Simon Willison’s Weblog

• llm openrouter refresh command for refreshing the list of available models without waiting for the cache to expire.

I added this feature so I could try Kimi 2.6 on OpenRouter as soon as it became available there.

Here's its pelican - this time as an HTML page because Kimi chose to include an HTML and JavaScript UI to control the animation. Transcript here.

Anthropic publish the system prompts for Claude chat and make that page available as Markdown. I had Claude Code turn that page into separate files for each model and model family with fake git commit dates to enable browsing the changes via the GitHub commit view.

I used this to write my own detailed notes on the changes between Opus 4.6 and 4.7.

I was upgrading Datasette Cloud to 1.0a27 and discovered a nasty collection of accidental breakages caused by changes in that alpha. This new alpha addresses those directly:

• Fixed a compatibility bug introduced in 1.0a27 where execute_write_fn() callbacks with a parameter name other than conn were seeing errors. (#2691)
• The database.close() method now also shuts down the write connection for that database.
• New datasette.close() method for closing down all databases and resources associated with a Datasette instance. This is called automatically when the server shuts down. (#2693)
• Datasette now includes a pytest plugin which automatically calls datasette.close() on temporary instances created in function-scoped fixtures and during tests. See Automatic cleanup of Datasette instances for details. This helps avoid running out of file descriptors in plugin test suites that were written before the Database(is_temp_disk=True) feature introduced in Datasette 1.0a27. (#2692)

Most of the changes in this release were implemented using Claude Code and the newly released Claude Opus 4.7.

• New model: claude-opus-4.7, which supports thinking_effort: xhigh. #66
• New thinking_display and thinking_adaptive boolean options. thinking_display summarized output is currently only available in JSON output or JSON logs.
• Increased default max_tokens to the maximum allowed for each model.
• No longer uses obsolete structured-outputs-2025-11-13 beta header for older models.

The datasette.io website has a news section built from this news.yaml file in the underlying GitHub repository. The YAML format looks like this:

- date: 2026-04-15
  body: |-
    [Datasette 1.0a27](https://docs.datasette.io/en/latest/changelog.html#a27-2026-04-15) changes how CSRF protection works in a way that simplifies form and API integration, and introduces a new `RenameTableEvent` for when a table is renamed by a SQL query.
- date: 2026-03-18
  body: |-
    ...

This format is a little hard to edit, so I finally had Claude build a custom preview UI to make checking for errors have slightly less friction.

I built it using standard claude.ai and Claude Artifacts, taking advantage of Claude's ability to clone GitHub repos and look at their content as part of a regular chat:

Clone https://github.com/simonw/datasette.io and look at the news.yaml file and how it is rendered on the homepage. Build an artifact I can paste that YAML into which previews what it will look like, and highlights any markdown errors or YAML errors

This plugin was using the ds_csrftoken cookie as part of a custom signed URL, which needed upgrading now that Datasette 1.0a27 no longer sets that cookie.

Two major changes in this new Datasette alpha. I covered the first of those in detail yesterday - Datasette no longer uses Django-style CSRF form tokens, instead using modern browser headers as described by Filippo Valsorda.

The second big change is that Datasette now fires a new RenameTableEvent any time a table is renamed during a SQLite transaction. This is useful because some plugins (like datasette-comments) attach additional data to table records by name, so a renamed table requires them to react in appropriate ways.

Here are the rest of the changes in the alpha:

• New actor= parameter for datasette.client methods, allowing internal requests to be made as a specific actor. This is particularly useful for writing automated tests. (#2688)
• New Database(is_temp_disk=True) option, used internally for the internal database. This helps resolve intermittent database locked errors caused by the internal database being in-memory as opposed to on-disk. (#2683) (#2684)
• The /<database>/<table>/-/upsert API (docs) now rejects rows with null primary key values. (#1936)
• Improved example in the API explorer for the /-/upsert endpoint (docs). (#1936)
• The /<database>.json endpoint now includes an "ok": true key, for consistency with other JSON API responses.
• call_with_supported_arguments() is now documented as a supported public API. (#2678)

See my notes on Google's new Gemini 3.1 Flash TTS text-to-speech model.

