diff --git a/src/script.js b/src/script.js
index e523332a..e1b4e74e 100644
--- a/src/script.js
+++ b/src/script.js
@@ -248,7 +248,7 @@ import {
 } from './scripts/utils.js';
 import { debounce_timeout, GENERATION_TYPE_TRIGGERS, IGNORE_SYMBOL, inject_ids, MEDIA_DISPLAY, MEDIA_SOURCE, MEDIA_TYPE, OVERSWIPE_BEHAVIOR, SCROLL_BEHAVIOR, SWIPE_DIRECTION, SWIPE_SOURCE, SWIPE_STATE } from './scripts/constants.js';
 
-import { activateDeferredThirdPartyExtensions, activateStartupSystemExtensions, applyExtensionSettings, cancelDebouncedMetadataSave, doDailyExtensionUpdatesCheck, extension_settings, initExtensions, runGenerationInterceptors, startOfflineExtensionsDiscovery } from './scripts/extensions.js';
+import { activateDeferredThirdPartyExtensions, activateStartupSystemExtensions, applyExtensionSettings, cancelDebouncedMetadataSave, doDailyExtensionUpdatesCheck, extension_settings, initExtensions, isCodeRenderDelegatedToThirdPartyRenderer, runGenerationInterceptors, startOfflineExtensionsDiscovery } from './scripts/extensions.js';
 import { COMMENT_NAME_DEFAULT, CONNECT_API_MAP, executeSlashCommandsOnChatInput, initDefaultSlashCommands, initSlashCommandAutoComplete, isExecutingCommandsFromChatInput, pauseScriptExecution, stopScriptExecution, UNIQUE_APIS } from './scripts/slash-commands.js';
 import { initMacroAutoComplete } from './scripts/autocomplete/MacroAutoComplete.js';
 import {
@@ -315,6 +315,7 @@ import {
     renderInteractiveHtmlCodeBlocks,
     setHtmlCodeRenderEnabled,
     setHtmlCodeRenderReplaceLastMessageByDefault,
+    setHtmlCodeRenderSuppressedByExternalRenderer,
 } from './scripts/html-code-preview.js';
 import { getPresetManager, initPresetManager } from './scripts/preset-manager.js';
 import { evaluateMacros, getLastMessageId, initMacros } from './scripts/macros.js';
@@ -2964,8 +2965,10 @@ export function appendMediaToMessage(mes, messageElement, scrollBehavior = SCROL
 }
 
 export function addCopyToCodeBlocks(messageElement) {
-    setHtmlCodeRenderEnabled(extension_settings.code_render?.enabled === true);
+    const shouldRunHtmlCodeRender = extension_settings.code_render?.enabled === true;
+    setHtmlCodeRenderEnabled(shouldRunHtmlCodeRender);
     setHtmlCodeRenderReplaceLastMessageByDefault(extension_settings.code_render?.replace_last_message_by_default === true);
+    setHtmlCodeRenderSuppressedByExternalRenderer(shouldRunHtmlCodeRender && isCodeRenderDelegatedToThirdPartyRenderer());
     renderInteractiveHtmlCodeBlocks(messageElement);
 
     const coordinator = getCodeHighlightCoordinator();
diff --git a/src/scripts/extensions.js b/src/scripts/extensions.js
index 7255659b..6b6077d6 100644
--- a/src/scripts/extensions.js
+++ b/src/scripts/extensions.js
@@ -616,6 +616,19 @@ export function findExtension(name) {
     return { name: internalExtensionName, enabled: isEnabled };
 }
 
