feat(renderer): ascii-table helper for export-time table formatting

src/renderer/lib/ascii-table.ts

@@ -0,0 +1,38 @@
+/**
+ * Convert a 2D string array to a fixed-width ASCII table with `| ... |` rows
+ * and a `| --- |` separator.
+ */
+export function toAsciiTable(rows: string[][]): string {
+  if (rows.length === 0) return '';
+  const numCols = Math.max(...rows.map((r) => r.length));
+  const widths: number[] = Array.from({ length: numCols }, (_, c) =>
+    Math.max(...rows.map((r) => (r[c] ?? '').length))
+  );
+  const lines = rows.map((row) =>
+    '| ' +
+    Array.from({ length: numCols }, (_, c) => (row[c] ?? '').padEnd(widths[c])).join(' | ') +
+    ' |'
+  );
+  // Insert separator after first row
+  const sep =
+    '| ' + Array.from({ length: numCols }, (_, c) => '-'.repeat(widths[c])).join(' | ') + ' |';
+  return [lines[0], sep, ...lines.slice(1)].join('\n');
+}
+
+// Matches a markdown table block: header row, separator, ≥1 data row.
+const TABLE_RE = /^\|.+\|\n^\|[\s:|-]+\|\n((?:^\|.+\|\n?)+)/gm;
+
+/**
+ * Replace all markdown tables in `source` with fenced code blocks containing
+ * the ASCII-rendered equivalent. Non-table content is preserved verbatim.
+ */
+export function applyAsciiTransform(source: string): string {
+  return source.replace(TABLE_RE, (block) => {
+    const lines = block.trim().split('\n');
+    const header = lines[0].slice(1, -1).split('|').map((s) => s.trim());
+    const body = lines.slice(2).map((l) =>
+      l.slice(1, -1).split('|').map((s) => s.trim())
+    );
+    return '```\n' + toAsciiTable([header, ...body]) + '\n```';
+  });
+}