feat: Improve data source robustness by probing multiple recent files and add clipboard copy fallback for wider compatibility.

Author: yharby

src/App.tsx

@@ -96,7 +96,23 @@ function ErrorScreen() {
 
   const handleCopy = () => {
     const text = `Error: ${error?.message}\n\n${errorDetail || 'No logs'}`;
-    navigator.clipboard.writeText(text).then(() => {
+    // navigator.clipboard fails on iOS WebKit without secure context;
+    // fall back to textarea + execCommand
+    const copy = () => {
+      if (navigator.clipboard?.writeText) {
+        return navigator.clipboard.writeText(text);
+      }
+      const ta = document.createElement('textarea');
+      ta.value = text;
+      ta.style.position = 'fixed';
+      ta.style.opacity = '0';
+      document.body.appendChild(ta);
+      ta.select();
+      document.execCommand('copy');
+      document.body.removeChild(ta);
+      return Promise.resolve();
+    };
+    copy().then(() => {
       setCopied(true);
       setTimeout(() => setCopied(false), 2000);
     });

src/lib/duckdb-client.ts

@@ -122,11 +122,13 @@ export async function configureHttpFS(): Promise<void> {
  */
 function generateFallbackFileList(): ParquetFileInfo[] {
   const START = new Date(2026, 0, 1); // Jan 1 2026 — earliest data
-  const today = new Date();
+  // Stop at yesterday — today's file may not be uploaded yet
+  const yesterday = new Date();
+  yesterday.setDate(yesterday.getDate() - 1);
   const files: ParquetFileInfo[] = [];
   const cur = new Date(START);
 
-  while (cur <= today) {
+  while (cur <= yesterday) {
     const y = cur.getFullYear();
     const m = String(cur.getMonth() + 1).padStart(2, '0');
     const d = String(cur.getDate()).padStart(2, '0');
@@ -183,19 +185,22 @@ export async function discoverParquetFiles(): Promise<ParquetFileInfo[]> {
 
 /**
  * Test if a data source works by running a lightweight probe query.
+ * Tries the last few files in case the very latest doesn't exist yet.
  */
 export async function testDataSource(root: DataRoot, files: ParquetFileInfo[]): Promise<boolean> {
-  try {
-    // Always probe with a single file — avoids glob scanning all files
-    const sampleFile = files[files.length - 1]!;
-    const url = `${DATA_ROOTS[root]}${PATH_PREFIX}${sampleFile.filename}`;
-    const sql = `SELECT 1 FROM read_parquet('${url}') LIMIT 1`;
-    await executeQuery(sql);
-    return true;
-  } catch (error) {
-    console.warn(`Data source '${root}' probe failed:`, error);
-    return false;
+  // Try up to 3 files from the end (latest may not exist with fallback list)
+  const candidates = files.slice(-3).reverse();
+  for (const file of candidates) {
+    try {
+      const url = `${DATA_ROOTS[root]}${PATH_PREFIX}${file.filename}`;
+      const sql = `SELECT 1 FROM read_parquet('${url}') LIMIT 1`;
+      await executeQuery(sql);
+      return true;
+    } catch (error) {
+      console.warn(`Data source '${root}' probe failed for ${file.filename}:`, error);
+    }
   }
+  return false;
 }
 
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