[hrj]

💡 What: Replaced the $O(N)$ filter scan per month and account inside WebAPI.makeMonthlyRegister with pre-grouped posts by month (postsByMonth) and sequential running balance accumulation per account (runningBalances). Additionally used groupedPosts in getDetailsByMonth to avoid repeated full-sequence filtering.

🎯 Why: Previously, for every month and account, currPosts was filtered repeatedly to calculate prior post totals and month posts, leading to $O(N \cdot M \cdot A)$ time complexity. Pre-grouping posts and maintaining running balances reduces the complexity to $O(N + M \cdot A)$.

📊 Measured Improvement: Measured with WebAPIBenchmarkTest:

• Baseline: ~586.8 ms average per WebAPI.makeReport call on a 2-year / 50-account dataset.
• Optimized: ~212.2 ms average per call.
• Improvement: ~63.8% reduction in overall makeReport execution time (~2.76x speedup).

---

PR created automatically by Jules for task 4032760993074246349 started by @hrj

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.