diff --git a/platform/mv3/extension/_locales/en/messages.json b/platform/mv3/extension/_locales/en/messages.json
index e0c2038f2..f248475c1 100644
--- a/platform/mv3/extension/_locales/en/messages.json
+++ b/platform/mv3/extension/_locales/en/messages.json
@@ -295,6 +295,30 @@
     "message": "Exit element zapper mode",
     "description": "Tooltip for the button used to exit zapper mode"
   },
+  "developDropdownLabel": {
+    "message": "View:",
+    "description": "A label of a dropdown list"
+  },
+  "developOptionFilteringModeDetails": {
+    "message": "Filtering mode details",
+    "description": "An option in a dropdown list"
+  },
+  "developOptionCustomDnrRules": {
+    "message": "Custom DNR rules",
+    "description": "An option in a dropdown list"
+  },
+  "developOptionDnrRulesOf": {
+    "message": "DNR rules of …",
+    "description": "A section header in a dropdown list"
+  },
+  "developOptionDynamicRuleset": {
+    "message": "Dynamic ruleset",
+    "description": "An option in a dropdown list"
+  },
+  "developOptionSessionRuleset": {
+    "message": "Session ruleset",
+    "description": "An option in a dropdown list"
+  },
   "saveButton": {
     "message": "Save",
     "description": "Text for buttons used to save changes"
@@ -311,8 +335,8 @@
     "message": "Export…",
     "description": "Text for buttons used to export content"
   },
-  "dnrRulesSummary": {
-    "message": "Enter your own DNR rules below. <b>Do not add content from untrusted sources.</b>",
+  "dnrRulesWarning": {
+    "message": "Do not add content from untrusted sources",
     "description": "Short description of the DNR rules editor pane"
   },
   "dnrRulesCountInfo": {
diff --git a/platform/mv3/extension/css/develop.css b/platform/mv3/extension/css/develop.css
index 1ecc3ffd3..665206d00 100644
--- a/platform/mv3/extension/css/develop.css
+++ b/platform/mv3/extension/css/develop.css
@@ -19,38 +19,35 @@ section[data-pane="develop"] > div > * {
     margin-top: 1em;
     }
 
-#cm-dnrRules {
+#cm-container {
     flex-grow: 1;
     font-size: var(--monospace-size);
     overflow: hidden;
     }
 
 /* https://discuss.codemirror.net/t/how-to-set-max-height-of-the-editor/2882/2 */
-#cm-dnrRules .cm-editor {
+#cm-container .cm-editor {
     background-color: var(--surface-0);
     height: 100%;
     }
 
-#cm-dnrRules .cm-editor .cm-line {
-    border-bottom: 1px dotted transparent;
-    border-top: 1px dotted transparent;
+#cm-container .cm-editor .cm-line:has(.ͼ5),
+#cm-container .cm-editor .cm-line:has(.ͼw) {
+    background-image: url('line-hor-dashed.png'), url('line-hor-dashed.png');
+    background-position: left 3px, left calc(100% - 3px);
+    background-repeat: repeat-x;
     }
 
-#cm-dnrRules .cm-editor .cm-line:has(.ͼc) {
-    border-bottom: 1px dotted var(--border-1);
-    border-top: 1px dotted var(--border-1);
-    }
-
-#cm-dnrRules .cm-editor .cm-line.badline:not(.cm-activeLine) {
+#cm-container .cm-editor .cm-line.badline:not(.cm-activeLine) {
     background-color: color-mix(in srgb, var(--info3-ink) 15%, transparent 85%);
     }
 
-#cm-dnrRules .cm-editor .cm-line .badmark {
+#cm-container .cm-editor .cm-line .badmark {
     text-decoration: underline var(--cm-negative) wavy;
     text-decoration-skip-ink: none;
     }
 
-#cm-dnrRules .cm-editor .cm-panel.cm-search {
+#cm-container .cm-editor .cm-panel.cm-search {
     display: flex;
     flex-wrap: wrap;
     font-family: sans-serif;
@@ -59,13 +56,13 @@ section[data-pane="develop"] > div > * {
     padding: 0.5em 1.5em 0.5em 0.5em;
     }
 
-#cm-dnrRules .cm-editor .cm-panel.cm-search > * {
+#cm-container .cm-editor .cm-panel.cm-search > * {
     margin: 0;
     }
 
-#cm-dnrRules .cm-editor .cm-panel.cm-search .cm-textfield,
-#cm-dnrRules .cm-editor .cm-panel.cm-search .cm-button,
-#cm-dnrRules .cm-editor .cm-panel.cm-search label {
+#cm-container .cm-editor .cm-panel.cm-search .cm-textfield,
+#cm-container .cm-editor .cm-panel.cm-search .cm-button,
+#cm-container .cm-editor .cm-panel.cm-search label {
     background-image: inherit;
     border: inherit;
     flex-grow: 0;
@@ -73,40 +70,77 @@ section[data-pane="develop"] > div > * {
     min-height: calc(var(--button-font-size) * 1.8);
     }
 
-#cm-dnrRules .cm-editor .cm-panel.info-panel {
+#cm-container .cm-editor .cm-panel .warning {
+    color: var(--info3-ink);
+    }
+
+#cm-container .cm-editor .cm-panel.io-panel {
+    background-color: var(--surface-1);
+    box-sizing: border-box;
+    display: inline-flex;
+    gap: 0.25em;
+    padding: 0.25em;
+    padding-inline-start: 0;
+    width: 100%;
+    }
+#cm-container .cm-editor .cm-panel.io-panel button {
+    min-height: 30px;
+    }
+#cm-container .cm-editor .cm-panel.io-panel button#revert {
+    margin-inline-end: 1em;
+    }
+#cm-container .cm-editor .cm-panel.io-panel:not([data-io~="apply"]) button#apply {
+    display: none;
+    }
+#cm-container .cm-editor .cm-panel.io-panel:not([data-io~="revert"]) button#revert {
+    display: none;
+    }
+#cm-container .cm-editor .cm-panel.io-panel:not([data-io~="import"]) button#import {
+    display: none;
+    }
+#cm-container .cm-editor .cm-panel.io-panel:not([data-io~="export"]) button#export {
+    display: none;
+    }
+
+#cm-container .cm-editor .cm-panel.info-panel {
     display: flex;
     flex-wrap: nowrap;
     font-size: var(--font-size);
     padding: var(--default-gap-xxsmall) var(--default-gap-xsmall);
     }
-#cm-dnrRules .cm-editor .cm-panel.info-panel .info {
+#cm-container .cm-editor .cm-panel.info-panel .info {
     flex-grow: 1;
     overflow: auto;
     }
-#cm-dnrRules .cm-editor .cm-panel.info-panel .close {
+#cm-container .cm-editor .cm-panel.info-panel .close {
     cursor: default;
     flex-shrink: 0;
     padding-inline-start: 1em;
     }
-#cm-dnrRules .cm-editor .cm-panel.info-panel .close::after {
+#cm-container .cm-editor .cm-panel.info-panel .close::after {
     content: '\2715';
     }
-#cm-dnrRules .cm-editor .cm-panel.summary-panel {
+
+#cm-container .cm-editor .cm-panel.summary-panel {
     background-color: color-mix(in srgb, var(--info1-ink) 15%, transparent 85%);
+    gap: 1em;
+    }
+#cm-container .cm-editor .cm-panel.summary-panel .info {
+    flex-shrink: 0;
     }
 
-#cm-dnrRules .cm-editor .cm-panel.feedback-panel {
+#cm-container .cm-editor .cm-panel.feedback-panel {
     background-color: color-mix(in srgb, var(--info3-ink) 15%, transparent 85%);
     white-space: pre;
     max-height: 10cqh;
     }
 
-#cm-dnrRules .cm-editor .cm-gutterElement {
+#cm-container .cm-editor .cm-gutterElement {
     cursor: default;
     user-select: none;
     }
 
-#cm-dnrRules .cm-editor .cm-tooltip .badmark-tooltip {
+#cm-container .cm-editor .cm-tooltip .badmark-tooltip {
     background-color: color-mix(in srgb, var(--info3-ink) 15%, transparent 85%);
     padding: var(--default-gap-xxsmall) var(--default-gap-xsmall);
     }
\ No newline at end of file
diff --git a/platform/mv3/extension/css/line-hor-dashed.png b/platform/mv3/extension/css/line-hor-dashed.png
new file mode 100644
index 000000000..cb124a2b5
Binary files /dev/null and b/platform/mv3/extension/css/line-hor-dashed.png differ
diff --git a/platform/mv3/extension/dashboard.html b/platform/mv3/extension/dashboard.html
index 91306b845..ee64de6bf 100644
--- a/platform/mv3/extension/dashboard.html
+++ b/platform/mv3/extension/dashboard.html
@@ -89,12 +89,6 @@
             <p><label id="strictBlockMode" data-i18n="enableStrictBlockLabel"><span class="input checkbox"><input type="checkbox"><svg viewBox="0 0 24 24"><path d="M1.73,12.91 8.1,19.28 22.79,4.59"/></svg></span>_</label><legend data-i18n="enableStrictBlockLegend"></legend>
             <p id="developerMode"><label data-i18n="developerModeLabel"><span class="input checkbox"><input type="checkbox"><svg viewBox="0 0 24 24"><path d="M1.73,12.91 8.1,19.28 22.79,4.59"/></svg></span>_</label><legend data-i18n="developerModeLegend"></legend>
         </div>
-
-        <div>
-            <h3 data-i18n="filteringMode0Name"></h3>
-            <p data-i18n="noFilteringModeDescription">_</p>
-            <div id="trustedSites"></div>
-        </div>
     </section>
     <!-- -------- -->
     <section data-pane="rulesets">
@@ -108,14 +102,17 @@
     <section data-pane="develop">
         <div>
             <p>
-                <button id="dnrRulesApply" class="preferred iconified" type="button" disabled><span class="fa-icon">save</span><span data-i18n="saveButton">_</span><span class="hover"></span></button>
-                <button id="dnrRulesRevert" class="iconified" type="button" disabled><span class="fa-icon">undo</span><span data-i18n="revertButton">_</span><span class="hover"></span></button>
-                &emsp;
-                <button id="dnrRulesImport" class="iconified" type="button"><span class="fa-icon">download-alt</span><span data-i18n="importAndAppendButton">_</span><span class="hover"></span></button>
-                <button id="dnrRulesExport" class="iconified" type="button"><span class="fa-icon">upload-alt</span><span data-i18n="exportButton">_</span><span class="hover"></span></button><input type="file" accept="json/application">
+                <label for="editors" data-i18n="developDropdownLabel"></label> <select id="editors">
+                    <option value="modes" selected data-i18n="developOptionFilteringModeDetails"></option>
+                    <option value="dnr.rw.user" data-i18n="developOptionCustomDnrRules"></option>
+                    <hr>
+                    <optgroup label="" data-i18n-label="developOptionDnrRulesOf">
+                        <option value="dnr.ro.dynamic" data-i18n="developOptionDynamicRuleset"></option>
+                        <option value="dnr.ro.session" data-i18n="developOptionSessionRuleset"></option>
+                    </optgroup>
+                </select>&nbsp;
             </p>
-            <p data-i18n="dnrRulesSummary"></p>
-            <div id="cm-dnrRules"></div>
+            <div id="cm-container"></div>
         </div>
     </section>
     <!-- -------- -->
@@ -165,16 +162,24 @@
             </span>
         </div>
         <div class="listEntry expandable" data-role="rootnode">
-            <span class="detailbar">
+            <div class="detailbar">
                 <h3 class="listname"></h3>
                 <span class="count"></span>
                 <span class="fa-icon listExpander">angle-up</span>
-            </span>
+            </div>
         </div>
     </div>
+    <template class="io-panel">
+        <span class="io-panel">
+            <button id="apply" class="preferred iconified" type="button" disabled><span class="fa-icon">save</span><span data-i18n="saveButton">_</span><span class="hover"></span></button>
+            <button id="revert" class="iconified" type="button" disabled><span class="fa-icon">undo</span><span data-i18n="revertButton">_</span><span class="hover"></span></button>
+            <button id="import" class="iconified" type="button"><span class="fa-icon">download-alt</span><span data-i18n="importAndAppendButton">_</span><span class="hover"></span></button>
+            <button id="export" class="iconified" type="button"><span class="fa-icon">upload-alt</span><span data-i18n="exportButton">_</span><span class="hover"></span></button><input type="file" accept="json/application">
+        </span>
+    </template>
     <template class="summary-panel">
         <div class="info-panel summary-panel">
-            <div class="info"></div>
+            <span class="info"></span><span class="warning" data-i18n="dnrRulesWarning"></span>
         </div>
     </template>
     <template class="feedback-panel">
@@ -183,6 +188,10 @@
             <div class="close"></div>
         </div>
     </template>
+    <template class="ro-summary-panel">
+        <div class="info-panel summary-panel">
+        </div>
+    </template>
     <template class="badmark-tooltip">
         <div class="badmark-tooltip">
         </div>
diff --git a/platform/mv3/extension/js/admin.js b/platform/mv3/extension/js/admin.js
index 865f37dda..1df2c5079 100644
--- a/platform/mv3/extension/js/admin.js
+++ b/platform/mv3/extension/js/admin.js
@@ -21,7 +21,7 @@
 
 import {
     adminRead,
-    localRead, localWrite,
+    localRead, localRemove, localWrite,
     sessionRead, sessionWrite,
 } from './ext.js';
 
@@ -33,7 +33,6 @@ import {
 
 import {
     getDefaultFilteringMode,
-    getTrustedSites,
     readFilteringModeDetails,
 } from './mode-manager.js';
 
@@ -132,9 +131,8 @@ const adminSettings = {
         }
         if ( this.keys.has('noFiltering') ) {
             ubolLog('admin setting "noFiltering" changed');
-            await readFilteringModeDetails(true);
-            const trustedSites = await getTrustedSites();
-            broadcastMessage({ trustedSites: Array.from(trustedSites) });
+            const filteringModeDetails = await readFilteringModeDetails(true);
+            broadcastMessage({ filteringModeDetails });
         }
         if ( this.keys.has('showBlockedCount') ) {
             ubolLog('admin setting "showBlockedCount" changed');
@@ -192,17 +190,18 @@ export async function getAdminRulesets() {
 
 export async function adminReadEx(key) {
     let cacheValue;
-    const session = await sessionRead(`admin_${key}`);
+    const session = await sessionRead(`admin.${key}`);
     if ( session ) {
         cacheValue = session.data;
     } else {
-        const local = await localRead(`admin_${key}`);
+        const local = await localRead(`admin.${key}`);
         if ( local ) {
             cacheValue = local.data;
         }
+        localRemove(`admin_${key}`); // TODO: remove eventually
     }
     adminRead(key).then(async value => {
-        const adminKey = `admin_${key}`;
+        const adminKey = `admin.${key}`;
         await Promise.all([
             sessionWrite(adminKey, { data: value }),
             localWrite(adminKey, { data: value }),
diff --git a/platform/mv3/extension/js/background.js b/platform/mv3/extension/js/background.js
index f07adb301..ffeb0314f 100644
--- a/platform/mv3/extension/js/background.js
+++ b/platform/mv3/extension/js/background.js
@@ -24,10 +24,10 @@ import {
     MODE_OPTIMAL,
     getDefaultFilteringMode,
     getFilteringMode,
-    getTrustedSites,
+    getFilteringModeDetails,
     setDefaultFilteringMode,
     setFilteringMode,
-    setTrustedSites,
+    setFilteringModeDetails,
     syncWithBrowserPermissions,
 } from './mode-manager.js';
 
