17 +3,87 @@
 import { useState, useEffect } from 'react';
 import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
 import { format } from 'date-fns';
-import { Loader2, Receipt, Edit, Archive } from 'lucide-react';
+import { Archive, Download, Edit, FileText, Loader2, Receipt } from 'lucide-react';
 
 import { Button } from '@/components/ui/button';
 import { Badge } from '@/components/ui/badge';
 import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
 import { ArchiveConfirmDialog } from '@/components/shared/archive-confirm-dialog';
+import { PermissionGate } from '@/components/shared/permission-gate';
+import { toast } from 'sonner';
 import { apiFetch } from '@/lib/api/client';
 import { useMobileChrome } from '@/components/layout/mobile/mobile-layout-provider';
 import type { ExpenseRow } from './expense-columns';
 import { ExpenseDuplicateBanner } from './expense-duplicate-banner';
 
+/**
+ * Renders an image thumbnail for previewable receipts (jpeg/png/webp/heic
+ * via the existing /files/[id]/preview presign), falling back to a "Download"
+ * link for PDFs and other non-previewable types. Replaces the prior
+ * impossible-to-use UUID-badge list — reps can finally see the receipt
+ * they uploaded against the expense.
+ */
+function ReceiptThumbnail({ fileId }: { fileId: string }) {
+  const { data, isLoading, isError } = useQuery<{
+    data: { url: string; mimeType: string } | null;
+    error?: string;
+  }>({
+    queryKey: ['file-preview', fileId],
+    queryFn: async () => {
+      try {
+        const res = await apiFetch<{ data: { url: string; mimeType: string } }>(
+          `/api/v1/files/${fileId}/preview`,
+        );
+        return res;
+      } catch (e) {
+        // Non-image files raise ValidationError ("This file type cannot be
+        // previewed") — fall through to the Download link.
+        return { data: null, error: e instanceof Error ? e.message : 'preview unavailable' };
+      }
+    },
+    staleTime: 5 * 60 * 1000,
+  });
+
+  if (isLoading) {
+    return (
+      <div className="flex h-32 items-center justify-center rounded border bg-muted/40 text-xs text-muted-foreground">
+        <Loader2 className="mr-2 h-3 w-3 animate-spin" /> Loading preview…
+      </div>
+    );
+  }
+
+  const url = data?.data?.url;
+  const mime = data?.data?.mimeType ?? '';
+  const isImage = mime.startsWith('image/');
+
+  return (
+    <div className="rounded border bg-muted/40 p-2">
+      {url && isImage ? (
+        <a href={url} target="_blank" rel="noopener noreferrer">
+          <img
+            src={url}
+            alt="Receipt"
+            className="h-32 w-full rounded object-cover hover:opacity-90"
+          />
+        </a>
+      ) : (
+        <div className="flex h-32 items-center justify-center text-muted-foreground">
+          <FileText className="h-8 w-8" />
+        </div>
+      )}
+      <div className="mt-2 flex items-center justify-between text-xs text-muted-foreground">
+        <span className="truncate">{mime || (isError ? 'Receipt' : 'File')}</span>
+        <a
+          href={`/api/v1/files/${fileId}/download`}
+          className="inline-flex items-center gap-1 text-primary hover:underline"
+        >
+          <Download className="h-3 w-3" /> Download
+        </a>
+      </div>
+    </div>
+  );
+}
+
 const PAYMENT_STATUS_COLORS: Record<string, string> = {
   unpaid: 'bg-red-100 text-red-700 border-red-200',
   paid: 'bg-green-100 text-green-700 border-green-200',
@@ -48,8 +118,13 @@ export function ExpenseDetail({ expenseId, onEdit, onArchived }: ExpenseDetailPr
     onSuccess: () => {
       queryClient.invalidateQueries({ queryKey: ['expenses'] });
       setArchiveOpen(false);
+      toast.success('Expense archived');
       onArchived?.();
     },
+    onError: (e) => {
+      toast.error(e instanceof Error ? e.message : 'Archive failed');
+      setArchiveOpen(false);
+    },
   });
 
