From dd70afd00d1c860c5fdba51b4887197c28b6bfc7 Mon Sep 17 00:00:00 2001
From: anshul23102 <anshul23102@iiitd.ac.in>
Date: Tue, 19 May 2026 06:51:55 +0530
Subject: [PATCH] fix(metrics): correct merged PR count and merge rate
 calculation

Two bugs in fetchPRMetrics() caused incorrect dashboard data for all users.

Bug 1 - Wrong merged count:
The GitHub Search API returns state "closed" for both merged PRs and PRs
that were closed without merging (rejected, abandoned, spam). The old code
counted all closed PRs as merged. Fixed by checking pull_request.merged_at,
which is non-null only for actually merged PRs.

Bug 2 - Wrong merge rate denominator:
mergeRate was computed as merged / data.total_count where total_count is
the user's all-time PR count (potentially thousands) while merged was
derived from data.items, capped at 100 results. This produced a near-zero
rate for any active user regardless of their actual merge history. Fixed
by using data.items.length (the fetched sample size) as the denominator.

Also tightened avgReviewHours to measure open-to-merge time using
merged_at instead of closed_at, which excluded unmerged PRs implicitly
but used the wrong timestamp for the end of the review window.
---
 src/app/api/metrics/prs/route.ts | 41 +++++++++++++++++++++++++-------
 1 file changed, 33 insertions(+), 8 deletions(-)

diff --git a/src/app/api/metrics/prs/route.ts b/src/app/api/metrics/prs/route.ts
index fb28df2..1972c33 100644
--- a/src/app/api/metrics/prs/route.ts
+++ b/src/app/api/metrics/prs/route.ts
@@ -34,30 +34,55 @@ async function fetchPRMetrics(token: string): Promise<PRMetricsBase> {
 
   const data = (await searchRes.json()) as {
     total_count: number;
-    items: Array<{ state: string; created_at: string; closed_at: string | null }>;
+    items: Array<{
+      state: string;
+      created_at: string;
+      closed_at: string | null;
+      // GitHub Search API includes a pull_request object on PR items.
+      // merged_at is non-null only when the PR was actually merged, as
+      // opposed to closed without merging.
+      pull_request?: { merged_at: string | null };
+    }>;
   };
 
   const open = data.items.filter((pr) => pr.state === "open").length;
-  const merged = data.items.filter((pr) => pr.state === "closed").length;
 
-  const closedPRs = data.items.filter((pr) => pr.closed_at);
+  // A PR with state "closed" may have been merged OR closed without merging
+  // (e.g. rejected, abandoned). Only count those with a non-null merged_at
+  // as truly merged so the dashboard does not inflate the merged count.
+  const merged = data.items.filter(
+    (pr) => pr.pull_request?.merged_at != null
+  ).length;
+
+  // Average review time: use only actually merged PRs so we measure the time
+  // from open to merge, not open to close-without-merge.
+  const mergedPRs = data.items.filter(
+    (pr) => pr.pull_request?.merged_at != null
+  );
   const avgReviewMs =
-    closedPRs.length > 0
-      ? closedPRs.reduce(
+    mergedPRs.length > 0
+      ? mergedPRs.reduce(
           (sum, pr) =>
             sum +
-            (new Date(pr.closed_at!).getTime() -
+            (new Date(pr.pull_request!.merged_at!).getTime() -
               new Date(pr.created_at).getTime()),
           0
-        ) / closedPRs.length
+        ) / mergedPRs.length
       : 0;
 
+  // Use the number of fetched items as the denominator for mergeRate.
+  // data.total_count is the all-time GitHub total (potentially thousands)
+  // while data.items is capped at 100, so dividing merged/total_count
+  // produces a near-zero rate for any active user. The fetched sample
+  // (open + merged + closed-without-merge) is the correct base.
+  const sampleTotal = data.items.length;
+
   return {
     open,
     merged,
     total: data.total_count,
     avgReviewHours: Math.round(avgReviewMs / 3600000),
-    mergeRate: data.total_count > 0 ? merged / data.total_count : 0,
+    mergeRate: sampleTotal > 0 ? merged / sampleTotal : 0,
   };
 }