diff --git a/.jules/sentinel.md b/.jules/sentinel.md
new file mode 100644
index 00000000..bedc8d0e
--- /dev/null
+++ b/.jules/sentinel.md
@@ -0,0 +1,11 @@
+# Sentinel Security Journal
+
+## 2025-05-14 - [Vulnerability] Mass Assignment in Drizzle Server Actions
+**Vulnerability:** Use of the spread operator (`...noteData`) in Drizzle `.set()` or `.values()` calls allowed client-supplied input to overwrite protected fields like `userId`.
+**Learning:** Even if the `where` clause checks for the correct `userId`, mass assignment can still allow a user to "transfer" their records to another user by changing the `userId` in the payload.
+**Prevention:** Always explicitly list mutable columns in database operations within server actions.
+
+## 2025-05-14 - [Vulnerability] Wildcard Enumeration in ILIKE Queries
+**Vulnerability:** Unsanitized user input in `ILIKE` patterns (`%${query}%`) allowed authenticated users to enumerate records (e.g., all user emails) by using `%` or `_` wildcards.
+**Learning:** Drizzle's `ilike` operator does not automatically escape wildcards. Postgres requires an explicit `ESCAPE` clause to treat these characters as literals.
+**Prevention:** Sanitize user input by escaping `%`, `_`, and `\` and using `sql`${column} ILIKE ${pattern} ESCAPE '\\'` template literals.
diff --git a/lib/actions/calendar.ts b/lib/actions/calendar.ts
index d2e4dcf9..d3d9c81e 100644
--- a/lib/actions/calendar.ts
+++ b/lib/actions/calendar.ts
@@ -73,7 +73,15 @@ export async function saveNote(noteData: NewCalendarNote | CalendarNote): Promis
         try {
             const [updatedNote] = await db
                 .update(calendarNotes)
-                .set({ ...noteData, updatedAt: new Date() })
+                .set({
+                    content: noteData.content,
+                    date: noteData.date,
+                    chatId: noteData.chatId,
+                    locationTags: noteData.locationTags,
+                    userTags: noteData.userTags,
+                    mapFeatureId: noteData.mapFeatureId,
+                    updatedAt: new Date()
+                })
                 .where(and(eq(calendarNotes.id, noteData.id), eq(calendarNotes.userId, userId)))
                 .returning();
             return updatedNote;
@@ -86,7 +94,15 @@ export async function saveNote(noteData: NewCalendarNote | CalendarNote): Promis
         try {
             const [newNote] = await db
                 .insert(calendarNotes)
-                .values({ ...noteData, userId })
+                .values({
+                    userId,
+                    content: noteData.content,
+                    date: noteData.date,
+                    chatId: noteData.chatId,
+                    locationTags: noteData.locationTags,
+                    userTags: noteData.userTags,
+                    mapFeatureId: noteData.mapFeatureId,
+                })
                 .returning();
 
             if (newNote && newNote.chatId) {
diff --git a/lib/actions/users.ts b/lib/actions/users.ts
index 6fba7f8b..5bce6fff 100644
--- a/lib/actions/users.ts
+++ b/lib/actions/users.ts
@@ -3,7 +3,7 @@
 import { revalidatePath, unstable_noStore as noStore } from 'next/cache';
 import { db } from '@/lib/db';
 import { users } from '@/lib/db/schema';
-import { eq, ilike } from 'drizzle-orm';
+import { eq, ilike, sql } from 'drizzle-orm';
 import { getCurrentUserIdOnServer } from '@/lib/auth/get-current-user';
 
 export type UserRole = "admin" | "editor" | "viewer";
@@ -187,7 +187,8 @@ export async function saveSelectedModel(model: string): Promise<{ success: boole
  */
 export async function searchUsers(query: string) {
   noStore();
-  if (!query) return [];
+  // Enforce length limit and handle empty query to prevent DoS/enumeration
+  if (!query || query.length > 100) return [];
 
   const userId = await getCurrentUserIdOnServer();
   if (!userId) {
@@ -195,12 +196,15 @@ export async function searchUsers(query: string) {
   }
 
   try {
+    // Escape special ILIKE characters (%, _, \) to prevent wildcard enumeration
+    const escapedQuery = query.replace(/[%_\\]/g, '\\$&');
+
     const result = await db.select({
       id: users.id,
       email: users.email,
     })
     .from(users)
-    .where(ilike(users.email, `%${query}%`))
+    .where(sql`${users.email} ILIKE ${'%' + escapedQuery + '%'} ESCAPE '\\'`)
     .limit(10);
 
     return result;