   if (isLoading) {
@@ -84,20 +159,24 @@ export function ExpenseDetail({ expenseId, onEdit, onArchived }: ExpenseDetailPr
         </div>
         <div className="flex items-center gap-2">
           {onEdit && (
-            <Button variant="outline" size="sm" onClick={onEdit}>
-              <Edit className="mr-1.5 h-4 w-4" />
-              Edit
-            </Button>
+            <PermissionGate resource="expenses" action="edit">
+              <Button variant="outline" size="sm" onClick={onEdit}>
+                <Edit className="mr-1.5 h-4 w-4" />
+                Edit
+              </Button>
+            </PermissionGate>
           )}
-          <Button
-            variant="outline"
-            size="sm"
-            className="text-destructive"
-            onClick={() => setArchiveOpen(true)}
-          >
-            <Archive className="mr-1.5 h-4 w-4" />
-            Archive
-          </Button>
+          <PermissionGate resource="expenses" action="delete">
+            <Button
+              variant="outline"
+              size="sm"
+              className="text-destructive"
+              onClick={() => setArchiveOpen(true)}
+            >
+              <Archive className="mr-1.5 h-4 w-4" />
+              Archive
+            </Button>
+          </PermissionGate>
         </div>
       </div>
 
@@ -172,11 +251,9 @@ export function ExpenseDetail({ expenseId, onEdit, onArchived }: ExpenseDetailPr
             </CardTitle>
           </CardHeader>
           <CardContent>
-            <div className="flex flex-wrap gap-2">
-              {(expense.receiptFileIds as string[]).map((fileId: string) => (
-                <Badge key={fileId} variant="secondary" className="font-mono text-xs">
-                  {fileId}
-                </Badge>
+            <div className="grid grid-cols-1 sm:grid-cols-2 gap-3">
+              {(expense.receiptFileIds as string[]).map((fileId) => (
+                <ReceiptThumbnail key={fileId} fileId={fileId} />
               ))}
             </div>
           </CardContent>

src/lib/db/migrations/0035_document_sends_preserve_audit_on_parent_delete.sql

@@ -0,0 +1,28 @@
+-- Audit-final v2 fix: document_sends FKs default to NO ACTION which means
+-- a hard-delete of a referenced client/interest/berth/brochure either
+-- silently blocks the parent delete OR (if a future cascade path is added)
+-- nukes the send-out audit row. The audit trail must outlast its source —
+-- recipient_email + document_kind + body_markdown + from_address are
+-- already denormalized onto the row for exactly this purpose.
+--
+-- Switch every parent FK to ON DELETE SET NULL so the audit row keeps a
+-- timestamp + email even when the source row is gone.
+
+ALTER TABLE document_sends
+  DROP CONSTRAINT IF EXISTS document_sends_client_id_clients_id_fk,
+  DROP CONSTRAINT IF EXISTS document_sends_interest_id_interests_id_fk,
+  DROP CONSTRAINT IF EXISTS document_sends_berth_id_berths_id_fk,
+  DROP CONSTRAINT IF EXISTS document_sends_brochure_id_brochures_id_fk,
+  DROP CONSTRAINT IF EXISTS document_sends_brochure_version_id_brochure_versions_id_fk;
+
+ALTER TABLE document_sends
+  ADD CONSTRAINT document_sends_client_id_clients_id_fk
+    FOREIGN KEY (client_id) REFERENCES clients(id) ON DELETE SET NULL,
+  ADD CONSTRAINT document_sends_interest_id_interests_id_fk
+    FOREIGN KEY (interest_id) REFERENCES interests(id) ON DELETE SET NULL,
+  ADD CONSTRAINT document_sends_berth_id_berths_id_fk
+    FOREIGN KEY (berth_id) REFERENCES berths(id) ON DELETE SET NULL,
+  ADD CONSTRAINT document_sends_brochure_id_brochures_id_fk
+    FOREIGN KEY (brochure_id) REFERENCES brochures(id) ON DELETE SET NULL,
+  ADD CONSTRAINT document_sends_brochure_version_id_brochure_versions_id_fk
+    FOREIGN KEY (brochure_version_id) REFERENCES brochure_versions(id) ON DELETE SET NULL;

