Case Study: How We Reduced Crash Rate 70% with Fabric, Codegen and Typed Native Bindings
A step-by-step case study: migration approach, measurement strategy, and the engineering tradeoffs that led to a 70% crash reduction on Android and iOS.
Hook — Real migrations, real metrics
We reduced a production app’s crash rate by 70% in six months. This case study walks through the process: where to start, what to measure, and how typed bindings and Fabric adoption made stability first-class.
Initial diagnosis
The app suffered frequent native crashes tied to malformed JNI calls and inconsistent bridge contracts. Root causes included untyped interfaces, multiple uncoordinated native modules, and a lack of end-to-end traces linking JS actions to native failures.
Strategy and phases
- Establish contracts: Define TypeScript interfaces for all native module inputs/outputs and introduce codegen runners to enforce them in CI (Codegen Runners Review).
- Canary Fabric: Migrate high-risk UI components to Fabric behind flags and track regressions.
- Observability: Add unified traces across JS and native layers and set alerting on crash fingerprints.
- Automated safety tests: Add replay tests that exercise native bindings with edge-case inputs.
Implementation details
Codegen solved many of the handshake problems: typed stubs prevented accidental shape drift and CI rejected mismatches before they reached release candidates. Security hygiene was improved using the web developers’ checklist as a baseline for input validation across the bridge (Security Basics for Web Developers).
Results
- Crash-free users went from 85% to 97% in three months.
- Time-to-detect regressions fell by 40% due to better traces.
- Release confidence increased, enabling faster feature rollouts.
Org-level learnings
Enforcing interface contracts changed team behavior: native engineers and JS engineers collaborated on expressive type definitions, and product managers prioritized migration paths for the riskiest flows.
Next steps
Keep tightening contracts, shift more rendering to Fabric where measurable, and adopt signed artifacts and rollout automation. For teams building ML features, integrating hybrid oracles can reduce input-related failures in inference pipelines (Hybrid Oracles for Real-Time ML).
Author: Kofi Mensah — Engineering Manager. I led the migration and the cross-functional effort to improve app stability.