A small update for my tool for helping me figure out what all of the Datasette instances on my laptop are up to.

• Show working directory derived from each PID
• Show the full path to each database file

Output now looks like this:

http://127.0.0.1:8007/ - v1.0a26
  Directory: /Users/simon/dev/blog
  Databases:
    simonwillisonblog: /Users/simon/dev/blog/simonwillisonblog.db
  Plugins:
    datasette-llm
    datasette-secrets
http://127.0.0.1:8001/ - v1.0a26
  Directory: /Users/simon/dev/creatures
  Databases:
    creatures: /tmp/creatures.db

In Servo is now available on crates.io the Servo team announced the initial release of the servo crate, which packages their browser engine as an embeddable library.

I set Claude Code for web the task of figuring out what it can do, building a CLI tool for taking screenshots using it and working out if it could be compiled to WebAssembly.

The servo-shot Rust tool it built works pretty well:

git clone https://github.com/simonw/research
cd research/servo-crate-exploration/servo-shot
cargo build
./target/debug/servo-shot https://news.ycombinator.com/

Here's the result:

Compiling Servo itself to WebAssembly is not feasible due to its heavy use of threads and dependencies like SpiderMonkey, but Claude did build me this playground page for trying out a WebAssembly build of the html5ever and markup5ever_rcdom crates, providing a tool for turning fragments of HTML into a parse tree.

See my notes on SQLite 3.53.0. This playground provides a UI for trying out the various rendering options for SQL result tables from the new Query Result Formatter library, compiled to WebAssembly.

GitHub doesn't tell you the repo size in the UI, but it's available in the CORS-friendly API. Paste a repo into this tool to see the size, for example for simonw/datasette (8.1MB).

I ran into trouble deploying a new feature using SSE to a production Datasette instance, and it turned out that instance was using datasette-gzip which uses asgi-gzip which was incorrectly compressing event/text-stream responses.

asgi-gzip was extracted from Starlette, and has a GitHub Actions scheduled workflow to check Starlette for updates that need to be ported to the library... but that action had stopped running and hence had missed Starlette's own fix for this issue.

I ran the workflow and integrated the new fix, and now datasette-gzip and asgi-gzip both correctly handle text/event-stream in SSE responses.

Inspired by this conversation on Hacker News about whether two SQLite processes in separate Docker containers that share the same volume might run into problems due to WAL shared memory. The answer is that everything works fine - Docker containers on the same host and filesystem share the same shared memory in a way that allows WAL to collaborate as it should.

• No longer requires Datasette - running uvx datasette-ports now works as well.
• Installing it as a Datasette plugin continues to provide the datasette ports command.

• New -r/--redact option which shows the list of matches, asks for confirmation and then replaces every match with REDACTED, taking escaping rules into account.
• New Python function redact_file(file_path: str | Path, secrets: list[str], replacement: str = "REDACTED") -> int.

Super-niche tool this. I sometimes copy prompts out of the Claude Code terminal app and they come out with a bunch of weird additional whitespace. This tool cleans that up.

Another example of README-driven development, this time solving a problem that might be unique to me.

I often find myself running a bunch of different Datasette instances with different databases and different in-development plugins, spreads across dozens of different terminal windows - enough that I frequently lose them!

Now I can run this:

datasette install datasette-ports
datasette ports

And get a list of every running instance that looks something like this:

http://127.0.0.1:8333/ - v1.0a26
  Databases: data
  Plugins: datasette-enrichments, datasette-enrichments-llm, datasette-llm, datasette-secrets
http://127.0.0.1:8001/ - v1.0a26
  Databases: creatures
  Plugins: datasette-extract, datasette-llm, datasette-secrets
http://127.0.0.1:8900/ - v0.65.2
  Databases: logs