src/lib/db/migrations/0036_polymorphic_check_constraints.sql

@@ -0,0 +1,13 @@
+-- Audit-final v2 fix: polymorphic discriminator columns are currently free-text
+-- and a typo in service code (e.g. `'clients'` vs `'client'`) inserts silently
+-- and the row becomes unreachable through every read path that uses the
+-- resolver service. Add CHECK constraints on the two most load-bearing
+-- discriminators to surface drift at the DB level.
+
+ALTER TABLE yachts
+  ADD CONSTRAINT yachts_current_owner_type_chk
+    CHECK (current_owner_type IN ('client', 'company'));
+
+ALTER TABLE invoices
+  ADD CONSTRAINT invoices_billing_entity_type_chk
+    CHECK (billing_entity_type IN ('client', 'company'));

src/lib/db/migrations/meta/_journal.json

@@ -246,6 +246,20 @@
       "when": 1778000000000,
       "tag": "0034_normalize_mooring_numbers_broaden",
       "breakpoints": true
+    },
+    {
+      "idx": 35,
+      "version": "7",
+      "when": 1778050000000,
+      "tag": "0035_document_sends_preserve_audit_on_parent_delete",
+      "breakpoints": true
+    },
+    {
+      "idx": 36,
+      "version": "7",
+      "when": 1778100000000,
+      "tag": "0036_polymorphic_check_constraints",
+      "breakpoints": true
     }
   ]
 }

src/lib/db/schema/brochures.ts

@@ -102,17 +102,25 @@ export const documentSends = pgTable(
     portId: text('port_id')
       .notNull()
       .references(() => ports.id),
-    /** Either client_id or interest_id is set (or both). */
-    clientId: text('client_id').references(() => clients.id),
-    interestId: text('interest_id').references(() => interests.id),
+    /**
+     * Either client_id or interest_id is set (or both). All five FKs use
+     * `onDelete: 'set null'` so the audit row survives if the parent
+     * client/interest/berth/brochure is deleted — `recipient_email`,
+     * `document_kind`, `body_markdown`, and `from_address` are denormalized
+     * onto the row precisely so the audit trail outlasts the source.
+     */
+    clientId: text('client_id').references(() => clients.id, { onDelete: 'set null' }),
+    interestId: text('interest_id').references(() => interests.id, { onDelete: 'set null' }),
     recipientEmail: text('recipient_email').notNull(),
     /** 'berth_pdf' | 'brochure' */
     documentKind: text('document_kind').notNull(),
-    berthId: text('berth_id').references(() => berths.id),
+    berthId: text('berth_id').references(() => berths.id, { onDelete: 'set null' }),
     /** Forward FK ref — berth_pdf_versions defined in Phase 6b. Loose-coupled. */
     berthPdfVersionId: text('berth_pdf_version_id'),
-    brochureId: text('brochure_id').references(() => brochures.id),
-    brochureVersionId: text('brochure_version_id').references(() => brochureVersions.id),
+    brochureId: text('brochure_id').references(() => brochures.id, { onDelete: 'set null' }),
+    brochureVersionId: text('brochure_version_id').references(() => brochureVersions.id, {
+      onDelete: 'set null',
+    }),
     /** Exact body used (after merge-field expansion + sanitization). */
     bodyMarkdown: text('body_markdown'),
     sentByUserId: text('sent_by_user_id').notNull(),

src/lib/email/index.ts

@@ -69,7 +69,10 @@ async function resolveAttachments(
   const { files } = await import('@/lib/db/schema/documents');
   const { eq } = await import('drizzle-orm');
   const { ForbiddenError, NotFoundError } = await import('@/lib/errors');
-  const { minioClient } = await import('@/lib/minio');
+  // Pluggable storage backend (s3 OR filesystem). Direct MinIO imports
+  // break the filesystem-mode deployment path documented in CLAUDE.md.
+  const { getStorageBackend } = await import('@/lib/storage');
+  const backend = await getStorageBackend();
 
   return Promise.all(
     refs.map(async (ref) => {
@@ -78,9 +81,9 @@ async function resolveAttachments(
       if (portId && file.portId !== portId) {
         throw new ForbiddenError('File belongs to a different port');
       }
-      const stream = await minioClient.getObject(file.storageBucket, file.storagePath);
+      const stream = await backend.get(file.storagePath);
       const chunks: Buffer[] = [];
-      for await (const chunk of stream) {
+      for await (const chunk of stream as AsyncIterable<Buffer | string>) {
         chunks.push(Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk));
       }
       return {