+const CODE_RENDER_DELEGATE_EXTENSION_NAMES = Object.freeze([
+    'JS-Slash-Runner',
+    'LittleWhiteBox',
+]);
+
+/**
+ * Returns true when a known third-party message code renderer should own HTML/script code blocks.
+ * @returns {boolean}
+ */
+export function isCodeRenderDelegatedToThirdPartyRenderer() {
+    return CODE_RENDER_DELEGATE_EXTENSION_NAMES.some(name => findExtension(name)?.enabled === true);
+}
+
 /**
  * Returns a deep clone of the manifest for the given extension name.
  * Accepts either the short name (e.g. `SillyTavern-MyExtension`) or the full internal key
diff --git a/src/scripts/extensions/code-render/index.js b/src/scripts/extensions/code-render/index.js
index 03ddbb4b..87a353f2 100644
--- a/src/scripts/extensions/code-render/index.js
+++ b/src/scripts/extensions/code-render/index.js
@@ -2,10 +2,15 @@ import {
     reloadCurrentChat,
     saveSettingsDebounced,
 } from '../../../script.js';
-import { extension_settings, renderExtensionTemplateAsync } from '../../extensions.js';
+import {
+    extension_settings,
+    isCodeRenderDelegatedToThirdPartyRenderer,
+    renderExtensionTemplateAsync,
+} from '../../extensions.js';
 import {
     setHtmlCodeRenderEnabled,
     setHtmlCodeRenderReplaceLastMessageByDefault,
+    setHtmlCodeRenderSuppressedByExternalRenderer,
 } from '../../html-code-preview.js';
 
 const MODULE_NAME = 'code-render';
@@ -14,6 +19,18 @@ const defaultSettings = {
     replace_last_message_by_default: false,
 };
 
+function syncHtmlCodeRenderState() {
+    const delegated = isCodeRenderDelegatedToThirdPartyRenderer();
+
+    setHtmlCodeRenderEnabled(extension_settings.code_render.enabled);
+    setHtmlCodeRenderReplaceLastMessageByDefault(extension_settings.code_render.replace_last_message_by_default);
+    setHtmlCodeRenderSuppressedByExternalRenderer(delegated);
+
+    $('#code_render_enabled').prop('checked', extension_settings.code_render.enabled);
+    $('#code_render_replace_last_message_by_default').prop('checked', extension_settings.code_render.replace_last_message_by_default);
+    $('#code_render_delegated_notice').toggle(delegated);
+}
+
 function loadSettings() {
     if (!extension_settings.code_render || typeof extension_settings.code_render !== 'object') {
         extension_settings.code_render = { ...defaultSettings };
@@ -27,17 +44,13 @@ function loadSettings() {
         extension_settings.code_render.replace_last_message_by_default = defaultSettings.replace_last_message_by_default;
     }
 
-    setHtmlCodeRenderEnabled(extension_settings.code_render.enabled);
-    setHtmlCodeRenderReplaceLastMessageByDefault(extension_settings.code_render.replace_last_message_by_default);
-    $('#code_render_enabled').prop('checked', extension_settings.code_render.enabled);
-    $('#code_render_replace_last_message_by_default').prop('checked', extension_settings.code_render.replace_last_message_by_default);
+    syncHtmlCodeRenderState();
 }
 
 async function onSettingsInput() {
     extension_settings.code_render.enabled = !!$('#code_render_enabled').prop('checked');
     extension_settings.code_render.replace_last_message_by_default = !!$('#code_render_replace_last_message_by_default').prop('checked');
-    setHtmlCodeRenderEnabled(extension_settings.code_render.enabled);
-    setHtmlCodeRenderReplaceLastMessageByDefault(extension_settings.code_render.replace_last_message_by_default);
+    syncHtmlCodeRenderState();
     saveSettingsDebounced();
     await reloadCurrentChat();
 }
diff --git a/src/scripts/extensions/code-render/settings.html b/src/scripts/extensions/code-render/settings.html
index 1fcef568..6699a552 100644
--- a/src/scripts/extensions/code-render/settings.html
+++ b/src/scripts/extensions/code-render/settings.html
@@ -21,6 +21,10 @@
                 data-i18n="When enabled, previews in the newest message automatically replace the current last message view.">
                 When enabled, previews in the newest message automatically replace the current last message view.
             </small>
+            <small id="code_render_delegated_notice" class="extensions_info" style="display: none;"
+                data-i18n="Code Render is disabled while JS-Slash-Runner or LittleWhiteBox is enabled.">
+                Code Render is disabled while JS-Slash-Runner or LittleWhiteBox is enabled.
+            </small>
         </div>
     </div>
-</div>
\ No newline at end of file
+</div>
diff --git a/src/scripts/html-code-preview.js b/src/scripts/html-code-preview.js
index 58ed6181..c69476fe 100644
--- a/src/scripts/html-code-preview.js
+++ b/src/scripts/html-code-preview.js
@@ -15,6 +15,7 @@ const HTML_ROOT_PATTERN = /<\s*html[\s>]/i;
 const DOCTYPE_PATTERN = /<!doctype\b/i;
 const SCRIPT_PATTERN = /<\s*script\b/i;
 let htmlCodeRenderEnabled = false;
+let htmlCodeRenderSuppressedByExternalRenderer = false;
 let replaceLastMessageByDefault = false;
 let previewCounter = 0;
 let isPreviewMessageListenerBound = false;
@@ -599,6 +600,15 @@ export function setHtmlCodeRenderEnabled(enabled) {
     htmlCodeRenderEnabled = !!enabled;
 }
 
