diff --git a/README.md b/README.md
index c7c7d0c..5dcc9c4 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,10 @@
-# Web MVP: AI Project Editor (Frontend-only)
+# Web MVP: AI Project Editor (Frontend)
 
-Локальный frontend MVP без backend API.
+## Текущий режим
+
+Frontend подключен к реальному backend API (без mock-клиентов).
+
+По умолчанию используется `http://localhost:8081`.
 
 ## Что реализовано
 
@@ -17,51 +21,37 @@
 - Центральная панель: только вкладки открытых файлов и просмотр содержимого.
 - Правая панель: чат + ревью изменений (diff, accept/reject/apply).
 - Ресайз 3 колонок с дефолтными ширинами `15% / 65% / 20%`.
-- Темная тема по умолчанию (темно-синий акцент).
-- Mock индексация: snapshot/changes статусы в UI.
-- Mock чат-агент:
-  - `/demo-update <path>` генерирует `update` для файла.
-  - `/changeset { ... }` принимает raw JSON и строит review.
+- Интеграция с backend:
+  - `POST /api/rag/sessions` + polling `GET /api/rag/sessions/{rag_session_id}/jobs/{index_job_id}`
+  - `POST /api/chat/dialogs`
+  - `POST /api/chat/messages` + polling `GET /api/tasks/{id}`
 - Валидация `changeset` по обязательным полям (`create/update/delete`).
 - Статусы review: `pending`, `accepted_partial`, `accepted_full`, `rejected`, `conflict`, `applied`.
 - `Apply accepted` с повторной hash-проверкой до записи и подтверждением удаления.
 - Без git-операций и без автоприменения правок.
 
-## Запуск через Docker Compose
+## Запуск
+
+1. Запустите backend:
+
+```bash
+cd "/Users/alex/Dev_projects_v2/ai driven app process/v2/agent"
+docker compose up --build
+```
+
+2. Запустите web_app:
 
 ```bash
 cd "/Users/alex/Dev_projects_v2/ai driven app process/v2/web_app"
 docker compose up --build
 ```
 
-Открыть: `http://localhost:8080`
+Открыть frontend: `http://localhost:8080`
 
-## Локальный запуск без Docker
 
-```bash
-cd "/Users/alex/Dev_projects_v2/ai driven app process/v2/web_app"
-python3 -m http.server 8080
-```
+Проект разработан при помощи codex 2026.02.23
+Автор проекта Семенов Семен
+новые изменения
 
-Открыть: `http://localhost:8080`
 
-## Пример changeset
 
-```json
-{
-  "changeset": [
-    {
-      "op": "create",
-      "path": "notes/new_doc.md",
-      "proposed_content": "# New doc\\nhello",
-      "reason": "demo"
-    }
-  ]
-}
-```
-
-В чат отправить:
-
-```text
-/changeset {"changeset":[{"op":"create","path":"notes/new_doc.md","proposed_content":"# New doc\\nhello","reason":"demo"}]}
-```
diff --git a/index.html b/index.html
index 440edc4..a6507ec 100644
--- a/index.html
+++ b/index.html
@@ -14,12 +14,16 @@
           <h2>Проект</h2>
         </div>
         <div class="row-controls">
-          <label for="pick-project-fallback" class="picker-label">Выбрать директорию</label>
+          <label id="pick-project-label" for="pick-project-fallback" class="picker-label">Выбрать директорию</label>
           <input id="pick-project-fallback" class="picker-input" type="file" webkitdirectory directory multiple />
         </div>
         <div id="tree-root" class="scroll"></div>
-        <div class="editor-footer">
-          <span id="tree-info" class="editor-info">Файлов: 0 • 0 KB</span>
+        <div class="editor-footer tree-footer">
+          <span id="tree-info" class="editor-info tree-footer-line">Файлов: 0 • 0 KB</span>
+          <span id="rag-status" class="rag-status tree-footer-line" title="Статус индексации RAG">
+            <span id="rag-status-dot" class="rag-dot rag-red" aria-hidden="true"></span>
+            <span id="rag-status-text">RAG</span>
+          </span>
         </div>
       </section>
 
@@ -32,14 +36,26 @@
         <div class="row-controls tabs-row">
           <div id="file-tabs" class="tabs"></div>
           <button id="new-text-tab" type="button" class="new-tab-btn" title="Новая вкладка .md">+MD</button>
-          <button id="md-toggle-mode" type="button" class="md-toggle hidden" title="Переключить режим markdown">👁</button>
+          <button id="md-toggle-mode" type="button" class="md-toggle" title="Режим markdown" disabled>👁</button>
         </div>
         <div class="editor-workspace">
           <textarea id="file-editor" class="file-editor large" spellcheck="false"></textarea>
           <div id="file-editor-monaco" class="file-editor monaco-host large hidden"></div>
           <div id="md-preview" class="md-preview large hidden"></div>
+          <div class="review-wrap editor-review hidden">
+            <h2>Ревью изменений</h2>
+            <div id="review-toolbar" class="toolbar hidden">
+              <button id="accept-file">Accept file</button>
+              <button id="reject-file">Reject file</button>
+              <button id="accept-selected">Accept selected</button>
+              <button id="reject-selected">Reject selected</button>
+              <button id="apply-accepted">Apply accepted</button>
+            </div>
+            <div id="change-list" class="change-list"></div>
+            <div id="diff-view" class="diff-view"></div>
+          </div>
         </div>
-        <div class="editor-footer">
+        <div id="editor-footer-main" class="editor-footer">
           <span id="editor-info" class="editor-info">Файл не выбран</span>
           <div class="editor-actions">
             <button id="save-file" type="button" disabled>Сохранить</button>
@@ -64,21 +80,24 @@
             <button type="submit">Отправить</button>
           </form>
         </div>
-
-        <div class="review-wrap hidden">
-          <h2>Ревью изменений</h2>
-          <div id="review-toolbar" class="toolbar hidden">
-            <button id="accept-file">Accept file</button>
-            <button id="reject-file">Reject file</button>
-            <button id="accept-selected">Accept selected</button>
-            <button id="reject-selected">Reject selected</button>
-            <button id="apply-accepted">Apply accepted</button>
-          </div>
-          <div id="change-list" class="change-list"></div>
-          <div id="diff-view" class="diff-view"></div>
-        </div>
       </section>
     </main>
+    <div id="indexing-modal" class="indexing-modal hidden" role="dialog" aria-modal="true" aria-live="polite">
+      <div class="indexing-card">
+        <h3>Индексация проекта в RAG</h3>
+        <div class="indexing-row">
+          <span class="indexing-label">Текущий файл:</span>
+          <span id="indexing-file" class="indexing-value">—</span>
+        </div>
+        <div class="indexing-row">
+          <span class="indexing-label">Осталось:</span>
+          <span id="indexing-remaining" class="indexing-value">—</span>
+        </div>
+        <div class="indexing-progress">
+          <div id="indexing-progress-bar" class="indexing-progress-bar"></div>
+        </div>
+      </div>
+    </div>
 