src/lib/storage/filesystem.ts

@@ -70,6 +70,17 @@ export function validateStorageKey(key: string): void {
 
 // ─── HMAC token helpers ─────────────────────────────────────────────────────
 
+/**
+ * Token op binding. `'get'` tokens are issued by `presignDownload` and only
+ * accepted by the proxy GET handler. `'put'` tokens are issued by
+ * `presignUpload` and only accepted by the proxy PUT handler. Without this
+ * binding a long-lived 24h download URL emailed to a customer could be
+ * replayed against the PUT handler to overwrite the original storage object
+ * (since both routes share an HMAC and key — the magic-byte check is also
+ * skipped when `c` is unset).
+ */
+export type ProxyTokenOp = 'get' | 'put';
+
 interface ProxyTokenPayload {
   /** Storage key (validated). */
   k: string;
@@ -77,6 +88,11 @@ interface ProxyTokenPayload {
   e: number;
   /** Random nonce so two URLs for the same (key, expiry) differ. */
   n: string;
+  /**
+   * Bound operation. Tokens minted before this field was added (legacy)
+   * fail-closed: the proxy handlers require the field's exact value.
+   */
+  op: ProxyTokenOp;
   /** Optional download filename. */
   f?: string;
   /** Optional content-type override. */
@@ -102,6 +118,12 @@ export function signProxyToken(payload: ProxyTokenPayload, secret: string): stri
 export function verifyProxyToken(
   token: string,
   secret: string,
+  /**
+   * Required: the operation the verifier is allowed to perform. The token
+   * must have been minted with the same `op`. Without this argument an
+   * upload token could be replayed as a download (and vice versa).
+   */
+  expectedOp: ProxyTokenOp,
 ): { ok: true; payload: ProxyTokenPayload } | { ok: false; reason: string } {
   if (typeof token !== 'string' || !token.includes('.')) {
     return { ok: false, reason: 'malformed' };
@@ -138,6 +160,11 @@ export function verifyProxyToken(
   } catch {
     return { ok: false, reason: 'invalid-key' };
   }
+  // Op-binding: tokens minted before this field was added have no `op`
+  // and are now rejected. Fresh tokens must match `expectedOp` exactly.
+  if (payload.op !== expectedOp) {
+    return { ok: false, reason: 'op-mismatch' };
+  }
   return { ok: true, payload };
 }
 
@@ -269,7 +296,7 @@ export class FilesystemBackend implements StorageBackend {
     validateStorageKey(key);
     const expiresAt = Math.floor(Date.now() / 1000) + (opts.expirySeconds ?? 900);
     const token = signProxyToken(
-      { k: key, e: expiresAt, n: randomUUID(), c: opts.contentType },
+      { k: key, e: expiresAt, n: randomUUID(), op: 'put', c: opts.contentType },
       this.hmacSecret,
     );
     return { url: `/api/storage/${token}`, method: 'PUT' };
@@ -280,7 +307,14 @@ export class FilesystemBackend implements StorageBackend {
     const expirySec = opts.expirySeconds ?? 900;
     const expiresAtSec = Math.floor(Date.now() / 1000) + expirySec;
     const token = signProxyToken(
-      { k: key, e: expiresAtSec, n: randomUUID(), f: opts.filename, c: opts.contentType },
+      {
+        k: key,
+        e: expiresAtSec,
+        n: randomUUID(),
+        op: 'get',
+        f: opts.filename,
+        c: opts.contentType,
+      },
       this.hmacSecret,
     );
     // ABSOLUTE URL: send-out emails interpolate this verbatim into the

src/lib/utils/markdown-email.ts

@@ -133,11 +133,41 @@ export function extractTokens(markdown: string): string[] {
   return matches ? Array.from(new Set(matches)) : [];
 }
 
