diff --git a/static/js/postAceInit.js b/static/js/postAceInit.js
index 62e896b..f8c3640 100644
--- a/static/js/postAceInit.js
+++ b/static/js/postAceInit.js
@@ -41,9 +41,14 @@ exports.postAceInit = () => {
   }
   const toc = getToc();
   if (!toc) return;
+  toc.bindShareUrlSync();
 
   const state = tocToggle.init({
-    onChange: (enabled) => { enabled ? toc.enable() : toc.disable(); },
+    onChange: (enabled) => {
+      enabled ? toc.enable() : toc.disable();
+      toc.syncLocationUrl(enabled);
+      toc.syncShareUrls(enabled);
+    },
   });
 
   // ?toc=true / ?toc=false URL parameter still overrides the resolved
@@ -52,6 +57,7 @@ exports.postAceInit = () => {
   if (tocParam === true || tocParam === false) {
     tocParam ? toc.enable() : toc.disable();
     $('#options-toc').prop('checked', tocParam);
+    toc.syncShareUrls(tocParam);
   } else {
     // No URL override — make sure the editor matches the helper's effective
     // value. (init() already fired onChange once, so this is belt-and-braces.)
diff --git a/static/js/toc.js b/static/js/toc.js
index c453ede..75255b9 100644
--- a/static/js/toc.js
+++ b/static/js/toc.js
@@ -57,6 +57,29 @@ const getOutlineEntries = (toc) => {
   });
 };
 
+const ETHERPAD_FIELD_REWRITE_DELAY_MS = 0;
+const getWindowHref = () => (typeof window !== 'undefined' ? window.location.href : undefined);
+
+const setBooleanUrlParam = (rawUrl, name, enabled, contextUrl = getWindowHref()) => {
+  let url;
+  try {
+    url = contextUrl == null ? new URL(rawUrl) : new URL(rawUrl, contextUrl);
+  } catch (err) {
+    return rawUrl;
+  }
+  url.searchParams.set(name, String(enabled));
+  return url.toString();
+};
+
+const setEmbedCodeUrlParam = (
+  embedCode, name, enabled, contextUrl = getWindowHref()
+) => embedCode.replace(
+    /\bsrc=(['"])([^'"]+)\1/g,
+    (match, quote, rawUrl) => {
+      const urlWithParam = setBooleanUrlParam(rawUrl, name, enabled, contextUrl);
+      return `src=${quote}${urlWithParam}${quote}`;
+    });
+
 if (typeof $ !== 'undefined') {
   $('#tocButton').click(() => {
     $('#toc').toggle();
@@ -81,6 +104,48 @@ const tableOfContents = globalThis.tableOfContents = {
     $('#toc').hide();
   },
 
+  syncShareUrls: (enabled) => {
+    const $linkInput = $('#linkinput');
+    if ($linkInput.length > 0) {
+      const linkValue = $linkInput.val();
+      if (typeof linkValue === 'string' && linkValue !== '') {
+        $linkInput.val(setBooleanUrlParam(linkValue, 'toc', enabled));
+      }
+    }
+
+    const $embedInput = $('#embedinput');
+    if ($embedInput.length > 0) {
+      const embedValue = $embedInput.val();
+      if (typeof embedValue === 'string' && embedValue.includes('<iframe') && embedValue.includes('src=')) {
+        $embedInput.val(setEmbedCodeUrlParam(embedValue, 'toc', enabled));
+      }
+    }
+  },
+
+  syncLocationUrl: (enabled) => {
+    if (!window.history || typeof window.history.replaceState !== 'function') return;
+    const nextUrl = setBooleanUrlParam(window.location.href, 'toc', enabled);
+    window.history.replaceState(window.history.state, document.title, nextUrl);
+  },
+
+  bindShareUrlSync: () => {
+    if (tableOfContents._shareUrlSyncBound) return;
+    tableOfContents._shareUrlSyncBound = true;
+
+    $(document).on('focusin.ep_table_of_contents', '#linkinput, #embedinput', () => {
+      tableOfContents.syncShareUrls($('#options-toc').is(':checked'));
+    });
+
+    $(document).on('change.ep_table_of_contents', '#readonlyinput', () => {
+      // Etherpad rewrites the share/embed fields after the readonly checkbox
+      // change handler runs, so wait a tick before patching the generated URLs.
+      setTimeout(
+          () => tableOfContents.syncShareUrls($('#options-toc').is(':checked')),
+          ETHERPAD_FIELD_REWRITE_DELAY_MS,
+      );
+    });
+  },
+
   // Find Tags
   findTags: () => {
     const toc = [];
@@ -213,4 +278,6 @@ const tableOfContents = globalThis.tableOfContents = {
     return true;
   },
 
+  _shareUrlSyncBound: false,
+
 };
diff --git a/tests/toc-numbering.test.js b/tests/toc-numbering.test.js
index e7b62ae..5a8ba0d 100644
--- a/tests/toc-numbering.test.js
+++ b/tests/toc-numbering.test.js
@@ -12,18 +12,99 @@ const loadTocHelpers = () => {
   const sandbox = {
     console,
     URLSearchParams,
+    URL,
     globalThis: {},
+    window: {
+      location: {href: 'https://example.com/p/test-pad?showChat=false#section'},
+    },
     $: () => ({
-      click() {},
+      click: () => {},
     }),
   };
   sandbox.globalThis = sandbox;
-  vm.runInNewContext(`${source}
-globalThis.__tocTestExports = {getHeadingLevel, getOutlineEntries};`, sandbox, {filename: tocPath});
+  vm.runInNewContext(
+      `${source}
+globalThis.__tocTestExports = {
+  getHeadingLevel,
+  getOutlineEntries,
+  setBooleanUrlParam,
+  setEmbedCodeUrlParam,
+};`,
+      sandbox,
+      {filename: tocPath},
+  );
   return sandbox.__tocTestExports;
 };
 
