01
Reladraw — a diagram language where you say where things go, and it computes the coordinates
Reladraw (Apache-2.0, TypeScript, zero runtime dependencies, 866 stars, 94 commits, one contributor, created September 7, v0.11.1 on npm today) sits between Mermaid and draw.io. Mermaid, Graphviz and D2 decide the layout for you. draw.io and Excalidraw let you place everything, which means clicking and dragging, or an agent editing coordinates in verbose XML. In Reladraw you write node store "Database" right of app level with app and edge app.api -> store from: right to: left, and the layout engine turns those relations into absolute positions and renders SVG. npm install -g reladraw gives you the CLI, there is a browser playground, and npx skills add reladraw/reladraw -g installs a skill for Claude Code, Codex, Cursor and others.
The Show HN reached 397 points and 115 comments on Saturday, and the author answered the questions a tool like this has to answer. Conflicting statements: anything that can hold together applies, and if the statements can't all hold, you get an error that names the clashing ones. "Nothing silently wins." Routing: there is no obstacle avoidance, but edges that share a side of a box space themselves out, and you can say which nodes an edge passes between. Asked whether the positions could be exported for other renderers, the author said the logic exists but the CLI can't emit positions-only JSON yet. One commenter found an edge that failed to curve; it was fixed in the playground within the thread. Commenters compared it to TikZ's positioning library without LaTeX, and to Pikchr, which the author distinguished as cursor-walking "turtle" graphics.
Reach for it if you keep asking an agent for an architecture diagram and then fixing Mermaid's layout by hand in draw.io; it replaces the render-look-fiddle loop, for you and for the agent. Delete the draw.io XML files nobody can diff. Tradeoffs: the README says the syntax will change, so pin the version; one maintainer, three weeks old; one dark default theme for now; and relative placement covers boxes, groups and arrows, not the full range of TikZ.