Read what ships.

01Shopify · architecture

We gave AI agents a mobile dev environment

Engineering teams outgrew their local machines while running parallel AI mobile development agents, constrained by heavy builds and lack of iOS tools on Linux. To solve this, they built Remote Dev using warm pools of remote Macs connected via SSH alongside separate Linux VMs for Android virtualization, paired with agent skills and live browser streaming. This setup shifted workflow bottlenecks, increasing AI-merged pull requests from 6 percent to 61 percent.

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ArchitectureMobile

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02Martin Fowler · architecture

When Software Meets Hardware

A software engineering team modernizing a large-scale retail IoT system of 800,000 battery-powered sensors faced challenges integrating software practices with embedded hardware. By building physical sensor farms, virtual emulators, and self-diagnosing firmware, the team learned to design for intermittent connectivity, power efficiency, and fleet-level observability. The project succeeded by treating the physical world, hardware constraints, and engineering environments as core parts of the system lifecycle.

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03Shopify · architecture

How Shopify turns open models into task experts

Shopify uses a continual learning flywheel to post-train open models, such as NVIDIA Nemotron, to serve as dedicated subagents for specific tasks like GraphQL generation. By optimizing inference and utilizing automated self-healing to generate training data from production failures, the team successfully created task experts that outperform frontier models while reducing serving costs by 90-98% and improving response times.

DEPTH ■■■■■5 min read4 days ago

Architecture

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04Sentry · architecture

Sentry JavaScript SDK v11 adds tracing for all JS platforms

Sentry replaced its OpenTelemetry-based JavaScript SDK instrumentation with a source-code transformation approach using diagnostics channels in version 11. This change removes reliance on Node-specific module loader hooks, enabling reliable tracing across non-Node runtimes like Deno, Bun, and Cloudflare Workers, while also supporting bundled applications. The result is a simplified architecture that reduces bundle weight and fixes previous limitations with load order and immutable exports.

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05Shopify · architecture

Cross-store product clustering across millions of stores

Shopify needed to group identical product listings from millions of different merchants under a single global identifier. To solve this at scale without comparing every possible pair, the team implemented a multi-stage pipeline using vector retrieval, a tiered scoring system of ML models, and a bounded graph clustering approach. This architecture successfully standardizes product data across the entire platform while controlling computational costs.

DEPTH ■■■■■13 min read5 days ago

Architecture

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06Martin Fowler · performance

Are Harnesses Worth the Cost?

An experiment was conducted to evaluate whether behavioral harnesses improve coding agent reliability when building a complex backend-for-frontend service. While frontier models succeeded consistently with or without a harness, the harness significantly increased token usage, time, and cost without improving final output. However, for a cost-optimized model, the harness improved success rates from 30 percent to 100 percent.

DEPTH ■■■■■17 min read12 days ago

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07Sentry · performance

Reducing Android scope-sync overhead in Sentry Flutter

The Sentry Flutter team investigated scope-sync overhead on Android and found redundant data normalization across isolates alongside unnecessary buffer copies during JSON encoding. By removing the duplicate normalization and encoding directly to UTF-8 bytes, the team reduced processing time by 27 to 30 percent across benchmarked payloads.

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08Shopify · tooling

Building Overexposed: understanding application exposure

The team built an automated scanner called Overexposed to track internet-facing services and verify access controls across Kubernetes and Cloud Run. By querying live cloud inventories and probing endpoints like an outsider, the scanner classifies exposure while avoiding false assumptions from static config files. As a result, the engineering organization improved accuracy and significantly reduced inconclusive findings over time.

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09Sentry · performance

The Sentry Android SDK is now 20-30% faster!

The Sentry team optimized the Android SDK to reduce initialization time by 20-30% and background CPU usage by up to 10%. Improvements were achieved by profiling with Perfetto, replacing slow runtime manifest parsing and DSN parsing with build-time bytecode writing and lightweight parsers, and reusing thread pools. Upgrading to the latest SDK version allows applications to realize these startup performance gains.

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10Martin Fowler · practice

Fragments: October 21

This post discusses commentary on AI usage in writing, the cancellation of the Grace Hopper Celebration, and reviews a detailed article by Cindy Sridharan on debugging with AI agents. The reviewed article highlights that AI agents excel at processing raw data rather than reading code first, and outlines a three-step debugging process involving controls, signals, and hypothesis validation. The lesson is that engineers must guide AI agents by setting up verification loops and providing raw data rather than human-centric abstractions.