-const {getOutlineEntries} = loadTocHelpers();
+const {getOutlineEntries, setBooleanUrlParam, setEmbedCodeUrlParam} = loadTocHelpers();
+
+const loadTocRuntime = () => {
+  const tocPath = path.join(__dirname, '..', 'static', 'js', 'toc.js');
+  const source = fs.readFileSync(tocPath, 'utf8');
+  const fields = {
+    '#linkinput': 'https://example.com/p/test-pad?showChat=false',
+    '#embedinput': '<iframe name="embed_readwrite" src="https://example.com/p/test-pad?showControls=true&showChat=true" width="100%" height="600" frameborder="0"></iframe>',
+    '#options-toc': true,
+  };
+  const sandbox = {
+    console,
+    URLSearchParams,
+    URL,
+    globalThis: {},
+    document: {title: 'Test Pad'},
+    historyCalls: [],
+    window: {
+      location: {href: 'https://example.com/p/test-pad?showChat=false'},
+      history: {
+        state: {padId: 'test-pad'},
+        replaceState(state, title, url) {
+          sandbox.historyCalls.push({state, title, url});
+          sandbox.window.location.href = url;
+        },
+      },
+    },
+  };
+  sandbox.$ = (selector) => {
+    if (selector === '#linkinput' || selector === '#embedinput') {
+      return {
+        length: 1,
+        val(value) {
+          if (value === undefined) return fields[selector];
+          fields[selector] = value;
+          return this;
+        },
+      };
+    }
+    if (selector === '#options-toc') {
+      return {
+        is(query) {
+          assert.equal(query, ':checked');
+          return fields[selector];
+        },
+      };
+    }
+    if (selector === '#tocButton') {
+      return {click: () => {}};
+    }
+    if (selector === sandbox.document) {
+      return {on: () => {}};
+    }
+    throw new Error(`Unexpected selector: ${selector}`);
+  };
+  sandbox.globalThis = sandbox;
+  vm.runInNewContext(
+      `${source}
+globalThis.__tocRuntimeExports = {tableOfContents};`,
+      sandbox,
+      {filename: tocPath},
+  );
+  return {
+    tableOfContents: sandbox.__tocRuntimeExports.tableOfContents,
+    fields,
+    historyCalls: sandbox.historyCalls,
+    window: sandbox.window,
+  };
+};
 
 const makeEntries = (tags) => tags.map((tag, index) => ({
   tag,
@@ -88,3 +169,52 @@ test('keeps numbering stable across many sibling headings', () => {
   assert.deepEqual(summary[99], {depth: 1, numbering: '100'});
   assert.deepEqual(summary[199], {depth: 1, numbering: '200'});
 });
+
+test('adds the toc state to shared pad links without dropping existing params', () => {
+  assert.equal(
+      setBooleanUrlParam('https://example.com/p/test-pad?showChat=false#section', 'toc', true),
+      'https://example.com/p/test-pad?showChat=false&toc=true#section',
+  );
+  assert.equal(
+      setBooleanUrlParam('https://example.com/p/test-pad?showChat=false#section', 'toc', false),
+      'https://example.com/p/test-pad?showChat=false&toc=false#section',
+  );
+});
+
+test('adds the toc state to embed iframe src urls', () => {
+  const embedCode =
+      '<iframe name="embed_readwrite" src="https://example.com/p/test-pad?showControls=true&showChat=true" width="100%" height="600" frameborder="0"></iframe>';
+  assert.equal(
+      setEmbedCodeUrlParam(embedCode, 'toc', true),
+      '<iframe name="embed_readwrite" src="https://example.com/p/test-pad?showControls=true&showChat=true&toc=true" width="100%" height="600" frameborder="0"></iframe>',
+  );
+  assert.equal(
+      setEmbedCodeUrlParam(embedCode, 'toc', false),
+      '<iframe name="embed_readwrite" src="https://example.com/p/test-pad?showControls=true&showChat=true&toc=false" width="100%" height="600" frameborder="0"></iframe>',
+  );
+});
+
+test('syncShareUrls updates both share fields for the active toc state', () => {
+  const {tableOfContents, fields} = loadTocRuntime();
+
+  tableOfContents.syncShareUrls(true);
+  assert.equal(fields['#linkinput'], 'https://example.com/p/test-pad?showChat=false&toc=true');
+  assert.match(fields['#embedinput'], /src="https:\/\/example\.com\/p\/test-pad\?showControls=true&showChat=true&toc=true"/);
+
+  tableOfContents.syncShareUrls(false);
+  assert.equal(fields['#linkinput'], 'https://example.com/p/test-pad?showChat=false&toc=false');
+  assert.match(fields['#embedinput'], /src="https:\/\/example\.com\/p\/test-pad\?showControls=true&showChat=true&toc=false"/);
+});
+
+test('syncLocationUrl keeps the current pad url in sync with toc state', () => {
+  const {tableOfContents, historyCalls, window} = loadTocRuntime();
+
+  tableOfContents.syncLocationUrl(true);
+  tableOfContents.syncLocationUrl(false);
+
+  assert.deepEqual(historyCalls.map(({url}) => url), [
+    'https://example.com/p/test-pad?showChat=false&toc=true',
+    'https://example.com/p/test-pad?showChat=false&toc=false',
+  ]);
+  assert.equal(window.location.href, 'https://example.com/p/test-pad?showChat=false&toc=false');
+});