@@ -53,6 +53,8 @@ import {
 import {
     enableRulesets,
     excludeFromStrictBlock,
+    getEffectiveDynamicRules,
+    getEffectiveSessionRules,
     getEffectiveUserRules,
     getEnabledRulesetsDetails,
     getRulesetDetails,
@@ -219,11 +221,10 @@ function onMessage(request, sender, callback) {
         return true;
     }
 
-    case 'getOptionsPageData': {
+    case 'getOptionsPageData':
         Promise.all([
             hasBroadHostPermissions(),
             getDefaultFilteringMode(),
-            getTrustedSites(),
             getRulesetDetails(),
             dnr.getEnabledRulesets(),
             getAdminRulesets(),
@@ -232,7 +233,6 @@ function onMessage(request, sender, callback) {
             const [
                 hasOmnipotence,
                 defaultFilteringMode,
-                trustedSites,
                 rulesetDetails,
                 enabledRulesets,
                 adminRulesets,
@@ -241,7 +241,6 @@ function onMessage(request, sender, callback) {
             callback({
                 hasOmnipotence,
                 defaultFilteringMode,
-                trustedSites: Array.from(trustedSites),
                 enabledRulesets,
                 adminRulesets,
                 maxNumberOfEnabledRulesets: dnr.MAX_NUMBER_OF_ENABLED_STATIC_RULESETS,
@@ -258,7 +257,12 @@ function onMessage(request, sender, callback) {
             process.firstRun = false;
         });
         return true;
-    }
+
+    case 'getRulesetDetails':
+        getRulesetDetails().then(rulesetDetails => {
+            callback(Array.from(rulesetDetails.values()));
+        });
+        return true;
 
     case 'setAutoReload':
         rulesetConfig.autoReload = request.state && true || false;
@@ -353,7 +357,7 @@ function onMessage(request, sender, callback) {
         return true;
     }
 
-    case 'setDefaultFilteringMode': {
+    case 'setDefaultFilteringMode':
         getDefaultFilteringMode().then(beforeLevel =>
             setDefaultFilteringMode(request.level).then(afterLevel =>
                 ({ beforeLevel, afterLevel })
@@ -365,19 +369,21 @@ function onMessage(request, sender, callback) {
             callback(afterLevel);
         });
         return true;
-    }
 
-    case 'setTrustedSites':
-        setTrustedSites(request.hostnames).then(( ) => {
+    case 'getFilteringModeDetails':
+        getFilteringModeDetails(true).then(details => {
+            callback(details);
+        });
+        return true;
+
+    case 'setFilteringModeDetails':
+        setFilteringModeDetails(request.modes).then(( ) => {
             registerInjectables();
-            return Promise.all([
-                getDefaultFilteringMode(),
-                getTrustedSites(),
-            ]);
-        }).then(results => {
-            callback({
-                defaultFilteringMode: results[0],
-                trustedSites: Array.from(results[1]),
+            getDefaultFilteringMode().then(defaultFilteringMode => {
+                broadcastMessage({ defaultFilteringMode });
+            });
+            getFilteringModeDetails(true).then(details => {
+                callback(details);
             });
         });
         return true;
@@ -402,6 +408,18 @@ function onMessage(request, sender, callback) {
         });
         break;
 
+    case 'getEffectiveDynamicRules':
+        getEffectiveDynamicRules().then(result => {
+            callback(result);
+        });
+        return true;
+
+    case 'getEffectiveSessionRules':
+        getEffectiveSessionRules().then(result => {
+            callback(result);
+        });
+        return true;
+
     case 'getEffectiveUserRules':
         getEffectiveUserRules().then(result => {
             callback(result);
diff --git a/platform/mv3/extension/js/dashboard.js b/platform/mv3/extension/js/dashboard.js
index 20f6b5ed5..d5c27078e 100644
--- a/platform/mv3/extension/js/dashboard.js
+++ b/platform/mv3/extension/js/dashboard.js
@@ -41,13 +41,13 @@ dom.on('#dashboard-nav', 'click', '.tabButton', ev => {
     const { pane } = ev.target.dataset;
     dom.body.dataset.pane = pane;
     if ( pane === 'settings' ) {
-        localRemove('activeDashboardPane');
+        localRemove('dashboard.activePane');
     } else {
-        localWrite('activeDashboardPane', pane);
+        localWrite('dashboard.activePane', pane);
     }
 });
 
-localRead('activeDashboardPane').then(pane => {
+localRead('dashboard.activePane').then(pane => {
     if ( typeof pane !== 'string' ) { return; }
     dom.body.dataset.pane = pane;
 });
diff --git a/platform/mv3/extension/js/develop.js b/platform/mv3/extension/js/develop.js
index 5fdee6e29..c671384aa 100644
--- a/platform/mv3/extension/js/develop.js
+++ b/platform/mv3/extension/js/develop.js
@@ -19,871 +19,598 @@
     Home: https://github.com/gorhill/uBlock
 */
 
-import {
-    browser,
-    localRead,
-    localRemove,
-    localWrite,
-    sendMessage,
-} from './ext.js';
-import { dom, qs$ } from './dom.js';
-import { rulesFromText, textFromRules } from './dnr-parser.js';
-import { dnr } from './ext-compat.js';
-import { i18n$ } from './i18n.js';
+import { dom, qs$, qsa$ } from './dom.js';
+import { localRead, localWrite, sendMessage } from './ext.js';
+import { ModeEditor } from './mode-editor.js';
+import { ReadOnlyDNREditor } from './ro-dnr-editor.js';
+import { ReadWriteDNREditor } from './rw-dnr-editor.js';
+import { faIconsInit } from './fa-icons.js';
+import { i18n } from './i18n.js';
 
 /******************************************************************************/
 
-// Details of YAML document(s) intersecting with a text span. If the text span
-// starts on a YAML document divider, the previous YAML document will be
-// included. If the text span ends on a YAML document divider, the next YAML
-// document will be included.
+class Editor {
+    constructor() {
+        this.lastSavedText = '';
+        this.view = null;
+        this.reYamlDocSeparator = /^(?:---|...)\s*$/;
+        this.modifiedRange = { start: 0, end: 0 };
+        this.updateTimer = undefined;
+        this.ioPanel = self.cm6.createViewPanel();
+        this.summaryPanel = self.cm6.createViewPanel();
+        this.panels = [];
+    }
 
-function snapToYamlDocument(doc, start, end) {
-    let yamlDocStart = doc.lineAt(start).number;
-    if ( reYamlDocSeparator.test(doc.line(yamlDocStart).text) ) {
-        if ( yamlDocStart > 1 ) {
+    async init() {
+        this.editors = {
+             'modes': new ModeEditor(this),
+            'dnr.rw': new ReadWriteDNREditor(this),
+            'dnr.ro': new ReadOnlyDNREditor(this),
+        };
+        const rulesetDetails = await sendMessage({ what: 'getRulesetDetails' });
+        const parent = qs$('#editors optgroup');
+        for ( const details of rulesetDetails ) {
+            const option = document.createElement('option');
+            option.value = `dnr.ro.${details.id}`;
+            option.textContent = details.name;
+            parent.append(option);
+        }
+        this.validModes = Array.from(qsa$('#editors option')).map(a => a.value);
+        const mode = await localRead('dashboard.develop.editor');
+        this.editorFromMode(mode);
+        const text = this.normalizeEditorText(await this.editor.getText(this.mode));
+        const viewConfig = {
+            text,
+            yamlLike: true,
+            oneDark: dom.cl.has(':root', 'dark'),
+            updateListener: info => { this.viewUpdateListener(info); },
+            saveListener: ( ) => { this.saveEditorText(); },
+            lineError: true,
+            spanError: true,
+            // https://codemirror.net/examples/autocompletion/
+            autocompletion: {
+                override: [
+                    context => {
+                        return this.autoComplete(context);
+                    },
+                ],
+                activateOnCompletion: ( ) => true,
+            },
+            gutterClick: (view, info) => {
+                return this.gutterClick(view, info);
+            },
+            hoverTooltip: (view, pos, side) => {
+                return this.hoverTooltip(view, pos, side);
+            },
+            streamParser: this.streamParser,
+            foldService: (state, from) => {
+                return this.foldService(state, from);
+            },
+            readOnly: this.isReadOnly(),
+        };
+        viewConfig.panels = [ this.ioPanel, this.summaryPanel, ...this.panels ];
+        this.view = self.cm6.createEditorView(viewConfig, qs$('#cm-container'));
+        this.lastSavedText = text;
+        self.cm6.foldAll(this.view);
+        self.cm6.resetUndoRedo(this.view);
+        this.updateIOPanel();
+        this.editor.on?.(this);
+        this.modifiedRange.start = 1;
+        this.modifiedRange.end = this.view.state.doc.lines;
+        this.updateViewAsync();
+    }
+
+    normalizeEditorText(text) {
+        text ||= '';
+        text = text.trim();
+        if ( text !== '' ) { text += '\n'; }
+        return text;
+    }
+
+    setEditorText(text, saved = false) {
+        text = this.normalizeEditorText(text);
+        if ( saved ) {
+            this.lastSavedText = text;
+        }
+        this.view.dispatch({
+            changes: {
+                from: 0, to: this.view.state.doc.length,
+                insert: text,
+            },
+        });
+        this.view.focus();
+    }
+
+    getEditorText() {
+        return this.view.state.doc.toString();
+    }
+
+    editorTextChanged() {
+        const text = this.normalizeEditorText(this.getEditorText());
+        return text !== this.lastSavedText;
+    }
+
+    async selectEditor(mode) {
+        if ( mode === this.mode ) { return; }
+        this.editorFromMode(mode);
+        const text = await this.editor.getText(this.mode);
+        this.setEditorText(text);
+        this.lastSavedText = this.getEditorText();
+        self.cm6.foldAll(this.view)
+        self.cm6.resetUndoRedo(this.view);
+        self.cm6.toggleReadOnly(this.view, this.isReadOnly());
+        this.updateIOPanel();
+        this.editor.on?.(this);
+        this.modifiedRange.start = 1;
+        this.modifiedRange.end = this.view.state.doc.lines;
+        this.updateViewAsync();
+    }
+
+    editorFromMode(mode) {
+        if ( this.validModes.includes(mode) === false ) {
+            mode = 'modes';
+        }
+        if ( mode === this.mode ) { return mode; }
+        let editor;
+        if ( mode === 'modes' ) {
+            editor = this.editors['modes'];
+        } else if ( mode.startsWith('dnr.rw.') ) {
+            editor = this.editors['dnr.rw'];
+        } else if ( mode.startsWith('dnr.ro.') ) {
+            editor = this.editors['dnr.ro'];
+        } else {
+            return;
+        }
+        this.editor?.off?.(this);
+        this.editor = editor;
+        this.mode = mode;
+        const select = qs$('#editors');
+        select.value = mode;
+    }
+
+    isReadOnly() {
+        return typeof this.editor.saveEditorText !== 'function';
+    }
+
+    viewUpdateListener(info) {
+        if ( info.docChanged === false ) { return; }
+        for ( const transaction of info.transactions ) {
+            if ( transaction.docChanged === false ) { continue; }
+            this.addToModifiedRange(transaction);
+            if ( transaction.isUserEvent('delete.backward') ) {
+                this.smartBackspace(transaction);
+            } else if ( transaction.isUserEvent('input.paste') ) {
+                if ( this.editor.importFromPaste ) {
+                    this.editor.importFromPaste(this, transaction);
+                }
+            } else if ( transaction.isUserEvent('input') ) {
+                if ( this.smartReturn(transaction) ) { continue; }
+                this.smartSpacebar(transaction);
+            }
+        }
+        this.updateViewAsync();
+    }
+
+    updateViewAsync() {
+        if ( this.updateTimer !== undefined ) { return; }
+        this.updateTimer = self.setTimeout(( ) => {
+            this.updateTimer = undefined;
+            this.updateView();
+        }, 71);
+    }
+
+    updateView() {
+        const { doc } = this.view.state;
+        const changed = this.editorTextChanged();
+        dom.attr('#apply', 'disabled', changed ? null : '');
+        dom.attr('#revert', 'disabled', changed ? null : '');
+        if ( typeof this.editor.updateView !== 'function' ) { return; }
+        let { start, end } = this.modifiedRange;
+        if ( start === 0 || end === 0 ) { return; }
+        this.modifiedRange.start = this.modifiedRange.end = 0;
+        if ( start > doc.lines ) { start = doc.lines; }
+        if ( end > doc.lines ) { end = doc.lines; }
+        self.cm6.lineErrorClear(this.view, start, end);
+        self.cm6.spanErrorClear(this.view, start, end);
+        const firstLine = doc.line(start);
+        const lastLine = doc.line(end);
+        this.editor.updateView(this, firstLine, lastLine);
+    }
+
+    updateIOPanel() {
+        const ioButtons = [];
+        if ( this.editor.saveEditorText ) {
+            ioButtons.push('apply', 'revert');
+        }
+        if ( this.editor.importFromFile ) {
+            ioButtons.push('import');
+        }
+        if ( this.editor.exportToFile ) {
+            ioButtons.push('export');
+        }
+        if ( ioButtons.length === 0 ) {
+            return this.ioPanel.render(this.view, null);
+        }
+        const template = document.querySelector('template.io-panel');
+        const fragment = template.content.cloneNode(true);
+        const root = fragment.querySelector('.io-panel');
+        i18n.render(root);
+        faIconsInit(root);
+        root.dataset.io = ioButtons.join(' ');
+        const config = {
+            dom: root,
+            mount: ( ) => {
+                dom.on('#apply', 'click', ( ) => {
+                    this.saveEditorText();
+                });
+                dom.on('#revert', 'click', ( ) => {
+                    this.revertEditorText();
+                });
+                dom.on('#import', 'click', ( ) => {
+                    this.importFromFile()
+                });
+                dom.on('#export', 'click', ( ) => {
+                    this.exportToFile();
+                });
+            }
+        };
+        this.ioPanel.render(this.view, config);
+    }
+
+    updateSummaryPanel(dom) {
+        if ( dom instanceof Object ) {
+            if ( this.updateSummaryPanel.timer !== undefined ) {
+                self.clearTimeout(this.updateSummaryPanel.timer);
+                this.updateSummaryPanel.timer = undefined;
+            }
+            return this.summaryPanel.render(this.view, { dom });
+        }
+        if ( this.updateSummaryPanel.timer !== undefined ) { return; }
+        this.updateSummaryPanel.timer = self.setTimeout(( ) => {
+            this.updateSummaryPanel.timer = undefined;
+            this.summaryPanel.render(this.view, null);
+        }, 157);
+    }
+
+    autoComplete(context) {
+        if ( typeof this.editor.autoComplete !== 'function' ) { return null; }
+        return this.editor.autoComplete(this, context);
+    }
+
+    hoverTooltip(view, pos, side) {
+        if ( typeof this.editor.createTooltipWidget !== 'function' ) { return null; }
+        const details = view.domAtPos(pos);
+        const textNode = details.node;
+        if ( textNode.nodeType !== 3 ) { return null; }
+        const { parentElement } = textNode;
+        const targetElement = parentElement.closest('[data-tooltip]');
+        if ( targetElement === null ) { return null; }
+        const tooltipText = targetElement.getAttribute('data-tooltip');
+        if ( Boolean(tooltipText) === false ) { return null; }
+        const start = pos - details.offset;
+        const end = start + textNode.nodeValue.length;
+        if ( start === pos && side < 0 || end === pos && side > 0 ) { return null; }
+        return {
+            above: true,
+            pos: start,
+            end,
+            create: ( ) => {
+                return { dom: this.editor.createTooltipWidget(tooltipText) };
+            },
+        };
+    }
+
+    foldService(state, from) {
+        if ( typeof this.editor.foldService !== 'function' ) { return null; }
+        return this.editor.foldService(state, from);
+    }
+
+    // Details of YAML document(s) intersecting with a text span. If the text span
+    // starts on a YAML document divider, the previous YAML document will be
+    // included. If the text span ends on a YAML document divider, the next YAML
+    // document will be included.
+
+    snapToYamlDocument(doc, start, end) {
+        let yamlDocStart = doc.lineAt(start).number;
+        if ( this.reYamlDocSeparator.test(doc.line(yamlDocStart).text) ) {
+            if ( yamlDocStart > 1 ) {
+                yamlDocStart -= 1;
+            }
+        }
+        while ( yamlDocStart > 1 ) {
+            const line = doc.line(yamlDocStart);
+            if ( this.reYamlDocSeparator.test(line.text) ) { break; }
             yamlDocStart -= 1;
         }
-    }
-    while ( yamlDocStart > 1 ) {
-        const line = doc.line(yamlDocStart);
-        if ( reYamlDocSeparator.test(line.text) ) { break; }
-        yamlDocStart -= 1;
-    }
-    const lastLine = doc.lines;
-    let yamlDocEnd = doc.lineAt(end).number;
-    if ( reYamlDocSeparator.test(doc.line(yamlDocEnd).text) ) {
-        if ( yamlDocEnd < lastLine ) {
+        const lastLine = doc.lines;
+        let yamlDocEnd = doc.lineAt(end).number;
+        if ( this.reYamlDocSeparator.test(doc.line(yamlDocEnd).text) ) {
+            if ( yamlDocEnd < lastLine ) {
+                yamlDocEnd += 1;
+            }
+        }
+        while ( yamlDocEnd < lastLine ) {
+            const line = doc.line(yamlDocEnd);
+            if ( this.reYamlDocSeparator.test(line.text) ) { break; }
             yamlDocEnd += 1;
         }
+        return { yamlDocStart, yamlDocEnd };
     }
-    while ( yamlDocEnd < lastLine ) {
-        const line = doc.line(yamlDocEnd);
-        if ( reYamlDocSeparator.test(line.text) ) { break; }
-        yamlDocEnd += 1;
-    }
-    return { yamlDocStart, yamlDocEnd };
-}
 
