diff --git a/README.md b/README.md
index 12de9d7..6b49ec7 100644
--- a/README.md
+++ b/README.md
@@ -424,7 +424,10 @@ window.__glpythonMount = (args, send) => {
       ...codeFiles.map(({ path, source }) => [path, { path, label: path, kind: /\.py$/i.test(path) ? "python" : "text", code: source }]),
     ])
     const heading = frame?.closest(".lia-slide__content")?.querySelector("h1, h2, h3, h4, h5, h6")?.textContent?.trim()
-    const json = JSON.stringify({ v: libraries.length > 0 ? 2 : 1, name: heading || document.title || strings.ideProject, mainFile: program.mainFile, files })
+    // The block's own features= (what it shows) set the IDE's parts too; a
+    // block without features= leaves the IDE as it is.
+    const features = featuresOption ? requestedFeatures.filter((name) => featureNames.includes(name)) : null
+    const json = JSON.stringify({ v: libraries.length > 0 ? 2 : 1, name: heading || document.title || strings.ideProject, mainFile: program.mainFile, ...(features ? { features } : {}), files })
     const [param, encoded] = fflate
       ? ["p", base64Url(fflate.deflateSync(new TextEncoder().encode(json), { level: 9 }))]
       : ["project", lzString.compressToEncodedURIComponent(json)]
@@ -1139,7 +1142,12 @@ libraries by their URL - the IDE fetches them, so a block with a library keeps
 a short link (an Etappe 4 hand-in measured 1,980 characters in the IDE's old
 form and 1,185 in the compact one).
 Libraries are read-only in the IDE (a lock, no editing, renaming or deleting),
-as they are here. A link longer than 2,083 characters - OneNote, for one, cuts
+as they are here. A block with `features=` passes them on: the IDE then shows
+the same parts (▶, Tests, Visualisieren, the console's input line, the →
+chain export, coverage, `listtree`, «Baum»; `ide` and `reset` mean nothing
+there), as the starting state of that IDE tab - its ⋮ «Optionen» can switch
+each part, e.g. for a teacher looking at a hand-in. A block without
+`features=` passes nothing, and the IDE shows what it always does. A link longer than 2,083 characters - OneNote, for one, cuts
 links there - is still copied, with a note to choose «In IDE öffnen» and
 download the project there for a hand-in.
 A link longer than GitHub Pages accepts (8192 characters of path and query, a
diff --git a/scripts/check-ready.mjs b/scripts/check-ready.mjs
index f04562c..25f917e 100644
--- a/scripts/check-ready.mjs
+++ b/scripts/check-ready.mjs
@@ -32,13 +32,15 @@ const blocks = [
   { id: 'empty', mode: 'visual', editors: [{ text: '', fill: null }] },
   { id: 'files', mode: 'eval', editors: [{ text: '', fill: 'start' }, { text: 'import datei1\nz = 3', fill: 'start' }] },
   { id: 'click', mode: 'eval', editors: [{ text: 'w = 4', fill: 1000 }] },
+  // A block with features= (LiaScript splits the argument at its commas).
+  { id: 'feat', mode: 'eval', options: ['features=run', 'repl', 'visualize', 'tests', 'ide', 'coverage', 'listtree', 'tree'], editors: [{ text: 'v = 5', fill: 'start' }] },
 ]
 
 const escape = (text) => text.replace(/&/g, '&amp;').replace(/"/g, '&quot;').replace(/</g, '&lt;')
 const page = `<!doctype html>
 <html><head><meta charset="utf-8"><title>glpython ready check</title></head>
 <body>
-${blocks.map((block) => `<div class="lia-slide__content" data-block="${block.id}">
+${blocks.map((block) => `<div class="lia-slide__content" data-block="${block.id}" data-options="${escape(JSON.stringify(block.options ?? []))}">
   <div class="lia-code--block">${block.editors.map((editor) => `<lia-editor data-text="${escape(editor.text)}" data-fill="${editor.fill}"></lia-editor>`).join('')}</div>
   ${template.replaceAll('@0', block.id).replaceAll('@1', block.mode)}
 </div>`).join('\n')}
@@ -79,7 +81,8 @@ window.addEventListener('message', (event) => {
 ${onload}
 for (const block of document.querySelectorAll('.lia-slide__content')) {
   const id = block.dataset.block
-  window.__glpythonMount([id, block.querySelector('.glpython-embed').className.split('--')[1], '@0', '@1', '@2', '@3', '@4', '@5', '@6', '@7'], { lia: () => {} })
+  const options = JSON.parse(block.dataset.options)
+  window.__glpythonMount([id, block.querySelector('.glpython-embed').className.split('--')[1], ...['@0', '@1', '@2', '@3', '@4', '@5', '@6', '@7'].map((placeholder, index) => options[index] ?? placeholder)], { lia: () => {} })
 }
 </script>
 </body></html>`
@@ -198,8 +201,19 @@ try {
       if (compact !== null) assert.match(compact, /^[A-Za-z0-9_-]+$/, 'base64url without padding')
       const payload = JSON.parse(compact !== null ? inflateRawSync(Buffer.from(compact, 'base64url')).toString('utf8') : lz.decompressFromEncodedURIComponent(old))
       assert.equal(payload.mainFile, 'datei2.py')
+      assert.equal(payload.features, undefined, 'a block without features= writes none')
       assert.deepEqual(Object.values(payload.files).map((file) => [file.path, file.code]), [['datei1.py', ''], ['datei2.py', 'import datei1\nz = 3']])
     })
+    if (fflateLoads) {
+      await check('«IDE-Link kopieren» carries the block\'s features=', async () => {
+        await linkTab.waitForFunction(() => document.querySelector('#glpython-ide-feat')?.disabled === false, null, { timeout: 10000 })
+        await linkTab.locator('#glpython-ide-feat').click()
+        await linkTab.waitForTimeout(300)
+        const link = new URL(await linkTab.evaluate(() => navigator.clipboard.readText()))
+        const payload = JSON.parse(inflateRawSync(Buffer.from(link.searchParams.get('p'), 'base64url')).toString('utf8'))
+        assert.deepEqual(payload.features, ['run', 'repl', 'visualize', 'tests', 'ide', 'coverage', 'listtree', 'tree'])
+      })
+    }
     await linkContext.close()
   }
 } finally {