diff --git a/backend/src/config/env.ts b/backend/src/config/env.ts
index 307e75d5..2badf5f9 100644
--- a/backend/src/config/env.ts
+++ b/backend/src/config/env.ts
@@ -29,8 +29,11 @@ export function validateEnvVars(): void {
   );
 
   if (missing.length > 0) {
-    const boldRed = (msg: string) => `\x1b[1;31m${msg}\x1b[0m`;
-    const bold = (msg: string) => `\x1b[1m${msg}\x1b[0m`;
+    const isTest = process.env.NODE_ENV === "test";
+    const useColor = process.stdout.isTTY && !isTest;
+
+    const boldRed = (msg: string) => useColor ? `\x1b[1;31m${msg}\x1b[0m` : msg;
+    const bold = (msg: string) => useColor ? `\x1b[1m${msg}\x1b[0m` : msg;
 
     const errorPrefix = boldRed("FATAL ERROR: Environment validation failed");
     const missingVarMsg = `Missing or empty required variables: ${bold(missing.join(", "))}`;
@@ -45,8 +48,12 @@ export function validateEnvVars(): void {
       node_env: process.env.NODE_ENV,
     });
 
-    // Stop execution immediately
-    process.exit(1);
+    if (isTest) {
+      throw new Error(`Environment validation failed: ${missing.join(", ")}`);
+    } else {
+      // Stop execution immediately in production/dev
+      process.exit(1);
+    }
   }
 
   logger.info("Environment variables validated successfully.");
diff --git a/frontend/package-lock.json b/frontend/package-lock.json
index 8806f7ff..72451f07 100644
--- a/frontend/package-lock.json
+++ b/frontend/package-lock.json
@@ -13284,6 +13284,7 @@
       "version": "2.3.2",
       "resolved": "https://registry.npmjs.org/fsevents/-/fsevents-2.3.2.tgz",
       "integrity": "sha512-xiqMQR4xAeHTuB9uWm+fFRcIOgKBMiOBP+eXiyT7jsgVCq1bkVygt00oASowB7EdtpOHaaPgKt812P9ab+DDKA==",
+      "dev": true,
       "hasInstallScript": true,
       "license": "MIT",
       "optional": true,
diff --git a/frontend/src/app/components/providers/WalletProvider.tsx b/frontend/src/app/components/providers/WalletProvider.tsx
index 3dccb095..83b832d8 100644
--- a/frontend/src/app/components/providers/WalletProvider.tsx
+++ b/frontend/src/app/components/providers/WalletProvider.tsx
@@ -10,6 +10,7 @@ interface WalletProviderContextValue {
   connectWallet: () => Promise<void>;
   disconnectWallet: () => void;
   refreshWallet: () => Promise<void>;
+  signTransaction: (unsignedTxXdr: string) => Promise<string>;
   isFreighterAvailable: boolean;
 }
 
@@ -43,6 +44,13 @@ const NETWORK_CHAIN_IDS: Record<string, number> = {
   STANDALONE: 4,
 };
 
+const NETWORK_PASSPHRASES: Record<string, string> = {
+  PUBLIC: "Public Global Stellar Network ; October 2015",
+  TESTNET: "Test SDF Network ; September 2015",
+  FUTURENET: "Test SDF Future Network ; October 2022",
+  STANDALONE: "Standalone Network ; Separate from SDF",
+};
+
 function normalizeWalletError(error: unknown): string {
   if (typeof error === "string" && error.length > 0) {
     return error;
@@ -95,6 +103,7 @@ async function loadFreighterApi(): Promise<FreighterApi> {
 
 export function WalletProvider({ children }: WalletProviderProps) {
   const address = useWalletStore((state) => state.address);
+  const network = useWalletStore((state) => state.network);
   const shouldAutoReconnect = useWalletStore((state) => state.shouldAutoReconnect);
   const setConnected = useWalletStore((state) => state.setConnected);
   const disconnect = useWalletStore((state) => state.disconnect);
@@ -218,6 +227,29 @@ export function WalletProvider({ children }: WalletProviderProps) {
     await syncWallet(true);
   }
 