-function rangeFromTransaction(transaction) {
-    let from, to;
-    transaction.changes.iterChangedRanges((fromA, toA, fromB, toB) => {
-        if ( from === undefined || fromB < from ) { from = fromB; }
-        if ( to === undefined || toB > to ) { to = toB; }
-    });
-    return { from, to };
-}
+    rangeFromTransaction(transaction) {
+        let from, to;
+        transaction.changes.iterChangedRanges((fromA, toA, fromB, toB) => {
+            if ( from === undefined || fromB < from ) { from = fromB; }
+            if ( to === undefined || toB > to ) { to = toB; }
+        });
+        return { from, to };
+    }
 
-function addToModifiedRange(transaction) {
-    const { from, to } = rangeFromTransaction(transaction);
-    if ( from === undefined || to === undefined ) { return; }
-    const { newDoc } = transaction;
-    const { yamlDocStart, yamlDocEnd } = snapToYamlDocument(newDoc, from, to);
-    if ( modifiedRange.start === -1 || yamlDocStart < modifiedRange.start ) {
-        modifiedRange.start = yamlDocStart;
-    }
-    if ( modifiedRange.end === -1 || yamlDocEnd > modifiedRange.end ) {
-        modifiedRange.end = yamlDocEnd;
-    }
-}
-
-const reYamlDocSeparator = /^(?:---|...)\s*$/;
-const modifiedRange = { start: -1, end: -1 };
-
-/******************************************************************************/
-
-function rulesFromJSON(json) {
-    let content = json.trim();
-    if ( /^[[{]/.test(content) === false ) {
-        const match = /^[^[{]+/.exec(content);
-        if ( match === null ) { return; }
-        content = content.slice(match[0].length);
-    }
-    const firstChar = content.charAt(0);
-    const expectedLastChar = firstChar === '[' ? ']' : '}';
-    if ( content.at(-1) !== expectedLastChar ) {
-        const re = new RegExp(`\\${expectedLastChar}[^\\${expectedLastChar}]+$`);
-        const match = re.exec(content);
-        if ( match === null ) { return; }
-        content = content.slice(0, match.index+1);
-    }
-    if ( content.startsWith('{') && content.endsWith('}') ) {
-        content = `[${content}]`;
-    }
-    try {
-        const rules = JSON.parse(content);
-        if ( Array.isArray(rules) ) { return rules; }
-    }
-    catch {
-    }
-}
-
-/******************************************************************************/
-
-function lineIndentAt(line) {
-    const match = /^(?: {2})*/.exec(line.text);
-    const indent = match !== null ? match[0].length : -1;
-    if ( indent === -1 || (indent & 1) !== 0 ) { return -1; }
-    return indent / 2;
-}
-
-function getScopeAt(from) {
-    const { doc }  = cmRules.state;
-    const lineFrom = doc.lineAt(from);
-    let depth = lineIndentAt(lineFrom);
-    if ( depth === -1 ) { return; }
-    const text = lineFrom.text.trim();
-    if ( text.startsWith('#') ) { return; }
-    const path = [];
-    const pos = text.indexOf(':');
-    if ( pos !== -1 ) {
-        path.push(text.slice(0, pos+1));
-    }
-    let lineNo = lineFrom.number;
-    while ( depth > 0 && lineNo > 1 ) {
-        lineNo -= 1;
-        const lineBefore = doc.line(lineNo);
-        const text = lineBefore.text.trim();
-        if ( text.startsWith('#') ) { continue; }
-        if ( lineIndentAt(lineBefore) > (depth-1) ) { continue; }
-        const match = /^- ([^:]+:)/.exec(text);
-        if ( match !== null ) {
-            path.unshift(match[1]);
-        } else {
-            path.unshift(text);
+    addToModifiedRange(transaction) {
+        const { from, to } = this.rangeFromTransaction(transaction);
+        if ( from === undefined || to === undefined ) { return; }
+        const { newDoc } = transaction;
+        const { yamlDocStart, yamlDocEnd } = this.snapToYamlDocument(newDoc, from, to);
+        if ( this.modifiedRange.start === 0 || yamlDocStart < this.modifiedRange.start ) {
+            this.modifiedRange.start = yamlDocStart;
         }
-        depth -= 1;
-    }
-    return path.join('');
-}
-
-function getAutocompleteCandidates(from) {
-    const scope = getScopeAt(from);
-    switch ( scope ) {
-    case '':
-        return {
-            before: /^$/,
-            candidates: [
-                { token: 'action:', after: '\n  ' },
-                { token: 'condition:', after: '\n  ' },
-                { token: 'priority:', after: ' ' },
-                { token: '---', after: '\n' },
-            ]
-        };
-    case 'action:':
-        return {
-            before: /^ {2}$/,
-            candidates: [
-                { token: 'type:', after: ' ' },
-                { token: 'redirect:', after: '\n    ' },
-                { token: 'requestHeaders:', after: '\n    - header: ' },
-                { token: 'responseHeaders:', after: '\n    - header: ' },
-            ],
-        };
-    case 'action:type:':
-        return {
-            before: /: $/,
-            candidates: [
-                { token: 'block', after: '\n  ' },
-                { token: 'redirect', after: '\n  ' },
-                { token: 'allow', after: '\n  ' },
-                { token: 'modifyHeaders', after: '\n  ' },
-                { token: 'upgradeScheme', after: '\n  ' },
-                { token: 'allowAllRequest', after: '\n  ' },
-            ],
-        };
-    case 'action:redirect:':
-        return {
-            before: /^ {4}$/,
-            candidates: [
-                { token: 'extensionPath:', after: ' ' },
-                { token: 'regexSubstitution:', after: ' ' },
-                { token: 'transform:', after: '\n      ' },
-                { token: 'url:', after: ' ' },
-            ],
-        };
-    case 'action:redirect:transform:':
-        return {
-            before: /^ {6}$/,
-            candidates: [
-                { token: 'fragment:', after: ' ' },
-                { token: 'host:', after: ' ' },
-                { token: 'path:', after: ' ' },
-                { token: 'port:', after: ' ' },
-                { token: 'query:', after: ' ' },
-                { token: 'scheme:', after: ' ' },
-                { token: 'queryTransform:', after: '\n        ' },
-            ],
-        };
-    case 'action:redirect:transform:queryTransform:':
-        return {
-            before: /^ {8}$/,
-            candidates: [
-                { token: 'addOrReplaceParams:', after: '\n          - ' },
-                { token: 'removeParams:', after: '\n          - ' },
-            ],
-        };
-    case 'action:responseHeaders:':
-    case 'action:requestHeaders:':
-        return {
-            before: /^ {4}- $/,
-            candidates: [
-                { token: 'header:', after: ' ' },
-            ],
-        };
-    case 'action:responseHeaders:header:':
-    case 'action:requestHeaders:header:':
-        return {
-            before: /^ {6}$/,
-            candidates: [
-                { token: 'operation:', after: ' ' },
-                { token: 'value:', after: ' ' },
-            ],
-        };
-    case 'action:responseHeaders:header:operation:':
-    case 'action:requestHeaders:header:operation:':
-        return {
-            before: /: $/,
-            candidates: [
-                { token: 'append', after: '\n      value: ' },
-                { token: 'set', after: '\n      value: ' },
-                { token: 'remove', after: '\n    ' },
-            ],
-        };
-    case 'condition:':
-        return {
-            before: /^ {2}$/,
-            candidates: [
-                { token: 'domainType:', after: ' ' },
-                { token: 'isUrlFilterCaseSensitive:', after: ' ' },
-                { token: 'regexFilter:', after: ' ' },
-                { token: 'urlFilter:', after: ' ' },
-                { token: 'initiatorDomains:', after: '\n    - ' },
-                { token: 'excludedInitiatorDomains:', after: '\n    - ' },
-                { token: 'requestDomains:', after: '\n    - ' },
-                { token: 'excludedRequestDomains:', after: '\n    - ' },
-                { token: 'resourceTypes:', after: '\n    - ' },
-                { token: 'excludedResourceTypes:', after: '\n    - ' },
-                { token: 'requestMethods:', after: '\n    - ' },
-                { token: 'excludedRequestMethods:', after: '\n    - ' },
-                { token: 'responseHeaders:', after: '\n    - ' },
-                { token: 'excludedResponseHeaders:', after: '\n    - ' },
-            ],
-        };
-    case 'condition:domainType:':
-        return {
-            before: /: $/,
-            candidates: [
-                { token: 'firstParty', after: '\n  ' },
-                { token: 'thirdParty', after: '\n  ' },
-            ],
-        };
-    case 'condition:isUrlFilterCaseSensitive:':
-        return {
-            before: /: $/,
-            candidates: [
-                { token: 'true', after: '\n  ' },
-                { token: 'false', after: '\n  ' },
-            ],
-        };
-    case 'condition:requestMethods:':
-    case 'condition:excludedRequestMethods:':
-        return {
-            before: /^ {4}- $/,
-            candidates: [
-                { token: 'connect', after: '\n    - ' },
-                { token: 'delete', after: '\n    - ' },
-                { token: 'get', after: '\n    - ' },
-                { token: 'head', after: '\n    - ' },
-                { token: 'options', after: '\n    - ' },
-                { token: 'patch', after: '\n    - ' },
-                { token: 'post', after: '\n    - ' },
-                { token: 'put', after: '\n    - ' },
-                { token: 'other', after: '\n  ' },
-            ],
-        };
-    case 'condition:resourceTypes:':
-    case 'condition:excludedResourceTypes:':
-        return {
-            before: /^ {4}- $/,
-            candidates: [
-                { token: 'main_frame', after: '\n    - ' },
-                { token: 'sub_frame', after: '\n    - ' },
-                { token: 'stylesheet', after: '\n    - ' },
-                { token: 'script', after: '\n    - ' },
-                { token: 'image', after: '\n    - ' },
-                { token: 'font', after: '\n    - ' },
-                { token: 'object', after: '\n    - ' },
-                { token: 'xmlhttprequest', after: '\n    - ' },
-                { token: 'ping', after: '\n    - ' },
-                { token: 'csp_report', after: '\n    - ' },
-                { token: 'media', after: '\n    - ' },
-                { token: 'websocket', after: '\n    - ' },
-                { token: 'webtransport', after: '\n    - ' },
-                { token: 'webbundle', after: '\n    - ' },
-                { token: 'other', after: '\n  ' },
-            ],
-        };
-    }
-}
-
-function autoComplete(context) {
-    const match = context.matchBefore(/[\w-]*/);
-    if ( match === undefined ) { return null; }
-    const result = getAutocompleteCandidates(match.from);
-    if ( result === undefined ) { return null; }
-    if ( result.before !== undefined ) {
-        const { doc } = context.state;
-        const line = doc.lineAt(context.pos);
-        const before = doc.sliceString(line.from, match.from);
-        if ( result.before.test(before) === false ) { return null; }
-    }
-    const filtered = result.candidates.filter(e =>
-        e.token !== match.text || e.after !== '\n'
-    ); 
-    return {
-        from: match.from,
-        options: filtered.map(e => ({ label: e.token, apply: `${e.token}${e.after}` })),
-        validFor: /\w*/,
-    };
-}
-
-/******************************************************************************/
-
-function setEditorText(text) {
-    if ( text === undefined ) { return; }
-    if ( text !== '' ) { text += '\n'; }
-    cmRules.dispatch({
-        changes: {
-            from: 0, to: cmRules.state.doc.length,
-            insert: text,
-        },
-    });
-    cmRules.focus();
-}
-
-function getEditorText() {
-    return cmRules.state.doc.toString();
-}
-
-/******************************************************************************/
-
-function saveEditorText() {
-    const text = getEditorText().trim();
-    const promise = text.length !== 0
-        ? localWrite('userDnrRules', text)
-        : localRemove('userDnrRules');
-    promise.then(( ) => {
-        lastSavedText = text;
-        updateView();
-    }).then(( ) =>
-        sendMessage({ what: 'updateUserDnrRules' })
-    ).then(result => {
-        if ( result instanceof Object === false ) { return; }
-        updateFeedbackPanel(result);
-    });
-}
-
-/******************************************************************************/
-
-async function validateRegexes(regexes) {
-    if ( regexes.length === 0 ) { return; }
-    const promises = regexes.map(regex => validateRegex(regex));
-    await Promise.all(promises);
-    for ( const regex of regexes ) {
-        const i = validatedRegexes.regexes.indexOf(regex);
-        if ( i === -1 ) { continue; }
-        const reason = validatedRegexes.results[i];
-        if ( reason === true ) { continue; }
-        const entries = self.cm6.findAll(cmRules,
-            `(?<=\\bregexFilter: )${RegExp.escape(regex)}`
-        );
-        for ( const entry of entries ) {
-            self.cm6.spanErrorAdd(cmRules, entry.from, entry.to, reason);
+        if ( this.modifiedRange.end === 0 || yamlDocEnd > this.modifiedRange.end ) {
+            this.modifiedRange.end = yamlDocEnd;
         }
     }
-}
 
