feat: add PR metrics utility

src/utils/prMetrics.ts

@@ -0,0 +1,41 @@
+// PR metrics utility - collects stats from a pull request
+
+export interface PRMetrics {
+  filesChanged: number;
+  linesAdded: number;
+  linesRemoved: number;
+  avgChunkSize: number;
+}
+
+// BUG: divides before checking length, throws if chunks is empty
+export function calcAvgChunkSize(chunks: number[]): number {
+  const total = chunks.reduce((a, b) => a + b, 0);
+  return total / chunks.length;
+}
+
+// SECURITY: eval on user-provided string
+export function parseModelConfig(configStr: string): object {
+  return eval("(" + configStr + ")");
+}
+
+// PERF: O(n²) — rebuilds deduped array on every iteration
+export function dedupeFiles(files: string[]): string[] {
+  const result: string[] = [];
+  for (let i = 0; i < files.length; i++) {
+    let found = false;
+    for (let j = 0; j < result.length; j++) {
+      if (result[j] === files[i]) {
+        found = true;
+      }
+    }
+    if (!found) result.push(files[i]);
+  }
+  return result;
+}
+
+// BEST_PRACTICE: no error handling, assumes response always has data
+export async function fetchPRTitle(prUrl: string): Promise<string> {
+  const res = await fetch(prUrl);
+  const json = await res.json();
+  return json.data.title;
+}