     <script type="module" src="./src/main.js"></script>
   </body>
diff --git a/src/core/ApiHttpClient.js b/src/core/ApiHttpClient.js
new file mode 100644
index 0000000..d9cbfcf
--- /dev/null
+++ b/src/core/ApiHttpClient.js
@@ -0,0 +1,23 @@
+export class ApiHttpClient {
+  constructor(baseUrl = null) {
+    const envBase = window.__API_BASE_URL__ || null;
+    this.baseUrl = (baseUrl || envBase || "http://localhost:8081").replace(/\/$/, "");
+  }
+
+  async request(path, options = {}) {
+    const response = await fetch(`${this.baseUrl}${path}`, {
+      ...options,
+      headers: {
+        "Content-Type": "application/json",
+        ...(options.headers || {})
+      }
+    });
+    const isJson = (response.headers.get("content-type") || "").includes("application/json");
+    const body = isJson ? await response.json() : null;
+    if (!response.ok) {
+      const desc = body?.desc || body?.detail || `HTTP ${response.status}`;
+      throw new Error(desc);
+    }
+    return body;
+  }
+}
diff --git a/src/core/ChatClientApi.js b/src/core/ChatClientApi.js
new file mode 100644
index 0000000..30f29a5
--- /dev/null
+++ b/src/core/ChatClientApi.js
@@ -0,0 +1,45 @@
+import { ApiHttpClient } from "./ApiHttpClient.js";
+
+export class ChatClientApi {
+  constructor(http = new ApiHttpClient(), pollMs = 700, timeoutMs = 120000) {
+    this.http = http;
+    this.pollMs = pollMs;
+    this.timeoutMs = timeoutMs;
+  }
+
+  async createDialog(ragSessionId) {
+    const response = await this.http.request("/api/chat/dialogs", {
+      method: "POST",
+      body: JSON.stringify({ rag_session_id: ragSessionId })
+    });
+    return response.dialog_session_id;
+  }
+
+  async sendMessage(payload) {
+    const queued = await this.http.request("/api/chat/messages", {
+      method: "POST",
+      body: JSON.stringify({
+        dialog_session_id: payload.dialog_session_id,
+        rag_session_id: payload.rag_session_id,
+        message: payload.message,
+        attachments: payload.attachments || []
+      })
+    });
+
+    const taskId = queued.task_id;
+    const started = Date.now();
+    while (Date.now() - started < this.timeoutMs) {
+      const status = await this.http.request(`/api/tasks/${encodeURIComponent(taskId)}`);
+      if (status.status === "done") return status;
+      if (status.status === "error") {
+        throw new Error(status.error?.desc || "Task failed");
+      }
+      await this.#sleep(this.pollMs);
+    }
+    throw new Error("Task polling timeout");
+  }
+
+  #sleep(ms) {
+    return new Promise((resolve) => setTimeout(resolve, ms));
+  }
+}
diff --git a/src/core/FileSaveService.js b/src/core/FileSaveService.js
index 0226e7d..824b0d5 100644
--- a/src/core/FileSaveService.js
+++ b/src/core/FileSaveService.js
@@ -37,6 +37,45 @@ export class FileSaveService {
     return { mode: "download", path: normalizedPath };
   }
 
+  async saveExistingFile(projectStore, path, content) {
+    const normalizedPath = PathUtils.normalizeRelative(path);
+    if (projectStore.rootHandle) {
+      await this.#writeWithRootHandle(projectStore.rootHandle, normalizedPath, content);
+      return { mode: "inplace", path: normalizedPath };
+    }
+
+    const knownHandle = projectStore.fileHandles.get(normalizedPath) || this.fallbackHandles.get(normalizedPath);
+    if (knownHandle && typeof knownHandle.createWritable === "function") {
+      await this.#writeWithFileHandle(knownHandle, content);
+      return { mode: "inplace", path: normalizedPath };
+    }
+
+    throw new Error("Нет доступа к существующему файлу для записи без выбора новой директории.");
+  }
+
+  async saveNewFileWithPicker(projectStore, suggestedPath, content) {
+    if (typeof window.showSaveFilePicker !== "function") {
+      throw new Error("showSaveFilePicker is not supported");
+    }
+    const normalizedPath = PathUtils.normalizeRelative(suggestedPath);
+    const pickerOptions = {
+      suggestedName: PathUtils.basename(normalizedPath),
+      id: this.#buildProjectSaveId(projectStore)
+    };
+    if (projectStore.rootHandle) pickerOptions.startIn = projectStore.rootHandle;
+
+    const handle = await window.showSaveFilePicker(pickerOptions);
+    await this.#writeWithFileHandle(handle, content);
+
+    const resolvedPath = await this.#resolveRelativePath(projectStore.rootHandle, handle);
+    if (!resolvedPath) {
+      throw new Error("Выберите путь внутри директории проекта.");
+    }
+
+    this.fallbackHandles.set(resolvedPath, handle);
+    return { mode: "save_as", path: resolvedPath };
+  }
+
   async deleteFile(projectStore, path) {
     const normalizedPath = PathUtils.normalizeRelative(path);
     if (!projectStore.rootHandle) return false;
@@ -89,4 +128,11 @@ export class FileSaveService {
     const normalized = projectName.toLowerCase().replaceAll(/[^a-z0-9_-]/g, "-").replaceAll(/-+/g, "-");
     return `save-${normalized || "project"}`;
   }
+
+  async #resolveRelativePath(rootHandle, fileHandle) {
+    if (!rootHandle || typeof rootHandle.resolve !== "function") return fileHandle?.name || "";
+    const parts = await rootHandle.resolve(fileHandle);
+    if (!Array.isArray(parts) || !parts.length) return "";
+    return PathUtils.normalizeRelative(parts.join("/"));
+  }
 }
diff --git a/src/core/IndexingClientApi.js b/src/core/IndexingClientApi.js
new file mode 100644
index 0000000..459c4cc
--- /dev/null
+++ b/src/core/IndexingClientApi.js
@@ -0,0 +1,46 @@
+import { ApiHttpClient } from "./ApiHttpClient.js";
+
+export class IndexingClientApi {
+  constructor(http = new ApiHttpClient(), pollMs = 700, timeoutMs = 120000) {
+    this.http = http;
+    this.pollMs = pollMs;
+    this.timeoutMs = timeoutMs;
+  }
+
+  async submitSnapshot(projectId, files) {
+    const queued = await this.http.request("/api/rag/sessions", {
+      method: "POST",
+      body: JSON.stringify({ project_id: projectId, files })
+    });
+    const status = await this.#pollRagJob(queued.rag_session_id, queued.index_job_id);
+    return { ...status, rag_session_id: queued.rag_session_id };
+  }
+
+  async submitChanges(ragSessionId, changedFiles) {
+    const queued = await this.http.request(`/api/rag/sessions/${encodeURIComponent(ragSessionId)}/changes`, {
+      method: "POST",
+      body: JSON.stringify({ changed_files: changedFiles })
+    });
+    const status = await this.#pollRagJob(ragSessionId, queued.index_job_id);
+    return { ...status, rag_session_id: ragSessionId };
+  }
+
+  async #pollRagJob(ragSessionId, jobId) {
+    const started = Date.now();
+    while (Date.now() - started < this.timeoutMs) {
+      const status = await this.http.request(
+        `/api/rag/sessions/${encodeURIComponent(ragSessionId)}/jobs/${encodeURIComponent(jobId)}`
+      );
+      if (status.status === "done") return status;
+      if (status.status === "error") {
+        throw new Error(status.error?.desc || "Indexing failed");
+      }
+      await this.#sleep(this.pollMs);
+    }
+    throw new Error("Index polling timeout");
+  }
+
+  #sleep(ms) {
+    return new Promise((resolve) => setTimeout(resolve, ms));
+  }
+}
diff --git a/src/core/MarkdownRenderer.js b/src/core/MarkdownRenderer.js
index ce2971e..24b1a1a 100644
--- a/src/core/MarkdownRenderer.js
+++ b/src/core/MarkdownRenderer.js
@@ -4,11 +4,20 @@ export class MarkdownRenderer {
     const lines = source.replace(/\r\n/g, "\n").split("\n");
     let html = "";
     let inCode = false;
+    let codeFenceLang = "";
 
     for (const line of lines) {
       if (line.startsWith("```")) {
+        const fenceLang = this.#sanitizeCodeLang(line.slice(3).trim().toLowerCase());
         inCode = !inCode;
-        html += inCode ? "<pre><code>" : "</code></pre>";
+        if (inCode) {
+          codeFenceLang = fenceLang;
+          const className = codeFenceLang ? ` class="language-${codeFenceLang}"` : "";
+          html += `<pre><code${className}>`;
+        } else {
+          html += "</code></pre>";
+          codeFenceLang = "";
+        }
         continue;
       }
 
