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Lessons (17)

• Atomic Design & Component Libraries

  … Styling can be shared; accessibility cannot be postponed. Keep domain logic out of generic components Atomic Design becomes …

• Design a Ride-Sharing Service

  … candidates, an atomic assignment leases a driver, and live updates flow separately](/img/system-design-l6/ride-sharing …

• Flash Sale: 10 Million Buyers, No Oversell

  … queueing controls traffic while the inventory owner atomically reserves the unit](/img/system-design-l6/flash-sale.svg …

• Payment Retries: Prevent Duplicate Charges

  Safe payment retries need a durable idempotency record, atomic state transition and provider-side deduplication. The problem in …

• Design an E-Commerce Checkout

  … catalog/search are read paths while inventory, payment and order transitions are owned and idempotent](/img/system-design …

• Time, Consistency and Distributed Transactions

  … Avoid distributed locks where atomic database/queue claiming owns the state. Two-phase commit offers coordinated atomicity but …

• Design System Operations

  … library needs a contract The Atomic Design lesson explains composition. Operating a design system means keeping that composition …

• A WhatsApp OTP Is Only Single Use If You Make It So

  … hashed codes, atomic consume, attempt limits, crash recovery and race-condition tests. The problem in context A user …

• Big Data: ETL, Warehouses and Streaming

  … Publish the replacement atomically instead of exposing a half-rebuilt report. How to prove it worked Reconcile reported …

• The L6 System-Design Thinking Loop

  … invariant first, then scale, failure, recovery and blast radius](/img/system-design-l6/design-loop.svg) Five questions …

• Distributed Coordination: Consensus, Heartbeats and Gossip

  … leader agreement, heartbeats, gossip membership and checksums solve different failure questions](/img/system-design-l6/coordination.svg) Problem …

• Concurrency, Resilience & Distributed Workflows

  … Prefer an atomic database statement or a transaction that owns the invariant: sql UPDATE inventory SET available = available …

• DynamoDB Modeling, RDS Scaling and Data Resilience

  … In DynamoDB you list your access patterns first , then design keys to serve them. Example access patterns for …

• Event-Driven Patterns, Step Functions and Reliable Lambdas

  … A single boolean does not make an external side effect atomic. Use a stable operation key, a conditional …

• Domain-Driven Design: Tactical Patterns

  … customerId only The four rules of aggregate design (Vaughn Vernon) Rule Why --- --- 1. Protect invariants inside the boundary …

• 500 Users Upload Documents at Once: Design the Background Job Pipeline

  … This is the same atomic-check-and-set idea used for idempotent payments and single-use OTPs. The …

• Backend Design Scenarios

  Ten production-style backend questions about caching, data growth, scaling, reliability and system design, with structured answers and …