-async function validateRegex(regex) {
-    const details = await dnr.isRegexSupported({ regex });
-    const result = details.isSupported || details.reason;
-    if ( validatedRegexes.regexes.length > 32 ) {
-        validatedRegexes.regexes.pop();
-        validatedRegexes.results.pop();
+    lineIndentAt(line) {
+        const match = /^(?: {2})*/.exec(line.text);
+        const indent = match !== null ? match[0].length : -1;
+        if ( indent === -1 || (indent & 1) !== 0 ) { return -1; }
+        return indent / 2;
     }
-    validatedRegexes.regexes.unshift(regex);
-    validatedRegexes.results.unshift(result);
-}
 
-const validatedRegexes = {
-    regexes: [],
-    results: [],
-};
-
-/******************************************************************************/
-
-function updateView() {
-    const { doc } = cmRules.state;
-    const changed = doc.toString().trim() !== 
-        lastSavedText.trim();
-    dom.attr('#dnrRulesApply', 'disabled', changed ? null : '');
-    dom.attr('#dnrRulesRevert', 'disabled', changed ? null : '');
-    const { start, end } = modifiedRange;
-    if ( start === -1 || end === -1 ) { return; }
-    modifiedRange.start = modifiedRange.end = -1;
-    self.cm6.lineErrorClear(cmRules, start, end);
-    self.cm6.spanErrorClear(cmRules, start, end);
-    const firstLine = doc.line(start);
-    const lastLine = doc.line(end);
-    const text = doc.sliceString(firstLine.from, lastLine.to);
-    const { bad } = rulesFromText(text);
-    if ( Array.isArray(bad) && bad.length !== 0 ) {
-        self.cm6.lineErrorAdd(cmRules, bad.map(i => i + start));
-    }
-    const entries = self.cm6.findAll(
-        cmRules,
-        '\\bregexFilter: (\\S+)',
-        firstLine.from,
-        lastLine.to
-    );
-    const regexes = [];
-    for ( const entry of entries ) {
-        const regex = entry.match[1];
-        const i = validatedRegexes.regexes.indexOf(regex);
-        if ( i !== -1 ) {
-            const reason = validatedRegexes.results[i];
-            if ( reason === true ) { continue; }
-            self.cm6.spanErrorAdd(cmRules, entry.from+13, entry.to, reason);
-        } else { 
-            regexes.push(regex);
+    getScopeAt(from, doc) {
+        doc ||= this.view.state.doc;
+        const lineFrom = doc.lineAt(from);
+        const out = {};
+        let depth = this.lineIndentAt(lineFrom);
+        if ( depth === -1 ) { return out; }
+        const text = lineFrom.text.trim();
+        if ( text.startsWith('#') ) { return out; }
+        const path = [];
+        const pos = text.indexOf(':');
+        if ( pos !== -1 ) {
+            path.push(text.slice(0, pos+1));
         }
-    }
-    validateRegexes(regexes);
-}
-
-function updateViewAsync() {
-    if ( updateViewAsync.timer !== undefined ) { return; }
-    updateViewAsync.timer = self.setTimeout(( ) => {
-        updateViewAsync.timer = undefined;
-        updateView();
-    }, 71);
-}
-
-/******************************************************************************/
-
-function updateSummaryPanel(info) {
-    self.cm6.showSummaryPanel(cmRules, {
-        template: '.summary-panel',
-        text: i18n$('dnrRulesCountInfo')
-            .replace('{count}', (info.userDnrRuleCount || 0).toLocaleString()),
-    });
-}
-
-function updateFeedbackPanel(info) {
-    const errors = [];
-    if ( Array.isArray(info.errors) ) {
-        info.errors.forEach(e => errors.push(e));
-    }
-    const text = errors.join('\n');
-    self.cm6.showFeedbackPanel(cmRules, { template: '.feedback-panel', text });
-}
-
-/******************************************************************************/
-
-function importRulesFromFile() {
-    const input = qs$('input[type="file"]');
-    input.onchange = ev => {
-        input.onchange = null;
-        const file = ev.target.files[0];
-        if ( file === undefined || file.name === '' ) { return; }
-        if ( file.type !== 'application/json' ) { return; }
-        const fr = new FileReader();
-        fr.onload = ( ) => {
-            if ( typeof fr.result !== 'string' ) { return; }
-            const rules = rulesFromJSON(fr.result);
-            if ( rules === undefined ) { return; }
-            const text = textFromRules(rules);
-            if ( text === undefined ) { return; }
-            const { doc } = cmRules.state;
-            const lastChars = doc.toString().trimEnd().slice(-4);
-            const lastLine = doc.line(doc.lines);
-            let from = lastLine.to;
-            let prepend = '';
-            if ( lastLine.text !== '' ) {
-                prepend = '\n';
+        let lineNo = lineFrom.number;
+        while ( depth > 0 && lineNo > 1 ) {
+            lineNo -= 1;
+            const lineBefore = doc.line(lineNo);
+            const text = lineBefore.text.trim();
+            if ( text.startsWith('#') ) { continue; }
+            if ( this.lineIndentAt(lineBefore) > (depth-1) ) { continue; }
+            const match = /^- ([^:]+:)/.exec(text);
+            if ( match !== null ) {
+                path.unshift(match[1]);
             } else {
-                from = lastLine.from;
+                path.unshift(text);
             }
-            if ( /(?:^|\n)---$/.test(lastChars) === false ) {
-                prepend = `${prepend}---\n`;
+            depth -= 1;
+        }
+        out.scope = path.join('');
+        out.depth = path.length;
+        return out;
+    }
+
+    async saveEditorText() {
+        if ( typeof this.editor.saveEditorText !== 'function' ) { return; }
+        if ( this.editorTextChanged() === false ) { return; }
+        const saved = await this.editor.saveEditorText(this);
+        if ( saved !== true ) { return; }
+        this.lastSavedText = this.normalizeEditorText(this.getEditorText());
+        this.updateView();
+    }
+
+    revertEditorText() {
+        if ( this.editorTextChanged() === false ) { return; }
+        this.setEditorText(this.lastSavedText);
+    }
+
+    smartBackspace(transaction) {
+        const { from, to } = this.rangeFromTransaction(transaction);
+        if ( from === undefined || to === undefined ) { return; }
+        if ( to !== from ) { return; }
+        const { newDoc } = transaction;
+        const line = newDoc.lineAt(from);
+        if ( /^(?: {2})+-$/.test(line.text) === false ) { return; }
+        this.view.dispatch({ changes: { from: from-3, to: from, insert: '' } });
+        return true;
+    }
+
+    lineIsArrayItem(doc, lineNo) {
+        if ( lineNo < 1 || lineNo > doc.lines ) { return false; }
+        const line = doc.line(lineNo);
+        return /^(?: {2})+- /.test(line.text);
+    }
+
+    smartArrayItem(doc, from) {
+        const line = doc.lineAt(from);
+        const blanks = /^ *$/.exec(line.text);
+        if ( blanks === null ) { return; }
+        const lineNumberBefore = line.number - 1;
+        let targetIndent;
+        if ( this.lineIsArrayItem(doc, line.number-1) ) {
+            targetIndent = doc.line(line.number-1).text.indexOf('- ');
+        } else if ( this.lineIsArrayItem(doc, line.number+1) ) {
+            targetIndent = doc.line(line.number+1).text.indexOf('- ');
+        } else if ( this.editor.sequenceScopes && lineNumberBefore !== 0 ) {
+            const lineBefore = doc.line(lineNumberBefore);
+            const { scope, depth } = this.getScopeAt(lineBefore.to, doc);
+            if ( this.editor.sequenceScopes.includes(scope) ) {
+                targetIndent = depth * 2;
             }
-            cmRules.dispatch({ changes: { from, insert: `${prepend}${text}` } });
-            self.cm6.foldAll(cmRules);
-            cmRules.focus();
+        }
+        if ( targetIndent === undefined ) { return; }
+        const indent = targetIndent - blanks[0].length;
+        if ( indent < 0 || indent > 2 ) { return; }
+        return `${' '.repeat(indent)}- `;
+    }
+
+    smartReturn(transaction) {
+        const { from, to } = this.rangeFromTransaction(transaction);
+        if ( from === undefined || to === undefined ) { return; }
+        const { newDoc } = transaction;
+        const insert = this.smartArrayItem(newDoc, to);
+        if ( Boolean(insert) === false ) { return; }
+        this.view.dispatch({
+            changes: { from: to, insert },
+            selection: { anchor: to + insert.length },
+        });
+        return true;
+    }
+
+    smartSpacebar(transaction) {
+        const { from, to } = this.rangeFromTransaction(transaction);
+        if ( from === undefined || to === undefined ) { return; }
+        if ( (to - from) !== 1 ) { return; }
+        const { newDoc } = transaction;
+        const line = newDoc.lineAt(to);
+        const localTo = to - line.from;
+        const before = line.text.slice(0, localTo);
+        if ( /^(?: {1}| {3})$/.test(before) === false ) { return; }
+        const insert = this.smartArrayItem(newDoc, to) || ' ';
+        this.view.dispatch({
+            changes: { from: to, insert },
+            selection: { anchor: to + insert.length },
+        });
+        return true;
+    }
+
+    gutterClick(view, info) {
+        const reSeparator = /^---\s*/;
+        const { doc } = view.state;
+        const lineFirst = doc.lineAt(info.from);
+        if ( lineFirst.text === '' ) { return false; }
+        let { from, to } = lineFirst;
+        if ( reSeparator.test(lineFirst.text) ) {
+            let lineNo = lineFirst.number + 1;
+            while ( lineNo < doc.lines ) {
+                const line = doc.line(lineNo);
+                if ( reSeparator.test(line.text) ) { break; }
+                to = line.to;
+                lineNo += 1;
+            }
+        }
+        view.dispatch({
+            selection: { anchor: from, head: to+1 }
+        });
+        view.focus();
+        return true;
+    }
+
+    importFromFile() {
+        const editor = this.editor;
+        if ( typeof editor.importFromFile !== 'function' ) { return; }
+        const input = qs$('input[type="file"]');
+        input.accept = editor.ioAccept || '';
+        input.onchange = ev => {
+            input.onchange = null;
+            const file = ev.target.files[0];
+            if ( file === undefined || file.name === '' ) { return; }
+            const fr = new FileReader();
+            fr.onload = ( ) => {
+                if ( typeof fr.result !== 'string' ) { return; }
+                editor.importFromFile(this, fr.result);
+            };
+            fr.readAsText(file);
         };
-        fr.readAsText(file);
-    };
-    // Reset to empty string, this will ensure a change event is properly
-    // triggered if the user pick a file, even if it's the same as the last
-    // one picked.
-    input.value = '';
-    input.click();
-}
-
-/******************************************************************************/
-
-function exportRulesToFile() {
-    const text = getEditorText();
-    const { rules } = rulesFromText(text);
-    if ( Array.isArray(rules) === false ) { return; }
-    let ruleId = 1;
-    for ( const rule of rules ) {
-        rule.id = ruleId++;
+        // Reset to empty string, this will ensure a change event is properly
+        // triggered if the user pick a file, even if it's the same as the last
+        // one picked.
+        input.value = '';
+        input.click();
     }
-    const filename = 'my-ubol-dnr-rules.json';
-    const a = document.createElement('a');
-    a.href = `data:application/json;charset=utf-8,${JSON.stringify(rules, null, 2)}`;
-    dom.attr(a, 'download', filename || '');
-    dom.attr(a, 'type', 'application/json');
-    a.click();
-}
 
-/******************************************************************************/
-
-function importRulesFromPaste(transaction) {
-    const { from, to } = rangeFromTransaction(transaction);
-    if ( from === undefined || to === undefined ) { return; }
-    // Paste position must match start of a line
-    const { newDoc } = transaction;
-    const lineFrom = newDoc.lineAt(from);
-    if ( lineFrom.from !== from ) { return; }
-    // Paste position must match a rule boundary
-    if ( lineFrom.number !== 1 ) {
-        const lineBefore = newDoc.line(lineFrom.number-1);
-        if ( /^---\s*$/.test(lineBefore.text) === false ) { return; }
+    exportToFile() {
+        const editor = this.editor;
+        if ( typeof editor.exportToFile !== 'function' ) { return; }
+        const text = this.getEditorText();
+        const result = editor.exportToFile(text);
+        if ( result === undefined ) { return; }
+        const { fname, data, mime } = result;
+        const a = document.createElement('a');
+        a.href = `data:${mime};charset=utf-8,${encodeURIComponent(data)}`;
+        dom.attr(a, 'download', fname || '');
+        dom.attr(a, 'type', mime);
+        a.click();
     }
-    const pastedText = newDoc.sliceString(from, to);
-    const rules = rulesFromJSON(pastedText);
-    if ( rules === undefined ) { return; }
-    const yamlText = textFromRules(rules);
-    if ( yamlText === undefined ) { return; }
-    cmRules.dispatch({ changes: { from, to, insert: yamlText } });
-    self.cm6.foldAll(cmRules);
-    return true;
-}
 
