diff --git a/web/guide.js b/web/guide.js
index a6c8c60..6caa016 100644
--- a/web/guide.js
+++ b/web/guide.js
@@ -246,6 +246,18 @@
   modeSeg.addEventListener('click', (e) => { const b = e.target.closest('button'); if (b) setMode(b.dataset.v); });
   welcome.addEventListener('click', (e) => { const b = e.target.closest('[data-mode]'); if (b) setMode(b.dataset.mode); });
 
+  // ---------------------------------------------------------------- the command palette's hook
+  // The palette (web/palette.js) starts or resumes the study through this — the same jump the per-panel
+  // "?" buttons take (find the lesson, setMode). Additive: existing FusionLab keys untouched.
+  window.FusionLab = Object.assign(window.FusionLab || {}, { guided: {
+    start(lessonId) {
+      if (!L) return false;   // lessons not loaded (boot failed): the palette reports it, nothing breaks
+      if (lessonId != null) { const i = L.steps.findIndex((s) => s.id === lessonId); if (i >= 0) idx = i; }
+      setMode('guided');
+      return true;
+    },
+  } });
+
   async function boot() {
     const [lessons, glossary] = await Promise.all(['lessons', 'glossary'].map((f) => fetch(`/static/${f}.json`).then((r) => r.json())));
     L = lessons; G = glossary.terms;
diff --git a/web/index.html b/web/index.html
index f6c507c..ddabebc 100644
--- a/web/index.html
+++ b/web/index.html
@@ -14,6 +14,7 @@
   <script src="/static/replay.js" defer></script>
   <script src="/static/figures.js" defer></script>
   <script src="/static/guide.js" defer></script>
+  <script src="/static/palette.js" defer></script>
 </head>
 <body>
   <header>
@@ -28,7 +29,7 @@ <h1>FUSIONLAB<span class="dim"> · open-data tokamak twin</span></h1>
     </div>
     <span class="seg" id="mode" role="group" aria-label="Mode" title="Guided: a 15-minute study that teaches you to read this screen. Lab: the full app.">
       <button type="button" data-v="guided">Guided</button><button type="button" data-v="lab" class="on">Lab</button></span>
-    <button type="button" id="cmdk" class="tool" disabled title="Command palette (Ctrl/Cmd+K) — arriving with the palette change">⌘K</button>
+    <button type="button" id="cmdk" class="tool" disabled title="Command palette (Ctrl/Cmd+K)" aria-haspopup="dialog" aria-expanded="false">⌘K</button>
     <nav class="tabs" role="tablist" aria-label="Workspaces">
       <button type="button" role="tab" id="tabbtn-replay" data-tab="replay" aria-selected="true" aria-controls="tab-replay">Replay</button>
       <button type="button" role="tab" id="tabbtn-compare" data-tab="compare" aria-selected="false" aria-controls="tab-compare">Compare</button>
diff --git a/web/palette.js b/web/palette.js
new file mode 100644
index 0000000..9dd57f3
--- /dev/null
+++ b/web/palette.js
@@ -0,0 +1,243 @@
+// FusionLab command palette: a native <dialog> over every workspace, opened with Ctrl/Cmd+K or the
+// header ⌘K button. Sources are the app's existing registries — the three workspaces, the shot catalog
+// (fetched from /shots once and cached), the guided study's 43 lesson titles (lessons.json) and the 47
+// glossary terms (glossary.json) — plus actions that run existing public surfaces only: navigation goes
+// through window.FusionLabRouter / the URL grammar, the guided study through window.FusionLab.guided
+// (guide.js), the editor through the ?edit=1 deep link, the USD export through the replay toolbar's own
+// button handler. Case-insensitive substring search, keyboard-first: ↑/↓ move, Enter runs, Esc closes
+// (native <dialog> cancel); focus is scoped to the dialog while open and restored to the opener on close.
+// No dependency; plain script, no build step.
