Eleven picks from the GitHub trending board for the week of September 13, 2026. The week is heavy on agent skills — Claude Code and Codex are now the distribution channel for everything from diagrams to CAD — and on the plumbing that makes running several agents at once bearable. Grouped by theme:

Agent skills & methodology

  • cathrynlavery/diagram-design — 39 editorial diagram types as agent skills for Claude Code, Codex, Factory Droid, and Pi; self-contained HTML + SVG output, with layout grammars for Sankey, fishbone, Wardley maps, kanban, user journeys, dependency graphs, UML class, story maps, and database schemas. The week’s biggest mover at ~7.4k stars gained, and the explicit pitch is “no Mermaid slop.”
  • obra/superpowers — an agentic skills framework plus a software-development methodology, installable across the major coding agents. The largest repo here by total stars (~286k), and the clearest statement of the “skills as the unit of reuse” thesis.
  • github/spec-kit — GitHub’s own toolkit for spec-driven development: write the spec first, then let the agent plan and implement against it. Worth a look if your workflow already starts from a written spec rather than a prompt.
  • coreyhaines31/marketingskills — marketing skills for Claude Code and AI agents: conversion-rate optimization, copywriting, SEO, analytics, and growth engineering. Turns the agent into a marketing hire rather than a codegen tool.
  • petergyang/no-ai-slop — a skill that strips 20+ recognizable AI-writing tics out of any draft. Useful as a final pass on agent-authored prose before it ships anywhere public.
  • earthtojake/text-to-cad — a library of agent skills for CAD, CAE, and CAM work, i.e. driving mechanical-design and simulation tooling from natural language. Actively updated and the most concrete example this week of skills reaching past software.

Running several agents at once

  • kunchenguid/firstmate — you talk to one agent; it runs the crew. Spawns autonomous agents in a visible session backend, gives each its own git worktree, supervises them to completion, and hands back finished PRs, approved local merges, or investigation reports. Aimed squarely at the tab-juggling problem.
  • max-sixty/worktrunk — a Rust CLI for git worktree management built for parallel agent workflows: create, switch, and clean up per-agent worktrees without remembering paths. Small pick (~257 stars this week) but the most boring-necessary tool on the list.

Documents, knowledge & media

  • microsoft/markitdown — Microsoft’s Python tool for converting files and office documents into Markdown, presumably for feeding them to models. The mature, high-traffic option at ~183k total stars.
  • Tencent/WeKnora — an open-source LLM knowledge platform in Go: raw documents in, queryable RAG + an autonomous reasoning agent + a self-maintaining wiki out. The self-hosting-friendly answer to the hosted document-QA products.
  • heygen-com/hyperframes — “Write HTML. Render video. Built for agents.” Frames the render pipeline as an agent target, with a component catalog and playground, so programmatic video stops being a bespoke FFmpeg job.

Registry note: all eleven repo URLs are recorded in the roundup registry, so next week’s script won’t repeat them.