-/******************************************************************************/
-
-function foldService(state, from) {
-    const { doc } = state;
-    const lineFrom = doc.lineAt(from);
-    if ( reFoldable.test(lineFrom.text) === false ) { return null; }
-    if ( lineFrom.number <= 5 ) { return null ; }
-    const lineBlockStart = doc.line(lineFrom.number - 5);
-    if ( reFoldCandidates.test(lineBlockStart.text) === false ) { return null; }
-    for ( let i = lineFrom.number-4; i < lineFrom.number; i++ ) {
-        const line = doc.line(i);
-        if ( reFoldable.test(line.text) === false ) { return null; }
-    }
-    let i = lineFrom.number + 1;
-    for ( ; i <= doc.lines; i++ ) {
-        const lineNext = doc.line(i);
-        if ( reFoldable.test(lineNext.text) === false ) { break; }
-    }
-    i -= 1;
-    if ( i === lineFrom.number ) { return null; }
-    const lineFoldEnd = doc.line(i);
-    return { from: lineFrom.from+6, to: lineFoldEnd.to };
-}
-
-const reFoldable = /^ {4}- \S/;
-const reFoldCandidates = new RegExp(`^(?: {2})+${[
-    'initiatorDomains',
-    'excludedInitiatorDomains',
-    'requestDomains',
-    'excludedRequestDomains',
-].join('|')}:$`);
-
-/******************************************************************************/
-
-function smartBackspace(transaction) {
-    const { from, to } = rangeFromTransaction(transaction);
-    if ( from === undefined || to === undefined ) { return; }
-    if ( to !== from ) { return; }
-    const { newDoc } = transaction;
-    const line = newDoc.lineAt(from);
-    if ( /^(?: {2})+-$/.test(line.text) === false ) { return; }
-    cmRules.dispatch({ changes: { from: from-3, to: from, insert: '' } });
-    return true;
-}
-
-/******************************************************************************/
-
-function lineIsArrayItem(doc, lineNo) {
-    if ( lineNo < 1 || lineNo > doc.lines ) { return false; }
-    const line = doc.line(lineNo);
-    return line.text.startsWith('    - ');
-}
-
-/******************************************************************************/
-
-function smartArrayItem(doc, from) {
-    const line = doc.lineAt(from);
-    if ( lineIsArrayItem(doc, line.number-1) === false ) {
-        if ( lineIsArrayItem(doc, line.number+1) === false ) { return ''; }
-    }
-    const blanks = /^ {2,4}$/.exec(line.text);
-    if ( blanks === null ) { return ''; }
-    const count = blanks[0].length;
-    return `${' '.repeat(4-count)}- `;
-}
-
-/******************************************************************************/
-
-function smartReturn(transaction) {
-    const { from, to } = rangeFromTransaction(transaction);
-    if ( from === undefined || to === undefined ) { return; }
-    const { newDoc } = transaction;
-    const insert = smartArrayItem(newDoc, to);
-    if ( insert === '' ) { return; }
-    cmRules.dispatch({
-        changes: { from: to, insert },
-        selection: { anchor: to + insert.length },
-    });
-    return true;
-}
-
-/******************************************************************************/
-
-function smartSpacebar(transaction) {
-    const { from, to } = rangeFromTransaction(transaction);
-    if ( from === undefined || to === undefined ) { return; }
-    if ( (to - from) !== 1 ) { return; }
-    const { newDoc } = transaction;
-    const line = newDoc.lineAt(to);
-    const localTo = to - line.from;
-    const before = line.text.slice(0, localTo);
-    if ( /^(?: {1}| {3})$/.test(before) === false ) { return; }
-    const insert = smartArrayItem(newDoc, to) || ' ';
-    cmRules.dispatch({
-        changes: { from: to, insert },
-        selection: { anchor: to + insert.length },
-    });
-    return true;
-}
-
-/******************************************************************************/
-
-const dnryamlStreamParser = {
-    name: 'dnryaml',
-    startState() {
-        return {
-            scope: 0,
-            reKeywords: new RegExp(`\\b(${[
-                'block',
-                'redirect',
-                'allow',
-                'modifyHeaders',
-                'upgradeScheme',
-                'allowAllRequest',
-                'append',
-                'set',
-                'remove',
-                'firstParty',
-                'thirdParty',
-                'true',
-                'false',
-                'connect',
-                'delete',
-                'get',
-                'head',
-                'options',
-                'patch',
-                'post',
-                'put',
-                'other',
-                'main_frame',
-                'sub_frame',
-                'stylesheet',
-                'script',
-                'image',
-                'font',
-                'object',
-                'xmlhttprequest',
-                'ping',
-                'csp_report',
-                'media',
-                'websocket',
-                'webtransport',
-                'webbundle',
-                'other',
-            ].join('|')})\\b`),
-        };
-    },
-    token(stream, state) {
-        const c = stream.peek();
-        if ( c === '#' ) {
-            if ( (stream.pos === 0 || /\s/.test(stream.string.charAt(stream.pos - 1))) ) {
-                stream.skipToEnd();
-                return 'comment';
+    streamParser = {
+        startState: ( ) => {
+            return { scope: 0 };
+        },
+        token: (stream, state) => {
+            const c = stream.peek();
+            if ( c === '#' ) {
+                if ( (stream.pos === 0 || /\s/.test(stream.string.charAt(stream.pos - 1))) ) {
+                    stream.skipToEnd();
+                    return 'comment';
+                }
             }
-        }
-        if ( stream.sol() ) {
-            if ( stream.match('---') ) { return 'contentSeparator'; }
-            if ( stream.match('...') ) { return 'contentSeparator'; }
-        }
-        if ( stream.eatSpace() ) {
+            if ( stream.sol() ) {
+                if ( stream.match(/---\s*$/) ) { return 'meta'; }
+                if ( stream.match(/\.\.\.\s*$/) ) { return 'meta'; }
+            }
+            if ( stream.eatSpace() ) {
+                return null;
+            }
+            const { scope } = state;
+            state.scope = 0;
+            if ( scope === 0 && stream.match(/^[^:]+(?=:)/) ) {
+                state.scope = 1;
+                return 'keyword';
+            }
+            if ( scope === 1 && stream.match(/^:(?: |$)/) ) {
+                return 'punctuation';
+            }
+            if ( stream.match(/^- /) ) {
+                return 'punctuation';
+            }
+            if ( this.editor.streamParserKeywords ) {
+                if ( stream.match(this.editor.streamParserKeywords) ) {
+                    return 'literal';
+                }
+            }
+            if ( stream.match(/^\S+/) ) {
+                return null;
+            }
+            stream.next();
             return null;
-        }
-        const { scope } = state;
-        state.scope = 0;
-        if ( scope === 0 && stream.match(/^[^:]+(?=:)/) ) {
-            state.scope = 1;
-            return 'keyword';
-        }
-        if ( scope === 1 && stream.match(/^:(?: |$)/) ) {
-            return 'meta';
-        }
-        if ( stream.match(/^- /) ) {
-            return 'meta';
-        }
-        if ( stream.match(state.reKeywords) ) {
-            return 'literal';
-        }
-        if ( stream.match(/^\S+/) ) {
-            return null;
-        }
-        stream.next();
-        return null;
-    },
-};
-
-/******************************************************************************/
-
-function cmUpdateListener(info) {
-    if ( info.docChanged === false ) { return; }
-    for ( const transaction of info.transactions ) {
-        if ( transaction.docChanged === false ) { continue; }
-        addToModifiedRange(transaction);
-        if ( transaction.isUserEvent('delete.backward') ) {
-            smartBackspace(transaction);
-        } else if ( transaction.isUserEvent('input.paste') ) {
-            importRulesFromPaste(transaction);
-        } else if ( transaction.isUserEvent('input') ) {
-            if ( smartReturn(transaction) ) { continue; }
-            smartSpacebar(transaction);
-        }
-    }
-    updateViewAsync();
-}
-
-/******************************************************************************/
-
-function gutterClick(view, info) {
-    const reSeparator = /^---\s*/;
-    const { doc } = view.state;
-    const lineFirst = doc.lineAt(info.from);
-    if ( lineFirst.text === '' ) { return false; }
-    let { from, to } = lineFirst;
-    if ( reSeparator.test(lineFirst.text) ) {
-        let lineNo = lineFirst.number + 1;
-        while ( lineNo < doc.lines ) {
-            const line = doc.line(lineNo);
-            if ( reSeparator.test(line.text) ) { break; }
-            to = line.to;
-            lineNo += 1;
-        }
-    }
-    view.dispatch({
-        selection: { anchor: from, head: to+1 }
-    });
-    view.focus();
-    return true;
-}
-
-/******************************************************************************/
-
-function hoverTooltip(view, pos, side) {
-    const details = view.domAtPos(pos);
-    const textNode = details.node;
-    if ( textNode.nodeType !== 3 ) { return null; }
-    const { parentElement } = textNode;
-    const targetElement = parentElement.closest('[data-tooltip]');
-    if ( targetElement === null ) { return null; }
-    const tooltipText = targetElement.getAttribute('data-tooltip');
-    if ( Boolean(tooltipText) === false ) { return null; }
-    const start = pos - details.offset;
-    const end = start + textNode.nodeValue.length;
-    if ( start === pos && side < 0 || end === pos && side > 0 ) { return null; }
-    return {
-        above: true,
-        pos: start,
-        end,
-        create() {
-            const template = document.querySelector('.badmark-tooltip');
-            const fragment = template.content.cloneNode(true);
-            const dom = fragment.querySelector('.badmark-tooltip');
-            dom.textContent = tooltipText;
-            return { dom };
         },
     };
+
 }
 
 /******************************************************************************/
 
-let lastSavedText = '';
-
-const cmRules = await localRead('userDnrRules').then(text => {
-    text ||= '';
-
-    const view = self.cm6.createEditorView({
-        text,
-        dnrRules: true,
-        oneDark: dom.cl.has(':root', 'dark'),
-        updateListener: cmUpdateListener,
-        saveListener: ( ) => {
-            saveEditorText();
-        },
-        lineError: true,
-        spanError: true,
-        // https://codemirror.net/examples/autocompletion/
-        autocompletion: {
-            override: [ autoComplete ],
-            activateOnCompletion: ( ) => true,
-        },
-        gutterClick,
-        hoverTooltip,
-        streamParser: dnryamlStreamParser,
-        foldService,
-    }, qs$('#cm-dnrRules'));
-
-    lastSavedText = text;
-    self.cm6.foldAll(view);
-    self.cm6.resetUndoRedo(view);
-
-    browser.storage.onChanged.addListener((changes, area) => {
-        if ( area !== 'local' ) { return; }
-        const { userDnrRuleCount } = changes;
-        if ( userDnrRuleCount instanceof Object === false ) { return; }
-        const { newValue } = changes.userDnrRuleCount;
-        updateSummaryPanel({ userDnrRuleCount: newValue });
+async function start() {
+    const editor = new Editor();
+    await editor.init();
+    dom.on('#editors', 'change', ( ) => {
+        const select = qs$('#editors');
+        const mode = select.value;
+        if ( mode === editor.mode ) { return; }
+        editor.selectEditor(mode);
+        localWrite('dashboard.develop.editor', editor.mode);
     });
+}
 
-    localRead('userDnrRuleCount').then(userDnrRuleCount => {
-        updateSummaryPanel({ userDnrRuleCount })
-    });
-
-    dom.on('#dnrRulesApply', 'click', ( ) => {
-        saveEditorText();
-    });
-    dom.on('#dnrRulesRevert', 'click', ( ) => {
-        setEditorText(lastSavedText);
-        sendMessage({ what: 'updateUserDnrRules' });
-    });
-    dom.on('#dnrRulesImport', 'click', importRulesFromFile);
-    dom.on('#dnrRulesExport', 'click', exportRulesToFile);
-
-    return view;
+let observer = new IntersectionObserver(entries => {
+    for ( const entry of entries ) {
+        if ( entry.isIntersecting === false ) { continue; }
+        start();
+        observer.disconnect();
+        observer = null;
+        break;
+    }
 });
+observer.observe(qs$('section[data-pane="develop"]'));
 