+(() => {
+  'use strict';
+
+  const F = () => window.FusionLab || {};
+  const DEFAULT_SHOT = 30166;   // the shot the app itself lands on (replay.js) and Explore's edit link points at
+
+  // ---------------------------------------------------------------- the dialog (static chrome only)
+  const dlg = document.createElement('dialog');
+  dlg.className = 'palette';
+  dlg.setAttribute('aria-label', 'Command palette');
+  dlg.innerHTML =
+    '<input id="pal-q" type="text" role="combobox" aria-expanded="true" aria-controls="pal-list" aria-autocomplete="list"' +
+    ' autocomplete="off" spellcheck="false" placeholder="Search workspaces, shots, lessons, glossary — or run an action…"' +
+    ' aria-label="Search the app"><ul id="pal-list" role="listbox" aria-label="Results"></ul><p id="pal-status" role="status"></p>';
+  document.body.appendChild(dlg);
+  const q = dlg.querySelector('#pal-q'), list = dlg.querySelector('#pal-list'), status = dlg.querySelector('#pal-status');
+
+  const say = (t) => { status.textContent = t; };   // the dialog's status row: copy confirmations, fetch failures, definitions
+
+  // ---------------------------------------------------------------- cached sources (fetched once, lazily)
+  // A failed fetch clears the cache instead of poisoning it: the next open retries, the failure is
+  // named in the status row, and everything else keeps working.
+  let shotsP = null, srcP = null;
+  const shots = () => shotsP || (shotsP = fetch('/shots').then((r) => { if (!r.ok) throw new Error('HTTP ' + r.status); return r.json(); })
+    .then((d) => d.shots || []).catch((e) => { shotsP = null; throw e; }));
+  const sources = () => srcP || (srcP = Promise.all(['lessons', 'glossary'].map((f) => fetch('/static/' + f + '.json').then((r) => {
+    if (!r.ok) throw new Error('HTTP ' + r.status); return r.json();
+  }))).catch((e) => { srcP = null; throw e; }));
+
+  // ---------------------------------------------------------------- items and actions
+  // Every run() closes the palette unless it wants to stay open (share reports in the status row;
+  // glossary terms read their definition there). Navigation writes the URL grammar (workspaces.js
+  // applies it), so Back/Forward and Share follow every palette choice.
+  const close = () => { if (dlg.open) dlg.close(); };
+
+  function goHash(h) {
+    close();
+    if (location.hash !== h) location.hash = h;   // the router (workspaces.js) applies it; the same hash twice is already the view
+  }
+
+  function guidedStart(lessonId) {
+    const g = F().guided;
+    if (!g || !g.start || !g.start(lessonId)) return say('The guided study is not available right now');
+    close();
+  }
+
+  function copyShare() {   // copies the current view's URL (deep links are the share feature)
+    const url = location.href;
+    const legacy = () => {
+      const ta = document.createElement('textarea');
+      ta.value = url; ta.setAttribute('readonly', ''); ta.style.position = 'fixed'; ta.style.opacity = '0';
+      document.body.appendChild(ta); ta.select();
+      let ok = false; try { ok = document.execCommand('copy'); } catch (e) { ok = false; }
+      document.body.removeChild(ta);
+      say(ok ? 'Link copied — paste it anywhere to share this view' : 'Could not copy — the address bar still has the link');
+    };
+    if (navigator.clipboard && navigator.clipboard.writeText) {
+      navigator.clipboard.writeText(url).then(() => say('Link copied — paste it anywhere to share this view'), legacy);
+    } else legacy();
+  }
+
+  function exportUsd() {   // runs the replay toolbar's own export handler; needs a loaded shot first
+    const btn = document.getElementById('rp-usd'), R = F().replay;
+    if (!R || !btn) return say('The OpenUSD export needs the replay room');
+    if (R.state()) { close(); btn.click(); return; }
+    // No shot up yet: fire the same button the moment one draws (fusionlab:shot); a failed load renders
+    // its own error in the replay cell, and the timeout says why the export never ran.
