Simon Willison — Week of 2026-06-12 to 2026-06-18#

Highlight of the Week#

The most impactful release this week is the launch of datasette-apps, a major new plugin that allows developers to run self-contained, sandboxed HTML and JavaScript applications directly against a persistent Datasette backend. It brilliantly merges Simon’s ongoing experiments with AI-generated “vibe-coded” single-file tools and robust security architectures, pushing Datasette from a read-only publishing platform into a comprehensive ecosystem for building interfaces over data.

Engineering Reads — Week of 2026-06-17 to 2026-06-25#

Week in Review#

The dominant theme across this week’s reading is the persistent friction between idealized abstractions and messy, underlying hardware or operational realities. From the hidden environmental state that breaks reproducible C++ builds to the way mean latency metrics discard the user’s actual lived experience, the literature is heavily focused on the dangers of lossy compression in systems design. We are increasingly aware that whenever we try to flatten a complex domain—whether it’s AI capabilities, memory management, or performance monitoring—the suppressed complexity inevitably leaks back into the application layer.

Tech Videos — Week of 2026-06-20 to 2026-06-26#

Watch First#

Agents and Infrastructure, Sam Lambert | Compile 26 on the Cursor channel is the standout presentation this week because it cuts through the agent hype by demonstrating the concrete infrastructure primitives—like zero-data-loss rollbacks—required to safely let non-deterministic AI alter production databases.

Week in Review#

The core theme this week is the maturation of AI agents from brittle IDE novelties into asynchronous, infrastructure-bound workflows. There is a definitive industry consensus rallying around the Model Context Protocol (MCP) to standardize tool discovery, alongside a growing engineering realization that scaling AI throughput requires fundamentally overhauling test-driven development and implementing hard platform guardrails.

Hacker News — 2026-07-11#

Top Story#

Apple is suing OpenAI, alleging former employees stole trade secrets—including CAD files and prototype components—to bootstrap OpenAI’s nascent hardware division. The complaint claims a former VP of product design directed Apple engineers to bring actual hardware to OpenAI interviews for “show and tell” sessions, surfacing serious supply-chain and IP drama as Jony Ive builds out OpenAI’s devices.

Front Page Highlights#

After 7 years, Scarf has reluctantly moved away from Haskell Avi Press argues that LLM coding agents have fundamentally shifted the economics of software development, turning slow compile times from a papercut into a dealbreaker. Because AI workflows require cheap, disposable execution contexts to explore multiple branches in parallel, the heavy tax of Haskell’s cold-starts forced the team to migrate new API development to Python.

Engineering Reads — 2026-04-10#

The Big Idea#

As AI abstractions upend our relationship with code, engineering craft is bifurcating: we must simultaneously grapple with emergent, functional behaviors in massive models while deliberately preserving the mechanical, systems-level intuition that historically grounded software ethics.

Deep Reads#

watgo - a WebAssembly Toolkit for Go · Eli Bendersky This piece introduces watgo, a zero-dependency WebAssembly toolkit written in pure Go that parses, validates, encodes, and decodes WASM. The core of the system lowers WebAssembly Text (WAT) to a semantic intermediate representation called wasmir, flattening syntactic sugar to match WASM’s strict binary execution semantics. To guarantee correctness, watgo executes the official 200K-line WebAssembly specification test suite by converting .wast files to binary and running them against a Node.js harness. An earlier attempt to maintain a pure-Go execution pipeline using wazero was abandoned because the runtime lacked support for recent WASM garbage collection proposals. Engineers working on compilers, parsers, or WebAssembly infrastructure should read this for a masterclass in leveraging specification test suites to bootstrap confidence in new tooling.

Simon Willison — 2026-04-11#

Highlight#

The standout update today centers on the release of SQLite 3.53.0, where Simon highlights highly anticipated native ALTER TABLE constraint improvements and showcases his classic rapid-prototyping workflow by using Claude Code on his phone to build a WebAssembly-powered playground for the database’s new Query Result Formatter.