 /******************************************************************************/
diff --git a/platform/mv3/extension/js/dnr-editor.js b/platform/mv3/extension/js/dnr-editor.js
new file mode 100644
index 000000000..4600d552e
--- /dev/null
+++ b/platform/mv3/extension/js/dnr-editor.js
@@ -0,0 +1,180 @@
+/*******************************************************************************
+
+    uBlock Origin Lite - a comprehensive, MV3-compliant content blocker
+    Copyright (C) 2014-present Raymond Hill
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see {http://www.gnu.org/licenses/}.
+
+    Home: https://github.com/gorhill/uBlock
+*/
+
+import { dnr } from './ext-compat.js';
+import { rulesFromText } from './dnr-parser.js';
+
+/******************************************************************************/
+
+export class DNREditor {
+    constructor() {
+        this.validatedRegexes = [];
+        this.validatedRegexResults = [];
+    }
+
+    updateView(editor, firstLine, lastLine) {
+        const { doc } = editor.view.state;
+        const text = doc.sliceString(firstLine.from, lastLine.to);
+        const { bad } = rulesFromText(text);
+        if ( Array.isArray(bad) && bad.length !== 0 ) {
+            self.cm6.lineErrorAdd(editor.view, bad.map(i => i + firstLine.number));
+        }
+        const entries = self.cm6.findAll(
+            editor.view,
+            '\\bregexFilter: (\\S+)',
+            firstLine.from,
+            lastLine.to
+        );
+        const regexes = [];
+        for ( const entry of entries ) {
+            const regex = entry.match[1];
+            const i = this.validatedRegexes.indexOf(regex);
+            if ( i !== -1 ) {
+                const reason = this.validatedRegexResults[i];
+                if ( reason === true ) { continue; }
+                self.cm6.spanErrorAdd(editor.view, entry.from+13, entry.to, reason);
+            } else { 
+                regexes.push(regex);
+            }
+        }
+        this.validateRegexes(editor, regexes);
+    }
+
+    exportToFile(text, fname) {
+        const { rules } = rulesFromText(text);
+        if ( Array.isArray(rules) === false ) { return; }
+        let ruleId = 1;
+        for ( const rule of rules ) {
+            rule.id = ruleId++;
+        }
+        return {
+            fname,
+            data: JSON.stringify(rules, null, 2),
+            mime: 'application/json',
+        };
+    }
+
+    async validateRegexes(editor, regexes) {
+        if ( regexes.length === 0 ) { return; }
+        const promises = regexes.map(regex => this.validateRegex(regex));
+        await Promise.all(promises);
+        for ( const regex of regexes ) {
+            const i = this.validatedRegexes.indexOf(regex);
+            if ( i === -1 ) { continue; }
+            const reason = this.validatedRegexResults[i];
+            if ( reason === true ) { continue; }
+            const entries = self.cm6.findAll(editor.view,
+                `(?<=\\bregexFilter: )${RegExp.escape(regex)}`
+            );
+            for ( const entry of entries ) {
+                self.cm6.spanErrorAdd(editor.view, entry.from, entry.to, reason);
+            }
+        }
+    }
+
+    async validateRegex(regex) {
+        const details = await dnr.isRegexSupported({ regex });
+        const result = details.isSupported || details.reason;
+        if ( this.validatedRegexes.length > 32 ) {
+            this.validatedRegexes.pop();
+            this.validatedRegexResults.pop();
+        }
+        this.validatedRegexes.unshift(regex);
+        this.validatedRegexResults.unshift(result);
+    }
+
+    createTooltipWidget(text) {
+        const template = document.querySelector('.badmark-tooltip');
+        const fragment = template.content.cloneNode(true);
+        const dom = fragment.querySelector('.badmark-tooltip');
+        dom.textContent = text;
+        return dom;
+    }
+
+    foldService(state, from) {
+        const { doc } = state;
+        const lineFrom = doc.lineAt(from);
+        if ( this.reFoldable.test(lineFrom.text) === false ) { return null; }
+        if ( lineFrom.number <= 5 ) { return null ; }
+        const lineBlockStart = doc.line(lineFrom.number - 5);
+        if ( this.reFoldCandidates.test(lineBlockStart.text) === false ) { return null; }
+        for ( let i = lineFrom.number-4; i < lineFrom.number; i++ ) {
+            const line = doc.line(i);
+            if ( this.reFoldable.test(line.text) === false ) { return null; }
+        }
+        let i = lineFrom.number + 1;
+        for ( ; i <= doc.lines; i++ ) {
+            const lineNext = doc.line(i);
+            if ( this.reFoldable.test(lineNext.text) === false ) { break; }
+        }
+        i -= 1;
+        if ( i === lineFrom.number ) { return null; }
+        const lineFoldEnd = doc.line(i);
+        return { from: lineFrom.from+6, to: lineFoldEnd.to };
+    }
+    reFoldable = /^ {4}- \S/;
+    reFoldCandidates = new RegExp(`^(?: {2})+${[
+        'initiatorDomains',
+        'excludedInitiatorDomains',
+        'requestDomains',
+        'excludedRequestDomains',
+    ].join('|')}:$`);
+
+    streamParserKeywords = new RegExp(`\\b(${[
+        'block',
+        'redirect',
+        'allow',
+        'modifyHeaders',
+        'upgradeScheme',
+        'allowAllRequest',
+        'append',
+        'set',
+        'remove',
+        'firstParty',
+        'thirdParty',
+        'true',
+        'false',
+        'connect',
+        'delete',
+        'get',
+        'head',
+        'options',
+        'patch',
+        'post',
+        'put',
+        'other',
+        'main_frame',
+        'sub_frame',
+        'stylesheet',
+        'script',
+        'image',
+        'font',
+        'object',
+        'xmlhttprequest',
+        'ping',
+        'csp_report',
+        'media',
+        'websocket',
+        'webtransport',
+        'webbundle',
+        'other',
+    ].join('|')})\\b`);
+};
diff --git a/platform/mv3/extension/js/dnr-parser.js b/platform/mv3/extension/js/dnr-parser.js
index a852a5f03..37e2d227b 100644
--- a/platform/mv3/extension/js/dnr-parser.js
+++ b/platform/mv3/extension/js/dnr-parser.js
@@ -94,9 +94,15 @@ const perScopeParsers = {
             rule[key] = {};
             scope.push(key);
             break;
+        case 'id': {
+            const n = parseInt(val, 10);
+            if ( isNaN(n) || n < 1) { return false; }
+            rule.id = n;
+            break;
+        }
         case 'priority': {
             const n = parseInt(val, 10);
-            if ( isNaN(n) || n <= 1 ) { return false; }
+            if ( isNaN(n) || n < 1 ) { return false; }
             rule.priority = n;
             break;
         }
@@ -283,6 +289,10 @@ const perScopeParsers = {
             rule.condition[key] = [];
             scope.push(key);
             break;
+        case 'tabIds':
+            rule.condition.tabIds = [];
+            scope.push('tabIds');
+            break;
         default:
             return false;
         }
@@ -412,6 +422,12 @@ const perScopeParsers = {
         item.excludedValues.push(node.val);
         return true;
     },
+    'condition.tabIds': function(scope, rule, node) {
+        if ( node.list !== true ) { return false; }
+        const n = parseInt(node.val, 10);
+        if ( isNaN(n) || n === 0 ) { return false; }
+        rule.condition.tabIds.push(n);
+    },
 };
 
 /******************************************************************************/
@@ -479,16 +495,17 @@ export function rulesFromText(text) {
     const indices = [];
     for ( let i = 0; i < lines.length; i++ ) {
         const line = lines[i].trimEnd();
-        const trimmed = line.trimStart();
-        if ( trimmed.startsWith('#') ) { continue; }
-        // Discard leading empty lines
-        if ( trimmed === '' ) {
-            if ( indices.length === 0 ) { continue; }
-        }
+        if ( line.trim().startsWith('#') ) { continue; }
         if ( line !== '---' && line !== '...' ) {
             indices.push(i);
             continue;
         }
+        // Discard leading empty lines
+        while ( indices.length !== 0 ) {
+            const s = lines[indices[0]].trim();
+            if ( s.length !== 0 ) { break; }
+            indices.shift();
+        }
         // Discard trailing empty lines
         while ( indices.length !== 0 ) {
             const s = lines[indices.at(-1)].trim();
@@ -544,18 +561,21 @@ function textFromValue(val, depth) {
 
 /******************************************************************************/
 
-export function textFromRules(rules) {
+export function textFromRules(rules, option = {}) {
     if ( Array.isArray(rules) === false ) {
         if ( rules instanceof Object === false ) { return; }
         rules = [ rules ];
     }
     const out = [];
     for ( const rule of rules ) {
-        if ( rule.id ) { rule.id = undefined };
+        if ( option.keepId !== true && rule.id ) { rule.id = undefined };
         const text = textFromValue(rule, 0);
         if ( text === undefined ) { continue; }
         out.push(text, '---' );
     }
-    out.push('');
+    if ( out.length !== 0 ) {
+        out.unshift('---');
+        out.push('');
+    }
     return out.join('\n');
 }
diff --git a/platform/mv3/extension/js/mode-editor.js b/platform/mv3/extension/js/mode-editor.js
new file mode 100644
index 000000000..3fc527eff
--- /dev/null
+++ b/platform/mv3/extension/js/mode-editor.js
@@ -0,0 +1,76 @@
+/*******************************************************************************
+
+    uBlock Origin Lite - a comprehensive, MV3-compliant content blocker
+    Copyright (C) 2014-present Raymond Hill
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see {http://www.gnu.org/licenses/}.
+
+    Home: https://github.com/gorhill/uBlock
+*/
+
+import {
+    modesFromText,
+    textFromModes,
+} from './mode-parser.js';
+import { i18n$ } from './i18n.js';
+import { sendMessage } from './ext.js';
+
+/******************************************************************************/
+
+export class ModeEditor {
+    constructor(editor) {
+        this.editor = editor;
+        this.bc = new self.BroadcastChannel('uBOL');
+        this.bc.onmessage = ev => {
+            const message = ev.data;
+            if ( message instanceof Object === false ) { return; }
+            if ( message.filteringModeDetails === undefined ) { return; }
+            // TODO: merge with ongoing edits?
+            const text = textFromModes(message.filteringModeDetails);
+            editor.setEditorText(text, true);
+        };
+    }
+
+    async getText() {
+        const modes = await sendMessage({ what: 'getFilteringModeDetails' });
+        return textFromModes(modes);
+    }
+
+    async saveEditorText(editor) {
+        const { modes } = modesFromText(editor.getEditorText());
+        if ( modes instanceof Object === false ) { return; }
+        const modesAfter = await sendMessage({ what: 'setFilteringModeDetails', modes });
+        const text = textFromModes(modesAfter);
+        editor.setEditorText(text);
+        return true;
+    }
+
+    updateView(editor, firstLine, lastLine) {
+        const { doc } = editor.view.state;
+        const text = doc.sliceString(firstLine.from, lastLine.to);
+        const { bad } = modesFromText(text, true);
+        if ( Array.isArray(bad) && bad.length !== 0 ) {
+            self.cm6.lineErrorAdd(editor.view, bad.map(i => i + firstLine.number));
+        }
+    }
+
+    sequenceScopes = [
+        `${i18n$('filteringMode0Name')}:`, 'none:',
+        `${i18n$('filteringMode1Name')}:`, 'basic:',
+        `${i18n$('filteringMode2Name')}:`, 'optimal:',
+        `${i18n$('filteringMode3Name')}:`, 'complete:',
+    ];
+
+    ioAccept = '.json,application/json';
+};
diff --git a/platform/mv3/extension/js/mode-manager.js b/platform/mv3/extension/js/mode-manager.js
index 6affead57..ae139a825 100644
--- a/platform/mv3/extension/js/mode-manager.js
+++ b/platform/mv3/extension/js/mode-manager.js
@@ -225,7 +225,7 @@ export async function readFilteringModeDetails(bypassCache = false) {
         }
     }
     let [
-        userModes,
+        userModes = { optimal: [ 'all-urls' ] },
         adminDefaultFiltering,
         adminNoFiltering,
     ] = await Promise.all([
@@ -233,9 +233,6 @@ export async function readFilteringModeDetails(bypassCache = false) {
         adminReadEx('defaultFiltering'),
         adminReadEx('noFiltering'),
     ]);
-    if ( userModes === undefined ) {
-        userModes = { optimal: [ 'all-urls' ] };
-    }
     userModes = unserializeModeDetails(userModes);
     if ( adminDefaultFiltering !== undefined ) {
         const modefromName = {
@@ -277,29 +274,34 @@ async function writeFilteringModeDetails(afterDetails) {
     readFilteringModeDetails.cache = unserializeModeDetails(data);
     return Promise.all([
         getDefaultFilteringMode(),
-        getTrustedSites(),
         hasBroadHostPermissions(),
         localWrite('filteringModeDetails', data),
         sessionWrite('filteringModeDetails', data),
     ]).then(results => {
         broadcastMessage({
             defaultFilteringMode: results[0],
-            trustedSites: Array.from(results[1]),
-            hasOmnipotence: results[2],
+            hasOmnipotence: results[1],
+            filteringModeDetails: readFilteringModeDetails.cache,
         });
     });
 }
 
 /******************************************************************************/
 
-export async function getFilteringModeDetails() {
+export async function getFilteringModeDetails(serializable = false) {
     const actualDetails = await readFilteringModeDetails();
-    return {
+    const out = {
         none: new Set(actualDetails.none),
         basic: new Set(actualDetails.basic),
         optimal: new Set(actualDetails.optimal),
         complete: new Set(actualDetails.complete),
     };
+    return serializable ? serializeModeDetails(out) : out;
+}
+
+export async function setFilteringModeDetails(details) {
+    await localWrite('filteringModeDetails', serializeModeDetails(details));
+    await readFilteringModeDetails(true);
 }
 
 /******************************************************************************/
@@ -328,45 +330,6 @@ export function setDefaultFilteringMode(afterLevel) {
 
