A tiny FedWiki-friendly console that can cold-boot the DM6 Elm app with either the current page JSON or an empty {} model, and lets you run jq filters against that same page JSON. commit 
, matrix
# Frame
* Clicking **Boot JSON** sends `{ slug, stored: JSON.stringify(window.data) }`. * Clicking **Cold {}** sends `{ slug, stored: "{}" }`.
//wiki.ralfbarkow.ch/assets/pages/cold-boot/cold-boot.html HEIGHT 300
Assets
pages/cold-boot
# produce a bundle that exposes Elm.AppEmbed npx elm make src/AppEmbed.elm --debug --output="$HOME/.wiki/wiki.ralfbarkow.ch/assets/pages/cold-boot/elm.js" Success! AppEmbed ───> /Users/rgb/.wiki/wiki.ralfbarkow.ch/assets/pages/cold-boot/elm.js
See DM6 Elm bedded
Roster
elm.dm6.dreyeck.ch
~
The following little snippet inspects the wiki page to see what iframes are present. It climbs to the top-level document, collects all `<iframe>` elements, and then prints a table to the browser console showing each frame’s index, its `src` URL, and its current `sandbox` attribute. It’s a quick way to identify which iframe is hosting your Elm app so you know which one to patch or adjust.
(() => { const topDoc = (() => { let w = window; while (w.parent !== w) w = w.parent; return w.document; })(); const frames = [...topDoc.querySelectorAll('iframe')]; console.table(frames.map((f, i) => ({ i, src: f.getAttribute('src'), sandbox: f.getAttribute('sandbox') }))); })();
The next script reshapes the wiki page so you can debug Elm inline. It locates the first iframe (your Elm app), wraps it in a new vertical container, and then inserts a second iframe underneath to host the Elm Debugger. It adjusts the sandbox so the app frame can be patched, then injects a helper that redirects Elm’s built-in `window.open` call into the lower debugger frame. After reloading the app iframe, any interaction with your Elm app will cause the debugger UI to appear directly beneath it, stacked on the same page.
(() => { // always operate on the TOP document let topWin = window; while (topWin.parent !== topWin) topWin = topWin.parent; const topDoc = topWin.document; const frames = [...topDoc.querySelectorAll('iframe')]; const app = frames[0]; if (!app) { console.warn('Elm app iframe not found at that index'); return; } // Make a vertical wrapper and move app into it (idempotent) let wrap = topDoc.getElementById('elm-stack'); if (!wrap) { wrap = topDoc.createElement('div'); wrap.id = 'elm-stack'; wrap.style.cssText = 'display:flex; flex-direction:column; gap:8px; height:90vh; margin:8px 0;'; app.parentElement.insertBefore(wrap, app); } app.style.cssText = 'flex:0 0 300px; border:1px solid #ddd;'; // fixed height for app if (app.parentElement !== wrap) wrap.appendChild(app); // Add / reuse the debugger iframe beneath let dbg = topDoc.getElementById('elm-debug'); if (!dbg) { dbg = topDoc.createElement('iframe'); dbg.id = 'elm-debug'; dbg.name = 'elm-debug'; dbg.style.cssText = 'flex:1; border:1px solid #ddd;'; // fills remaining height wrap.appendChild(dbg); } // Relax sandbox so we can inject into the app iframe (no popups needed) app.setAttribute('sandbox', 'allow-scripts allow-same-origin'); // Inject AFTER load; retry if contentDocument not ready yet const inject = () => { const doc = app.contentDocument; if (!doc) { console.log('waiting for app.contentDocument…'); return false; } const s = doc.createElement('script'); s.textContent = ` (function(){ // Redirect Elm debugger's window.open into the lower frame const getDbg = () => parent.document.getElementById('elm-debug')?.contentWindow; window.open = function(_url, _name, _features){ const w = getDbg(); if(!w) return null; try { w.document.open(); w.document.write('<!doctype html><title>Elm Debugger</title>'); w.document.close(); } catch(_) {} return w; }; console.log('✅ Elm debugger redirection installed inside app iframe'); })(); `; (doc.head || doc.documentElement).appendChild(s); return true; }; // Ensure reload so new sandbox applies, then inject on load (+poll fallback) app.addEventListener('load', () => { let tries = 0; const t = setInterval(() => { if (inject() || ++tries > 20) clearInterval(t); }, 100); }, { once: true }); // force reload to apply changed sandbox app.src = app.src; console.log('➡️ Vertical stack ready; iframe reloading; debugger redirect will install on load.'); })();