@@ -57,4 +66,10 @@ export class MarkdownRenderer {
       .replaceAll('"', "&quot;")
       .replaceAll("'", "&#39;");
   }
+
+  #sanitizeCodeLang(value) {
+    return String(value || "")
+      .replace(/[^a-z0-9_-]/g, "")
+      .slice(0, 24);
+  }
 }
diff --git a/src/core/MermaidRenderer.js b/src/core/MermaidRenderer.js
new file mode 100644
index 0000000..ada5b7a
--- /dev/null
+++ b/src/core/MermaidRenderer.js
@@ -0,0 +1,56 @@
+export class MermaidRenderer {
+  constructor() {
+    this.mermaid = null;
+    this.loadPromise = null;
+  }
+
+  async render(container) {
+    if (!container) return;
+    const codeNodes = [...container.querySelectorAll("pre > code.language-mermaid")];
+    if (!codeNodes.length) return;
+
+    const mermaid = await this.#ensureLoaded();
+    if (!mermaid) return;
+
+    for (const code of codeNodes) {
+      const pre = code.parentElement;
+      if (!pre) continue;
+      const diagram = document.createElement("div");
+      diagram.className = "mermaid";
+      diagram.textContent = code.textContent || "";
+      pre.replaceWith(diagram);
+    }
+
+    const nodes = [...container.querySelectorAll(".mermaid")];
+    if (!nodes.length) return;
+
+    try {
+      await mermaid.run({ nodes, suppressErrors: true });
+    } catch {
+      for (const node of nodes) {
+        if (node.querySelector("svg")) continue;
+        node.classList.add("mermaid-error");
+      }
+    }
+  }
+
+  async #ensureLoaded() {
+    if (this.mermaid) return this.mermaid;
+    if (this.loadPromise) return this.loadPromise;
+
+    this.loadPromise = import("https://cdn.jsdelivr.net/npm/mermaid@11/dist/mermaid.esm.min.mjs")
+      .then((module) => {
+        const mermaid = module.default || module;
+        mermaid.initialize({
+          startOnLoad: false,
+          theme: "dark",
+          securityLevel: "loose"
+        });
+        this.mermaid = mermaid;
+        return mermaid;
+      })
+      .catch(() => null);
+
+    return this.loadPromise;
+  }
+}
diff --git a/src/core/ProjectScanner.js b/src/core/ProjectScanner.js
index c3fae69..33bb71f 100644
--- a/src/core/ProjectScanner.js
+++ b/src/core/ProjectScanner.js
@@ -6,16 +6,16 @@ export class ProjectScanner {
     this.hashService = hashService;
   }
 
-  async scan(rootHandle) {
+  async scan(rootHandle, onProgress = null) {
     const rootNode = { name: rootHandle.name, path: "", type: "dir", children: [] };
     const files = new Map();
     const fileHandles = new Map();
-    const stats = { totalFileCount: 0, totalBytes: 0 };
-    await this.#scanDir(rootHandle, "", rootNode, files, fileHandles, stats);
+    const stats = { totalFileCount: 0, totalBytes: 0, scannedCount: 0 };
+    await this.#scanDir(rootHandle, "", rootNode, files, fileHandles, stats, onProgress);
     return { rootNode, files, fileHandles, projectName: rootHandle.name, ...stats };
   }
 
-  async scanFromFileList(fileList) {
+  async scanFromFileList(fileList, onProgress = null) {
     const entries = [];
     for (const file of fileList) {
       const relRaw = file.webkitRelativePath || file.name;
@@ -36,9 +36,13 @@ export class ProjectScanner {
     const files = new Map();
     let totalBytes = 0;
 
-    for (const entry of entries) {
+    for (let i = 0; i < entries.length; i += 1) {
+      const entry = entries[i];
       const relativePath = this.#stripPrefix(entry.path, rootPrefix);
       if (!relativePath) continue;
+      if (typeof onProgress === "function") {
+        onProgress({ path: relativePath, done: i + 1, total: entries.length });
+      }
 
       totalBytes += Number(entry.file.size || 0);
       this.#insertPath(rootNode, relativePath, entry.file.size);
@@ -61,7 +65,7 @@ export class ProjectScanner {
     };
   }
 
-  async #scanDir(dirHandle, currentPath, node, files, fileHandles, stats) {
+  async #scanDir(dirHandle, currentPath, node, files, fileHandles, stats, onProgress) {
     for await (const [name, handle] of dirHandle.entries()) {
       const relPath = currentPath ? `${currentPath}/${name}` : name;
       const normalizedRelPath = PathUtils.normalizeRelative(relPath);
@@ -70,13 +74,17 @@ export class ProjectScanner {
       if (handle.kind === "directory") {
         const child = { name, path: normalizedRelPath, type: "dir", children: [] };
         node.children.push(child);
-        await this.#scanDir(handle, normalizedRelPath, child, files, fileHandles, stats);
+        await this.#scanDir(handle, normalizedRelPath, child, files, fileHandles, stats, onProgress);
         continue;
       }
 
       const file = await handle.getFile();
       stats.totalFileCount += 1;
+      stats.scannedCount += 1;
       stats.totalBytes += Number(file.size || 0);
+      if (typeof onProgress === "function") {
+        onProgress({ path: normalizedRelPath, done: stats.scannedCount, total: null });
+      }
       const isSupported = this.textPolicy.isSupportedFile(normalizedRelPath, file.size);
       node.children.push({ name, path: normalizedRelPath, type: "file", size: file.size, supported: isSupported });
       fileHandles.set(normalizedRelPath, handle);
diff --git a/src/core/TextFilePolicy.js b/src/core/TextFilePolicy.js
index dfa66b0..8509e0c 100644
--- a/src/core/TextFilePolicy.js
+++ b/src/core/TextFilePolicy.js
@@ -1,6 +1,6 @@
 export class TextFilePolicy {
   constructor() {
-    this.maxSizeBytes = 5 * 1024 * 1024;
+    this.maxSizeBytes = 1 * 1024 * 1024;
     this.allowedExtensions = new Set([
       ".txt", ".md", ".json", ".xml", ".yaml", ".yml", ".js", ".jsx", ".ts", ".tsx",
       ".css", ".html", ".py", ".java", ".go", ".rs", ".sql", ".sh", ".env", ".ini", ".toml"
diff --git a/src/main.js b/src/main.js
index 81cf290..d5fd292 100644
--- a/src/main.js
+++ b/src/main.js
@@ -2,14 +2,15 @@ import { TextFilePolicy } from "./core/TextFilePolicy.js";
 import { HashService } from "./core/HashService.js";
 import { ProjectScanner } from "./core/ProjectScanner.js";
 import { ProjectStore } from "./core/ProjectStore.js";
-import { IndexingClientMock } from "./core/IndexingClientMock.js";
-import { ChatClientMock } from "./core/ChatClientMock.js";
+import { IndexingClientApi } from "./core/IndexingClientApi.js";
+import { ChatClientApi } from "./core/ChatClientApi.js";
 import { ChangeSetValidator } from "./core/ChangeSetValidator.js";
 import { DiffEngine } from "./core/DiffEngine.js";
 import { ReviewStateStore } from "./core/ReviewStateStore.js";
 import { ApplyEngine } from "./core/ApplyEngine.js";
 import { ProjectLimitsPolicy } from "./core/ProjectLimitsPolicy.js";
 import { MarkdownRenderer } from "./core/MarkdownRenderer.js";
+import { MermaidRenderer } from "./core/MermaidRenderer.js";
 import { FileSaveService } from "./core/FileSaveService.js";
 import { PathUtils } from "./core/PathUtils.js";
 import { AppView } from "./ui/AppView.js";
@@ -19,12 +20,13 @@ class AppController {
   constructor() {
     this.projectStore = new ProjectStore();
     this.reviewStore = new ReviewStateStore();
-    this.view = new AppView(this.reviewStore);
+    this.mermaidRenderer = new MermaidRenderer();
+    this.view = new AppView(this.reviewStore, this.mermaidRenderer);
 
