feat(flattener): prompt for detailed stats; polish .stats.md with emojis (#422)

* feat: add detailed statistics and markdown report generation to flattener tool

* fix: remove redundant error handling for project root detection

tools/flattener/stats.js

@@ -1,29 +1,79 @@
-function calculateStatistics(aggregatedContent, xmlFileSize) {
+const H = require("./stats.helpers.js");
+
+async function calculateStatistics(aggregatedContent, xmlFileSize, rootDir) {
   const { textFiles, binaryFiles, errors } = aggregatedContent;
 
-  const totalTextSize = textFiles.reduce((sum, file) => sum + file.size, 0);
-  const totalBinarySize = binaryFiles.reduce((sum, file) => sum + file.size, 0);
-  const totalSize = totalTextSize + totalBinarySize;
-
-  const totalLines = textFiles.reduce((sum, file) => sum + file.lines, 0);
-
+  const totalLines = textFiles.reduce((sum, f) => sum + (f.lines || 0), 0);
   const estimatedTokens = Math.ceil(xmlFileSize / 4);
 
-  const formatSize = (bytes) => {
-    if (bytes < 1024) return `${bytes} B`;
-    if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(1)} KB`;
-    return `${(bytes / (1024 * 1024)).toFixed(1)} MB`;
-  };
+  // Build enriched file list
+  const allFiles = await H.enrichAllFiles(textFiles, binaryFiles);
+  const totalBytes = allFiles.reduce((s, f) => s + f.size, 0);
+  const sizes = allFiles.map((f) => f.size).sort((a, b) => a - b);
+  const avgSize = sizes.length ? totalBytes / sizes.length : 0;
+  const medianSize = sizes.length ? H.percentile(sizes, 50) : 0;
+  const p90 = H.percentile(sizes, 90);
+  const p95 = H.percentile(sizes, 95);
+  const p99 = H.percentile(sizes, 99);
+
+  const histogram = H.buildHistogram(allFiles);
+  const byExtensionArr = H.aggregateByExtension(allFiles);
+  const byDirectoryArr = H.aggregateByDirectory(allFiles);
+  const { depthDist, longestPaths } = H.computeDepthAndLongest(allFiles);
+  const temporal = H.computeTemporal(allFiles, Date.now());
+  const quality = H.computeQuality(allFiles, textFiles);
+  const duplicateCandidates = H.computeDuplicates(allFiles, textFiles);
+  const compressibilityRatio = H.estimateCompressibility(textFiles);
+  const git = H.computeGitInfo(allFiles, rootDir, quality.largeThreshold);
+  const largestFiles = H.computeLargestFiles(allFiles, totalBytes);
+  const markdownReport = H.buildMarkdownReport(
+    largestFiles,
+    byExtensionArr,
+    byDirectoryArr,
+    totalBytes,
+  );
 
   return {
+    // Back-compat summary
     totalFiles: textFiles.length + binaryFiles.length,
     textFiles: textFiles.length,
     binaryFiles: binaryFiles.length,
     errorFiles: errors.length,
-    totalSize: formatSize(totalSize),
-    xmlSize: formatSize(xmlFileSize),
+    totalSize: H.formatSize(totalBytes),
+    totalBytes,
+    xmlSize: H.formatSize(xmlFileSize),
     totalLines,
     estimatedTokens: estimatedTokens.toLocaleString(),
+
+    // Distributions and percentiles
+    avgFileSize: avgSize,
+    medianFileSize: medianSize,
+    p90,
+    p95,
+    p99,
+    histogram,
+
+    // Extensions and directories
+    byExtension: byExtensionArr,
+    byDirectory: byDirectoryArr,
+    depthDistribution: depthDist,
+    longestPaths,
+
+    // Temporal
+    temporal,
+
+    // Quality signals
+    quality,
+
+    // Duplicates and compressibility
+    duplicateCandidates,
+    compressibilityRatio,
+
+    // Git-aware
+    git,
+
+    largestFiles,
+    markdownReport,
   };
 }