diff --git a/src/components/ScenarioEditor.svelte b/src/components/ScenarioEditor.svelte
new file mode 100644
index 0000000..646fc35
--- /dev/null
+++ b/src/components/ScenarioEditor.svelte
@@ -0,0 +1,325 @@
+<script>
+  import { sanitizeScenario } from "../lib/scenarioUtils.js";
+  /**
+   * Scenario editor with syntax highlighting for IoTManager scenario language.
+   * Uses a mirror div behind a transparent textarea so we don't need CodeMirror.
+   * Paste is sanitized so control chars and wrong line endings don't enter (IoTScenario compatibility).
+   */
+  export let value = "";
+  export let rows = 10;
+  export let placeholder = "";
+  export let disabled = false;
+  /** Optional CSS class for the wrapper */
+  export let className = "";
+
+  const baseClass =
+    "px-2 py-1.5 bg-gray-50 border-2 border-gray-200 rounded text-gray-700 leading-tight focus:outline-none focus:bg-white focus:border-indigo-500 w-full font-mono text-sm resize-none";
+
+  // Keywords and built-ins for IoTManager scenario language
+  const KEYWORDS = new Set([
+    "if",
+    "then",
+    "else",
+    "and",
+    "or",
+    "not",
+  ]);
+  const FUNCTIONS = new Set([
+    "getIP",
+    "getUptime",
+    "getHours",
+    "getMinutes",
+    "getSeconds",
+    "sendMsg",
+    "createItemFromNet",
+  ]);
+
+  function escapeHtml(s) {
+    return s
+      .replace(/&/g, "&amp;")
+      .replace(/</g, "&lt;")
+      .replace(/>/g, "&gt;")
+      .replace(/"/g, "&quot;");
+  }
+
+  function tokenizeLine(line) {
+    const tokens = [];
+    let i = 0;
+    const n = line.length;
+
+    while (i < n) {
+      // Comment from # to EOL
+      if (line[i] === "#") {
+        const start = i;
+        while (i < n) i++;
+        tokens.push({ type: "comment", text: line.slice(start, i) });
+        continue;
+      }
+      // Double-quoted string
+      if (line[i] === '"') {
+        const start = i;
+        i++;
+        while (i < n && line[i] !== '"') {
+          if (line[i] === "\\") i++;
+          i++;
+        }
+        if (i < n) i++;
+        tokens.push({ type: "string", text: line.slice(start, i) });
+        continue;
+      }
+      // Number
+      if (/\d/.test(line[i])) {
+        const start = i;
+        while (i < n && /[\d.]/.test(line[i])) i++;
+        tokens.push({ type: "number", text: line.slice(start, i) });
+        continue;
+      }
+      // Word (identifier / keyword / function)
+      if (/[a-zA-Z_]\w*/.test(line[i]) || (line[i] === "_" && line[i + 1]?.match(/\w/))) {
+        const start = i;
+        while (i < n && /\w/.test(line[i])) i++;
+        const word = line.slice(start, i);
+        let type = "identifier";
+        if (KEYWORDS.has(word)) type = "keyword";
+        else if (FUNCTIONS.has(word)) type = "function";
+        tokens.push({ type, text: word });
+        continue;
+      }
+      // Single character (operator, brace, etc.)
+      tokens.push({ type: "default", text: line[i] });
+      i++;
+    }
+    return tokens;
+  }
+
+  function highlight(text) {
+    if (text == null) text = "";
+    const lines = text.split("\n");
+    const out = [];
+    for (const line of lines) {
+      const tokens = tokenizeLine(line);
+      let lineHtml = "";
+      for (const t of tokens) {
+        const esc = escapeHtml(t.text);
+        lineHtml += `<span class="scn-${t.type}">${esc}</span>`;
+      }
+      out.push(lineHtml);
+    }
+    return out.join("\n");
+  }
+
+  $: highlightedHtml = highlight(value);
+  $: containerStyle = `min-height: calc(1.5em * ${rows} + 1rem);`;
+  $: validation = validateScenario(value);
+
+  const INDENT = "  "; // 2 spaces per level
+
+  /**
+   * Validate scenario: balanced braces { }, no unclosed strings.