 /******************************************************************************/
 
-export async function getTrustedSites() {
-    const filteringModes = await getFilteringModeDetails();
-    return filteringModes.none;
-}
-
-export async function setTrustedSites(hostnames) {
-    const [
-        filteringModes,
-        hasOmnipotence,
-    ] = await Promise.all([
-        getFilteringModeDetails(),
-        hasBroadHostPermissions(),
-    ]);
-    const { none } = filteringModes;
-    const hnSet = new Set(hostnames);
-    let modified = false;
-    if ( none.has('all-urls') && hnSet.has('all-urls') === false ) {
-        applyFilteringMode(filteringModes, 'all-urls', hasOmnipotence ? MODE_OPTIMAL : MODE_BASIC);
-        modified = true;
-    }
-    for ( const hn of none ) {
-        if ( hnSet.has(hn) ) {
-            hnSet.delete(hn);
-        } else {
-            none.delete(hn);
-            modified = true;
-        }
-    }
-    for ( const hn of hnSet ) {
-        const level = applyFilteringMode(filteringModes, hn, MODE_NONE);
-        if ( level !== MODE_NONE ) { continue; }
-        modified = true;
-    }
-    if ( modified === false ) { return; }
-    return writeFilteringModeDetails(filteringModes);
-}
-
-/******************************************************************************/
-
 export async function syncWithBrowserPermissions() {
     const [
         permissions,
diff --git a/platform/mv3/extension/js/mode-parser.js b/platform/mv3/extension/js/mode-parser.js
new file mode 100644
index 000000000..719a29efe
--- /dev/null
+++ b/platform/mv3/extension/js/mode-parser.js
@@ -0,0 +1,211 @@
+/*******************************************************************************
+
+    uBlock Origin Lite - a comprehensive, MV3-compliant content blocker
+    Copyright (C) 2014-present Raymond Hill
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see {http://www.gnu.org/licenses/}.
+
+    Home: https://github.com/gorhill/uBlock
+*/
+
+import { i18n$ } from './i18n.js';
+import punycode from './punycode.js';
+
+/******************************************************************************/
+
+function selectParser(scope, modes, node) {
+    const parser = perScopeParsers[scope.join('.')];
+    if ( parser === undefined ) { return false; }
+    return parser(scope, modes, node);
+}
+
+const validModes = [
+    'none',
+    'basic',
+    'optimal',
+    'complete',
+];
+
+const uglyModeNames = {
+    [i18n$('filteringMode0Name')]: 'none',
+    [i18n$('filteringMode1Name')]: 'basic',
+    [i18n$('filteringMode2Name')]: 'optimal',
+    [i18n$('filteringMode3Name')]: 'complete',
+};
+
+const prettyModeNames = {
+    none: i18n$('filteringMode0Name'),
+    basic: i18n$('filteringMode1Name'),
+    optimal: i18n$('filteringMode2Name'),
+    complete: i18n$('filteringMode3Name'),
+};
+
+const perScopeParsers = {
+    '': function(scope, modes, node) {
+        const { key, val } = node;
+        switch ( key ) {
+        case 'none':
+        case 'basic':
+        case 'optimal':
+        case 'complete':
+        case prettyModeNames.none:
+        case prettyModeNames.basic:
+        case prettyModeNames.optimal:
+        case prettyModeNames.complete: {
+            const mode = uglyModeNames[key] || key;
+            if ( val !== undefined ) { return false; }
+            modes[mode] ||= [];
+            scope.push(mode);
+            break;
+        }
+        default:
+            return false;
+        }
+        return true;
+    },
+    none: function(scope, modes, node) {
+        return addHostnameToMode(modes, 'none', node)
+    },
+    basic: function(scope, modes, node) {
+        return addHostnameToMode(modes, 'basic', node)
+    },
+    optimal: function(scope, modes, node) {
+        return addHostnameToMode(modes, 'optimal', node)
+    },
+    complete: function(scope, modes, node) {
+        return addHostnameToMode(modes, 'complete', node)
+    },
+};
+
+const addHostnameToMode = (modes, mode, node) => {
+    if ( node.list !== true ) { return false; }
+    modes[mode].push(punycode.toASCII(node.val));
+};
+
+/******************************************************************************/
+
+function depthFromIndent(line) {
+    const match = /^\s*/.exec(line);
+    const count = match[0].length;
+    if ( (count & 1) !== 0 ) { return -1; }
+    return count / 2;
+}
+
+/******************************************************************************/
+
+function nodeFromLine(line) {
+    const match = reNodeParser.exec(line);
+    const out = {};
+    if ( match === null ) { return out; }
+    if ( match[1] ) {
+        out.list = true;
+    }
+    if ( match[4] ) {
+        out.val = match[4].trim();
+    } else if ( match[3] ) {
+        out.key = match[2];
+        out.val = match[3].trim();
+        if ( out.val === "''" ) { out.val = '' };
+    } else {
+        out.key = match[2];
+    }
+    return out;
+}
+
+const reNodeParser = /^\s*(- )?(?:([^:]+):( \S.*)?|(\S.*))$/;
+
+/******************************************************************************/
+
+export function modesFromText(text, justbad = false) {
+    const lines = [ ...text.split(/\n\r|\r\n|\n|\r/) ];
+    const indices = [];
+    for ( let i = 0; i < lines.length; i++ ) {
+        const line = lines[i].trimEnd();
+        if ( line.trim().startsWith('#') ) { continue; }
+        indices.push(i);
+    }
+    // Discard leading empty lines
+    while ( indices.length !== 0 ) {
+        const s = lines[indices[0]].trim();
+        if ( s.length !== 0 ) { break; }
+        indices.shift();
+    }
+    // Discard trailing empty lines
+    while ( indices.length !== 0 ) {
+        const s = lines[indices.at(-1)].trim();
+        if ( s.length !== 0 ) { break; }
+        indices.pop();
+    }
+    // Parse
+    const modes = {};
+    const bad = [];
+    const scope = [];
+    for ( const i of indices ) {
+        const line = lines[i];
+        const depth = depthFromIndent(line);
+        if ( depth < 0 ) {
+            bad.push(i);
+            continue;
+        }
+        scope.length = depth;
+        const node = nodeFromLine(line);
+        const result = selectParser(scope, modes, node);
+        if ( result === false ) {
+            bad.push(i);
+        }
+    }
+    if ( justbad ) {
+        return bad.length !== 0 ? { bad } : { };
+    }
+    // Ensure all modes are present, and that one mode is the default one
+    const seen = new Map();
+    let defaultMode = '';
+    for ( const mode of validModes ) {
+        modes[mode] = new Set(modes[mode]);
+        if ( modes[mode].has('all-urls') ) {
+            defaultMode = mode;
+        }
+        for ( const hn of modes[mode] ) {
+            if ( seen.has(hn) ) {
+                modes[seen.get(hn)].delete(hn);
+            }
+            seen.set(hn, mode);
+        }
+    }
+    if ( defaultMode === '' ) {
+        defaultMode = 'optimal';
+    }
+    modes[defaultMode].clear();
+    modes[defaultMode].add('all-urls');
+    for ( const mode of validModes ) {
+        modes[mode] = Array.from(modes[mode]);
+    }
+    return { modes };
+}
+
+/******************************************************************************/
+
+export function textFromModes(modes) {
+    const out = [];
+    for ( const mode of validModes ) {
+        const hostnames = modes[mode];
+        if ( hostnames === undefined ) { continue; }
+        out.push(`${prettyModeNames[mode]}:`);
+        for ( const hn of hostnames ) {
+            out.push(`  - ${punycode.toUnicode(hn)}`);
+        }
+    }
+    out.push('');
+    return out.join('\n');
+}
diff --git a/platform/mv3/extension/js/ro-dnr-editor.js b/platform/mv3/extension/js/ro-dnr-editor.js
new file mode 100644
index 000000000..c2e960bc7
--- /dev/null
+++ b/platform/mv3/extension/js/ro-dnr-editor.js
@@ -0,0 +1,95 @@
+/*******************************************************************************
+
+    uBlock Origin Lite - a comprehensive, MV3-compliant content blocker
+    Copyright (C) 2014-present Raymond Hill
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see {http://www.gnu.org/licenses/}.
+
+    Home: https://github.com/gorhill/uBlock
+*/
+
+import { DNREditor } from './dnr-editor.js';
+import { i18n$ } from './i18n.js';
+import { sendMessage } from './ext.js';
+import { textFromRules } from './dnr-parser.js';
+
+/******************************************************************************/
+
+export class ReadOnlyDNREditor extends DNREditor {
+    async getText(hint) {
+        if ( hint === 'dnr.ro.dynamic' ) {
+            const rules = await sendMessage({ what: 'getEffectiveDynamicRules' });
+            if ( Array.isArray(rules) === false ) { return; }
+            this.id = 'dynamic';
+            this.count = rules.length;
+            return textFromRules(rules, { keepId: true });
+        }
+        if ( hint === 'dnr.ro.session' ) {
+            const rules = await sendMessage({ what: 'getEffectiveSessionRules' });
+            if ( Array.isArray(rules) === false ) { return; }
+            this.id = 'session';
+            this.count = rules.length;
+            return textFromRules(rules, { keepId: true });
+        }
+        const match = /^dnr\.ro\.(.+)$/.exec(hint);
+        if ( match === null ) { return; }
+        this.id = match[1];
+        const allRulesetDetails = await sendMessage({ what: 'getRulesetDetails' });
+        const rulesetDetails = allRulesetDetails.find(a => a.id === this.id);
+        if ( rulesetDetails === undefined ) { return; }
+        const realms = {
+            plain: 'main',
+            regex: 'regex',
+            redirect: 'redirect',
+            modifyHeaders: 'modify-headers',
+            removeparam: 'removeparam',
+        };
+        const promises = [];
+        for ( const [ realm, dir ] of Object.entries(realms) ) {
+            if ( Boolean(rulesetDetails.rules?.[realm]) === false ) { continue; }
+            promises.push(
+                fetch(`./rulesets/${dir}/${this.id}.json`).then(response => response.json())
+            );
+        }
+        const parts = await Promise.all(promises);
+        const allRules = [];
+        for ( const rules of parts ) {
+            for ( const rule of rules ) {
+                allRules.push(rule);
+            }
+        }
+        this.count = allRules.length;
+        return textFromRules(allRules, { keepId: true });
+    }
+
+    on(editor) {
+        if ( typeof this.count !== 'number' ) {
+            return editor.updateSummaryPanel(null);
+        }
+        const template = document.querySelector('template.ro-summary-panel');
+        const fragment = template.content.cloneNode(true);
+        const root = fragment.querySelector('.summary-panel');
+        root.textContent = i18n$('dnrRulesCountInfo')
+            .replace('{count}', (this.count || 0).toLocaleString())
+        editor.updateSummaryPanel(root);
+    }
+
+    off(editor) {
+        editor.updateSummaryPanel(null);
+    }
+
+    exportToFile(text) {
+        return super.exportToFile(text, `${this.id}-dnr-ruleset.json`);
+    }
+};
diff --git a/platform/mv3/extension/js/ruleset-manager.js b/platform/mv3/extension/js/ruleset-manager.js
index 16e041f34..d1d9eeb42 100644
--- a/platform/mv3/extension/js/ruleset-manager.js
+++ b/platform/mv3/extension/js/ruleset-manager.js
@@ -306,19 +306,30 @@ async function updateDynamicRules() {
     if ( dynamicRegexCount !== 0 ) {
         ubolLog(`Using ${dynamicRegexCount}/${dnr.MAX_NUMBER_OF_REGEX_RULES} dynamic regex-based DNR rules`);
     }
-    return Promise.all([
-        dnr.updateDynamicRules({ addRules, removeRuleIds }).then(( ) => {
-            if ( removeRuleIds.length !== 0 ) {
-                ubolLog(`Remove ${removeRuleIds.length} dynamic DNR rules`);
-            }
-            if ( addRules.length !== 0 ) {
-                ubolLog(`Add ${addRules.length} dynamic DNR rules`);
-            }
-        }).catch(reason => {
-            console.error(`updateDynamicRules() / ${reason}`);
-        }),
-        updateSessionRules(),
-    ]);
+    try {
+        await dnr.updateDynamicRules({ addRules, removeRuleIds });
+        if ( removeRuleIds.length !== 0 ) {
+            ubolLog(`Remove ${removeRuleIds.length} dynamic DNR rules`);
+        }
+        if ( addRules.length !== 0 ) {
+            ubolLog(`Add ${addRules.length} dynamic DNR rules`);
+        }
+    } catch(reason) {
+        console.error(`updateDynamicRules() / ${reason}`);
+    }
+    await updateSessionRules();
+}
+
+/******************************************************************************/
+
+async function getEffectiveDynamicRules() {
+    const allRules = await dnr.getDynamicRules();
+    const dynamicRules = [];
+    for ( const rule of allRules ) {
+        if ( rule.id >= USER_RULES_BASE_RULE_ID ) { continue; }
+        dynamicRules.push(rule);
+    }
+    return dynamicRules;
 }
 
 /******************************************************************************/
@@ -441,16 +452,29 @@ async function updateSessionRules() {
     if ( sessionRegexCount !== 0 ) {
         ubolLog(`Using ${sessionRegexCount}/${dnr.MAX_NUMBER_OF_REGEX_RULES} session regex-based DNR rules`);
     }
-    return dnr.updateSessionRules({ addRules, removeRuleIds }).then(( ) => {
+    try {
+        await dnr.updateSessionRules({ addRules, removeRuleIds });
         if ( removeRuleIds.length !== 0 ) {
             ubolLog(`Remove ${removeRuleIds.length} session DNR rules`);
         }
         if ( addRules.length !== 0 ) {
             ubolLog(`Add ${addRules.length} session DNR rules`);
         }
-    }).catch(reason => {
+    } catch(reason) {
         console.error(`updateSessionRules() / ${reason}`);
-    });
+    }
+}
+
+/******************************************************************************/
+
+async function getEffectiveSessionRules() {
+    const allRules = await dnr.getSessionRules();
+    const sessionRules = [];
+    for ( const rule of allRules ) {
+        if ( rule.id >= USER_RULES_BASE_RULE_ID ) { continue; }
+        sessionRules.push(rule);
+    }
+    return sessionRules;
 }
 