+    const fire = () => { document.removeEventListener('fusionlab:shot', fire); clearTimeout(giveUp); btn.click(); };
+    const giveUp = setTimeout(() => {
+      document.removeEventListener('fusionlab:shot', fire);
+      say("The export didn't start — the shot didn't finish loading. Try again once a shot is up.");
+    }, 10000);
+    document.addEventListener('fusionlab:shot', fire);
+    if (/^#\/replay\b/.test(location.hash)) say('Waiting for the shot to finish loading, then exporting…');
+    else goHash('#/replay/' + DEFAULT_SHOT);   // land on the default shot; its draw event fires the export
+  }
+
+  function editShot() {   // the same edit intent Explore's "Edit a real shot instead →" link writes (workspaces.js ?edit=1)
+    const R = F().replay, st = R && R.state();
+    const h = '#/replay/' + (st && st.shot_id ? st.shot_id : DEFAULT_SHOT) + '?edit=1';
+    if (location.hash === h && R) { close(); return R.whatIf(true); }   // same route twice: the router would no-op, so open the editor directly
+    goHash(h);
+  }
+
+  const WORKSPACES = [
+    { label: 'Replay — watch a real shot', run: () => goHash('#/replay') },
+    { label: 'Compare — pick shots side by side', run: () => goHash('#/compare') },
+    { label: 'Explore — ask the reduced model', run: () => goHash('#/explore') },
+  ].map((w) => Object.assign(w, { hint: 'workspace' }));
+
+  const ACTIONS = [
+    { label: 'Share this view — copy the link', run: copyShare },
+    { label: 'Export OpenUSD stage (this slice of the replayed shot)', run: exportUsd },
+    { label: 'Start the guided study', run: () => guidedStart(null) },
+    { label: "Edit this shot's programme", run: editShot },
+    { label: 'Open the shot catalog', run: () => goHash('#/compare') },
+  ].map((a) => Object.assign(a, { hint: 'action' }));
+
+  let dyn = { shots: null, lessons: null, terms: null };
+
+  function items() {
+    const out = WORKSPACES.concat(ACTIONS);
+    (dyn.shots || []).forEach((s) => out.push({
+      hint: 'shot' + (s.campaign ? ' · ' + s.campaign : ''),
+      label: '#' + s.shot_id + ' · ' + (s.heating || 'unknown heating') + ' · ' + (isFinite(s.Ip_max_MA) ? s.Ip_max_MA.toFixed(2) : '–') + ' MA',
+      hay: '#' + s.shot_id + ' ' + (s.campaign || '') + ' ' + (s.heating || ''),
+      run: () => goHash('#/replay/' + s.shot_id),
+    }));
+    const lessons = dyn.lessons || {}, chapters = lessons.chapters || [];
+    (lessons.steps || []).forEach((s) => {
+      const ch = (chapters.find((c) => c.n === s.ch) || {}).title || '';
+      out.push({
+        hint: 'lesson ' + s.id + (ch ? ' · ' + ch : ''), label: s.title, hay: s.title + ' ' + s.id + ' ' + ch,
+        run: () => guidedStart(s.id),
+      });
+    });
+    Object.entries(dyn.terms || {}).forEach(([key, g]) => out.push({
+      hint: 'glossary', label: g.name || key, hay: (g.name || '') + ' ' + key,
+      run: () => say((g.name || key) + ' — ' + (g.def || '')),   // the definition, from the same data the tooltips show
+    }));
+    return out;
+  }
+
+  // ---------------------------------------------------------------- search + paint
+  let shown = [], sel = 0;
+
+  function paint() {
+    list.innerHTML = '';   // options are rebuilt below with createElement/textContent — dynamic data never becomes HTML
+    if (!shown.length) {
+      const li = document.createElement('li');
+      li.className = 'pal-none';
+      li.textContent = 'Nothing matches' + (q.value ? ' “' + q.value + '”' : '') + ' — shots, lessons and glossary load as you type.';
+      list.appendChild(li);
+      q.setAttribute('aria-activedescendant', '');
+      return;
+    }
+    shown.forEach((it, i) => {
+      const li = document.createElement('li');
+      li.id = 'pal-opt-' + i;
+      li.setAttribute('role', 'option');
+      const b = document.createElement('b');
