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21Stack Overflow · architecture

Part 1: Make your AI agents boring: the determinism layer

This post outlines a maturity model for running LLM agents in production by containing the model to a single node within a deterministic, fixed-graph system. The team utilizes structured outputs, validation, and a rigid substrate to turn unpredictable AI behavior into auditable, testable proposals. As a result, the system gains safety, predictable latency, and a clear audit trail while keeping model judgment strictly isolated.

DEPTH ■■■■■13 min read2 weeks ago

Machine Learning

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22PlanetScale · architecture

Building a faster, lazier router for Postgres

To reduce overhead when routing queries across PostgreSQL shards, the Neki router avoids unnecessary parsing and decodes responses lazily. By keeping data in its original wire format and only decoding columns when strictly required for operations like limits or sorting, the router significantly improves performance.

DEPTH ■■■■■16 min read3 weeks ago

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23Cloudflare · scaling

Rewinding the exponential: How we keep hardware usage down

Cloudflare tackled exponential traffic growth against linear hardware growth by continuously evolving their data pipeline architecture over five years. Key optimizations included breaking up monolithic schemas, switching to zstd compression, decoupling pipeline transit from database replication, decentralizing sampling, and moving aggregations earlier in the pipeline. These strategies significantly reduced backbone bandwidth usage, network congestion, and storage requirements while preserving data quality.

DEPTH ■■■■■12 min read2 weeks ago

Infrastructure

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24Meta · architecture

GenRecs Tokenization: Transforming Ads Recommendation at Meta with Stable Model Vocabulary

Meta implemented GenRecs Tokenization to replace dedicated item IDs with a stable semantic vocabulary for ads recommendation. Using a three-stage encoding and quantization pipeline, the system enables language models to reason about ad content and user preferences simultaneously. This approach resulted in a +0.35% lift in conversions and improved cold-start performance for new entities.

DEPTH ■■■■■6 min read8 days ago

Machine Learning

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25Stack Overflow · architecture

Part 6: An operating system for coding agents: the disciplined build

Engineering coding agents often degrade over long projects due to harness and configuration failures rather than model limitations. The team implemented an operational harness featuring a constitution, tiered context files, durable memory, a multi-lens review panel, and post-edit hooks. This approach maintains code quality and enables multiple autonomous agents to collaborate safely without silent regressions.

DEPTH ■■■■■12 min read2 weeks ago

Machine Learning

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26PlanetScale · architecture

Sequences and other volatiles in Neki

Neki implements PostgreSQL sequences in a sharded system by handling volatile and stable expressions at the router level rather than pushing them to shards. Because sequences require centralized control to guarantee unique values without duplication across distributed shards, sequence operations are routed exclusively through an authoritative source. The query planner ensures that volatile expressions are evaluated with the correct row cardinality based on the final table expression.

DEPTH ■■■■■14 min read13 days ago

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27Cloudflare · architecture

Filter, reshape, and redact logs before export with Transformers

Cloudflare integrated SQL-based log transformation directly into its Logpush export pipeline, allowing customers to filter, redact, and reshape logs before delivery. The team chose to embed the Apache DataFusion engine in-process using Rust and Go across an Arrow IPC boundary to ensure high throughput and avoid network latency. As a result, the system processes high-volume log streams efficiently while maintaining predictable resource usage and strict delivery reliability.

DEPTH ■■■■■8 min read2 weeks ago

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28Meta · scaling

2026 World Cup: Breaking Records, Spiky Charts and Reliability at Scale

Meta's infrastructure handled record-breaking traffic during the 2026 World Cup, including 30 million messages per second on WhatsApp, by relying on automated load balancing, capacity buffers, and targeted pre-builds. Traffic patterns revealed that surges occurred primarily during breaks rather than gameplay, requiring region-specific forecasting rather than cross-region load shifting. The systems maintained full reliability and allowed normal continuous deployment schedules to continue without manual intervention or system freezes.

DEPTH ■■■■■5 min read12 days ago

Infrastructure

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29PlanetScale · architecture

PlanetScale is now available on Azure

PlanetScale expanded its database offering to Microsoft Azure by adapting its Kubernetes-based infrastructure to handle Azure's networking constraints. The engineering team overcame Azure's private IP limits and slow pod startup times by implementing block-based IP allocation via a custom CNI plugin. This approach successfully increased IP capacity and removed the Kubernetes API server from the critical path during pod initialization.

DEPTH ■■■■■3 min read2 weeks ago

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30Cloudflare · architecture

Cloudflare deploys protections against php2shell vulnerability

Recent disclosures revealed critical remote code execution and data exposure vulnerabilities in the PHP runtime. To mitigate the threat before public disclosure, Cloudflare developed full transaction detection to combine request and response signals within the WAF. This capability enabled automatic deployment of rules protecting customers against the php2shell exploits.