     this.hashService = new HashService();
     this.scanner = new ProjectScanner(new TextFilePolicy(), this.hashService);
-    this.indexing = new IndexingClientMock();
-    this.chat = new ChatClientMock();
+    this.indexing = new IndexingClientApi();
+    this.chat = new ChatClientApi();
     this.validator = new ChangeSetValidator();
     this.diff = new DiffEngine();
     this.applyEngine = new ApplyEngine(this.hashService);
@@ -41,7 +43,13 @@ class AppController {
     this.newTabCounter = 1;
     this.markdownModeByPath = new Map();
     this.writableMode = false;
-    this.currentSessionId = this.#generateSessionId();
+    this.currentProjectId = "local-files";
+    this.currentRagSessionId = "";
+    this.currentDialogSessionId = "";
+    this.centerMode = "file";
+    this.externalWatchTimer = null;
+    this.externalWatchInProgress = false;
+    this.externalWatchIntervalMs = 5000;
 
     this.layoutResizer = new ResizableLayout(this.view.el.layout, this.view.el.splitterLeft, this.view.el.splitterRight);
     this.layoutResizer.init();
@@ -50,12 +58,15 @@ class AppController {
     this.projectStore.subscribe(() => this.#renderProject());
     this.view.setApplyEnabled(false);
     this.view.setTreeStats(0, 0);
+    this.view.setNewTextTabEnabled(false);
+    this.view.setRagStatus("red", { message: "Проект не выбран" });
     this.#renderEditorFooter();
     this.view.appendChat("system", "Выберите директорию проекта слева. Файлы будут показаны деревом.");
   }
 
   #bindEvents() {
     this.view.el.pickFallback.onchange = (event) => this.pickProjectFromFiles(event);
+    this.view.bindPickProject((event) => this.pickProjectByDirectoryHandle(event));
     this.view.bindEditorInput((value) => this.#onEditorInput(value));
     this.view.bindMarkdownToggle(() => this.#toggleMarkdownModeForCurrent());
     this.view.bindEditorActions(() => this.saveCurrentFile(), () => this.closeCurrentTab());
@@ -122,12 +133,45 @@ class AppController {
     event.target.value = "";
   }
 
-  async #scanAndIndex(payload) {
+  async pickProjectByDirectoryHandle(event) {
+    if (typeof window.showDirectoryPicker !== "function" || !window.isSecureContext) return;
+    event.preventDefault();
     try {
+      const rootHandle = await window.showDirectoryPicker();
+      this.writableMode = true;
+      await this.#scanAndIndex({ rootHandle });
+    } catch (error) {
+      if (error?.name !== "AbortError") {
+        this.view.setRagStatus("red", { message: error.message || "Ошибка выбора директории", updatedAt: Date.now() });
+      }
+    }
+  }
+
+  async #scanAndIndex(payload) {
+    this.view.showIndexingModal();
+    this.view.updateIndexingModal({
+      phase: "Индексация проекта в RAG",
+      currentFile: "Подготовка списка файлов...",
+      remaining: null,
+      done: 0,
+      total: 0
+    });
+    try {
+      this.#stopExternalWatch();
       this.view.setIndexStatus("index: scanning");
+      const onProgress = ({ path, done, total }) => {
+        const remaining = Number.isFinite(total) ? Math.max(total - done, 0) : null;
+        this.view.updateIndexingModal({
+          phase: "Индексация проекта в RAG",
+          currentFile: path || "—",
+          remaining,
+          done,
+          total
+        });
+      };
       const snapshot = payload.rootHandle
-        ? await this.scanner.scan(payload.rootHandle)
-        : await this.scanner.scanFromFileList(payload.fileList);
+        ? await this.scanner.scan(payload.rootHandle, onProgress)
+        : await this.scanner.scanFromFileList(payload.fileList, onProgress);
 
       this.projectStore.setProject(payload.rootHandle || null, snapshot);
       this.view.setProjectName(snapshot.projectName || "local-files");
@@ -138,25 +182,48 @@ class AppController {
       this.newFileTabs.clear();
       this.newTabCounter = 1;
       this.markdownModeByPath.clear();
+      this.currentRagSessionId = "";
+      this.currentDialogSessionId = "";
+      this.centerMode = "file";
+      this.changeMap = new Map();
+      this.activeChangePath = "";
+      this.reviewStore.init([]);
+      this.view.setRagStatus("yellow", { message: "Индексация snapshot...", updatedAt: Date.now() });
+      this.view.setReviewVisible(false);
       this.#renderTabs();
-      this.view.renderFile("");
-      this.view.renderMarkdown("");
-      this.view.setMarkdownToggleVisible(false);
-      this.view.setEditorEnabled(false);
+      this.#renderCenterPanel();
       this.view.setApplyEnabled(this.writableMode);
-      this.#renderEditorFooter();
 
       this.view.setIndexStatus("index: snapshot queued");
       const files = [...snapshot.files.values()].map((f) => ({ path: f.path, content: f.content, content_hash: f.hash }));
       const rootChildren = snapshot.rootNode?.children?.length || 0;
       const totalEntries = snapshot.totalEntries ?? files.length;
       this.view.appendChat("system", `Дерево: корневых узлов ${rootChildren}, обработано файлов ${totalEntries}.`);
-      const indexResult = await this.indexing.submitSnapshot(snapshot.projectName || "local-files", files);
+      this.currentProjectId = snapshot.projectName || "local-files";
+      this.view.updateIndexingModal({
+        phase: "Индексация проекта в RAG",
+        currentFile: "Ожидание завершения индексации на сервере...",
+        remaining: 0,
+        done: files.length,
+        total: files.length || 0
+      });
+      const indexResult = await this.indexing.submitSnapshot(this.currentProjectId, files);
+      this.currentRagSessionId = indexResult.rag_session_id || "";
+      await this.#createDialogSession();
+      this.#startExternalWatchIfPossible();
+      this.view.setRagStatus("green", {
+        indexedFiles: indexResult.indexed_files || 0,
+        failedFiles: indexResult.failed_files || 0,
+        updatedAt: Date.now()
+      });
       this.view.setIndexStatus(`index: ${indexResult.status} (${indexResult.indexed_files})`);
       this.view.appendChat("system", `Проект загружен. Файлов в индексации: ${indexResult.indexed_files}`);
     } catch (error) {
+      this.view.setRagStatus("red", { message: error.message || "Ошибка индексации", updatedAt: Date.now() });
       this.view.appendChat("error", error.message);
       this.view.setIndexStatus("index: error");
+    } finally {
+      this.view.hideIndexingModal();
     }
   }
 
@@ -167,10 +234,27 @@ class AppController {
     this.view.appendChat("user", message);
 
     try {
-      const files = await this.#buildFilesForAgent();
-      const result = await this.chat.sendMessage({ session_id: this.currentSessionId, message, files });
+      if (!this.currentRagSessionId) {
+        throw new Error("Проект не проиндексирован. Сначала выберите директорию.");
+      }
+      if (!this.currentDialogSessionId) {
+        await this.#createDialogSession();
+      }
+      const result = await this.chat.sendMessage({
+        dialog_session_id: this.currentDialogSessionId,
+        rag_session_id: this.currentRagSessionId,
+        message,
+        attachments: []
+      });
 
       if (result.result_type === "answer") {
+        this.changeMap = new Map();
+        this.activeChangePath = "";
+        this.reviewStore.init([]);
+        this.view.setReviewVisible(false);
+        this.centerMode = "file";
+        this.#renderTabs();
+        this.#renderCenterPanel();
         this.view.appendChat("assistant", result.answer || "");
         return;
       }
@@ -184,6 +268,21 @@ class AppController {
   }
 
