Show HN: A Markdown and Mermaid pane for Herdr, the terminal for coding agents

Developer daneb released a Herdr mod called Live Markdown + Mermaid that renders Markdown files, Mermaid diagrams and images in a pane beside the terminal, updating live as a coding agent rewrites the file. The mod requires the Herdr app 0.1.15 or later on macOS and is installed either through Herdr's mod gallery or by cloning the herdr-markdown GitHub repository and running ./scripts/install.sh, which copies the mods/files-md folder into ~/.config/herdr-app/mods/. The mod is read-only, makes no network requests, starts only the sh and git programs Herdr's own Files panel uses, and caches rendered diagrams and copied images in ~/.config/herdr-app/data/files-md/ under 100 MB.

Read your agents' Markdown the way it was meant to look, right beside the terminal: headings, tables, task lists, Mermaid diagrams and images , in Herdr's own file panel. It updates as the agent writes. - The file tree you know , from Herdr's built-in Files panel: your terminal's folder, with git marks. - Markdown, formatted. Click a .md file and read it, not its source. A Formatted | Source switch is there when you want the raw text. - Diagrams drawn. Flowcharts, sequence, state, class, ER and XY charts, in your theme's colours. Wide ones scroll sideways instead of shrinking to nothing. - Images shown , from your project folder: PNG, JPEG, GIF, WebP, SVG, BMP. - Links that work. Web links open your browser; links to other files in the folder open in the panel, and ← takes you back. - Live. When an agent rewrites the file, you see it change. - Copy any text with ⌘C . You need the Herdr app https://herdr.dev 0.1.15 or later, on macOS. From Herdr's gallery recommended . Find Live Markdown + Mermaid in the mod gallery https://herdr.dev/gallery/?type=mods , copy its line, and give it to an agent running in Herdr. It's this: Read ~/.config/herdr-app/AGENTS.md, then add this mod: https://github.com/daneb/herdr-markdown/tree/master https://github.com/daneb/herdr-markdown/tree/master The agent follows Herdr's own instructions: it tells you what the mod runs and reads before adding it, and asks before adding its suggested key. By hand: git clone https://github.com/daneb/herdr-markdown cd herdr-markdown ./scripts/install.sh This copies one folder, mods/files-md , into ~/.config/herdr-app/mods/ and checks that it loads. Nothing else on your machine changes. From a terminal in Herdr, in the folder you want to browse: herdr-app do pane.split '{"direction":"right","mod":"files-md"}' It opens as a pane to the right. Close, resize or zoom it like any pane. Prefer a key? Add this line to the "global" section of ~/.config/herdr-app/keys.json to open it with ⌘⇧M : "cmd-shift-m": { "command": "pane.split", "args": { "direction": "right", "mod": "files-md" } } Once you edit keys.json , Herdr stops updating its default keys for you. That is Herdr's rule, not ours. Open it on a particular file: herdr-app do pane.split '{"direction":"right","mod":"files-md","props":{"file":"docs/PLAN.md"}}' | To | Do | |---|---| | Open a folder or file | Click it in the tree | | See the raw Markdown | Click Source in the header it stays on until you switch back | | Follow a link | Click it: web links open your browser, file links open here | | Go back | Click ← : back through the files you followed, then to the tree | | Copy text | Select it, then ⌘C | | Copy a diagram's source | Click Copy source under the diagram | A note under the header tells you when something can't be shown, for example a link outside the folder or an image that's too large. - Read-only. It never changes your files. - No network. Web images are shown as links, not downloaded. - Runs nothing new. The only programs it starts are the ones Herdr's own Files panel starts sh to list folders, git for status . - One folder of its own: drawn diagrams and copied images are cached in ~/.config/herdr-app/data/files-md/ , kept under 100 MB. - Diagram types beyond the six above gantt, pie, mindmap… show as source, with the reason. - Very large files over 400,000 characters open as source. - Remote machines: the tree and text work; images on another machine aren't shown. - Tested on macOS with Herdr 0.1.15 and 0.1.16. Windows and Linux aren't tested yet. Every change is checked automatically for these promises: no network, no new programs, writes only to its cache. See docs/QUALITY.md https://github.com/daneb/herdr-markdown/blob/master/docs/QUALITY.md . Delete two folders, and the key if you added it: rm -rf ~/.config/herdr-app/mods/files-md ~/.config/herdr-app/data/files-md Apache-2.0. Built on Herdr's own Files panel Apache-2.0 . Diagrams are drawn by beautiful-mermaid https://github.com/lukilabs/beautiful-mermaid MIT with elkjs https://github.com/kieler/elkjs EPL-2.0 , and the diagram approach follows herdr-files-plus https://github.com/jjongkwann/herdr-files-plus MIT . Details in NOTICE https://github.com/daneb/herdr-markdown/blob/master/NOTICE and THIRD-PARTY-NOTICES https://github.com/daneb/herdr-markdown/blob/master/mods/files-md/THIRD-PARTY-NOTICES.md . Want to build on it or report a problem? See CONTRIBUTING.md https://github.com/daneb/herdr-markdown/blob/master/CONTRIBUTING.md , or open an issue https://github.com/daneb/herdr-markdown/issues .