+   * Returns { valid: boolean, errors: { line: number, message: string }[] }
+   */
+  function validateScenario(text) {
+    const errors = [];
+    if (!text || typeof text !== "string") return { valid: true, errors };
+
+    const lines = text.split("\n");
+    const stack = []; // { lineNum } for each unmatched {
+
+    for (let lineNum = 1; lineNum <= lines.length; lineNum++) {
+      const line = lines[lineNum - 1];
+      let i = 0;
+      const n = line.length;
+
+      while (i < n) {
+        // Comment: skip to EOL
+        if (line[i] === "#") break;
+        // String: skip to closing "
+        if (line[i] === '"') {
+          i++;
+          while (i < n && line[i] !== '"') {
+            if (line[i] === "\\") i++;
+            i++;
+          }
+          if (i < n) i++;
+          continue;
+        }
+        if (line[i] === "{") {
+          stack.push(lineNum);
+          i++;
+          continue;
+        }
+        if (line[i] === "}") {
+          if (stack.length === 0) {
+            errors.push({ line: lineNum, message: "Лишняя закрывающая скобка }" });
+          } else {
+            stack.pop();
+          }
+          i++;
+          continue;
+        }
+        i++;
+      }
+    }
+
+    while (stack.length > 0) {
+      const openLine = stack.pop();
+      errors.push({ line: openLine, message: "Нет закрывающей скобки } для открывающей {" });
+    }
+
+    // Unclosed string: odd number of " outside comments
+    let quoteCount = 0;
+    for (let lineNum = 0; lineNum < lines.length; lineNum++) {
+      const line = lines[lineNum];
+      for (let i = 0; i < line.length; i++) {
+        if (line[i] === "#") break;
+        if (line[i] === '"') quoteCount++;
+      }
+    }
+    if (quoteCount % 2 !== 0) {
+      errors.push({ line: 1, message: "Незакрытая строка (нечётное число кавычек)" });
+    }
+
+    return { valid: errors.length === 0, errors };
+  }
+
+  /**
+   * Format scenario: indent by block level (then {, else {, }), trim lines, blank line between logical blocks.
+   */
+  function formatScenario(text) {
+    if (!text || typeof text !== "string") return text;
+    const lines = text.split("\n");
+    const out = [];
+    let level = 0;
+
+    for (let i = 0; i < lines.length; i++) {
+      let line = lines[i];
+      const trimmed = line.trim();
+      if (trimmed === "") {
+        out.push("");
+        continue;
+      }
+      // Comment-only: keep as-is with current indent
+      if (trimmed.startsWith("#")) {
+        out.push(INDENT.repeat(level) + trimmed);
+        continue;
+      }
+      // Line that starts with }: decrease level then output
+      if (trimmed.startsWith("}")) {
+        level = Math.max(0, level - 1);
+      }
+      out.push(INDENT.repeat(level) + trimmed);
+      // Line ends with { (e.g. then {, else {): increase level for next
+      if (trimmed.endsWith("{") && !trimmed.startsWith("#")) {
+        level++;
+      }
+    }
+    return out.join("\n");
+  }
+
+  function handleFormat() {
+    value = formatScenario(value);
+  }
+
+  function handleInput(e) {
+    value = e.target.value;
+  }
+
+  function handlePaste(e) {
+    const pasted = (e.clipboardData || window.clipboardData)?.getData("text");
+    if (pasted == null) return;
+    const sanitized = sanitizeScenario(pasted);
+    if (sanitized === pasted) return; // let default paste happen
+    e.preventDefault();
+    const ta = e.target;
+    const start = ta.selectionStart;
+    const end = ta.selectionEnd;
+    value = value.slice(0, start) + sanitized + value.slice(end);
+    const newPos = start + sanitized.length;
+    setTimeout(() => ta.setSelectionRange(newPos, newPos), 0);
+  }
+</script>
+
+<div
+  class="scenario-editor relative {className}"
+  style={containerStyle}
+>
+  <div class="scenario-toolbar flex justify-end mb-1">
+    <button
+      type="button"
+      class="text-sm px-2 py-1 rounded border border-gray-300 bg-gray-100 hover:bg-gray-200 text-gray-700"
+      on:click={handleFormat}
+      title="Format scenario (indent blocks)"
+    >Форматировать</button>
+  </div>
+  <div class="scenario-editor-area relative" style={containerStyle}>
+    <!-- Mirror: highlighted content behind -->
+    <pre
+      class="scenario-mirror {baseClass}"
+      aria-hidden="true"
+      style="margin:0; overflow:auto; white-space: pre; position:absolute; inset:0;"
+    >{@html highlightedHtml}</pre>
+
+    <!-- Textarea on top: transparent text, caret visible -->
+    <textarea
+      class="scenario-input {baseClass}"
+      style="position:absolute; inset:0; color:transparent; caret-color: #374151; background:transparent; white-space: pre;"