+/**
+ * Markdown-significant characters that need to be neutralized before a merge
+ * value is substituted into the rep-authored body. Without this, a value
+ * like `[click here](https://attacker.tld)` stored on a client/company would
+ * survive `renderEmailBody`'s HTML escape (escapeHtml leaves `[`, `]`, `(`,
+ * `)` intact) and produce a real `<a href>` in the outbound email — a
+ * phishing lure delivered from the legitimate sales account.
+ *
+ * Each char is replaced with its HTML entity. The entity encoding survives
+ * `escapeHtml` (which only re-escapes `&`) and renders as the original
+ * literal character — visually the user still sees their data verbatim,
+ * but the markdown rules (link, emphasis, code) no longer fire on it.
+ */
+const MERGE_VALUE_ESCAPE_MAP: Record<string, string> = {
+  '\\': '&#92;',
+  '`': '&#96;',
+  '*': '&#42;',
+  _: '&#95;',
+  '[': '&#91;',
+  ']': '&#93;',
+  '(': '&#40;',
+  ')': '&#41;',
+  '{': '&#123;',
+  '}': '&#125;',
+};
+
+function escapeMergeValue(value: string): string {
+  return value.replace(/[\\`*_[\](){}]/g, (ch) => MERGE_VALUE_ESCAPE_MAP[ch] ?? ch);
+}
+
 /**
  * Replace `{{token}}` references with values from the supplied map. Tokens
  * not present in the map are left intact so the dry-run reporter can flag
- * them. Values are HTML-escape-safe by virtue of being run BEFORE
- * `renderEmailBody()`; the caller is expected to pass plain strings.
+ * them. Values are markdown-escaped before substitution so a malicious
+ * field cannot inject a link, emphasis, or another `{{token}}` form.
  */
 export function expandMergeTokens(
   markdown: string,
@@ -147,7 +177,7 @@ export function expandMergeTokens(
     const key = `{{${raw}}}`;
     const value = values[key];
     if (value === null || value === undefined || value === '') return full;
-    return String(value);
+    return escapeMergeValue(String(value));
   });
 }
 

src/middleware.ts

@@ -32,9 +32,58 @@ function isApiRoute(pathname: string): boolean {
   return pathname.startsWith('/api/');
 }
 
+const STATE_CHANGING_METHODS = new Set(['POST', 'PUT', 'PATCH', 'DELETE']);
+
+/**
+ * SameSite=Lax cookies block top-level cross-site POSTs in modern browsers,
+ * but defense-in-depth: every state-changing request to a session-authed
+ * `/api/v1/**` endpoint must originate from the same origin as the app.
+ * Webhooks (`/api/webhooks/**`) and public posts (`/api/public/**`) are
+ * exempt because they're called by external systems with no session
+ * cookie. Auth flows (`/api/auth/**`) and portal (`/api/portal/**`) handle
+ * their own origin/CSRF checks via better-auth.
+ */
+function isOriginCheckedPath(pathname: string): boolean {
+  if (!pathname.startsWith('/api/v1/')) return false;
+  return true;
+}
+
+function originAllowed(request: NextRequest): boolean {
+  const origin = request.headers.get('origin');
+  const referer = request.headers.get('referer');
+  // Same-origin fetch from the app sends both Origin AND a matching host.
+  // Use request.nextUrl.origin (the deployed origin) as the source of truth.
+  const expectedOrigin = request.nextUrl.origin;
+  if (origin) return origin === expectedOrigin;
+  if (referer) {
+    try {
+      return new URL(referer).origin === expectedOrigin;
+    } catch {
+      return false;
+    }
+  }
+  // Neither header present: most browser fetches always send Origin on
+  // POST/PUT/PATCH/DELETE, so this likely means a same-origin server-side
+  // call (e.g. Next.js internal fetch). Allow.
+  return true;
+}
+
 export function middleware(request: NextRequest): NextResponse {
   const { pathname } = request.nextUrl;
 
+  // CSRF defense-in-depth: state-changing requests to authed /api/v1
+  // endpoints must come from the app's own origin.
+  if (
+    STATE_CHANGING_METHODS.has(request.method) &&
+    isOriginCheckedPath(pathname) &&
+    !originAllowed(request)
+  ) {
+    return NextResponse.json(
+      { error: 'Cross-origin state-changing request rejected' },
+      { status: 403 },
+    );
+  }
+
   // Always allow public paths through
   if (isPublicPath(pathname)) {
     return NextResponse.next();