How &Fold cut their build cycle from days to hours by spotting hidden performance bottlenecks
Challenge
Evermind™ — a fast-growing European SaaS company — was preparing a full platform redesign: new UI, new navigation, new onboarding, and a rebuilt permissions system. But the engineering team was stuck.
Their codebase had accumulated years of async drift — un-awaited promises, deeply nested chains, race-condition hazards, and logic that worked “most of the time… except when it didn’t.”
Approach
Nerdstack started with a full async map of the codebase — parsing every function, promise chain, and cross-module dependency.
The Editor flagged unstable flows, Debug surfaced non-awaited calls and silent failures, and Review mapped where side effects were leaking across boundaries.
Patterns emerged quickly:
- 47% of async handlers returned before their internal operations finished
- Several “harmless” utility functions introduced hidden parallel execution
- Error propagation was inconsistent across 6 core services
- One legacy module triggered three parallel writes without guaranteeing order
Using these insights, we built a prioritized repair roadmap:
- Resolve non-awaited critical paths
- Normalize error propagation
- Untangle chained conditionals into clear async sequences
- Stabilize flows powering the redesigned components
Solution
Within 5 weeks, Evermind shipped:
- A fully mapped async architecture across their 9 services
- Refactored logic in the top 14 error-prone modules
- Rewritten utility functions to enforce consistent awaiting
- Prediction of high-risk redesign components before they were built
- A unified code reasoning layer that prevented regressions during rollout
After stabilizing the async foundation, the platform redesign moved forward three times faster.
Results
What’s next
With the redesign shipped successfully and async issues under control, Evermind is now expanding Nerdstack to:
- monitor new modules proactively,
- onboard new engineers with automatic code explanations,
- and maintain long-term architectural clarity through continuous Review.
Their next milestone:
full system-wide observability of async flows by Q4 2026, ensuring the redesign becomes the foundation—not another layer of technical debt.