+      wrap="off"
+      {rows}
+      {placeholder}
+      {disabled}
+      value={value}
+      on:input={handleInput}
+      on:scroll={(e) => {
+        const mirror = e.target.previousElementSibling;
+        if (mirror) {
+          mirror.scrollTop = e.target.scrollTop;
+          mirror.scrollLeft = e.target.scrollLeft;
+        }
+      }}
+    ></textarea>
+  </div>
+  {#if validation.errors.length > 0}
+    <div class="scenario-errors mt-2 px-2 py-1.5 rounded border border-red-300 bg-red-50 text-red-800 text-sm">
+      <div class="font-semibold mb-1">Ошибки синтаксиса:</div>
+      <ul class="list-disc list-inside space-y-0.5">
+        {#each validation.errors as err}
+          <li>Строка {err.line}: {err.message}</li>
+        {/each}
+      </ul>
+    </div>
+  {/if}
+</div>
+
+<style>
+  .scenario-editor .scenario-mirror {
+    pointer-events: none;
+    min-height: 100%;
+  }
+  .scenario-editor .scenario-input {
+    resize: none;
+  }
+  /* IoTManager scenario syntax colors */
+  :global(.scn-comment) {
+    color: #a1a1aa;
+    font-style: italic;
+  }
+  :global(.scn-string) {
+    color: #b45309;
+  }
+  :global(.scn-keyword) {
+    color: #7c3aed;
+    font-weight: 600;
+  }
+  :global(.scn-function) {
+    color: #0d9488;
+  }
+  :global(.scn-number) {
+    color: #059669;
+  }
+  :global(.scn-identifier) {
+    color: #1e40af;
+  }
+  :global(.scn-default) {
+    color: #374151;
+  }
+</style>
diff --git a/src/lib/WebSocketManager.js b/src/lib/WebSocketManager.js
index 02e8fdb..a398226 100644
--- a/src/lib/WebSocketManager.js
+++ b/src/lib/WebSocketManager.js
@@ -8,6 +8,7 @@ import * as deviceConnection from "./deviceConnection.js";
 import * as deviceListManager from "./deviceListManager.js";
 import * as blobProtocol from "./blobProtocol.js";
 import * as wsReconnect from "./wsReconnect.js";
+import { sanitizeScenario } from "./scenarioUtils.js";
 import { eventEmitter } from "../eventEmitter.js";
 
 const LOG_MAX_MESSAGES = 100;
@@ -536,7 +537,7 @@ export default class WebSocketManager {
     this.wsSendMsg(this.selectedWs, "/tuoyal|" + JSON.stringify(this.generateLayout()));
     this._modify();
     this.wsSendMsg(this.selectedWs, "/gifnoc|" + JSON.stringify(this.configJson));
-    this.wsSendMsg(this.selectedWs, "/oiranecs|" + this.scenarioTxt);
+    this.wsSendMsg(this.selectedWs, "/oiranecs|" + sanitizeScenario(this.scenarioTxt));
     this.clearData();
     this.sendCurrentPageNameToSelectedWs();
   }
diff --git a/src/lib/scenarioUtils.js b/src/lib/scenarioUtils.js
new file mode 100644
index 0000000..808feb5
--- /dev/null
+++ b/src/lib/scenarioUtils.js
@@ -0,0 +1,23 @@
+/**
+ * Scenario text sanitization for IoTManager backend compatibility.
+ * Matches IoTScenario.cpp lexer: file is read byte-by-byte; isspace() and ';' are skipped;
+ * comments # to EOL; strings "..."; identifiers [a-zA-Z_][a-zA-Z0-9_]*; other ASCII as tokens.
+ * We normalize line endings and remove control chars that would break the parser.
+ */
+
+/**
+ * Sanitize scenario text before sending to device (/oiranecs|).
+ * - Normalize line endings to LF (\n): \r\n and \r -> \n
+ * - Remove control characters (0x00-0x1F) except \n (10) and \t (9)
+ * So no NUL, no other control chars; backend expects printable ASCII + \n \t in code.
+ * @param {string} text - raw scenario text
+ * @returns {string} sanitized text safe for IoTScenario parser
+ */
+export function sanitizeScenario(text) {
+  if (text == null || typeof text !== "string") return "";
+  // Normalize line endings to \n only (backend counts curLine on LastChar == 10)
+  let out = text.replace(/\r\n/g, "\n").replace(/\r/g, "\n");
+  // Remove control chars except \t (9) and \n (10)
+  out = out.replace(/[\x00-\x08\x0B\x0C\x0E-\x1F]/g, "");
+  return out;
+}
diff --git a/src/pages/Config.svelte b/src/pages/Config.svelte
index 1d46c3b..6422c7b 100644
--- a/src/pages/Config.svelte
+++ b/src/pages/Config.svelte
@@ -1,5 +1,6 @@
 <script>
   import Card from "../components/Card.svelte";
+  import ScenarioEditor from "../components/ScenarioEditor.svelte";
   import CrossIcon from "../svg/Cross.svelte";
   import OpenIcon from "../svg/Open.svelte";
   import Alarm from "../components/Alarm.svelte";
@@ -337,7 +338,7 @@
       </Card>
 
       <Card title="Сценарии">
-        <textarea bind:value={scenarioTxt} rows={height} class="px-2 bg-gray-50 border-2 border-gray-200 rounded text-gray-700 leading-tight focus:outline-none focus:bg-white focus:border-indigo-500 w-full" />
+        <ScenarioEditor bind:value={scenarioTxt} rows={height} />
       </Card>
     </div>
   </div>