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11Shopify · architecture

ShopGym: Realistic, reproducible sandboxes for shopping agents

Training and evaluating shopping agents is difficult due to changing live store environments, bot detection, and limited hand-built test stores. The team developed ShopGym, a framework that converts live storefronts into self-contained, anonymized sandbox shops and generates benchmark tasks. Evaluation showed that synthetic shops preserve key structural properties and behavioral alignment with live stores, giving agents a reliable environment to practice and improve.

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12Sentry · tooling

Unreal MCP now speaks Sentry

The Sentry team integrated their crash reporting plugin with Unreal Engine's new experimental Model Context Protocol (MCP) server, allowing coding agents to fully automate setup and debugging. By combining editor tools and Sentry MCP, an agent successfully configured the SDK, uploaded debug symbols, packaged a build, induced a crash, and traced the root cause without manual file editing. The integration streamlines crash reporting setup, though it currently suffers from occasional agent tool-discovery issues and server fragility across editor restarts.

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13Sentry · practice

Should you use a log or a metric?

This post explains the distinction between logs and metrics in application monitoring, noting that logs capture what was true during specific events for debugging while metrics track ongoing numerical trends over time. The author demonstrates how to implement both using Sentry SDKs during a user signup flow and outlines criteria for choosing between them. The resulting takeaway helps engineers decide whether to log an event or track it as a metric based on the questions they need to answer.

DEPTH ■■■■■12 min read3 days ago

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14Martin Fowler · practice

Practitioner Voice: The Writing Category Nobody has Named Yet

The author explores a missing category of writing called Practitioner Voice, which is grounded in earned experience and visible personal judgment rather than academic rigor, corporate polish, or AI generation. They examine how AI can be used as an extended cognitive tool for practitioners without losing human accountability. Ultimately, the piece argues that maintaining personal judgment and consequence-bearing experience is essential for authentic professional writing.

DEPTH ■■■■■39 min read12 days ago

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15Shopify · tooling

Helix: The internal tool powering our Shopify app's native migration

Shopify is migrating its mobile apps from React Native to native Swift and Kotlin using an internal LLM-powered tool called Helix. Helix breaks migrations down into small checkpoints and enforces strict quality gates covering behavior, UI equivalence, architectural compliance, and human review. This iterative loop allows the team to reliably generate and migrate hundreds of screens to native code.

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16Sentry · practice

How Etsy gets its mobile apps ready for peak traffic

Etsy prepares its mobile apps for peak holiday traffic through advance planning, operational guardrails, and risk management rather than relying on capacity scaling or the ability to quickly revert binaries. The engineering team utilizes a phased code slush, dual crash reporting, remote feature flags, and custom error tagging to surface and mitigate issues effectively under heavy loads. By connecting crash rates to business metrics and automating manual triage workflows incrementally, the organization maintains high visibility and reliability when updates cannot be instantly rolled back.

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17Martin Fowler · practice

Fragments: October 4

This post discusses the evolving role of software development and code in the era of large language models. It explores how shifting from deterministic building to inferential nurturing changes processes, why high-level representations remain critical for managing context windows, and how conceptual modeling becomes more important than the mechanical act of writing instructions.

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18Shopify · migration

Migrating Shop app from React Native to native

Shop migrated its mobile app from React Native to native Swift and Kotlin by leveraging AI coding agents to accelerate the rewrite. The migration resulted in improved startup times, higher session stability, smaller Android app sizes, and smoother rendering performance.

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19Martin Fowler · practice

Principles for effective slides

Presenters often rely on text-heavy slide decks that distract audiences and undermine storytelling. To fix this, speakers can use minimalist slides as a complementary visual channel to control the rate of information and manage cognitive load. This approach leads to more engaging presentations where visuals reinforce the spoken narrative rather than replace it.

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20Shopify · migration

Native is now the future of mobile at Shopify

Shopify is migrating its mobile applications from React Native back to native Swift and Kotlin. The team determined that the emergence of advanced coding agents significantly reduces the cost of maintaining platform parity, making native development the superior choice again. To execute this migration efficiently, Shopify developed a system called Helix and a CLI-driven, agent-addressable architecture to enable fast, autonomous testing.

DEPTH ■■■■■10 min read6 weeks ago

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