+  async function signTransaction(unsignedTxXdr: string): Promise<string> {
+    const api = await loadFreighterApi();
+
+    // Map the network name to the required passphrase string
+    const networkPassphrase =
+      NETWORK_PASSPHRASES[network?.name ?? "TESTNET"] || NETWORK_PASSPHRASES.TESTNET;
+
+    const result = await api.signTransaction(unsignedTxXdr, {
+      networkPassphrase,
+    });
+
+    if (typeof result === "string") {
+      return result;
+    }
+
+    // Handle potential error object returned by some versions of the API
+    if (result && typeof result === "object" && "error" in result) {
+      throw new Error(normalizeWalletError(result.error));
+    }
+
+    throw new Error("Failed to sign transaction or operation cancelled.");
+  }
+
   function disconnectWallet() {
     disconnect();
   }
@@ -291,6 +323,7 @@ export function WalletProvider({ children }: WalletProviderProps) {
         connectWallet,
         disconnectWallet,
         refreshWallet,
+        signTransaction,
         isFreighterAvailable,
       }}
     >
diff --git a/frontend/src/app/hooks/useSSE.ts b/frontend/src/app/hooks/useSSE.ts
index 0291a1ee..75bbaccb 100644
--- a/frontend/src/app/hooks/useSSE.ts
+++ b/frontend/src/app/hooks/useSSE.ts
@@ -2,7 +2,7 @@
 
 import { useEffect, useRef, useState } from "react";
 
-export type SSEStatus = "connecting" | "connected" | "disconnected";
+export type SSEStatus = "connecting" | "connected" | "disconnected" | "fallback";
 
 interface UseSSEOptions<T> {
   /** Full URL of the SSE endpoint. Pass null/undefined to disable. */
@@ -13,25 +13,34 @@ interface UseSSEOptions<T> {
   onOpen?: () => void;
   /** Called when the connection closes with an error. */
   onError?: (event: Event) => void;
+  /** Optional polling fallback function called when SSE is unavailable or fails. */
+  onPoll?: () => void;
+  /** Polling interval in ms. Defaults to 30s. */
+  pollingInterval?: number;
 }
 
 /**
- * Generic SSE hook with exponential backoff reconnection.
+ * Generic SSE hook with exponential backoff reconnection and optional polling fallback.
  *
  * Connects to `url` and calls `onMessage` with each parsed JSON payload.
  * Automatically reconnects on error, backing off up to 30 s.
  * Returns the current connection status for UI indicators.
+ *
+ * If `onPoll` is provided, it will be called every `pollingInterval` when the SSE stream is down.
  */
 export function useSSE<T = unknown>({
   url,
   onMessage,
   onOpen,
   onError,
+  onPoll,
+  pollingInterval = 30_000,
 }: UseSSEOptions<T>): SSEStatus {
   const [status, setStatus] = useState<SSEStatus>("connecting");
   const retryDelay = useRef(1_000);
   const esRef = useRef<EventSource | null>(null);
   const timeoutRef = useRef<ReturnType<typeof setTimeout> | null>(null);
+  const pollIntervalRef = useRef<ReturnType<typeof setInterval> | null>(null);
 
   // Keep callback refs stable so the effect doesn't need to re-run when they
   // change, which would needlessly restart the connection.
@@ -41,14 +50,40 @@ export function useSSE<T = unknown>({
   onOpenRef.current = onOpen;
   const onErrorRef = useRef(onError);
   onErrorRef.current = onError;
+  const onPollRef = useRef(onPoll);
+  onPollRef.current = onPoll;
 
   useEffect(() => {
     if (!url) return;
 
     let cancelled = false;
 
+    const startPolling = () => {
+      if (!onPollRef.current || pollIntervalRef.current) return;
+      // Immediate poll to refresh data as soon as fallback starts
+      onPollRef.current();
+      pollIntervalRef.current = setInterval(() => {
+        onPollRef.current?.();
+      }, pollingInterval);
+    };
+
+    const stopPolling = () => {
+      if (pollIntervalRef.current) {
+        clearInterval(pollIntervalRef.current);
+        pollIntervalRef.current = null;
+      }
+    };
+
     function connect() {
       if (cancelled) return;
+
+      // Fallback if browser doesn't support EventSource
+      if (typeof window !== "undefined" && !window.EventSource) {
+        setStatus("fallback");
+        startPolling();
+        return;
+      }
+
       setStatus("connecting");
 
       const es = new EventSource(url as string, { withCredentials: true });
@@ -57,6 +92,7 @@ export function useSSE<T = unknown>({
       es.onopen = () => {
         retryDelay.current = 1_000;
         setStatus("connected");
+        stopPolling(); // Stop fallback polling once stream is active
         onOpenRef.current?.();
       };
 
@@ -72,7 +108,14 @@ export function useSSE<T = unknown>({
       es.onerror = (event) => {
         es.close();
         esRef.current = null;
-        setStatus("disconnected");
+
+        if (onPollRef.current) {
+          setStatus("fallback");
+          startPolling();
+        } else {
+          setStatus("disconnected");
+        }
+
         onErrorRef.current?.(event);
 
         if (!cancelled) {
@@ -89,9 +132,10 @@ export function useSSE<T = unknown>({
       cancelled = true;
       esRef.current?.close();
       esRef.current = null;
+      stopPolling();
       if (timeoutRef.current) clearTimeout(timeoutRef.current);
     };
-  }, [url]);
+  }, [url, pollingInterval]);
 
   return status;
 }