+      b.textContent = it.label;
+      const h = document.createElement('span');
+      h.className = 'pal-hint';
+      h.textContent = it.hint;
+      li.appendChild(b); li.appendChild(h);
+      li.addEventListener('mouseenter', () => select(i));
+      li.addEventListener('click', () => run(it));
+      list.appendChild(li);
+    });
+    sel = Math.min(sel, shown.length - 1);
+    select(sel);
+  }
+
+  function select(i) {   // highlight + scroll + keep the combobox a11y wire pointing at the row
+    sel = i;
+    [...list.children].forEach((el, k) => {
+      el.classList.toggle('on', k === i);
+      if (el.getAttribute('role')) el.setAttribute('aria-selected', k === i ? 'true' : 'false');
+    });
+    q.setAttribute('aria-activedescendant', shown.length ? 'pal-opt-' + i : '');
+    const el = list.children[i];
+    if (el && el.scrollIntoView) el.scrollIntoView({ block: 'nearest' });
+  }
+
+  function search(needle) {
+    const all = items(), ql = needle.trim().toLowerCase();
+    if (!ql) return WORKSPACES.concat(ACTIONS);   // the empty palette: the places and verbs, not a wall of data
+    return all.map((it, i) => ({ it, i, hay: (it.hay || it.label).toLowerCase() }))
+      .filter((x) => x.hay.includes(ql))
+      .sort((a, b) => ((a.it.label.toLowerCase().startsWith(ql) ? 0 : 1) - (b.it.label.toLowerCase().startsWith(ql) ? 0 : 1)) || a.i - b.i)
+      .slice(0, 30)
+      .map((x) => x.it);
+  }
+
+  function run(it) {
+    try { it.run(); } catch (e) { say('That action failed: ' + (e && e.message ? e.message : e)); }   // surfaced, never silent
+  }
+
+  // ---------------------------------------------------------------- dynamic sources refresh (once per session, cached)
+  function refreshDynamic() {
+    const jobs = [];
+    if (!dyn.shots) jobs.push(shots().then((s) => { dyn.shots = s; }).catch((e) => say('Shot catalog unavailable (' + e.message + ') — the rest of the palette still works')));
+    if (!dyn.lessons || !dyn.terms) jobs.push(sources().then((pair) => {
+      dyn.lessons = pair[0]; dyn.terms = pair[1].terms || {};
+    }).catch((e) => say('Lessons and glossary unavailable (' + e.message + ') — the rest of the palette still works')));
+    if (jobs.length) Promise.all(jobs).then(() => { if (dlg.open) { shown = search(q.value); paint(); } });
+  }
+
+  // ---------------------------------------------------------------- open / close, focus in and out
+  let opener = null;
+
+  function open() {
+    if (dlg.open) return;
+    opener = document.activeElement instanceof Element ? document.activeElement : null;
+    q.value = ''; sel = 0; shown = search(''); paint(); say('');
+    dlg.showModal();   // native focus scoping: Tab cannot leave the dialog while it is open
+    q.focus();
+    btn.setAttribute('aria-expanded', 'true');
+    refreshDynamic();
+  }
+
+  dlg.addEventListener('close', () => {   // Esc (native cancel), the ✕ path, or run(): focus goes home
+    if (opener && opener.focus) opener.focus();
+    opener = null;
+    if (btn) btn.setAttribute('aria-expanded', 'false');
+  });
+  dlg.addEventListener('click', (e) => { if (e.target === dlg) close(); });   // a click on the backdrop closes, like the welcome modal
+
+  // ---------------------------------------------------------------- input + global keys
+  q.addEventListener('input', () => { sel = 0; shown = search(q.value); paint(); });
+  q.addEventListener('keydown', (e) => {
+    if (e.key === 'ArrowDown') { e.preventDefault(); if (shown.length) select((sel + 1) % shown.length); }
+    else if (e.key === 'ArrowUp') { e.preventDefault(); if (shown.length) select((sel - 1 + shown.length) % shown.length); }
+    else if (e.key === 'Enter') { e.preventDefault(); if (shown[sel]) run(shown[sel]); }
+    // Esc: the dialog's native cancel closes it; focus restore is the 'close' handler's job.