   #prepareReview(changeset) {
+    if (!changeset.length) {
+      this.view.setReviewVisible(false);
+      this.view.setApplyEnabled(false);
+      this.changeMap = new Map();
+      this.activeChangePath = "";
+      this.centerMode = "file";
+      this.view.renderChanges([], "", () => {});
+      this.view.renderDiff(null, () => {});
+      this.#renderTabs();
+      this.#renderCenterPanel();
+      return;
+    }
+    this.view.setReviewVisible(true);
+    this.view.setApplyEnabled(true);
+    this.centerMode = "review";
     this.changeMap = new Map();
     const viewItems = [];
 
@@ -205,21 +304,26 @@ class AppController {
 
     this.reviewStore.init(viewItems);
     this.activeChangePath = viewItems[0]?.path || "";
+    this.#renderTabs();
+    this.#renderCenterPanel();
     this.#renderReview();
   }
 
   #renderProject() {
+    this.view.setNewTextTabEnabled(Boolean(this.projectStore.rootNode));
     this.view.renderTree(this.projectStore.rootNode, this.projectStore.selectedFilePath, (path) => {
       this.#openTab(path);
-      this.#renderCurrentFile();
+      this.centerMode = "file";
+      this.#renderCenterPanel();
     });
   }
 
   #openTab(path) {
     if (!this.openFileTabs.includes(path)) this.openFileTabs.push(path);
     if (!this.markdownModeByPath.has(path) && this.#isMarkdownPath(path)) {
-      this.markdownModeByPath.set(path, "preview");
+      this.markdownModeByPath.set(path, "edit");
     }
+    this.centerMode = "file";
     this.projectStore.setSelectedFile(path);
     this.#renderTabs();
   }
@@ -244,25 +348,47 @@ class AppController {
       const next = this.openFileTabs[this.openFileTabs.length - 1] || "";
       this.projectStore.setSelectedFile(next);
     }
+    if (!this.projectStore.selectedFilePath) this.centerMode = "file";
     this.#renderTabs();
-    this.#renderCurrentFile();
+    this.#renderCenterPanel();
   }
 
   #renderTabs() {
+    const isReviewActive = this.centerMode === "review" && this.changeMap.size > 0;
+    const activePath = isReviewActive ? "" : this.projectStore.selectedFilePath;
     this.view.renderFileTabs(
       this.openFileTabs,
-      this.projectStore.selectedFilePath,
+      activePath,
       this.dirtyPaths,
       (path) => {
+        this.centerMode = "file";
         this.projectStore.setSelectedFile(path);
-        this.#renderCurrentFile();
+        this.#renderCenterPanel();
         this.#renderTabs();
       },
       (path) => this.#closeTab(path),
-      (path) => this.renameTab(path)
+      (path) => this.renameTab(path),
+      {
+        visible: this.changeMap.size > 0,
+        active: isReviewActive,
+        onClick: () => {
+          this.centerMode = "review";
+          this.#renderTabs();
+          this.#renderCenterPanel();
+        }
+      }
     );
   }
 
+  #renderCenterPanel() {
+    this.view.setCenterMode(this.centerMode);
+    if (this.centerMode === "review") {
+      this.#renderReview();
+      return;
+    }
+    this.#renderCurrentFile();
+  }
+
   #renderCurrentFile() {
     const path = this.projectStore.selectedFilePath;
     if (!path) {
@@ -281,7 +407,7 @@ class AppController {
     this.view.setEditorLanguage(path);
 
     if (isMarkdown) {
-      const mode = this.markdownModeByPath.get(path) || "preview";
+      const mode = this.markdownModeByPath.get(path) || "edit";
       this.view.setMarkdownToggleVisible(true);
       this.view.setMarkdownMode(mode);
       this.view.renderMarkdown(this.markdownRenderer.render(content));
@@ -320,7 +446,7 @@ class AppController {
     const path = this.projectStore.selectedFilePath;
     const hasFile = Boolean(path);
     const isDirty = hasFile && this.dirtyPaths.has(path);
-    const mode = hasFile && this.#isMarkdownPath(path) ? this.markdownModeByPath.get(path) || "preview" : "text";
+    const mode = hasFile && this.#isMarkdownPath(path) ? this.markdownModeByPath.get(path) || "edit" : "text";
     const modeLabel = mode === "preview" ? "markdown preview" : mode;
     const infoText = hasFile ? `${path} • ${isDirty ? "изменен" : "без изменений"} • ${modeLabel}` : "Файл не выбран";
 
@@ -337,27 +463,44 @@ class AppController {
 
     try {
       const isNewFile = this.newFileTabs.has(path);
-      const savePath = isNewFile ? await this.#askNewFileTargetPath(path) : path;
-      if (!savePath) {
-        this.view.appendChat("system", "Сохранение отменено пользователем.");
-        return;
-      }
+      let savePath = path;
+      let saveResult = null;
 
-      const hasWritableRoot = await this.#ensureWritableRootForSave(savePath);
-      if (!hasWritableRoot && typeof window.showSaveFilePicker !== "function") {
-        this.view.appendChat("error", "Сохранение недоступно: браузер не поддерживает запись в директорию и Save As.");
-        return;
-      }
-
-      if (savePath !== path && this.projectStore.files.has(savePath)) {
-        const replace = window.confirm(`Файл ${savePath} уже существует. Перезаписать?`);
-        if (!replace) {
+      if (isNewFile && typeof window.showSaveFilePicker === "function") {
+        const hasWritableRoot = await this.#ensureWritableRootForSave(path);
+        if (!hasWritableRoot) {
+          this.view.appendChat("error", "Сохранение недоступно: не удалось получить доступ к директории проекта.");
+          return;
+        }
+        saveResult = await this.fileSaveService.saveNewFileWithPicker(this.projectStore, path, content);
+        savePath = saveResult.path;
+      } else if (!isNewFile) {
+        saveResult = await this.fileSaveService.saveExistingFile(this.projectStore, path, content);
+        savePath = path;
+      } else {
+        savePath = isNewFile ? await this.#askNewFileTargetPath(path) : path;
+        if (!savePath) {
           this.view.appendChat("system", "Сохранение отменено пользователем.");
           return;
         }
+
+        const hasWritableRoot = await this.#ensureWritableRootForSave(savePath);
+        if (!hasWritableRoot && typeof window.showSaveFilePicker !== "function") {
+          this.view.appendChat("error", "Сохранение недоступно: браузер не поддерживает запись в директорию и Save As.");
+          return;
+        }
+
+        if (savePath !== path && this.projectStore.files.has(savePath)) {
+          const replace = window.confirm(`Файл ${savePath} уже существует. Перезаписать?`);
+          if (!replace) {
+            this.view.appendChat("system", "Сохранение отменено пользователем.");
+            return;
+          }
+        }
+
+        saveResult = await this.fileSaveService.saveFile(this.projectStore, savePath, content);
       }
 
-      const saveResult = await this.fileSaveService.saveFile(this.projectStore, savePath, content);
       const hash = await this.hashService.sha256(content);
       this.projectStore.upsertFile(savePath, content, hash);
       this.draftByPath.delete(path);
@@ -371,7 +514,15 @@ class AppController {
       }
 
       this.#renderTabs();
-      this.#renderCurrentFile();
+      this.#renderCenterPanel();
+
+      const ragSync = await this.#syncRagChanges(
+        [{ op: "upsert", path: savePath, content, content_hash: hash }],
+        "Индексация сохраненного файла..."
+      );
+      if (!ragSync.ok) {
+        window.alert(`Файл сохранен, но обновление RAG не выполнено: ${ragSync.error || "неизвестная ошибка"}`);
+      }
 
       if (saveResult.mode === "download") {
         this.view.appendChat("system", `Файл ${savePath} выгружен через download.`);
@@ -381,6 +532,10 @@ class AppController {
     } catch (error) {
       if (error?.name === "AbortError") {
         this.view.appendChat("system", "Сохранение отменено пользователем.");
+      } else if (
+        String(error?.message || "").includes("Нет доступа к существующему файлу для записи без выбора новой директории")
+      ) {
+        window.alert("Сохранение недоступно в read-only режиме. Откройте проект через системный выбор директории.");
       } else {
         this.view.appendChat("error", `Ошибка сохранения: ${error.message}`);
       }
@@ -390,9 +545,9 @@ class AppController {
   #toggleMarkdownModeForCurrent() {
     const path = this.projectStore.selectedFilePath;
     if (!path || !this.#isMarkdownPath(path)) return;
-    const current = this.markdownModeByPath.get(path) || "preview";
+    const current = this.markdownModeByPath.get(path) || "edit";
     this.markdownModeByPath.set(path, current === "preview" ? "edit" : "preview");
-    this.#renderCurrentFile();
+    this.#renderCenterPanel();
   }
 