Posts#

SQLite 3.53.0 · Source This is a substantial release following the withdrawal of SQLite 3.52.0, packed with accumulated user-facing and internal improvements. Simon specifically highlights that ALTER TABLE can now directly add and remove NOT NULL and CHECK constraints, a workflow he previously had to manage using his own sqlite-utils transform() method. The update also introduces json_array_insert() (alongside its jsonb equivalent) and brings significant upgrades to the CLI mode’s result formatting via a new Query Results Formatter library. True to form, Simon leveraged AI assistance—specifically Claude Code on his phone—to compile this new C library into WebAssembly to build a custom playground interface.

Simon Willison — 2026-04-13#

Highlight#

Today’s standout is Simon’s hands-on research into the newly released servo crate using Claude Code. It perfectly captures his classic approach to AI-assisted exploration, demonstrating how quickly you can prototype a Rust CLI tool and evaluate WebAssembly compatibility with an LLM sidekick.

Posts#

[Exploring the new servo crate] · Source Following the initial release of the embeddable servo browser engine on crates.io, Simon tasked Claude Code for web with exploring its capabilities. The AI successfully generated a working Rust CLI tool called servo-shot for taking web screenshots. While compiling Servo itself to WebAssembly proved unfeasible due to its heavy use of threads and SpiderMonkey dependencies, Claude instead built a playground page utilizing a WebAssembly build of the html5ever and markup5ever_rcdom crates to parse HTML fragments.

Engineering Reads — 2026-04-30#

The Big Idea#

As AI models become capable of writing vast amounts of code, our core bottleneck is shifting from generating logic to verifying it. The future of software engineering requires us to aggressively enforce mechanical constraints, utilize correct-by-construction tools, and focus on the “left tail” of subtle system failures to safely orchestrate agentic workflows.

Deep Reads#

Thoughts on WebAssembly as a stack machine · Eli Bendersky WebAssembly functions as a highly readable stack machine augmented by an infinite register file of local variables. Unlike purist stack machines (e.g., Forth) that require mental gymnastics with dup and tuck-swap contortions to organize data, WASM leverages locals to dramatically clarify data flow. At runtime, this semantic sugar doesn’t cost performance; sophisticated compilers like wasmtime easily perform redundant load elimination, mapping these consecutive local accesses directly to native registers without aliasing issues. It is a great reminder that virtual machine abstraction design should favor human readability when the compiler can trivially bridge the gap to hardware efficiency. Read this if you care about virtual machine design or want a deeper intuition for how WASM bridges stack-based execution with register-based hardware.

Simon Willison — 2026-05-04#

Highlight#

Simon’s WASM-compiled Redis Array Playground is today’s standout, showcasing how quickly we can now spin up interactive sandboxes for in-flight C pull requests using AI agents like Claude Code.

Posts#

Redis Array Playground Salvatore Sanfilippo recently submitted a PR adding a new array data type to Redis. To try out the newly proposed commands, including a server-side ARGREP powered by the vendored TRE regex library, Simon utilized Claude Code to build an interactive WASM playground that runs a subset of Redis directly in the browser. The post also points to Salvatore’s own write-up on the AI-assisted development process behind the new array type.

Engineering Reads — 2026-05-28#

The Big Idea#

True systems mastery requires breaking down monolithic black boxes into understandable, isolated components. Whether you are mathematically decomposing a complex signal into orthogonal basis vectors or strictly isolating untrusted code within a mocked WebAssembly sandbox, engineering craft comes down to defining rigorous boundaries and understanding the mechanisms beneath the abstraction.

Deep Reads#

Notes on Fourier series · Eli Bendersky The trigonometric Fourier series is more than a signal processing trick; it is deeply rooted in linear algebra within a Hilbert space. Bendersky walks through the mechanics of decomposing a periodic function into an infinite sum of sinusoids, demonstrating how the integral formulas for coefficients are actually just projections calculating the dot product of a function against orthogonal basis vectors. The post grounds these continuous concepts with practical constraints, noting that functions need only be square-integrable and piecewise smooth to guarantee pointwise convergence. It bridges the gap between pure math and engineering intuition, trading abstract analysis for concrete examples like complex exponentials and periodic extensions of non-periodic intervals. Engineers looking to build intuition for frequency-domain transforms or those rusty on the linear algebraic foundations of signal processing should read this.