diff --git a/drizzle/0001_far_winter_soldier.sql b/drizzle/0001_far_winter_soldier.sql
new file mode 100644
index 0000000..98f3afd
--- /dev/null
+++ b/drizzle/0001_far_winter_soldier.sql
@@ -0,0 +1,18 @@
+ALTER TABLE "file_attachments" DROP CONSTRAINT "file_attachments_note_id_fkey";
+--> statement-breakpoint
+ALTER TABLE "folders" DROP CONSTRAINT "folders_parent_id_folders_id_fk";
+--> statement-breakpoint
+DROP INDEX "idx_file_attachments_note_id";--> statement-breakpoint
+ALTER TABLE "file_attachments" ALTER COLUMN "note_id" SET NOT NULL;--> statement-breakpoint
+ALTER TABLE "file_attachments" ALTER COLUMN "uploaded_at" SET NOT NULL;--> statement-breakpoint
+ALTER TABLE "notes" ALTER COLUMN "tags" SET DEFAULT '{}';--> statement-breakpoint
+ALTER TABLE "notes" ALTER COLUMN "salt" SET DATA TYPE text;--> statement-breakpoint
+ALTER TABLE "notes" ADD COLUMN "type" text DEFAULT 'note' NOT NULL;--> statement-breakpoint
+ALTER TABLE "file_attachments" ADD CONSTRAINT "file_attachments_note_id_notes_id_fk" FOREIGN KEY ("note_id") REFERENCES "public"."notes"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+CREATE INDEX "idx_folders_user_id" ON "folders" USING btree ("user_id");--> statement-breakpoint
+CREATE INDEX "idx_folders_user_sort" ON "folders" USING btree ("user_id","sort_order");--> statement-breakpoint
+CREATE INDEX "idx_notes_user_id" ON "notes" USING btree ("user_id");--> statement-breakpoint
+CREATE INDEX "idx_notes_folder_id" ON "notes" USING btree ("folder_id");--> statement-breakpoint
+CREATE INDEX "idx_notes_user_updated" ON "notes" USING btree ("user_id","updated_at" DESC NULLS LAST);--> statement-breakpoint
+CREATE INDEX "idx_notes_type" ON "notes" USING btree ("type");--> statement-breakpoint
+CREATE INDEX "idx_file_attachments_note_id" ON "file_attachments" USING btree ("note_id");
\ No newline at end of file
diff --git a/drizzle/meta/0001_snapshot.json b/drizzle/meta/0001_snapshot.json
new file mode 100644
index 0000000..592bf7a
--- /dev/null
+++ b/drizzle/meta/0001_snapshot.json
@@ -0,0 +1,531 @@
+{
+  "id": "397ee404-7901-4e52-910e-dcf150145a54",
+  "prevId": "00000000-0000-0000-0000-000000000000",
+  "version": "7",
+  "dialect": "postgresql",
+  "tables": {
+    "public.file_attachments": {
+      "name": "file_attachments",
+      "schema": "",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "uuid",
+          "primaryKey": true,
+          "notNull": true,
+          "default": "gen_random_uuid()"
+        },
+        "note_id": {
+          "name": "note_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "filename": {
+          "name": "filename",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "original_name": {
+          "name": "original_name",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "mime_type": {
+          "name": "mime_type",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "size": {
+          "name": "size",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "encrypted_data": {
+          "name": "encrypted_data",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "encrypted_title": {
+          "name": "encrypted_title",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "'encrypted_placeholder'"
+        },
+        "iv": {
+          "name": "iv",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "salt": {
+          "name": "salt",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "uploaded_at": {
+          "name": "uploaded_at",
+          "type": "timestamp with time zone",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        }
+      },
+      "indexes": {
+        "idx_file_attachments_note_id": {
+          "name": "idx_file_attachments_note_id",
+          "columns": [
+            {
+              "expression": "note_id",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            }
+          ],
+          "isUnique": false,
+          "concurrently": false,
+          "method": "btree",
+          "with": {}
+        }
+      },
+      "foreignKeys": {
+        "file_attachments_note_id_notes_id_fk": {
+          "name": "file_attachments_note_id_notes_id_fk",
+          "tableFrom": "file_attachments",
+          "tableTo": "notes",
+          "columnsFrom": [
+            "note_id"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "cascade",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "policies": {},
