My primary project is Mermaid Studio, an IDE grade Mermaid diagram authoring experience for both humans and agents built for JetBrains IDEs. Semantic highlighting, refactoring, 120+ inspections covering everything from common rendering issues and foot-guns to obscure syntax quirks, contextual completions, interactive (drag-and-drop) diagram editing and styling. A suite of included MCP tools surfaces the plugin's intelligence and rendering capabilities, so your preferred agent (even using relatively small local models) can generate correct diagrams, even the newest or more obscure ones with ease.

https://mermaidstudio.dev/ | https://plugins.jetbrains.com/plugin/29870-mermaid-studio

Tinkering with several other IntelliJ plugin ideas that may or may not end up being released.

Still occasionally pushing up new features Tachi Code, my browser extension that brings a feature rich, highly customizable, Monaco Editor based code editor to the browser surfaces you always wished would be less of a pain to read. These days, I mostly use it for reading and printing Markdown files.

https://tachicode.com/

https://github.com/DavidSeptimus/alfred-jetbrains-launcher

Mostly, I use it to quickly open projects in cmux, but I use it for switching between git worktrees in IntelliJ too.

I migrated to macOS for development years ago and going back to Windows for development always felt gross, but I never had any issues with windows for entertainment/general productivity workflows. It's only once I tried 11 that I noped out for everything other than use as a Steam launcher.

It provides both syntax guides and syntax/semantic analysis as MCP Tools, so you can have an agent iteratively refine diagrams with good context for patterns like multi-line text and comments (LLMs love end-of-line comments, but Mermaid.js often doesn’t).

This post just inspired me to tackle this once and for all today.

I’ve had a lot of success dogfooding my own product, the Mermaid Studio plugin for JetBrains IDEs (https://mermaidstudio.dev).

It combines the deep semantic code intelligence of an IDE with a suite of integrated MCP tools that your preferred agent can plug into for static analysis, up to date syntax, etc.

I basically tell Claude Code to run the generated diagram through the analysis tool, fix issues it detects and repeat until fixed. Then generate a png or svg for a visual inspection before finalizing the diagram.

Now all of my planning and architecture docs are filled with illustrative flowcharts, sequence diagrams, and occasionally block diagrams for workshopping proposed UI layouts

Open a raw .md file in your browser and it'll automatically open in a side-by-side editor/preview. If viewing is all you want, you can set the default preview mode for markdown files to be fullscreen.

Alternatively, we could take the model makers’ view and say that if they didn’t want their code reused, they wouldn’t have made it publicly accessible on the internet.

Charging per minute for self-hosted runners seems absolutely bananas!

Even when I create the first draft of a project’s README with an LLM, part of the final pass is removing those slop-associated patterns to clarify to the reader that they’re not reading unfiltered LLM output.

This works great for refactors that touch a large number of files. You can knock out a refactor that might take 30 minutes, a persistent checklist, and possibly multiple conversations, and one-shot it in two minutes and a single prompt.

This time around, I worked with Claude Code and we basically filled in each other's knowledge gaps to finish implementing every feature I was looking for in about 3 days of work:

Day 1:

- Plugin initialization

- Syntax highlighting

- JSON Schema integration

- Error inspections

Day 2:

- Code formatter (the code style settings page probably took longer to get right than the formatter)

- Test suite for existing features

Day 3:

- Intentions, QuickFix actions, etc. to help quickly reformat or fix issues detected in the file

- More graceful parsing error recovery and reporting

- Contextual completions (e.g., relevant keys/values from a JSON schema, existing keys from elsewhere in the file, etc.)

- Color picker gutter icon from string values that represent colors (in various formats)

I'm sure there are a few other features that I'm forgetting, but at the end of the day, roughly 80-85% of the code was generated from the command line by conversing with Claude Code (Sonnet 4.5) to plan, implement, test, and revise individual features.

For IntelliJ plugins, the SDK docs tend to cover the bare minimum to get common functionality working, and beyond that, the way to learn is by reading the source of existing OSS plugins. Claude was shockingly good at finding extension points for features I'd never implemented before and figuring out how to wire them up (though not always 100% successfully). It turns out that Claude can be quite an accelerator for building plugins for the JetBrains ecosystem.

Bottom line, if you're sitting on an idea for a plugin because you thought it might to take too long to bootstrap and figure out all the IDE integration parts, there's never been a better time to just go for it.

EDIT: Repo link for anyone interested: https://github.com/DavidSeptimus/maml-intellij-plugin

If you don’t mind, could you post the url(s) that got blocked? The only calls to non-extension urls should be GitHub.