+/**
+ * Suppresses the built-in renderer while a richer third-party renderer owns code blocks.
+ * @param {boolean} suppressed
+ * @returns {void}
+ */
+export function setHtmlCodeRenderSuppressedByExternalRenderer(suppressed) {
+    htmlCodeRenderSuppressedByExternalRenderer = !!suppressed;
+}
+
 /**
  * Configures whether the newest rendered preview should replace the last message by default.
  * @param {boolean} enabled
@@ -614,7 +624,7 @@ export function setHtmlCodeRenderReplaceLastMessageByDefault(enabled) {
  * @returns {void}
  */
 export function renderInteractiveHtmlCodeBlocks(messageElement) {
-    if (!htmlCodeRenderEnabled) {
+    if (!htmlCodeRenderEnabled || htmlCodeRenderSuppressedByExternalRenderer) {
         return;
     }
 
diff --git a/tests/code-render-delegation-contract.test.mjs b/tests/code-render-delegation-contract.test.mjs
new file mode 100644
index 00000000..409b6e3c
--- /dev/null
+++ b/tests/code-render-delegation-contract.test.mjs
@@ -0,0 +1,157 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { readFile } from 'node:fs/promises';
+import path from 'node:path';
+import { fileURLToPath, pathToFileURL } from 'node:url';
+
+import { installFakeDom } from './helpers/fake-dom.mjs';
+
+const REPO_ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
+
+async function importFresh(modulePath) {
+    const url = `${pathToFileURL(modulePath).href}?t=${Date.now()}-${Math.random()}`;
+    return import(url);
+}
+
+function installJqueryShim() {
+    const previousDollar = Object.getOwnPropertyDescriptor(globalThis, '$');
+    const previousJquery = Object.getOwnPropertyDescriptor(globalThis, 'jQuery');
+
+    const createCollection = (elements) => ({
+        length: elements.length,
+        get(index) {
+            return elements[index];
+        },
+        is(selector) {
+            return Boolean(elements[0]?.matches?.(selector));
+        },
+        closest(selector) {
+            return createCollection(elements.map(el => el?.closest?.(selector)).filter(Boolean));
+        },
+        find(selector) {
+            const found = [];
+            for (const el of elements) {
+                if (!el?.querySelectorAll) {
+                    continue;
+                }
+
+                if (selector === 'pre > code') {
+                    found.push(...el.querySelectorAll('code').filter(code => code.parentElement?.matches('pre')));
+                    continue;
+                }
+
+                found.push(...el.querySelectorAll(selector));
+            }
+            return createCollection(found);
+        },
+    });
+
+    const shim = (input) => createCollection(input ? [input] : []);
+    Object.defineProperty(globalThis, '$', { value: shim, configurable: true });
+    Object.defineProperty(globalThis, 'jQuery', { value: shim, configurable: true });
+
+    return () => {
+        if (previousDollar) {
+            Object.defineProperty(globalThis, '$', previousDollar);
+        } else {
+            delete globalThis.$;
+        }
+
+        if (previousJquery) {
+            Object.defineProperty(globalThis, 'jQuery', previousJquery);
+        } else {
+            delete globalThis.jQuery;
+        }
+    };
+}
+
+function installButtonElementAlias() {
+    const previous = Object.getOwnPropertyDescriptor(globalThis, 'HTMLButtonElement');
+    Object.defineProperty(globalThis, 'HTMLButtonElement', {
+        value: globalThis.HTMLElement,
+        configurable: true,
+    });
+
+    return () => {
+        if (previous) {
+            Object.defineProperty(globalThis, 'HTMLButtonElement', previous);
+        } else {