+      "checkConstraints": {},
+      "isRLSEnabled": false
+    },
+    "public.folders": {
+      "name": "folders",
+      "schema": "",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "uuid",
+          "primaryKey": true,
+          "notNull": true,
+          "default": "gen_random_uuid()"
+        },
+        "user_id": {
+          "name": "user_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "name": {
+          "name": "name",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "color": {
+          "name": "color",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "default": "'#6b7280'"
+        },
+        "parent_id": {
+          "name": "parent_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "sort_order": {
+          "name": "sort_order",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "default": 0
+        },
+        "is_default": {
+          "name": "is_default",
+          "type": "boolean",
+          "primaryKey": false,
+          "notNull": false,
+          "default": false
+        },
+        "created_at": {
+          "name": "created_at",
+          "type": "timestamp",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        },
+        "updated_at": {
+          "name": "updated_at",
+          "type": "timestamp",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        }
+      },
+      "indexes": {
+        "idx_folders_user_id": {
+          "name": "idx_folders_user_id",
+          "columns": [
+            {
+              "expression": "user_id",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            }
+          ],
+          "isUnique": false,
+          "concurrently": false,
+          "method": "btree",
+          "with": {}
+        },
+        "idx_folders_user_sort": {
+          "name": "idx_folders_user_sort",
+          "columns": [
+            {
+              "expression": "user_id",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            },
+            {
+              "expression": "sort_order",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            }
+          ],
+          "isUnique": false,
+          "concurrently": false,
+          "method": "btree",
+          "with": {}
+        }
+      },
+      "foreignKeys": {
+        "folders_user_id_users_id_fk": {
+          "name": "folders_user_id_users_id_fk",
+          "tableFrom": "folders",
+          "tableTo": "users",
+          "columnsFrom": [
+            "user_id"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "cascade",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "policies": {},
+      "checkConstraints": {},
+      "isRLSEnabled": false
+    },
+    "public.notes": {
+      "name": "notes",
+      "schema": "",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "uuid",
+          "primaryKey": true,
+          "notNull": true,
+          "default": "gen_random_uuid()"
+        },
+        "user_id": {
+          "name": "user_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "folder_id": {
+          "name": "folder_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "title": {
+          "name": "title",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "content": {
+          "name": "content",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "default": "''"
+        },
+        "type": {
+          "name": "type",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "'note'"
+        },
+        "encrypted_title": {
+          "name": "encrypted_title",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "encrypted_content": {
+          "name": "encrypted_content",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "iv": {
+          "name": "iv",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "salt": {
+          "name": "salt",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "starred": {
+          "name": "starred",
+          "type": "boolean",
+          "primaryKey": false,
+          "notNull": false,
+          "default": false
+        },
+        "archived": {
+          "name": "archived",
+          "type": "boolean",
+          "primaryKey": false,
+          "notNull": false,
+          "default": false
+        },
+        "deleted": {
+          "name": "deleted",
+          "type": "boolean",
