🧱 Monolith to Modular SSR Migration

Business Impact

🚀 75% faster page loads (3.2s → 0.8s p95)
📈 50% higher SEO traffic in 6 months
🛠️ 40% reduced dev cycle time

Architecture Evolution

Legacy Monolith Architecture

Pain Points

12-minute production builds
98% unused CSS in most pages
Coupled deployments causing 30% rollbacks

Modular SSR Solution

Key Innovations:

Next.js SSR + Module Federation for independent deploys
CSS Scoping with CSS Modules + PostCSS

Technical Leadership

1. Performance Wins

Metric	Before	After
TTI	3.2s	0.8s
Build Time	12min	2min
CSS Payload	218KB	14KB

How We Did It:

Bundle splitting by business domain
React 18 streaming SSR for above-the-fold priority
Edge caching of shared dependencies

2. Cross-Team Coordination

Created "Golden Path" starter templates

Automated migration CLI:

npx migrate --page product --target-module commerce

Weekly "Architecture Office Hours" to unblock teams

3. Crisis Management

The CSS Conflict Incident:

Problem: Global CSS leaks after Module A v2 deploy
Solution:

Rolled back using module federation fallbacks
Implemented CSS containment enforcement
Added visual regression tests to CI

rtifacts

1. Migration Dashboard

Screenshot showing module health: 92/100, 5ms CSS analysis

Caption: "Real-time migration tracker with compatibility scoring"

2. Architecture Decision Record

# ADR 044: SSR Federation vs Static Extraction

        **Chose SSR Federation because:**
        - Supported dynamic tenant configurations
        - Enabled A/B testing at module level

        **Tradeoffs:**
        - 18% higher cold start times
        - Required shared React singleton

3. Open Source Contributions

nextjs-module-metrics (1.8K stars)
Webpack Bundle Archaeology toolkit

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