From ac0f6300458a51fb178ecf45c2b26adfa45e4231 Mon Sep 17 00:00:00 2001
From: seonghobae <8172694+seonghobae@users.noreply.github.com>
Date: Thu, 11 Jun 2026 21:27:58 +0000
Subject: [PATCH] perf: replace reduce/map chains with single for loops in
 reports and dashboard APIs

Refactored multiple `.reduce()` and `.map()` calls into single `for` loops within `weekly-report.ts` and the `sessions` API routes.
This reduces the number of iteration passes over large arrays (like Prisma relations) and minimizes intermediate array allocations, improving overall execution speed and memory usage.
---
 .jules/bolt.md                                |  3 ++
 .../dashboard/sessions/[sessionId]/route.ts   | 32 ++++++++++++-------
 .../[orgSlug]/dashboard/sessions/route.ts     | 20 ++++++++----
 packages/web/src/lib/server/weekly-report.ts  | 27 ++++++++++------
 4 files changed, 54 insertions(+), 28 deletions(-)
 create mode 100644 .jules/bolt.md

diff --git a/.jules/bolt.md b/.jules/bolt.md
new file mode 100644
index 0000000..2b1d6f4
--- /dev/null
+++ b/.jules/bolt.md
@@ -0,0 +1,3 @@
+## 2024-05-19 - Replace reduce() loops with single for loops for Prisma include relations
+**Learning:** Chained `.reduce()` and `.map()` calls on large in-memory arrays (like Prisma `include` results) cause multiple iteration passes and intermediate array allocations. `Object.values()` also allocates an intermediate array, compounding the issue.
+**Action:** Use a single `for` loop to accumulate multiple totals simultaneously. When iterating over objects, use `Object.keys()` in a `for` loop instead of `Object.values()` to avoid intermediate array allocation.
diff --git a/packages/web/src/app/api/orgs/[orgSlug]/dashboard/sessions/[sessionId]/route.ts b/packages/web/src/app/api/orgs/[orgSlug]/dashboard/sessions/[sessionId]/route.ts
index 35486b8..0c793d9 100644
--- a/packages/web/src/app/api/orgs/[orgSlug]/dashboard/sessions/[sessionId]/route.ts
+++ b/packages/web/src/app/api/orgs/[orgSlug]/dashboard/sessions/[sessionId]/route.ts
@@ -43,18 +43,26 @@ export async function GET(
       return forbiddenByRole(access.role, '본인 세션만 열람 가능')
     }
 
-    const totalInput = session.usageRecords.reduce((sum, r) => sum + r.inputTokens, 0)
-    const totalOutput = session.usageRecords.reduce((sum, r) => sum + r.outputTokens, 0)
-    const totalCost = session.usageRecords.reduce((sum, r) => sum + (r.estimatedCostUsd ?? 0), 0)
-
-    const usageTimeline: SessionTimelineUsage[] = session.usageRecords.map((r) => ({
-      timestamp: r.timestamp.toISOString(),
-      inputTokens: r.inputTokens,
-      outputTokens: r.outputTokens,
-      estimatedCostUsd: r.estimatedCostUsd ?? 0,
-      model: r.model,
-      isSubagent: r.isSubagent,
-    }))
+    let totalInput = 0
+    let totalOutput = 0
+    let totalCost = 0
+    const usageTimeline: SessionTimelineUsage[] = new Array(session.usageRecords.length)
+
+    for (let i = 0; i < session.usageRecords.length; i++) {
+      const r = session.usageRecords[i]
+      totalInput += r.inputTokens
+      totalOutput += r.outputTokens
+      totalCost += (r.estimatedCostUsd ?? 0)
+
+      usageTimeline[i] = {
+        timestamp: r.timestamp.toISOString(),
+        inputTokens: r.inputTokens,
+        outputTokens: r.outputTokens,
+        estimatedCostUsd: r.estimatedCostUsd ?? 0,
+        model: r.model,
+        isSubagent: r.isSubagent,
+      }
+    }
 
     // 각 UsageRecord를 "직전 ASSISTANT 턴"에 귀속시켜 메시지별 토큰/비용/모델 집계.
     // TOOL 메시지는 건너뛰고 가장 가까운 선행 ASSISTANT로 타고 올라감.
diff --git a/packages/web/src/app/api/orgs/[orgSlug]/dashboard/sessions/route.ts b/packages/web/src/app/api/orgs/[orgSlug]/dashboard/sessions/route.ts
index 25fbe70..cd11d0c 100644
--- a/packages/web/src/app/api/orgs/[orgSlug]/dashboard/sessions/route.ts
+++ b/packages/web/src/app/api/orgs/[orgSlug]/dashboard/sessions/route.ts
@@ -33,13 +33,21 @@ const sessionInclude = {
 type SessionWithInclude = Prisma.ClaudeSessionGetPayload<{ include: typeof sessionInclude }>
 
 function getSessionTotals(session: SessionWithInclude) {
+  let inputTokens = 0
+  let outputTokens = 0
+  let estimatedCostUsd = 0
+
+  for (let i = 0; i < session.usageRecords.length; i++) {
+    const r = session.usageRecords[i]
+    inputTokens += r.inputTokens
+    outputTokens += r.outputTokens
+    estimatedCostUsd += (r.estimatedCostUsd ?? 0)
+  }
+
   return {
-    inputTokens: session.usageRecords.reduce((sum, r) => sum + r.inputTokens, 0),
-    outputTokens: session.usageRecords.reduce((sum, r) => sum + r.outputTokens, 0),
-    estimatedCostUsd: session.usageRecords.reduce(
-      (sum, r) => sum + (r.estimatedCostUsd ?? 0),
-      0,
-    ),
+    inputTokens,
+    outputTokens,
+    estimatedCostUsd,
   }
 }
 
diff --git a/packages/web/src/lib/server/weekly-report.ts b/packages/web/src/lib/server/weekly-report.ts
index ace2f44..a5ae2f7 100644
--- a/packages/web/src/lib/server/weekly-report.ts
+++ b/packages/web/src/lib/server/weekly-report.ts
@@ -446,17 +446,24 @@ export async function getWeeklyReport(
   }
 
   // Insights — delegation
-  const totalAgentCalls = thisWeekRollups.reduce(
-    (sum, r) => sum + Object.values(r.agentCounts).reduce((a, b) => a + b, 0),
-    0,
-  )
-  const totalSkillCalls = thisWeekRollups.reduce(
-    (sum, r) => sum + Object.values(r.skillCounts).reduce((a, b) => a + b, 0),
-    0,
-  )
+  let totalAgentCalls = 0
+  let totalSkillCalls = 0
   const distinctSkillsThisWeek = new Set<string>()
-  for (const r of thisWeekRollups) {
-    for (const k of Object.keys(r.skillCounts)) distinctSkillsThisWeek.add(k)
+
+  for (let i = 0; i < thisWeekRollups.length; i++) {
+    const r = thisWeekRollups[i]
+
+    const agentKeys = Object.keys(r.agentCounts)
+    for (let j = 0; j < agentKeys.length; j++) {
+      totalAgentCalls += r.agentCounts[agentKeys[j]]
+    }
+
+    const skillKeys = Object.keys(r.skillCounts)
+    for (let j = 0; j < skillKeys.length; j++) {
+      const k = skillKeys[j]
+      totalSkillCalls += r.skillCounts[k]
+      distinctSkillsThisWeek.add(k)
+    }
   }
 
   const insights: WeeklyInsights = {