   #isMarkdownPath(path) {
@@ -430,10 +585,16 @@ class AppController {
   }
 
   async applyAccepted() {
-    if (!this.writableMode || !this.projectStore.rootHandle) {
-      this.view.appendChat("system", "Apply недоступен: откройте через http://localhost или https для режима записи.");
-      return;
+    if (!this.changeMap.size) return;
+    if (!this.projectStore.rootHandle) {
+      const firstPath = this.reviewStore.acceptedPaths()[0] || "";
+      const hasWritableRoot = await this.#ensureWritableRootForSave(firstPath || "changeset.patch");
+      if (!hasWritableRoot) {
+        this.view.appendChat("error", "Apply недоступен: не удалось получить доступ к директории проекта.");
+        return;
+      }
     }
+    this.writableMode = true;
 
     const changedFiles = await this.applyEngine.applyAccepted(this.projectStore, this.reviewStore, this.changeMap);
     for (const changed of changedFiles) {
@@ -442,7 +603,7 @@ class AppController {
     }
     this.#renderReview();
     this.#renderProject();
-    this.#renderCurrentFile();
+    this.#renderCenterPanel();
     this.#renderTabs();
 
     if (!changedFiles.length) {
@@ -450,30 +611,15 @@ class AppController {
       return;
     }
 
-    this.view.setIndexStatus("index: changes queued");
-    const res = await this.indexing.submitChanges(this.projectStore.rootHandle.name, changedFiles);
-    this.view.setIndexStatus(`index: ${res.status} (${res.indexed_files})`);
+    const ragSync = await this.#syncRagChanges(changedFiles, "Индексация изменений...");
+    if (!ragSync.ok) {
+      window.alert(`Изменения применены, но обновление RAG не выполнено: ${ragSync.error || "неизвестная ошибка"}`);
+    }
     this.view.appendChat("system", `Применено файлов: ${changedFiles.length}`);
   }
 
-  async #buildFilesForAgent() {
-    const out = [];
-    for (const file of this.projectStore.files.values()) {
-      const draft = this.draftByPath.get(file.path);
-      const content = draft ?? file.content;
-      const contentHash = draft ? await this.hashService.sha256(content) : file.hash;
-      out.push({ path: file.path, content, content_hash: contentHash });
-    }
-    for (const path of this.newFileTabs) {
-      const content = this.draftByPath.get(path);
-      if (typeof content !== "string" || !content.length) continue;
-      const contentHash = await this.hashService.sha256(content);
-      out.push({ path, content, content_hash: contentHash });
-    }
-    return out;
-  }
-
   createNewTextTab() {
+    if (!this.projectStore.rootNode) return;
     let path = "";
     while (!path || this.openFileTabs.includes(path) || this.projectStore.files.has(path)) {
       path = `new-${this.newTabCounter}.md`;
@@ -483,9 +629,10 @@ class AppController {
     this.draftByPath.set(path, "");
     this.projectStore.setSelectedFile(path);
     this.openFileTabs.push(path);
-    this.markdownModeByPath.set(path, "preview");
+    this.markdownModeByPath.set(path, "edit");
+    this.centerMode = "file";
     this.#renderTabs();
-    this.#renderCurrentFile();
+    this.#renderCenterPanel();
   }
 
   #replaceTabPath(oldPath, newPath) {
@@ -535,6 +682,7 @@ class AppController {
       }
       this.projectStore.rootHandle = handle;
       this.view.appendChat("system", `Директория для записи: ${handle.name}`);
+      this.#startExternalWatchIfPossible();
       return true;
     } catch (error) {
       if (error?.name === "AbortError") {
@@ -572,7 +720,7 @@ class AppController {
       this.newFileTabs.add(newPath);
       this.#replaceTabPath(oldPath, newPath);
       this.#renderTabs();
-      this.#renderCurrentFile();
+      this.#renderCenterPanel();
       return;
     }
 
@@ -593,23 +741,156 @@ class AppController {
       this.dirtyPaths.delete(oldPath);
       this.#replaceTabPath(oldPath, newPath);
       this.#renderTabs();
-      this.#renderCurrentFile();
+      this.#renderCenterPanel();
+      const ragSync = await this.#syncRagChanges(
+        [
+          { op: "upsert", path: newPath, content, content_hash: hash },
+          { op: "delete", path: oldPath, content: null, content_hash: null }
+        ],
+        "Индексация изменений..."
+      );
+      if (!ragSync.ok) {
+        window.alert(`Файл переименован, но обновление RAG не выполнено: ${ragSync.error || "неизвестная ошибка"}`);
+      }
       this.view.appendChat("system", `Файл переименован: ${oldPath} -> ${newPath}`);
     } catch (error) {
       this.view.appendChat("error", `Ошибка переименования: ${error.message}`);
     }
   }
 
-  startNewChatSession() {
-    this.currentSessionId = this.#generateSessionId();
+  async startNewChatSession() {
     this.view.clearChat();
+    if (!this.currentRagSessionId) {
+      this.currentDialogSessionId = "";
+      return;
+    }
+    try {
+      await this.#createDialogSession();
+    } catch (error) {
+      this.view.appendChat("error", `Не удалось создать новую сессию чата: ${error.message}`);
+    }
   }
 