+  });
+
+  document.addEventListener('keydown', (e) => {
+    if (!(e.ctrlKey || e.metaKey) || (e.key || '').toLowerCase() !== 'k') return;
+    e.preventDefault();
+    if (dlg.open) dlg.close(); else open();
+  });
+
+  // ---------------------------------------------------------------- the header ⌘K button (index.html ships it disabled)
+  const btn = document.getElementById('cmdk');
+  if (btn) {
+    btn.disabled = false;
+    btn.title = 'Command palette (Ctrl/Cmd+K)';
+    btn.setAttribute('aria-haspopup', 'dialog');
+    btn.setAttribute('aria-expanded', 'false');
+    btn.addEventListener('click', () => (dlg.open ? dlg.close() : open()));
+  }
+})();
diff --git a/web/style.css b/web/style.css
index 10b8284..0b4a1e2 100644
--- a/web/style.css
+++ b/web/style.css
@@ -277,6 +277,24 @@ body.guided header { margin-left:calc(-1 * var(--rail)); }
 .entry-action a:hover { color:var(--fg); }
 .entry-action a:focus-visible { outline:1px solid var(--accent); outline-offset:2px; }
 
+/* command palette (web/palette.js): native <dialog> in the top layer — no z-index, no overlay div.
+   Shares the control-room look: panel surface, hairlines, mono hints. */
+dialog.palette { background:var(--panel); color:var(--fg); border:1px solid var(--line); width:min(640px, calc(100vw - 24px));
+                 margin:12vh auto auto; padding:10px; }
+dialog.palette::backdrop { background:rgba(8,10,13,.72); backdrop-filter:blur(2px); }
+#pal-q { width:100%; background:var(--bg); color:var(--fg); border:1px solid var(--line); padding:10px 12px;
+         font:13px/1.4 var(--mono); }
+#pal-list { list-style:none; margin:8px 0 0; padding:0; max-height:52vh; overflow:auto; }
+#pal-list li { display:flex; align-items:baseline; gap:12px; padding:8px 10px; cursor:pointer; border-bottom:1px solid var(--line); }
+#pal-list li:last-child { border-bottom:0; }
+#pal-list li b { font-weight:400; font-size:13.5px; color:var(--fg); }
+#pal-list li .pal-hint { margin-left:auto; flex:none; font:600 9.5px/1.5 var(--mono); letter-spacing:.1em; text-transform:uppercase; color:var(--dim); }
+#pal-list li.on { background:var(--line); }
+#pal-list li.on b { color:var(--accent); }
+#pal-list li.pal-none { cursor:default; color:var(--muted); font-size:12.5px; }
+.pal-status { margin:6px 2px 0; min-height:1em; color:var(--accent); font:12px/1.5 var(--mono); }
+@media (max-width:760px) { dialog.palette { margin-top:6vh; } #pal-list { max-height:60vh; } }
+
 /* Mobile header: the legend (its tags repeat on every panel) and the subtitle step aside, and the
    tabs take their own row, so the title never clips (audit defect at 375 px, screenshot fl_AmO2E2fS).
    Last in the file: it must out-order the base .prov/.tabs rules it overrides (equal specificity). */