DEPTH ■■■■■6 min read6 days ago

Security

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31Meta · migration

Shipping Media Over QUIC at Meta Scale for Instagram Live Ingest

Meta deployed the emerging Media over QUIC (MoQ) protocol for Instagram Live ingest on iOS and Android to replace their legacy RUSH protocol. By using edge translation to avoid backend rewrites and a phased rollout strategy, the team achieved metric parity with the old protocol without regressions. This deployment establishes a foundation to extend MoQ across Meta's applications for lower-latency and more resilient video streaming.

DEPTH ■■■■■8 min read2 weeks ago

FrontendMobile

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32Stack Overflow · practice

Why model versioning is not enough for production AI

AI applications depend on many moving parts beyond model weights, such as retrieval configurations, prompts, and serving settings. The engineering team outlines how to build reliable AI infrastructure using a unified release manifest, comprehensive evaluation gates, and tested rollback procedures. The result is a systematic approach to managing generative AI deployments and avoiding production failures.

DEPTH ■■■■■8 min read4 weeks ago

Machine Learning

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33Cloudflare · architecture

How Commerce.com and Cloudflare are getting storefronts ready for AI agents

Commerce.com and Cloudflare collaborated to enable WebMCP at the edge for nearly 100,000 storefronts, allowing AI agents to interact reliably with e-commerce sites using structured tools rather than fragile HTML scraping. The team implemented edge-level configuration rules using custom hostname metadata to provide individual merchants with a seamless opt-out mechanism and added support for custom MCP paths. This integration allows agents to execute shopping tasks directly within the active browser session while ensuring fallback safety and zero extra latency for opted-out stores.

DEPTH ■■■■■6 min read6 days ago

Machine Learning

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34Stack Overflow · architecture

Is Your “Human-in-the-Loop” Actually Slowing You Down? Here’s What We Learned

The engineering team evaluated traditional human-in-the-loop AI workflows and found that reviewing every output creates bottlenecks and latency. By implementing a tiered routing system that automates 85 percent of predictions and reserves human oversight for high-risk or low-confidence cases, they reduced the false negative rate from 8.3 percent to 2.1 percent. This structured approach balances speed and safety while turning human feedback into a continuous learning loop.

DEPTH ■■■■■11 min read4 weeks ago

Machine Learning

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35Cloudflare · postmortem

8 eMudhra certificates are compromised. Here's what you need to know

Private keys associated with eight eMudhra intermediate certificates were compromised, allowing potential traffic interception. Cloudflare prioritized patching critical services, released client and tunnel updates, and deployed mitigations across its products. Customers are advised to upgrade affected software, update custom trust stores, and avoid disabling verification despite error messages.

DEPTH ■■■■■4 min read6 days ago

Security

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36Stack Overflow · practice

A green exit code is not evidence that the work happened

Autonomous AI agents and LLM-based coding tools frequently fail silently by reporting successful completion without actually performing the assigned work. The author explains that traditional feedback loops like exit codes are broken because agents can dynamically invent shortcuts, generate fake artifacts, or terminate cleanly while producing nothing. To restore trust, engineering teams must shift verification from agent self-assessments to independent state checks, artifact inspections, and monitoring for zero-effect successes.

DEPTH ■■■■■10 min read2 weeks ago

Machine Learning

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37Cloudflare · architecture

A fully programmable secure web gateway

Cloudflare integrated its secure web gateway and data loss prevention services with its edge computing platform to allow customers to run custom code inline during policy evaluation. The team introduced a new Forward action for traffic transformation and Custom Functions for dynamic rule evaluation without requiring external proxy infrastructure. This enables complex security logic, real-time alerting, and dynamic header injection with zero network hop overhead.

DEPTH ■■■■■13 min read12 days ago

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38Stack Overflow · practice

“Impossible to Hide Secret …”: Uncovering Security and Privacy Issues in LLM-Native IDEs

Researchers analyzed thousands of social media posts to identify security and privacy risks in LLM-native Integrated Development Environments. The study established a taxonomy of 32 issues across 10 categories, revealing that most problems stem from system-level design choices rather than LLM reasoning failures. The findings highlight widespread unauthorized file operations, privacy leaks, and a reliance on self-devised developer workarounds.

DEPTH ■■■■■3 min read2 weeks ago

Machine LearningSecurity

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39PlanetScale · scaling

Handling hot shards

Growing applications often encounter hot shards when certain tenants or data subsets outgrow initial sharding strategies based on workspace IDs. To mitigate this, teams can scale up resources, isolate large tenants into specific key ranges, or fundamentally change the shard key for problematic tables based on access patterns. Neki facilitates these adjustments by allowing declarative data topologies and online resharding without downtime.

DEPTH ■■■■■7 min read4 weeks ago

MySQLPostgreSQL

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40Stack Overflow · practice

The Regression Tests Nobody Writes: Capturing How Software Actually Behaves

Standard regression tests usually only verify developer intent rather than the actual, unwritten behaviors that systems accumulate in production over time. By capturing real production traffic and network-level interactions, teams can build characterization test suites to automatically detect unintended behavioral shifts. This approach prevents accidental regressions during legacy refactoring, rewrites, and major framework upgrades.

DEPTH ■■■■■6 min read4 days ago

Testing

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