+          "primaryKey": false,
+          "notNull": false,
+          "default": false
+        },
+        "hidden": {
+          "name": "hidden",
+          "type": "boolean",
+          "primaryKey": false,
+          "notNull": false,
+          "default": false
+        },
+        "hidden_at": {
+          "name": "hidden_at",
+          "type": "timestamp",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "tags": {
+          "name": "tags",
+          "type": "text[]",
+          "primaryKey": false,
+          "notNull": false,
+          "default": "'{}'"
+        },
+        "created_at": {
+          "name": "created_at",
+          "type": "timestamp",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        },
+        "updated_at": {
+          "name": "updated_at",
+          "type": "timestamp",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        }
+      },
+      "indexes": {
+        "idx_notes_user_id": {
+          "name": "idx_notes_user_id",
+          "columns": [
+            {
+              "expression": "user_id",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            }
+          ],
+          "isUnique": false,
+          "concurrently": false,
+          "method": "btree",
+          "with": {}
+        },
+        "idx_notes_folder_id": {
+          "name": "idx_notes_folder_id",
+          "columns": [
+            {
+              "expression": "folder_id",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            }
+          ],
+          "isUnique": false,
+          "concurrently": false,
+          "method": "btree",
+          "with": {}
+        },
+        "idx_notes_user_updated": {
+          "name": "idx_notes_user_updated",
+          "columns": [
+            {
+              "expression": "user_id",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            },
+            {
+              "expression": "updated_at",
+              "isExpression": false,
+              "asc": false,
+              "nulls": "last"
+            }
+          ],
+          "isUnique": false,
+          "concurrently": false,
+          "method": "btree",
+          "with": {}
+        },
+        "idx_notes_type": {
+          "name": "idx_notes_type",
+          "columns": [
+            {
+              "expression": "type",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            }
+          ],
+          "isUnique": false,
+          "concurrently": false,
+          "method": "btree",
+          "with": {}
+        }
+      },
+      "foreignKeys": {
+        "notes_user_id_users_id_fk": {
+          "name": "notes_user_id_users_id_fk",
+          "tableFrom": "notes",
+          "tableTo": "users",
+          "columnsFrom": [
+            "user_id"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "cascade",
+          "onUpdate": "no action"
+        },
+        "notes_folder_id_folders_id_fk": {
+          "name": "notes_folder_id_folders_id_fk",
+          "tableFrom": "notes",
+          "tableTo": "folders",
+          "columnsFrom": [
+            "folder_id"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "set null",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "policies": {},
+      "checkConstraints": {},
+      "isRLSEnabled": false
+    },
+    "public.users": {
+      "name": "users",
+      "schema": "",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "text",
+          "primaryKey": true,
+          "notNull": true
+        },
+        "email": {
+          "name": "email",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "first_name": {
+          "name": "first_name",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "last_name": {
+          "name": "last_name",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "created_at": {
+          "name": "created_at",
+          "type": "timestamp",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        },
+        "updated_at": {
+          "name": "updated_at",
+          "type": "timestamp",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {},
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "policies": {},
+      "checkConstraints": {},
+      "isRLSEnabled": false
+    }
+  },
+  "enums": {},
+  "schemas": {},
+  "sequences": {},
+  "roles": {},
+  "policies": {},
+  "views": {},