+            delete globalThis.HTMLButtonElement;
+        }
+    };
+}
+
+function createMessageWithFrontendCode() {
+    const message = document.createElement('div');
+    message.classList.add('mes');
+
+    const mesText = document.createElement('div');
+    mesText.classList.add('mes_text');
+
+    const pre = document.createElement('pre');
+    const code = document.createElement('code');
+    code.textContent = '<html><body>preview</body></html>';
+    pre.append(code);
+    mesText.append(pre);
+    message.append(mesText);
+    document.body.append(message);
+
+    return { message, pre };
+}
+
+test('html code preview suppression preserves code blocks for delegated renderers', async () => {
+    const dom = installFakeDom();
+    const cleanupJquery = installJqueryShim();
+    const cleanupButtonAlias = installButtonElementAlias();
+
+    try {
+        const {
+            renderInteractiveHtmlCodeBlocks,
+            setHtmlCodeRenderEnabled,
+            setHtmlCodeRenderReplaceLastMessageByDefault,
+            setHtmlCodeRenderSuppressedByExternalRenderer,
+        } = await importFresh(path.join(REPO_ROOT, 'src/scripts/html-code-preview.js'));
+
+        const suppressed = createMessageWithFrontendCode();
+        setHtmlCodeRenderEnabled(true);
+        setHtmlCodeRenderReplaceLastMessageByDefault(false);
+        setHtmlCodeRenderSuppressedByExternalRenderer(true);
+        renderInteractiveHtmlCodeBlocks(suppressed.message);
+
+        assert.equal(suppressed.pre.isConnected, true);
+        assert.equal(suppressed.message.querySelector('.mes-code-preview'), null);
+
+        const fallback = createMessageWithFrontendCode();
+        setHtmlCodeRenderSuppressedByExternalRenderer(false);
+        renderInteractiveHtmlCodeBlocks(fallback.message);
+
+        assert.equal(fallback.pre.isConnected, false);
+        assert.ok(fallback.message.querySelector('.mes-code-preview'));
+    } finally {
+        cleanupButtonAlias();
+        cleanupJquery();
+        dom.cleanup();
+    }
+});
+
+test('message render path delegates code-render to known third-party renderers', async () => {
+    const extensionsSource = await readFile(path.join(REPO_ROOT, 'src/scripts/extensions.js'), 'utf8');
+    assert.match(extensionsSource, /'JS-Slash-Runner'/);
+    assert.match(extensionsSource, /'LittleWhiteBox'/);
+    assert.match(extensionsSource, /export function isCodeRenderDelegatedToThirdPartyRenderer\(\)/);
+    assert.match(extensionsSource, /findExtension\(name\)\?\.enabled === true/);
+
+    const scriptSource = await readFile(path.join(REPO_ROOT, 'src/script.js'), 'utf8');
+    const start = scriptSource.indexOf('export function addCopyToCodeBlocks');
+    assert.ok(start >= 0, 'addCopyToCodeBlocks must exist');
+    const end = scriptSource.indexOf('const coordinator = getCodeHighlightCoordinator();', start);
+    assert.ok(end > start, 'addCopyToCodeBlocks setup section must contain code highlight coordinator');
+    const section = scriptSource.slice(start, end);
+
+    const suppressionIndex = section.indexOf('setHtmlCodeRenderSuppressedByExternalRenderer(');
+    const delegationIndex = section.indexOf('isCodeRenderDelegatedToThirdPartyRenderer()', suppressionIndex);
+    const renderIndex = section.indexOf('renderInteractiveHtmlCodeBlocks(messageElement);');
+    assert.ok(suppressionIndex >= 0, 'message render path must sync code-render delegation');
+    assert.ok(delegationIndex > suppressionIndex, 'delegation sync must consult known third-party renderers');
+    assert.ok(renderIndex > suppressionIndex, 'delegation state must be synced before rendering previews');
+});