# Built with AI mdlib-pure was designed by Michele Polo and written with Claude (Anthropic) through Claude Code. The maintainer sets the direction and makes the calls; agents write the code, the tests and the docs, review the work and try to break it. This page tells how, with facts from the git history and the [changelog](docs/changelog.md). The history has 49 commits, from 28 October 2026 to 2 November 2026; 47 of them carry a `Co-Authored-By: Claude` trailer. ## A contract written for agents The first commit already shipped [`AGENTS.md`](docs/extending.md): rules that each come with the command that verifies them, and recipes for extending the parser. To test it, an agent implemented the `:::` container plugin using only that file ([5a482ba]). Its friction log changed both the core (`finalize()` now closes a block's open children) and the guide, which gained the container recipe, the ordering rules against GFM table rows and the per-line cost of `continue`. From then on, first-party plugins were written by agents from `AGENTS.md`: | Plugin | gzip at the time | Tests | Commit | |:--|--:|--:|:--| | `mdlib-pure/container` | 0.81 KB | 37 | [5a482ba] | | `mdlib-pure/math` | 0.91 KB | 65 | [1c4dd87] | | `mdlib-pure/mark` | 0.13 KB | 37 | [1c4dd87] | | `mdlib-pure/frontmatter` | 0.57 KB | 38 | [1c4dd87] | | `mdlib-pure/deflist` | 1.22 KB | 54 | [53f6b0f] | The benchmark suite in `bench/` was built by an agent too ([cb973e5]). ## Bugs found by adversarial tests and reviews Every new syntax ships with adversarial-input tests, and agents reviewed the code looking for ways to break it. Some of what they found, with the numbers from the commits that fixed it: - **Inherited ReDoS.** The link title regex had overlapping alternatives (exponential backtracking), inherited from the reference implementation, and unanchored trailing-whitespace regexes were quadratic. Rewritten, and `AGENTS.md` gained its rule on linear regexes ([b6fde7c]). - **Prototype lookup.** `&constructor;` resolved to `Object.prototype` in the fallback entity decoder: now a `Map`, and a rule ([b6fde7c]). - **Quadratic GFM tables.** Opening a table split the whole paragraph on every delimiter-like line: 7.5 s on 30k lines, then 110 ms. Unbounded footnote labels: 805 ms, then 82 ms ([ea3dfd8]). - **Deep emphasis.** Interleaved delimiters nested past `MAX_NESTING` took 3.8 s at 60k, then 91 ms. Found by an agent review, with three more fixes in the same commit ([74de6d1]). - **Quadratic sibling search.** Many setext headings or one-row tables took 1.1 s at 100k; now linear ([53f6b0f]). - **Unsanitized adapter output.** With `html: true` and `sanitize`, `toVNodes()` was not sanitized, so the framework adapter passed raw HTML to `dangerouslySetInnerHTML`. The regression test fails on the previous version ([e440762]). - **Tailwind clash.** A real Tailwind CSS v4 build showed that `@theme inline { --radius-md }` replaced Tailwind's own `rounded-md` for the whole project ([27395d2]). - **CSS source order.** A screenshot of the first demo editor revealed that, with zero-specificity rules, source order decides: the first heading kept its top margin and alerts had extra space below. The edge resets moved to the end of the theme ([ea3dfd8]; the screenshot is below). - **A timing test that only failed on CI.** A 4 MB adversarial input took 2.2 s on the CI runner, over the 2 s limit, while parsing was linear (~130 ms/MB). The first attempted fix made paragraphs quadratic; measuring caught it and it was reverted. The input shrank to 1 MB and every timing limit became `budget(ms)`, tripled on CI ([a593dd7]). ## Web Components, then Blazor `mdlib-pure/element` added two custom elements that work in plain HTML and in any framework: ``, a viewer, and ``, an editor with toolbar and live preview ([7f25396]). They were written as the base of a Blazor wrapper. Core, every plugin and both elements came to 19.8 KB gzip at the time, within a 26 KB budget; KaTeX and Mermaid come through loaders, fetched only when a document needs them. The commit shipped with 7 Chromium tests. An agent then built `MdlibPure.Blazor` on the elements, and the work was reviewed ([13c87c3]): a Razor class library for .NET 10 with a viewer, an editor bound with `@bind-Value`, and a C# service for the AST. It has 48 bUnit tests and 20 Playwright end-to-end tests across Static SSR, Interactive Server, WebAssembly and Auto. Version 0.1.0 is attached to a [GitHub release](https://github.com/MichelePolo/mdlib-pure/releases/tag/blazor-v0.1.0); version 0.1.1 ([release](https://github.com/MichelePolo/mdlib-pure/releases/tag/blazor-v0.1.1)) adds `PodcastEditor`. The guide is [its README](docs/blazor.md). Building the wrapper found three problems in the elements, each reproduced in a test before the fix ([60c7298]): - **DOM morphing.** Blazor enhanced navigation (like Turbo and htmx) empties elements it did not create, and the elements never recovered. A `MutationObserver` now renders the viewer again and puts back the editor's toolbar and panes, keeping the typed text. - **A stylesheet that disappeared.** The KaTeX stylesheet was a `` added once, which a morph removed for good. It is now adopted through `document.adoptedStyleSheets`, with absolute font URLs. - **Late loaders.** Elements defined before their loaders never drew math or diagrams. Every `defineElements()` call now refreshes the elements already in the page. Then a rule for the docs ([8dcf108]): rule 10 of `AGENTS.md`, checked by `npm run check`, requires every public entry point to be documented in `docs/api.md` and the README, and every `docs/*.md` and `bindings/*/README.md` to be linked from the README. This site adds the other half: its build fails when one of those guides is not published as a docs page. That is how the [Web Components guide](docs/elements.md) and the [Blazor README](docs/blazor.md) became pages here. ## Then Angular A second agent built `ngx-mdlib-pure` on the same elements, in a git worktree of its own so that it could not collide with the agent updating this site ([5a551cd]). The package has standalone components whose tag *is* the Web Component (``, also a form control for `ngModel` and reactive forms, and ``), a provider, and a service for the AST that also runs on the server. It is checked by 29 unit tests in Chromium and 11 end-to-end tests against a server-rendered, hydrated demo. Its [README](docs/angular.md) became a docs page here in the same commit, since the site build requires it. Building and reviewing it found four problems outside the wrapper, each now covered by a test or a check: - **No disabled state.** Inside `
`, the editor still took typing. It now disables its text area and formatting buttons, like a disabled `