+  "_meta": {
+    "columns": {},
+    "schemas": {},
+    "tables": {}
+  }
+}
\ No newline at end of file
diff --git a/drizzle/meta/_journal.json b/drizzle/meta/_journal.json
index 8f87f3d..90ea23d 100644
--- a/drizzle/meta/_journal.json
+++ b/drizzle/meta/_journal.json
@@ -8,6 +8,13 @@
       "when": 1757373470045,
       "tag": "0000_crazy_medusa",
       "breakpoints": true
+    },
+    {
+      "idx": 1,
+      "version": "7",
+      "when": 1761780448921,
+      "tag": "0001_far_winter_soldier",
+      "breakpoints": true
     }
   ]
 }
\ No newline at end of file
diff --git a/src/__tests__/integration.test.ts b/src/__tests__/integration.test.ts
index e08ce7e..67a458c 100644
--- a/src/__tests__/integration.test.ts
+++ b/src/__tests__/integration.test.ts
@@ -170,4 +170,67 @@ describe("Test Infrastructure Integration", () => {
       expect(await countRows("notes")).toBe(0);
     });
   });
+
+  describe("Note Types", () => {
+    it("should create a note with default type 'note'", async () => {
+      const user = await createTestUser();
+      const note = await createTestNote(user.id, null);
+
+      expect(note.type).toBe("note");
+    });
+
+    it("should create a diagram note when type is specified", async () => {
+      const user = await createTestUser();
+      const note = await createTestNote(user.id, null, {
+        type: "diagram",
+        title: "UML Diagram",
+      });
+
+      expect(note.type).toBe("diagram");
+      expect(note.title).toBe("UML Diagram");
+    });
+
+    it("should query notes by type", async () => {
+      const user = await createTestUser();
+      const folder = await createTestFolder(user.id);
+
+      // Create mixed note types
+      await createTestNote(user.id, folder.id, { type: "note", title: "Regular Note 1" });
+      await createTestNote(user.id, folder.id, { type: "diagram", title: "Diagram 1" });
+      await createTestNote(user.id, folder.id, { type: "note", title: "Regular Note 2" });
+      await createTestNote(user.id, folder.id, { type: "diagram", title: "Diagram 2" });
+
+      // Query only diagrams
+      const diagrams = await db.query.notes.findMany({
+        where: eq(notes.type, "diagram"),
+      });
+
+      expect(diagrams).toHaveLength(2);
+      expect(diagrams.every((n) => n.type === "diagram")).toBe(true);
+
+      // Query only regular notes
+      const regularNotes = await db.query.notes.findMany({
+        where: eq(notes.type, "note"),
+      });
+
+      expect(regularNotes).toHaveLength(2);
+      expect(regularNotes.every((n) => n.type === "note")).toBe(true);
+    });
+
+    it("should update note type from note to diagram", async () => {
+      const user = await createTestUser();
+      const note = await createTestNote(user.id, null, { type: "note" });
+
+      expect(note.type).toBe("note");
+
+      // Update to diagram
+      const [updatedNote] = await db
+        .update(notes)
+        .set({ type: "diagram" })
+        .where(eq(notes.id, note.id))
+        .returning();
+
+      expect(updatedNote.type).toBe("diagram");
+    });
+  });
 });
diff --git a/src/db/__tests__/schema.test.ts b/src/db/__tests__/schema.test.ts
index c5485a1..46b55a8 100644
--- a/src/db/__tests__/schema.test.ts
+++ b/src/db/__tests__/schema.test.ts
@@ -217,6 +217,7 @@ describe("Database Schema (db/schema.ts)", () => {
         folderId: "folder-uuid",
         title: "My Note",
         content: "Note content",
+        type: "note",
         encryptedTitle: null,
         encryptedContent: null,
         iv: null,
@@ -242,6 +243,7 @@ describe("Database Schema (db/schema.ts)", () => {
         folderId: null,
         title: "Unfiled Note",
         content: "Content",
+        type: "note",
         encryptedTitle: null,
         encryptedContent: null,
         iv: null,
diff --git a/src/db/schema.ts b/src/db/schema.ts
index 5ff19de..47c310b 100644
--- a/src/db/schema.ts
+++ b/src/db/schema.ts
@@ -44,6 +44,9 @@ export const notes = pgTable(
 
     title: text("title").notNull(),
     content: text("content").default(""),
+    type: text("type", { enum: ["note", "diagram"] })
+      .default("note")
+      .notNull(),
 
     encryptedTitle: text("encrypted_title"),
     encryptedContent: text("encrypted_content"),
@@ -64,6 +67,7 @@ export const notes = pgTable(
