⚡ Bolt: Backend and Frontend Lifecycle Optimizations

[LVT-ENG]

💡 What

Implemented backend concurrency optimizations (sync 'def' for blocking calls) and frontend lifecycle optimizations (DOM caching, unobserve).

🎯 Why

The blocking LLM call in the AI engine was stalling the FastAPI event loop, and repeated DOM lookups/unnecessary observers were impacting frontend performance.

📊 Impact

• Prevents event loop stalling, allowing the backend to handle concurrent requests more efficiently.
• Saves CPU cycles by pre-encoding auth keys.
• Reduces DOM lookup overhead and observer callbacks on the frontend.

🔬 Measurement

Verified via pytest (backend logic) and vitest (frontend logic). Visual verification confirmed UI stability.

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PR created automatically by Jules for task 17780262876767202699 started by @LVT-ENG

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Project	Deployment	Actions	Updated (UTC)
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[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances both backend and frontend performance by implementing targeted optimizations. On the backend, it addresses event loop stalling caused by blocking LLM calls and reduces CPU usage during authentication. On the frontend, it minimizes DOM lookup overhead and streamlines observer callbacks, resulting in a more responsive and efficient user interface.

Highlights

• Backend Concurrency Optimization: The recommend_garment endpoint in the FastAPI backend was converted from an asynchronous (async def) to a synchronous (def) function. This change allows FastAPI to run the blocking LLM call in a separate thread pool, preventing it from stalling the main event loop and improving the backend's ability to handle concurrent requests.
• Authentication Key Pre-encoding: The secret keys used for authentication verification in both backend/DivineoBunker.py and backend/main.py are now pre-encoded to bytes during initialization. This optimization saves CPU cycles by avoiding repeated encoding operations during high-frequency authentication checks.
• Frontend DOM Caching: Frequently accessed DOM elements in js/main.js are now cached within a this.ui object in the TryOnYouBunker class. This reduces the overhead of repeated document.getElementById and document.querySelectorAll calls, leading to improved frontend performance.
• Optimized IntersectionObserver Usage: The animateOnScroll function in js/main.js now includes an observer.unobserve(entry.target) call. This stops observing elements once their scroll-triggered animation has been applied, reducing unnecessary observer callbacks and improving frontend efficiency.

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[gemini-code-assist]

Code Review

This pull request introduces several performance optimizations across both the backend Python services and the frontend JavaScript application. In the backend, the secret key used for HMAC authentication is now pre-encoded into bytes to avoid repeated encoding during high-frequency verification calls. Additionally, a FastAPI endpoint was converted from asynchronous to synchronous to allow it to run in a thread pool, preventing blocking LLM calls from stalling the event loop. On the frontend, frequently accessed DOM elements are now cached in a this.ui object to reduce repeated DOM queries, and an optimization was added to the IntersectionObserver to stop observing elements once their transition is triggered.