 /******************************************************************************/
@@ -751,6 +775,8 @@ export {
     enableRulesets,
     excludeFromStrictBlock,
     filteringModesToDNR,
+    getEffectiveDynamicRules,
+    getEffectiveSessionRules,
     getEffectiveUserRules,
     getEnabledRulesetsDetails,
     getRulesetDetails,
diff --git a/platform/mv3/extension/js/rw-dnr-editor.js b/platform/mv3/extension/js/rw-dnr-editor.js
new file mode 100644
index 000000000..a1e317e02
--- /dev/null
+++ b/platform/mv3/extension/js/rw-dnr-editor.js
@@ -0,0 +1,401 @@
+/*******************************************************************************
+
+    uBlock Origin Lite - a comprehensive, MV3-compliant content blocker
+    Copyright (C) 2014-present Raymond Hill
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see {http://www.gnu.org/licenses/}.
+
+    Home: https://github.com/gorhill/uBlock
+*/
+
+import {
+    browser,
+    localRead,
+    localRemove,
+    localWrite,
+    sendMessage,
+} from './ext.js';
+import { dom, qs$ } from './dom.js';
+import { i18n, i18n$ } from './i18n.js';
+import { DNREditor } from './dnr-editor.js';
+import { textFromRules } from './dnr-parser.js';
+
+/******************************************************************************/
+
+export class ReadWriteDNREditor extends DNREditor {
+    constructor(editor) {
+        super();
+        this.feedbackPanel = self.cm6.createViewPanel();
+        editor.panels.push(this.feedbackPanel);
+    }
+
+    async getText() {
+        return localRead('userDnrRules');
+    }
+
+    on(editor) {
+        localRead('userDnrRuleCount').then(userDnrRuleCount => {
+            this.updateSummaryPanel(editor, { userDnrRuleCount })
+        });
+        browser.storage.onChanged.addListener((changes, area) => {
+            if ( area !== 'local' ) { return; }
+            const { userDnrRuleCount } = changes;
+            if ( userDnrRuleCount instanceof Object === false ) { return; }
+            const { newValue } = changes.userDnrRuleCount;
+            this.updateSummaryPanel(editor, { userDnrRuleCount: newValue });
+        });
+    }
+
+    off(editor) {
+        this.updateSummaryPanel(editor, null);
+        this.updateFeedbackPanel(editor, null);
+    }
+
+    rulesFromJSON(json) {
+        let content = json.trim();
+        if ( /^[[{]/.test(content) === false ) {
+            const match = /^[^[{]+/.exec(content);
+            if ( match === null ) { return; }
+            content = content.slice(match[0].length);
+        }
+        const firstChar = content.charAt(0);
+        const expectedLastChar = firstChar === '[' ? ']' : '}';
+        if ( content.at(-1) !== expectedLastChar ) {
+            const re = new RegExp(`\\${expectedLastChar}[^\\${expectedLastChar}]+$`);
+            const match = re.exec(content);
+            if ( match === null ) { return; }
+            content = content.slice(0, match.index+1);
+        }
+        if ( content.startsWith('{') && content.endsWith('}') ) {
+            content = `[${content}]`;
+        }
+        try {
+            const rules = JSON.parse(content);
+            if ( Array.isArray(rules) ) { return rules; }
+        }
+        catch {
+        }
+    }
+
+    getAutocompleteCandidates(editor, from) {
+        const { scope } = editor.getScopeAt(from);
+        switch ( scope ) {
+        case '':
+            return {
+                before: /^$/,
+                candidates: [
+                    { token: 'action:', after: '\n  ' },
+                    { token: 'condition:', after: '\n  ' },
+                    { token: 'priority:', after: ' ' },
+                    { token: '---', after: '\n' },
+                ]
+            };
+        case 'action:':
+            return {
+                before: /^ {2}$/,
+                candidates: [
+                    { token: 'type:', after: ' ' },
+                    { token: 'redirect:', after: '\n    ' },
+                    { token: 'requestHeaders:', after: '\n    - header: ' },
+                    { token: 'responseHeaders:', after: '\n    - header: ' },
+                ],
+            };
+        case 'action:type:':
+            return {
+                before: /: $/,
+                candidates: [
+                    { token: 'block', after: '\n  ' },
+                    { token: 'redirect', after: '\n  ' },
+                    { token: 'allow', after: '\n  ' },
+                    { token: 'modifyHeaders', after: '\n  ' },
+                    { token: 'upgradeScheme', after: '\n  ' },
+                    { token: 'allowAllRequest', after: '\n  ' },
+                ],
+            };
+        case 'action:redirect:':
+            return {
+                before: /^ {4}$/,
+                candidates: [
+                    { token: 'extensionPath:', after: ' ' },
+                    { token: 'regexSubstitution:', after: ' ' },
+                    { token: 'transform:', after: '\n      ' },
+                    { token: 'url:', after: ' ' },
+                ],
+            };
+        case 'action:redirect:transform:':
+            return {
+                before: /^ {6}$/,
+                candidates: [
+                    { token: 'fragment:', after: ' ' },
+                    { token: 'host:', after: ' ' },
+                    { token: 'path:', after: ' ' },
+                    { token: 'port:', after: ' ' },
+                    { token: 'query:', after: ' ' },
+                    { token: 'scheme:', after: ' ' },
+                    { token: 'queryTransform:', after: '\n        ' },
+                ],
+            };
+        case 'action:redirect:transform:queryTransform:':
+            return {
+                before: /^ {8}$/,
+                candidates: [
+                    { token: 'addOrReplaceParams:', after: '\n          - ' },
+                    { token: 'removeParams:', after: '\n          - ' },
+                ],
+            };
+        case 'action:responseHeaders:':
+        case 'action:requestHeaders:':
+            return {
+                before: /^ {4}- $/,
+                candidates: [
+                    { token: 'header:', after: ' ' },
+                ],
+            };
+        case 'action:responseHeaders:header:':
+        case 'action:requestHeaders:header:':
+            return {
+                before: /^ {6}$/,
+                candidates: [
+                    { token: 'operation:', after: ' ' },
+                    { token: 'value:', after: ' ' },
+                ],
+            };
+        case 'action:responseHeaders:header:operation:':
+        case 'action:requestHeaders:header:operation:':
+            return {
+                before: /: $/,
+                candidates: [
+                    { token: 'append', after: '\n      value: ' },
+                    { token: 'set', after: '\n      value: ' },
+                    { token: 'remove', after: '\n    ' },
+                ],
+            };
+        case 'condition:':
+            return {
+                before: /^ {2}$/,
+                candidates: [
+                    { token: 'domainType:', after: ' ' },
+                    { token: 'isUrlFilterCaseSensitive:', after: ' ' },
+                    { token: 'regexFilter:', after: ' ' },
+                    { token: 'urlFilter:', after: ' ' },
+                    { token: 'initiatorDomains:', after: '\n    - ' },
+                    { token: 'excludedInitiatorDomains:', after: '\n    - ' },
+                    { token: 'requestDomains:', after: '\n    - ' },
+                    { token: 'excludedRequestDomains:', after: '\n    - ' },
+                    { token: 'resourceTypes:', after: '\n    - ' },
+                    { token: 'excludedResourceTypes:', after: '\n    - ' },
+                    { token: 'requestMethods:', after: '\n    - ' },
+                    { token: 'excludedRequestMethods:', after: '\n    - ' },
+                    { token: 'responseHeaders:', after: '\n    - ' },
+                    { token: 'excludedResponseHeaders:', after: '\n    - ' },
+                ],
+            };
+        case 'condition:domainType:':
+            return {
+                before: /: $/,
+                candidates: [
+                    { token: 'firstParty', after: '\n  ' },
+                    { token: 'thirdParty', after: '\n  ' },
+                ],
+            };
+        case 'condition:isUrlFilterCaseSensitive:':
+            return {
+                before: /: $/,
+                candidates: [
+                    { token: 'true', after: '\n  ' },
+                    { token: 'false', after: '\n  ' },
+                ],
+            };
+        case 'condition:requestMethods:':
+        case 'condition:excludedRequestMethods:':
+            return {
+                before: /^ {4}- $/,
+                candidates: [
+                    { token: 'connect', after: '\n    - ' },
+                    { token: 'delete', after: '\n    - ' },
+                    { token: 'get', after: '\n    - ' },
+                    { token: 'head', after: '\n    - ' },
+                    { token: 'options', after: '\n    - ' },
+                    { token: 'patch', after: '\n    - ' },
+                    { token: 'post', after: '\n    - ' },
+                    { token: 'put', after: '\n    - ' },
+                    { token: 'other', after: '\n  ' },
+                ],
+            };
+        case 'condition:resourceTypes:':
+        case 'condition:excludedResourceTypes:':
+            return {
+                before: /^ {4}- $/,
+                candidates: [
+                    { token: 'main_frame', after: '\n    - ' },
+                    { token: 'sub_frame', after: '\n    - ' },
+                    { token: 'stylesheet', after: '\n    - ' },
+                    { token: 'script', after: '\n    - ' },
+                    { token: 'image', after: '\n    - ' },
+                    { token: 'font', after: '\n    - ' },
+                    { token: 'object', after: '\n    - ' },
+                    { token: 'xmlhttprequest', after: '\n    - ' },
+                    { token: 'ping', after: '\n    - ' },
+                    { token: 'csp_report', after: '\n    - ' },
+                    { token: 'media', after: '\n    - ' },
+                    { token: 'websocket', after: '\n    - ' },
+                    { token: 'webtransport', after: '\n    - ' },
+                    { token: 'webbundle', after: '\n    - ' },
+                    { token: 'other', after: '\n  ' },
+                ],
+            };
+        }
+    }
+
+    autoComplete(editor, context) {
+        const match = context.matchBefore(/[\w-]*/);
+        if ( match === undefined ) { return null; }
+        const result = this.getAutocompleteCandidates(editor, match.from);
+        if ( result === undefined ) { return null; }
+        if ( result.before !== undefined ) {
+            const { doc } = context.state;
+            const line = doc.lineAt(context.pos);
+            const before = doc.sliceString(line.from, match.from);
+            if ( result.before.test(before) === false ) { return null; }
+        }
+        const filtered = result.candidates.filter(e =>
+            e.token !== match.text || e.after !== '\n'
+        ); 
+        return {
+            from: match.from,
+            options: filtered.map(e => ({ label: e.token, apply: `${e.token}${e.after}` })),
+            validFor: /\w*/,
+        };
+    }
+
+    async saveEditorText(editor) {
+        const text = editor.getEditorText().trim();
+        await (text.length !== 0
+            ? localWrite('userDnrRules', text)
+            : localRemove('userDnrRules')
+        );
+        const response = await sendMessage({ what: 'updateUserDnrRules' })
+        if ( response instanceof Object ) {
+            this.updateFeedbackPanel(editor, response);
+        }
+        return true;
+    }
+
+    updateSummaryPanel(editor, details) {
+        if ( details instanceof Object === false ) {
+            return editor.updateSummaryPanel(null);
+        }
+        const template = document.querySelector('template.summary-panel');
+        const fragment = template.content.cloneNode(true);
+        const root = fragment.querySelector('.summary-panel');
+        i18n.render(root);
+        const info = root.querySelector('.info');
+        info.textContent = i18n$('dnrRulesCountInfo')
+            .replace('{count}', (details.userDnrRuleCount || 0).toLocaleString())
+        editor.updateSummaryPanel(root);
+    }
+
+    updateFeedbackPanel(editor, details) {
+        if ( details instanceof Object === false ) {
+            return this.feedbackPanel.render(editor.view, null);
+        }
+        const errors = [];
+        if ( Array.isArray(details.errors) ) {
+            details.errors.forEach(e => errors.push(e));
+        }
+        const text = errors.join('\n');
+        const config = (( ) => {
+            if ( text === '' ) { return null; }
+            const template = document.querySelector('template.feedback-panel');
+            const fragment = template.content.cloneNode(true);
+            const root = fragment.querySelector('.feedback-panel');
+            const info = root.querySelector('.info');
+            info.textContent = text;
+            const closeFn = this.updateFeedbackPanel.bind(this, editor, null);
+            return {
+                dom: root,
+                mount() {
+                    dom.on(qs$('.feedback-panel .close'), 'click', closeFn);
+                }
+            };
+        })();
+        this.feedbackPanel.render(editor.view, config);
+    }
+
+    importFromFile(editor, json) {
+        const rules = this.rulesFromJSON(json);
+        if ( rules === undefined ) { return; }
+        const text = textFromRules(rules);
+        if ( text === undefined ) { return; }
+        const { doc } = editor.view.state;
+        const lastChars = doc.toString().trimEnd().slice(-4);
+        const lastLine = doc.line(doc.lines);
+        let from = lastLine.to;
+        let prepend = '';
+        if ( lastLine.text !== '' ) {
+            prepend = '\n';
+        } else {
+            from = lastLine.from;
+        }
+        if ( /(?:^|\n)---$/.test(lastChars) === false ) {
+            prepend = `${prepend}---\n`;
+        }
+        editor.view.dispatch({ changes: { from, insert: `${prepend}${text}` } });
+        self.cm6.foldAll(editor.view);
+        editor.view.focus();
+    }
+
+    exportToFile(text) {
+        return super.exportToFile(text, 'my-ubol-dnr-rules.json');
+    }
+
+    importFromPaste(editor, transaction) {
+        const { from, to } = editor.rangeFromTransaction(transaction);
+        if ( from === undefined || to === undefined ) { return; }
+        // Paste position must match start of a line
+        const { newDoc } = transaction;
+        const lineFrom = newDoc.lineAt(from);
+        if ( lineFrom.from !== from ) { return; }
+        // Paste position must match a rule boundary
+        if ( lineFrom.number !== 1 ) {
+            const lineBefore = newDoc.line(lineFrom.number-1);
+            if ( /^---\s*$/.test(lineBefore.text) === false ) { return; }
+        }
+        const pastedText = newDoc.sliceString(from, to);
+        const rules = this.rulesFromJSON(pastedText);
+        if ( rules === undefined ) { return; }
+        const yamlText = textFromRules(rules);
+        if ( yamlText === undefined ) { return; }
+        editor.view.dispatch({ changes: { from, to, insert: yamlText } });
+        self.cm6.foldAll(editor.view);
+        return true;
+    }
+
+    sequenceScopes = [
+        'action:redirect:transform:queryTransform:addOrReplaceParams:',
+        'action:redirect:transform:queryTransform:removeParams:',
+        'condition:resourceTypes:',
+        'condition:excludedResourceTypes:',
+        'condition:initiatorDomains:',
+        'condition:excludedInitiatorDomains:',
+        'condition:requestDomains:',
+        'condition:excludedRequestDomains:',
+        'condition:requestMethods:',
+        'condition:excludedRequestMethods:',
+        'condition:responseHeaders:',
+        'condition:excludedResponseHeaders:',
+    ];
+
+    ioAccept = '.json,application/json';
+};
diff --git a/platform/mv3/extension/js/settings.js b/platform/mv3/extension/js/settings.js
index 10815a9fb..254e321d7 100644
--- a/platform/mv3/extension/js/settings.js
+++ b/platform/mv3/extension/js/settings.js
@@ -22,23 +22,10 @@
 import { browser, sendMessage } from './ext.js';
 import { dom, qs$ } from './dom.js';
 import { hashFromIterable } from './dashboard.js';
-import { i18n$ } from './i18n.js';
-import punycode from './punycode.js';
 import { renderFilterLists } from './filter-lists.js';
 
 /******************************************************************************/
 
-const cm6 = self.cm6;
-
-const cmTrustedSites = (( ) => {
-    const options = {};
-    if ( dom.cl.has(':root', 'dark') ) {
-        options.oneDark = true;
-    }
-    options.placeholder = i18n$('noFilteringModePlaceholder');
-    return cm6.createEditorView(options, qs$('#trustedSites'));
-})();
-
 let cachedRulesetData = {};
 
 /******************************************************************************/
@@ -60,7 +47,6 @@ function renderWidgets() {
     }
 
     renderDefaultMode();
-    renderTrustedSites();
 
     qs$('#autoReload input[type="checkbox"]').checked = cachedRulesetData.autoReload;
 
@@ -175,48 +161,6 @@ dom.on('#developerMode input[type="checkbox"]', 'change', ev => {
 
 /******************************************************************************/
 
-function renderTrustedSites() {
-    const hostnames = cachedRulesetData.trustedSites || [];
-    let text = hostnames.map(hn => punycode.toUnicode(hn)).join('\n');
-    if ( text !== '' ) { text += '\n'; }
-    cmTrustedSites.dispatch({
-        changes: {
-            from: 0, to: cmTrustedSites.state.doc.length,
-            insert: text
-        },
-    });
-}
-
-function changeTrustedSites() {
-    const hostnames = getStagedTrustedSites();
-    const hash = hashFromIterable(cachedRulesetData.trustedSites || []);
-    if ( hashFromIterable(hostnames) === hash ) { return; }
-    sendMessage({
-        what: 'setTrustedSites',
-        hostnames,
-    });
-}
-
-function getStagedTrustedSites() {
-    const text = cmTrustedSites.state.doc.toString();
-    return text.split(/\s/).map(hn => {
-        if ( hn === '' ) { return ''; }
-        try {
-            return punycode.toASCII(
-                (new URL(`https://${hn}/`)).hostname
-            );
-        } catch {
-        }
-        return '';
-    }).filter(hn => hn !== '');
-}
-
-dom.on(cmTrustedSites.contentDOM, 'blur', changeTrustedSites);
-
-self.addEventListener('beforeunload', changeTrustedSites);
-
-/******************************************************************************/
-
 function listen() {
     const bc = new self.BroadcastChannel('uBOL');
     bc.onmessage = listen.onmessage;
@@ -228,21 +172,6 @@ listen.onmessage = ev => {
     const local = cachedRulesetData;
     let render = false;
 
-    // Keep added sites which have not yet been committed
-    if ( message.trustedSites !== undefined ) {
-        if ( hashFromIterable(message.trustedSites) !== hashFromIterable(local.trustedSites) ) {
-            const current = new Set(local.trustedSites);
-            const staged = new Set(getStagedTrustedSites());
-            for ( const hn of staged ) {
-                if ( current.has(hn) === false ) { continue; }
-                staged.delete(hn);
-            }
-            const combined = Array.from(new Set([ ...message.trustedSites, ...staged ]));
-            local.trustedSites = combined;
-            render = true;
-        }
-    }
-
     if ( message.hasOmnipotence !== undefined ) {
         if ( message.hasOmnipotence !== local.hasOmnipotence ) {
             local.hasOmnipotence = message.hasOmnipotence;
diff --git a/platform/mv3/extension/lib/codemirror/codemirror-ubol b/platform/mv3/extension/lib/codemirror/codemirror-ubol
index 4b9666da6..4352f5727 160000
--- a/platform/mv3/extension/lib/codemirror/codemirror-ubol
+++ b/platform/mv3/extension/lib/codemirror/codemirror-ubol
@@ -1 +1 @@
-Subproject commit 4b9666da6d3cf0321493c6a267b11cee88677411
+Subproject commit 4352f572758bc43ebabddb67b98875e8fde7c297
diff --git a/src/js/i18n.js b/src/js/i18n.js
index 2f6f7dc01..6232fdd46 100644
--- a/src/js/i18n.js
+++ b/src/js/i18n.js
@@ -263,6 +263,11 @@ if ( isBackgroundProcess !== true ) {
                 elem.setAttribute('aria-label', text);
             }
         }
+
+        for ( const elem of root.querySelectorAll('[data-i18n-label]') ) {
+            const text = i18n$(elem.getAttribute('data-i18n-label'));
+            elem.setAttribute('label', text);
+        }
     };
 
     i18n.renderElapsedTimeToString = function(tstamp) {