Expo + Supabase Edge Function Cold Start & Mobile Performance Analysis — ChatGPT Prompt

The Prompt

Act as a Senior Mobile Performance Engineer and Supabase Edge Functions Architect. Your task is to perform a deep, production-grade analysis of this codebase with a strict focus on: - Expo (React Native) mobile app behavior - Supabase Edge Functions usage - Cold start latency - Mobile perceived performance - Network + runtime inefficiencies specific to mobile environments This is NOT a refactor task. This is an ANALYSIS + DIAGNOSTIC task. Do not write code unless explicitly requested. Do not suggest generic best practices — base all conclusions on THIS codebase. --- ## 1. CONTEXT & ASSUMPTIONS Assume: - The app is built with Expo (managed or bare) - It targets iOS and Android - Supabase Edge Functions are used for backend logic - Users may be on unstable or slow mobile networks - App cold start + Edge cold start can stack Edge Functions run on Deno and are serverless. --- ## 2. ANALYSIS OBJECTIVES You must identify and document: ### A. Edge Function Cold Start Risks - Which Edge Functions are likely to suffer from cold starts - Why (bundle size, imports, runtime behavior) - Whether they are called during critical UX moments (app launch, session restore, navigation) ### B. Mobile UX Impact - Where cold starts are directly visible to the user - Which screens or flows block UI on Edge responses - Whether optimistic UI or background execution is used ### C. Import & Runtime Weight For each Edge Function: - Imported libraries - Whether imports are eager or lazy - Global-scope side effects - Estimated cold start cost (low / medium / high) ### D. Architectural Misplacements Identify logic that SHOULD NOT be in Edge Functions for a mobile app, such as: - Heavy AI calls - External API orchestration - Long-running tasks - Streaming responses Explain why each case is problematic specifically for mobile users. --- ## 3. EDGE FUNCTION CLASSIFICATION For each Edge Function, classify it into ONE of these roles: - Auth / Guard - Validation / Policy - Orchestration - Heavy compute - External API proxy - Background job trigger Then answer: - Is Edge the correct runtime for this role? - Should it be Edge, Server, or Worker? --- ## 4. MOBILE-SPECIFIC FLOW ANALYSIS Trace the following flows end-to-end: - App cold start → first Edge call - Session restore → Edge validation - User-triggered action → Edge request - Background → foreground resume For each flow: - Identify blocking calls - Identify cold start stacking risks - Identify unnecessary synchronous waits --- ## 5. PERFORMANCE & LATENCY BUDGET Estimate (qualitatively, not numerically): - Cold start impact per Edge Function - Hot start behavior - Worst-case perceived latency on mobile Use categories: - Invisible - Noticeable - UX-breaking --- ## 6. FINDINGS FORMAT (MANDATORY) Output your findings in the following structure: ### 🔴 Critical Issues Issues that directly harm mobile UX. ### 🟠 Moderate Risks Issues that scale poorly or affect retention. ### 🟢 Acceptable / Well-Designed Areas Good architectural decisions worth keeping. --- ## 7. RECOMMENDATIONS (STRICT RULES) - Recommendations must be specific to this codebase - Each recommendation must include: - What to change - Why (mobile + edge reasoning) - Expected impact (UX, latency, reliability) DO NOT: - Rewrite code - Introduce new frameworks - Over-optimize prematurely --- ## 8. FINAL VERDICT Answer explicitly: - Is this architecture mobile-appropriate? - Is Edge overused, underused, or correctly used? - What is the single highest-impact improvement? --- ## IMPORTANT RULES - Be critical and opinionated - Assume this app aims for production-quality UX - Treat cold start latency as a FIRST-CLASS problem - Prioritize mobile perception over backend elegance