fix(#387,#400,#402,#398): invert demo-history ternary, validate strea…

app/stream/[id]/page.tsx

@@ -77,19 +77,27 @@ export default function StreamPage() {
     setLoading(true);
     setError(null);
     try {
+      if (!/^\d+$/.test(id)) {
+        if (isCurrent()) setError('Invalid stream ID.');
+        return;
+      }
+
       const addr = await getStreamAddress(publicKey, BigInt(id));
       if (!isCurrent()) return;
       if (!addr) { setError('Stream not found.'); return; }
 
-      const [streamInfo, wAmt] = await Promise.all([
-        getStreamInfo(publicKey, addr),
-        getWithdrawable(publicKey, addr),
-      ]);
-
+      const streamInfo = await getStreamInfo(publicKey, addr);
       if (!isCurrent()) return;
+
       setStreamAddress(addr);
       setInfo(streamInfo);
-      setWithdrawable(wAmt);
+
+      try {
+        const wAmt = await getWithdrawable(publicKey, addr);
+        if (isCurrent()) setWithdrawable(wAmt);
+      } catch {
+        if (isCurrent()) setWithdrawable(0n);
+      }
     } catch (e) {
       if (!isCurrent()) return;
       setError(e instanceof Error ? e.message : 'Failed to load stream.');
@@ -109,17 +117,17 @@ export default function StreamPage() {
     const addr = streamAddress;
     const t = setInterval(async () => {
       try {
-        const [streamInfo, wAmt] = await Promise.all([
-          getStreamInfo(publicKey, addr),
-          getWithdrawable(publicKey, addr),
-        ]);
-        if (mounted.current) {
-          setInfo(streamInfo);
-          setWithdrawable(wAmt);
-        }
+        const streamInfo = await getStreamInfo(publicKey, addr);
+        if (mounted.current) setInfo(streamInfo);
       } catch {
         /* keep last-good data */
       }
+      try {
+        const wAmt = await getWithdrawable(publicKey, addr);
+        if (mounted.current) setWithdrawable(wAmt);
+      } catch {
+        /* keep last-good withdrawable */
+      }
     }, STREAM_REFRESH_MS);
     return () => clearInterval(t);
   }, [publicKey, streamAddress]);
@@ -200,6 +208,7 @@ export default function StreamPage() {
             <RateTicker
               ratePerSecond={info.ratePerSecond}
               startBalance={withdrawable}
+              endTime={info.endTime}
             />
           </p>
           <p className="text-xs text-gray-400 dark:text-gray-500 mt-1">{tokenSymbol}</p>

components/stream/RateTicker.tsx

@@ -10,13 +10,16 @@ interface RateTickerProps {
   startBalance: bigint;
   /** Decimal places to display (default: 7 for XLM) */
   decimals?: number;
+  /** Unix timestamp when the stream ends (0 = open-ended). Ticker freezes past this. */
+  endTime?: number;
 }
 
 /**
  * Live-updating balance counter.
  * Increments every 100ms based on ratePerSecond without any contract calls.
+ * Freezes at endTime so the ticker doesn't overshoot the contract balance (#398).
  */
-export function RateTicker({ ratePerSecond, startBalance, decimals = 7 }: RateTickerProps) {
+export function RateTicker({ ratePerSecond, startBalance, decimals = 7, endTime = 0 }: RateTickerProps) {
   const startRef  = useRef<{ ts: number; balance: bigint }>({
     ts:      Date.now(),
     balance: startBalance,
@@ -30,12 +33,23 @@ export function RateTicker({ ratePerSecond, startBalance, decimals = 7 }: RateTi
 
   useEffect(() => {
     const id = setInterval(() => {
-      const elapsed = BigInt(Math.floor((Date.now() - startRef.current.ts) / 1000));
-      const current = startRef.current.balance + elapsed * ratePerSecond;
+      const elapsedMs = Date.now() - startRef.current.ts;
+      let elapsedSec = BigInt(Math.floor(elapsedMs / 1000));
+
+      if (endTime > 0) {
+        const endMs = endTime * 1000;
+        const remainingMs = endMs - startRef.current.ts;
+        const remainingSec = BigInt(Math.max(0, Math.floor(remainingMs / 1000)));
+        if (elapsedSec > remainingSec) elapsedSec = remainingSec;
+      }
+
+      if (elapsedSec < 0n) elapsedSec = 0n;
+
+      const current = startRef.current.balance + elapsedSec * ratePerSecond;
       setDisplay(fromStroops(current, decimals));
     }, 100);
     return () => clearInterval(id);
-  }, [ratePerSecond, decimals]);
+  }, [ratePerSecond, decimals, endTime]);
 
   return (
     <span className="amount" aria-live="polite" aria-atomic="true">

lib/indexer.ts

@@ -74,7 +74,7 @@ export async function fetchTransactionHistory(
       return;
     }
     if (mock) {
-      resolve(publicKey ? DEMO_TXS : []);
+      resolve(publicKey ? [] : DEMO_TXS);
     } else {
       reject(
         new Error(