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Forensic teardowns of production systems: distributed systems, AI infrastructure, telemetry pipelines and cloud bills, down to the cost per request. Every claim reconstructed from public disclosures, every model runnable in your browser.

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By Mukul Kumar Mishra with Rook research desk · About the publication

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Figma multiplayer system design postmortem architecture illustration
Featured Postmortem Realtime Systems

Figma's Multiplayer Editor: The Server That Decides Who Wins

A practical teardown of WebSocket collaboration, Rust isolation, conflict resolution plus the hidden price of an always-live canvas.

WebSocketsRustRealtime
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Recent Engineering Writing

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Sandbox proxy bypass containment architecture diagram
Agent InfrastructureSeptember 2026

AI Sandbox Escape System Design: Proxy Bypass, Egress Gates plus Containment Cost

Proxy bypass first plus containment second. How tail-matched exceptions fail plus what identity-bound egress costs, modeled from the wiki swarm.

SandboxProxyEgress
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Discord message storage architecture diagram
Messaging InfrastructureSeptember 2026

How Discord Stores Trillions of Messages: Cassandra, Hot Partitions and ScyllaDB

Channel partitioning, quorum read fan-in, Rust coalescing plus the engine swap from 177 nodes to 72.

DiscordCassandraScyllaDB
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Kafka consumer rebalance storm diagram
Event InfrastructureSeptember 2026

Kafka Consumer Rebalance Explained: Storms, Cascades and Fixes

Eager versus cooperative protocols, static membership, fetch storms plus the 6x retry amplifier.

KafkaRebalancingRetries
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Figma multiplayer system design architecture diagram
Realtime SystemsSeptember 2026

Figma System Design: How Multiplayer Collaboration Actually Works

How Figma multiplayer works: WebSocket fan-out, server-authoritative resolution, Rust rewrite plus cost at scale.

FigmaWebSocketsRust
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Notion system design architecture diagram
Forensic ArchitectureSeptember 2026

Notion Architecture: How 200 Billion Blocks Survive Postgres, Kafka and AI Search

How Notion scales: 480 Postgres shards, CDC lake, vector tiering plus the bill behind a blank page.

NotionPostgresKafka
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Perplexity answer engine system design postmortem architecture illustration
AI InfrastructureSeptember 2026

Perplexity Postmortem: The Answer Engine That Pays for Every Question Twice

A forensic teardown of RAG retrieval, KV cache flaws, prefill tax, 780M monthly queries plus the cost difference at 1M events per second.

RAGInference1M RPS
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Replit Agent system design postmortem architecture illustration
Agent RuntimeSeptember 2026

Replit Agent Postmortem: The Day the Demo Became Production

A deep teardown of prompt-to-production software, sandbox execution, agent retries, deployment risk plus the cost difference at 1M events per second.

AI AgentsSandbox1M RPS
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Vercel Fluid Compute system design postmortem architecture illustration
Cloud InfrastructureSeptember 2026

Vercel Fluid Compute: The Serverless Bill Was Waiting for a Response

A forensic look at concurrency, cold starts, compute-resolver, AI Gateway waiting time plus the cost difference at 1M RPS.

ServerlessAI Gateway1M RPS
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Figma multiplayer system design postmortem architecture illustration
Realtime SystemsSeptember 2026

Figma's Multiplayer Editor: The Server That Decides Who Wins

A practical teardown of WebSocket collaboration, Rust isolation, conflict resolution plus the hidden price of an always-live canvas.

WebSocketsRustRealtime
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Notion data lake system design postmortem architecture illustration
Data InfrastructureAugust 2026

The Workspace That Ate the Warehouse

A forensic teardown of Notion's block database, 480 logical shards, CDC pipeline, vector search plus modeled cloud bill.

PostgresKafkaS3
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Distributed SystemsJuly 2026

Rethinking Control Planes: Cell-Based Architecture

A control-plane redesign focused on regional isolation, failure containment, Raft plus zero-blast-radius operations.

GoRaftAWS
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