TILs
Filters: Sorted by date
TIL
Running OpenClaw in Docker
— I'm not brave enough to run [OpenClaw](https://openclaw.ai/) (aka Clawdbot aka Moltbot) directly on my Mac, so I decided to try running it in a Docker instead container.
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Cloudflare response header transform rules
— I serve Python files from my `tools.simonwillison.net` subdomain, which is a GitHub Pages site that's served via Cloudflare. For example:
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Previewing Claude Code for web branches with GitHub Pages
— I'm a big user of [Claude Code on the web](https://code.claude.com/docs/en/claude-code-on-the-web), Anthropic's poorly named cloud-based version of Claude Code which can be driven via the web or their native mobile and desktop applications.
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Taking Neon I at the Crucible
— I took the Neon I intensive week-long evening class at [the Crucible](https://www.thecrucible.org/) in Oakland, with teachers Dan Kuppe and Kat. I learned to make a neon sign! It's still awaiting final infusion of gas, but I'll share photos here once it's finished.
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Downloading archived Git repositories from archive.softwareheritage.org
— Last February I [blogged about](https://simonwillison.net/2025/Feb/7/sqlite-s3vfs/) a neat script called `sqlite-s3vfs` which was released as MIT licensed open source by the UK government's Department for Business and Trade.
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Subtests in pytest 9.0.0+
— [pytest 9.0.0](https://pypi.org/project/pytest/9.0.0/) was released on November 8th 2025. I just got around to looking at the [release notes](https://docs.pytest.org/en/stable/changelog.html#pytest-9-0-0-2025-11-05) and the biggest new feature is **subtests**, previously available as the separate [pytest-subtests](https://pypi.org/project/pytest-subtests/) plugin.
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Dependency groups and uv run
— I've adopted a new (to me) pattern for my Python projects to make them easier to hack on using `uv run`. I'm using a [PEP 735 dependency group](https://peps.python.org/pep-0735/) called `dev` to declare my development dependencies - in particular `pytest` - such that running `uv run pytest` executes the tests for my project without me having to even think about setting up a virtual environment first.
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Using Codex CLI with gpt-oss:120b on an NVIDIA DGX Spark via Tailscale
— I've written about the [DGX Spark](https://simonwillison.net/2025/Oct/14/nvidia-dgx-spark/) before. Here's how I got OpenAI's Codex CLI to run on my Mac against a gpt-oss:120b model running on the DGX Spark via a Tailscale network.
TIL
Exploring OpenAI's deep research API model o4-mini-deep-research
— I was reviewing some older PRs and landed [this one](https://github.com/simonw/llm-prices/pull/9) by Manuel Solorzano adding pricing for [o4-mini-deep-research](https://platform.openai.com/docs/models/o4-mini-deep-research) and [o3-deep-research](https://platform.openai.com/docs/models/o3-deep-research) to my [llm-prices.com](https://www.llm-prices.com/) site. I realized I hadn't tried those models yet so I decided to give one of them a go.
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Testing different Python versions with uv with-editable and uv-test
— A quick `uv` recipe I figured out today, for running the tests for a project against multiple Python versions.
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Testing different Python versions with uv with-editable and uv-test
— A quick `uv` recipe I figured out today, for running the tests for a project against multiple Python versions.
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Error 153 Video player configuration error on YouTube embeds
— I recently noticed that almost every YouTube video on [my blog](https://simonwillison.net/) was displaying the same mysterious error message:
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Running a gpt-oss eval suite against LM Studio on a Mac
— OpenAI's [gpt-oss models](https://github.com/openai/gpt-oss/) come with an eval suite, which is described in their [Verifying gpt-oss implementations](https://cookbook.openai.com/articles/gpt-oss/verifying-implementations) cookbook. I figured out how to run it on my Mac against their `gpt-oss-20b` model hosted locally using LM Studio, using [uv](https://github.com/astral-sh/uv).
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Configuring GitHub Codespaces using devcontainers
— [GitHub Codespaces](https://github.com/features/codespaces) provides full development environments in your browser, and is free to use with anyone with a GitHub account. Each environment has a full Linux container and a browser-based UI using VS Code.