     userIdIdx: index("idx_notes_user_id").on(table.userId),
     folderIdIdx: index("idx_notes_folder_id").on(table.folderId),
     userUpdatedIdx: index("idx_notes_user_updated").on(table.userId, table.updatedAt.desc()),
+    typeIdx: index("idx_notes_type").on(table.type),
   })
 );
 
diff --git a/src/lib/openapi-schemas.ts b/src/lib/openapi-schemas.ts
index 7962845..babea37 100644
--- a/src/lib/openapi-schemas.ts
+++ b/src/lib/openapi-schemas.ts
@@ -305,6 +305,9 @@ export const noteSchema = z
       .openapi({ example: "123e4567-e89b-12d3-a456-426614174000", description: "Folder ID" }),
     title: z.string().openapi({ example: "[ENCRYPTED]", description: "Encrypted note title" }),
     content: z.string().openapi({ example: "[ENCRYPTED]", description: "Encrypted note content" }),
+    type: z
+      .enum(["note", "diagram"])
+      .openapi({ example: "note", description: "Note type: 'note' or 'diagram'" }),
     encryptedTitle: z
       .string()
       .nullable()
@@ -372,6 +375,10 @@ export const createNoteRequestSchema = z
       .max(20)
       .optional()
       .openapi({ example: ["work"], description: "Up to 20 tags, max 50 chars each" }),
+    type: z.enum(["note", "diagram"]).default("note").optional().openapi({
+      example: "note",
+      description: "Note type: 'note' or 'diagram' (defaults to 'note' if not specified)",
+    }),
     encryptedTitle: z
       .string()
       .optional()
@@ -411,6 +418,10 @@ export const updateNoteRequestSchema = z
       .max(20)
       .optional()
       .openapi({ example: ["work"], description: "Up to 20 tags" }),
+    type: z
+      .enum(["note", "diagram"])
+      .optional()
+      .openapi({ example: "note", description: "Note type: 'note' or 'diagram'" }),
     encryptedTitle: z
       .string()
       .optional()
@@ -470,6 +481,14 @@ export const notesQueryParamsSchema = z
         example: "false",
         description: "Filter by hidden status",
       }),
+    type: z
+      .enum(["note", "diagram"])
+      .optional()
+      .openapi({
+        param: { name: "type", in: "query" },
+        example: "diagram",
+        description: "Filter by note type",
+      }),
     search: z
       .string()
       .max(100)
diff --git a/src/lib/validation.ts b/src/lib/validation.ts
index fdc9378..b7386b1 100644
--- a/src/lib/validation.ts
+++ b/src/lib/validation.ts
@@ -45,6 +45,7 @@ export const createNoteSchema = z.object({
   ),
   starred: z.boolean().optional(),
   tags: z.array(z.string().max(50)).max(20).optional(),
+  type: z.enum(["note", "diagram"]).default("note").optional(),
 
   encryptedTitle: z.string().optional(),
   encryptedContent: z.string().optional(),
@@ -70,6 +71,7 @@ export const updateNoteSchema = z.object({
   deleted: z.boolean().optional(),
   hidden: z.boolean().optional(),
   tags: z.array(z.string().max(50)).max(20).optional(),
+  type: z.enum(["note", "diagram"]).optional(),
 
   encryptedTitle: z.string().optional(),
   encryptedContent: z.string().optional(),
@@ -89,6 +91,7 @@ export const notesQuerySchema = z
     archived: z.coerce.boolean().optional(),
     deleted: z.coerce.boolean().optional(),
     hidden: z.coerce.boolean().optional(),
+    type: z.enum(["note", "diagram"]).optional(),
     search: z
       .string()
       .max(100)
diff --git a/src/routes/notes/crud.ts b/src/routes/notes/crud.ts
index 9a01c6a..e26fa45 100644
--- a/src/routes/notes/crud.ts
+++ b/src/routes/notes/crud.ts
@@ -76,6 +76,10 @@ const listNotesHandler: RouteHandler<typeof listNotesRoute> = async (c) => {
     conditions.push(eq(notes.hidden, hidden));
   }
 
+  if (query.type !== undefined) {
+    conditions.push(eq(notes.type, query.type));
+  }
+
   if (query.search) {
     const escapedSearch = query.search
       .replace(/\\/g, "\\\\")
@@ -282,6 +286,7 @@ const createNoteHandler: RouteHandler<typeof createNoteRoute> = async (c) => {
     folderId?: string | null;
     starred?: boolean;
     tags?: string[];
+    type?: "note" | "diagram";
     encryptedTitle?: string;
     encryptedContent?: string;
     iv?: string;
diff --git a/src/version.ts b/src/version.ts
index da01141..68af4f4 100644
--- a/src/version.ts
+++ b/src/version.ts
@@ -1,2 +1,2 @@
 // This file is automatically updated by semantic-release
-export const VERSION = "1.11.11"
\ No newline at end of file
+export const VERSION = "1.11.11";