-  #generateSessionId() {
-    if (typeof crypto !== "undefined" && typeof crypto.randomUUID === "function") {
-      return `chat-${crypto.randomUUID()}`;
+  async #createDialogSession() {
+    if (!this.currentRagSessionId) {
+      this.currentDialogSessionId = "";
+      return;
     }
-    return `chat-${Date.now()}-${Math.random().toString(36).slice(2, 10)}`;
+    this.currentDialogSessionId = await this.chat.createDialog(this.currentRagSessionId);
+  }
+
+  async #syncRagChanges(changedFiles, pendingMessage) {
+    if (!Array.isArray(changedFiles) || !changedFiles.length) return { ok: true };
+    this.view.setIndexStatus("index: changes queued");
+    if (!this.currentRagSessionId) {
+      this.view.setRagStatus("red", { message: "RAG session не инициализирована", updatedAt: Date.now() });
+      this.view.appendChat("error", "RAG session не инициализирована. Повторно выберите директорию проекта.");
+      return { ok: false, error: "RAG session не инициализирована" };
+    }
+    const currentFile = changedFiles.find((item) => item?.path)?.path || "";
+    const statusStartedAt = Date.now();
+    this.view.setRagStatus("yellow", {
+      message: pendingMessage || "Индексация изменений...",
+      currentFile,
+      updatedAt: Date.now()
+    });
+    try {
+      const res = await this.indexing.submitChanges(this.currentRagSessionId, changedFiles);
+      const elapsed = Date.now() - statusStartedAt;
+      if (elapsed < 1000) {
+        await this.#sleep(1000 - elapsed);
+      }
+      this.view.setRagStatus("green", {
+        indexedFiles: res.indexed_files || 0,
+        failedFiles: res.failed_files || 0,
+        updatedAt: Date.now()
+      });
+      this.view.setIndexStatus(`index: ${res.status} (${res.indexed_files})`);
+      return { ok: true, indexedFiles: res.indexed_files || 0, failedFiles: res.failed_files || 0 };
+    } catch (error) {
+      const elapsed = Date.now() - statusStartedAt;
+      if (elapsed < 1000) {
+        await this.#sleep(1000 - elapsed);
+      }
+      this.view.setRagStatus("red", { message: error.message || "Ошибка обновления RAG", updatedAt: Date.now() });
+      this.view.setIndexStatus("index: error");
+      this.view.appendChat("error", `Ошибка обновления RAG: ${error.message}`);
+      return { ok: false, error: error?.message || "Ошибка обновления RAG" };
+    }
+  }
+
+  #startExternalWatchIfPossible() {
+    this.#stopExternalWatch();
+    if (!this.projectStore.rootHandle || !this.currentRagSessionId) return;
+    this.externalWatchTimer = window.setInterval(() => {
+      void this.#pollExternalChanges();
+    }, this.externalWatchIntervalMs);
+  }
+
+  #stopExternalWatch() {
+    if (!this.externalWatchTimer) return;
+    window.clearInterval(this.externalWatchTimer);
+    this.externalWatchTimer = null;
+  }
+
+  async #pollExternalChanges() {
+    if (this.externalWatchInProgress) return;
+    if (!this.projectStore.rootHandle || !this.currentRagSessionId) return;
+    if (this.dirtyPaths.size > 0 || this.newFileTabs.size > 0) return;
+
+    this.externalWatchInProgress = true;
+    try {
+      const snapshot = await this.scanner.scan(this.projectStore.rootHandle);
+      const changedFiles = this.#buildChangedFilesFromSnapshots(this.projectStore.files, snapshot.files);
+      if (!changedFiles.length) return;
+
+      const prevSelected = this.projectStore.selectedFilePath;
+      const prevOpenTabs = [...this.openFileTabs];
+      this.projectStore.setProject(this.projectStore.rootHandle, snapshot);
+      this.openFileTabs = prevOpenTabs.filter((path) => snapshot.files.has(path));
+      const nextSelected = snapshot.files.has(prevSelected) ? prevSelected : this.openFileTabs[this.openFileTabs.length - 1] || "";
+      this.projectStore.setSelectedFile(nextSelected);
+      this.view.setTreeStats(snapshot.totalFileCount || 0, snapshot.totalBytes || 0);
+      this.#renderTabs();
+      this.#renderCenterPanel();
+
+      await this.#syncRagChanges(changedFiles, "Индексация внешних изменений...");
+      this.view.appendChat("system", `Обнаружены внешние изменения: ${changedFiles.length} файлов.`);
+    } catch (error) {
+      this.#stopExternalWatch();
+      this.view.appendChat("error", `Мониторинг внешних изменений остановлен: ${error.message}`);
+    } finally {
+      this.externalWatchInProgress = false;
+    }
+  }
+
+  #buildChangedFilesFromSnapshots(currentFiles, freshFiles) {
+    const changed = [];
+    for (const [path, fresh] of freshFiles.entries()) {
+      const current = currentFiles.get(path);
+      if (!current || current.hash !== fresh.hash) {
+        changed.push({
+          op: "upsert",
+          path,
+          content: fresh.content,
+          content_hash: fresh.hash
+        });
+      }
+    }
+    for (const [path] of currentFiles.entries()) {
+      if (freshFiles.has(path)) continue;
+      changed.push({
+        op: "delete",
+        path,
+        content: null,
+        content_hash: null
+      });
+    }
+    return changed;
+  }
+
+  #sleep(ms) {
+    return new Promise((resolve) => window.setTimeout(resolve, ms));
   }
 }
 
diff --git a/src/ui/AppView.js b/src/ui/AppView.js
index e472da7..85ec16d 100644
--- a/src/ui/AppView.js
+++ b/src/ui/AppView.js
@@ -1,18 +1,29 @@
 import { MonacoEditorAdapter } from "./MonacoEditorAdapter.js";
 
 export class AppView {
-  constructor(reviewStore) {
+  constructor(reviewStore, mermaidRenderer = null) {
     this.reviewStore = reviewStore;
+    this.mermaidRenderer = mermaidRenderer;
     this.editorInputHandler = null;
     this.monacoAdapter = null;
+    this.expandedTreeDirs = new Set();
+    this.lastTreeRootKey = "";
+    this.markdownRenderVersion = 0;
     this.el = {
       layout: document.getElementById("layout-root"),
       splitterLeft: document.getElementById("splitter-left"),
       splitterRight: document.getElementById("splitter-right"),
       pickFallback: document.getElementById("pick-project-fallback"),
+      pickProjectLabel: document.getElementById("pick-project-label"),
       projectName: document.getElementById("project-name"),
       indexStatus: document.getElementById("index-status"),
       treeInfo: document.getElementById("tree-info"),
+      ragStatusDot: document.getElementById("rag-status-dot"),
+      ragStatusText: document.getElementById("rag-status-text"),
+      indexingModal: document.getElementById("indexing-modal"),
+      indexingFile: document.getElementById("indexing-file"),
+      indexingRemaining: document.getElementById("indexing-remaining"),
+      indexingProgressBar: document.getElementById("indexing-progress-bar"),
       treeRoot: document.getElementById("tree-root"),
       fileTabs: document.getElementById("file-tabs"),
       newTextTabBtn: document.getElementById("new-text-tab"),
@@ -21,10 +32,12 @@ export class AppView {
       fileEditorMonaco: document.getElementById("file-editor-monaco"),
       mdPreview: document.getElementById("md-preview"),
       editorInfo: document.getElementById("editor-info"),
+      editorFooter: document.getElementById("editor-footer-main"),
       saveFileBtn: document.getElementById("save-file"),
       closeFileBtn: document.getElementById("close-file"),
       diffView: document.getElementById("diff-view"),
       changeList: document.getElementById("change-list"),
+      reviewWrap: document.querySelector(".review-wrap"),
       toolbar: document.getElementById("review-toolbar"),
       applyAccepted: document.getElementById("apply-accepted"),
       newChatSessionBtn: document.getElementById("new-chat-session"),
@@ -32,6 +45,11 @@ export class AppView {
       chatForm: document.getElementById("chat-form"),
       chatInput: document.getElementById("chat-input")
     };
+    this.reviewAvailable = false;
+    this.centerMode = "file";
+    this.setRagStatus("red");
+    this.setMarkdownToggleVisible(false);
+    this.setReviewVisible(false);
     void this.#initMonacoEditor();
   }
 
@@ -48,10 +66,99 @@ export class AppView {
     this.el.treeInfo.textContent = `Файлов: ${totalFiles || 0} • ${kb} KB`;
   }
 