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Rate limiting by IP using Cloudflare's rate limiting rules
— My [blog](https://simonwillison.net/) was showing poor performance, with some pages taking several seconds to load or even failing entirely.
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Using Playwright MCP with Claude Code
— Inspired [by Armin](https://simonwillison.net/2025/Jun/29/agentic-coding/), I decided to figure out how to use the official [microsoft/playwright-mcp](https://github.com/microsoft/playwright-mcp) Playwright MCP server with Claude Code.
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Converting ORF raw files to JPEG on macOS
— One of our cameras takes raw photos in ORF format, which I believe stands for "Olympus Raw Format". Here's a recipe I found for converting them to JPEG on macOS:
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Publishing a Docker container for Microsoft Edit to the GitHub Container Registry
— Microsoft recently [released Edit](https://devblogs.microsoft.com/commandline/edit-is-now-open-source/), a new terminal text editor written in Rust. It's pretty nice - it's reminiscent of `nano` but with a retro MS DOS feel.
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Redirecting a domain using Cloudflare Pages
— I wanted to redirect https://global-power-plants.datasettes.com/ to https://datasette.io/ - I decided to spin up a Cloudflare Pages site to do the work.
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A tip for debugging pytest-httpx
— I use [pytest-httpx](https://colin-b.github.io/pytest_httpx/) in a bunch of my projects. Occasionally I run into test failures like this one, which can sometimes be really hard to figure out:
TIL
SQLite triggers
— I wrote a Python script, [triggers.py](https://github.com/simonw/til/blob/main/sqlite/triggers.py), to help me understand what data is available to SQLite triggers for which operations.
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Building and deploying a custom site using GitHub Actions and GitHub Pages
— I figured out a minimal pattern for building a completely custom website using GitHub Actions and deploying the result to GitHub Pages.
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Styling an HTML dialog modal to take the full height of the viewport
— I've been experimenting with the HTML [dialog element](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/dialog) recently, for example in my [Prompts.js](https://simonwillison.net/2024/Dec/7/prompts-js/) JavaScript library.
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Running jupyterlab via uv tool install
— I tried to get [jupyterlab](https://jupyter.org/install) working via `uv tool install` today and ran into some sharp edges.
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Using a Tailscale exit node with GitHub Actions
— For an (ethical) [scraping project](https://github.com/simonw/scrape-doge-gov) I found that my low-volume scraper was working from my laptop but was being blocked by Cloudflare when I attempted to run it in GitHub Actions, presumably because the GitHub Actions IP range was disallowed.
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Using S3 triggers to maintain a list of files in DynamoDB
— This is a three-quarters-baked experiment that I ran this morning. I'm interested in efficiently tracking which new files have been added to an S3 bucket, where that bucket could potentially hold millions of items.
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Trying out Python packages with ipython and uvx
— I figured out a really simple pattern for experimenting with new Python packages today:
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Running pytest against a specific Python version with uv run
— While [working on this issue](https://github.com/simonw/datasette/issues/2461) I figured out a neat pattern for running the tests for my project locally against a specific Python version using [uv run](https://docs.astral.sh/uv/guides/scripts/):
TIL
Running pytest against a specific Python version with uv run
— While [working on this issue](https://github.com/simonw/datasette/issues/2461) I figured out a neat pattern for running the tests for my project locally against a specific Python version using [uv run](https://docs.astral.sh/uv/guides/scripts/):
TIL
Geocoding from Python on macOS using pyobjc-framework-CoreLocation
— Rhet Turnbull [shared](https://twitter.com/RhetTurnbull/status/1883559820541956605) this [short script](https://gist.github.com/RhetTbull/db70c113efd03029c6ff619f4699ce34) for looking up the named timezone for a given location from Python on macOS using `objc` and the `CoreLocation` framework. It uses the `objc` package and [pyobjc-framework-CoreLocation](https://pypi.org/project/pyobjc-framework-CoreLocation/).