feat(security): implement CSRF protection

frontend/playwright.config.ts

@@ -22,7 +22,7 @@ export default defineConfig({
   // Locally, you may need to start them manually or use npm run dev
   webServer: process.env.CI ? [
     {
-      command: "cd ../backend && DATABASE_URL=file:./prisma/dev.db npm run dev",
+      command: "cd ../backend && DATABASE_URL=file:./dev.db npm run dev",
       url: "http://localhost:8000/health",
       reuseExistingServer: false,
       timeout: 120000,

frontend/src/api/index.ts

@@ -7,6 +7,91 @@ export const api = axios.create({
   baseURL: API_URL,
 });
 
+// CSRF Token Management
+let csrfToken: string | null = null;
+let csrfHeaderName: string = "x-csrf-token";
+let csrfTokenPromise: Promise<void> | null = null;
+
+/**
+ * Fetch a fresh CSRF token from the server
+ */
+export const fetchCsrfToken = async (): Promise<void> => {
+  try {
+    const response = await axios.get<{ token: string; header: string }>(
+      `${API_URL}/csrf-token`
+    );
+    csrfToken = response.data.token;
+    csrfHeaderName = response.data.header || "x-csrf-token";
+  } catch (error) {
+    console.error("Failed to fetch CSRF token:", error);
+    throw error;
+  }
+};
+
+/**
+ * Ensure we have a valid CSRF token, fetching one if needed
+ */
+const ensureCsrfToken = async (): Promise<void> => {
+  if (csrfToken) return;
+
+  // Prevent multiple simultaneous token fetches
+  if (!csrfTokenPromise) {
+    csrfTokenPromise = fetchCsrfToken().finally(() => {
+      csrfTokenPromise = null;
+    });
+  }
+  await csrfTokenPromise;
+};
+
+/**
+ * Clear the cached CSRF token (useful for handling 403 errors)
+ */
+export const clearCsrfToken = (): void => {
+  csrfToken = null;
+};
+
+// Add request interceptor to include CSRF token
+api.interceptors.request.use(
+  async (config) => {
+    // Only add CSRF token for state-changing methods
+    const method = config.method?.toUpperCase();
+    if (method && ["POST", "PUT", "DELETE", "PATCH"].includes(method)) {
+      await ensureCsrfToken();
+      if (csrfToken) {
+        config.headers[csrfHeaderName] = csrfToken;
+      }
+    }
+    return config;
+  },
+  (error) => Promise.reject(error)
+);
+
+// Add response interceptor to handle CSRF token errors
+api.interceptors.response.use(
+  (response) => response,
+  async (error) => {
+    // If we get a 403 with CSRF error, clear token and retry once
+    if (
+      error.response?.status === 403 &&
+      error.response?.data?.error?.includes("CSRF")
+    ) {
+      clearCsrfToken();
+
+      // Retry the request once with a fresh token
+      const originalRequest = error.config;
+      if (!originalRequest._csrfRetry) {
+        originalRequest._csrfRetry = true;
+        await fetchCsrfToken();
+        if (csrfToken) {
+          originalRequest.headers[csrfHeaderName] = csrfToken;
+        }
+        return api(originalRequest);
+      }
+    }
+    return Promise.reject(error);
+  }
+);
+
 const coerceTimestamp = (value: string | number | Date): number => {
   if (typeof value === "number") return value;
   if (value instanceof Date) return value.getTime();

frontend/src/utils/importUtils.ts

@@ -1,5 +1,5 @@
 import { exportToSvg } from "@excalidraw/excalidraw";
-import { API_URL } from "../api";
+import { api } from "../api";
 
 export const importDrawings = async (
   files: File[],
@@ -50,21 +50,22 @@ export const importDrawings = async (
           preview: svg.outerHTML,
         };
 
-        const res = await fetch(`${API_URL}/drawings`, {
-          method: "POST",
+        await api.post("/drawings", payload, {
           headers: {
-            "Content-Type": "application/json",
+            // Backend uses this header to apply stricter validation for imported files.
             "X-Imported-File": "true",
           },
-          body: JSON.stringify(payload),
         });
-
-        if (!res.ok) throw new Error("API Error");
         successCount++;
       } catch (err: any) {
         console.error(`Failed to import ${file.name}:`, err);
         failCount++;
-        errors.push(`${file.name}: ${err.message}`);
+        const apiMessage =
+          err?.response?.data?.message ||
+          err?.response?.data?.error ||
+          err?.message ||
+          "API Error";
+        errors.push(`${file.name}: ${apiMessage}`);
       }
     })
   );