Engineering memos
Engineering Notes
Practical notes on mobile architecture, fintech reliability, performance culture, and engineering leadership. Written as working notes, not tutorials.
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If you read one thing to understand how I think about mobile systems at scale, start here.
Token Refresh That Never Logs Users Out
A single-flight refresh guard, retry strategy, and clock-skew handling so users stay signed in.
15 Jan 20252 min readSecurity
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What you'll learn
- Single-flight refresh guard so 10 tabs don’t trigger 10 refreshes.
- Retry with backoff and clock-skew handling so expiry edge cases don’t boot users.
- Store tokens in Keystore; never in SharedPreferences or UserDefaults.
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Offline-First Sync Engines
Room/SQLite, a clear sync state machine, and conflict resolution rules that don’t surprise users.
10 Jan 20252 minReliabilityReadPerformance Budgets for Mobile Teams
SLOs for cold start, ANR, and crash-free—and gates in CI so we don’t ship regressions.
5 Jan 20251 minDeliveryPerformanceRead