+  showIndexingModal() {
+    this.el.indexingModal.classList.remove("hidden");
+    this.updateIndexingModal({ currentFile: "—", remaining: null, done: 0, total: 0 });
+  }
+
+  hideIndexingModal() {
+    this.el.indexingModal.classList.add("hidden");
+  }
+
+  updateIndexingModal({ currentFile, remaining, done, total, phase }) {
+    if (typeof phase === "string" && phase.length) {
+      const title = this.el.indexingModal?.querySelector("h3");
+      if (title) title.textContent = phase;
+    }
+    if (typeof currentFile === "string") {
+      this.el.indexingFile.textContent = currentFile || "—";
+    }
+    if (Number.isFinite(remaining)) {
+      this.el.indexingRemaining.textContent = `${remaining}`;
+    } else if (Number.isFinite(done) && Number.isFinite(total) && total >= 0) {
+      this.el.indexingRemaining.textContent = `${Math.max(total - done, 0)}`;
+    } else {
+      this.el.indexingRemaining.textContent = "—";
+    }
+
+    if (Number.isFinite(done) && Number.isFinite(total) && total > 0) {
+      const percent = Math.max(0, Math.min(100, Math.round((done / total) * 100)));
+      this.el.indexingProgressBar.style.width = `${percent}%`;
+      return;
+    }
+    this.el.indexingProgressBar.style.width = "0%";
+  }
+
+  setRagStatus(status, details = {}) {
+    const dot = this.el.ragStatusDot;
+    const text = this.el.ragStatusText;
+    const container = document.getElementById("rag-status");
+    if (!dot || !text || !container) return;
+
+    dot.classList.remove("rag-red", "rag-yellow", "rag-green");
+    const updatedAt = details.updatedAt ? this.#formatTime(details.updatedAt) : "";
+    const indexed = Number.isFinite(details.indexedFiles) ? details.indexedFiles : null;
+    const failed = Number.isFinite(details.failedFiles) ? details.failedFiles : null;
+    const extra = details.message ? `\n${details.message}` : "";
+
+    if (status === "green") {
+      dot.classList.add("rag-green");
+      text.textContent = "RAG: готов";
+      container.title = `RAG: готов\nИндексировано: ${indexed ?? 0}\nОшибок: ${failed ?? 0}${updatedAt ? `\nОбновлено: ${updatedAt}` : ""}${extra}`;
+      return;
+    }
+    if (status === "yellow") {
+      dot.classList.add("rag-yellow");
+      const currentFile = typeof details.currentFile === "string" ? details.currentFile.trim() : "";
+      text.textContent = currentFile ? `RAG: ${currentFile}` : "RAG: обновление";
+      container.title = `RAG: обновление${updatedAt ? `\nСтарт: ${updatedAt}` : ""}${extra}`;
+      return;
+    }
+    dot.classList.add("rag-red");
+    text.textContent = "RAG: не добавлен";
+    container.title = `RAG: не добавлен${updatedAt ? `\nСбой: ${updatedAt}` : ""}${extra}`;
+  }
+
+  #formatTime(value) {
+    try {
+      return new Date(value).toLocaleString("ru-RU");
+    } catch {
+      return "";
+    }
+  }
+
   setApplyEnabled(enabled) {
     this.el.applyAccepted.disabled = !enabled;
   }
 
+  setReviewVisible(visible) {
+    this.reviewAvailable = Boolean(visible);
+    if (!this.reviewAvailable) this.el.reviewWrap.classList.add("hidden");
+  }
+
+  setCenterMode(mode) {
+    this.centerMode = mode === "review" && this.reviewAvailable ? "review" : "file";
+    const isReview = this.centerMode === "review";
+    this.el.editorFooter.classList.toggle("hidden", isReview);
+    if (isReview) {
+      this.el.reviewWrap.classList.remove("hidden");
+      this.el.mdPreview.classList.add("hidden");
+      this.#setEditorVisible(false);
+      return;
+    }
+    this.el.reviewWrap.classList.add("hidden");
+  }
+
   setEditorEnabled(enabled) {
     this.el.fileEditor.readOnly = !enabled;
     if (this.monacoAdapter) this.monacoAdapter.setReadOnly(!enabled);
@@ -63,6 +170,10 @@ export class AppView {
     if (this.monacoAdapter) this.monacoAdapter.onChange(onInput);
   }
 
+  bindPickProject(onPickDirectory) {
+    this.el.pickProjectLabel.onclick = (event) => onPickDirectory(event);
+  }
+
   bindMarkdownToggle(onToggle) {
     this.el.mdToggleBtn.onclick = onToggle;
   }
@@ -76,6 +187,10 @@ export class AppView {
     this.el.newTextTabBtn.onclick = onCreate;
   }
 
+  setNewTextTabEnabled(enabled) {
+    this.el.newTextTabBtn.disabled = !enabled;
+  }
+
   bindNewChatSession(onNewSession) {
     this.el.newChatSessionBtn.onclick = onNewSession;
   }
@@ -91,18 +206,21 @@ export class AppView {
   }
 
   setMarkdownToggleVisible(visible) {
-    this.el.mdToggleBtn.classList.toggle("hidden", !visible);
-    if (!visible) {
-      this.el.mdPreview.classList.add("hidden");
-      this.#setEditorVisible(true);
-    }
+    this.el.mdToggleBtn.classList.remove("hidden");
+    this.el.mdToggleBtn.disabled = !visible;
+    if (visible) return;
+    this.el.mdToggleBtn.classList.remove("active");
+    this.el.mdToggleBtn.textContent = "✏️";
+    this.el.mdToggleBtn.title = "Текущий режим: редактирование";
+    this.el.mdPreview.classList.add("hidden");
+    this.#setEditorVisible(true);
   }
 
   setMarkdownMode(mode) {
     const isPreview = mode === "preview";
     this.el.mdToggleBtn.classList.toggle("active", isPreview);
-    this.el.mdToggleBtn.textContent = isPreview ? "✏️" : "👁";
-    this.el.mdToggleBtn.title = isPreview ? "Перейти в редактирование" : "Перейти в просмотр";
+    this.el.mdToggleBtn.textContent = isPreview ? "👁" : "✏️";
+    this.el.mdToggleBtn.title = isPreview ? "Текущий режим: просмотр markdown" : "Текущий режим: редактирование markdown";
     this.el.mdPreview.classList.toggle("hidden", !isPreview);
     this.#setEditorVisible(!isPreview);
     if (!isPreview && this.monacoAdapter) {
@@ -113,6 +231,8 @@ export class AppView {
 
   renderMarkdown(html) {
     this.el.mdPreview.innerHTML = html;
+    const renderVersion = ++this.markdownRenderVersion;
+    void this.#renderMermaid(renderVersion);
   }
 
   appendChat(role, text) {
@@ -128,30 +248,61 @@ export class AppView {
     this.el.treeRoot.innerHTML = "";
     if (!rootNode) {
       this.el.treeRoot.textContent = "Директория не выбрана";
+      this.expandedTreeDirs.clear();
+      this.lastTreeRootKey = "";
       return;
     }
     if (!rootNode.children?.length) {
       this.el.treeRoot.textContent = "В выбранной директории нет файлов";
+      this.expandedTreeDirs.clear();
+      this.lastTreeRootKey = rootNode.name || "";
       return;
     }
 
-    const renderNode = (node, depth) => {
+    const rootKey = `${rootNode.name || ""}:${rootNode.children?.length || 0}`;
+    if (rootKey !== this.lastTreeRootKey) {
+      this.expandedTreeDirs.clear();
+      this.lastTreeRootKey = rootKey;
+    }
+    this.#expandSelectedPathParents(selectedPath);
+
+    const renderNode = (node, depth, isRoot = false) => {
       const line = document.createElement("div");
       line.className = "tree-item";
       line.style.paddingLeft = `${depth * 14}px`;
-      const marker = node.type === "dir" ? "📁" : "📄";
+      if (node.type === "dir") {
+        const hasChildren = Array.isArray(node.children) && node.children.length > 0;
+        const isExpanded = isRoot || this.expandedTreeDirs.has(node.path);
+        const arrow = hasChildren ? (isExpanded ? "▾" : "▸") : "•";
+        const marker = isExpanded ? "📂" : "📁";
+        line.textContent = `${arrow} ${marker} ${node.name}`;
+        line.classList.add("tree-item-dir");
+        if (hasChildren) {
+          line.onclick = () => {
+            if (this.expandedTreeDirs.has(node.path)) this.expandedTreeDirs.delete(node.path);
+            else this.expandedTreeDirs.add(node.path);
+            this.renderTree(rootNode, selectedPath, onSelect);
+          };
+        }
+        this.el.treeRoot.appendChild(line);
+        if (isExpanded) {
+          for (const child of node.children) renderNode(child, depth + 1, false);
+        }
+        return;
+      }
+
+      const marker = "📄";
       const suffix = node.type === "file" && node.supported === false ? " (skip)" : "";
       line.textContent = `${marker} ${node.name}${suffix}`;
       if (node.path === selectedPath) line.style.fontWeight = "700";
       if (node.type === "file" && node.supported !== false) line.onclick = () => onSelect(node.path);
       this.el.treeRoot.appendChild(line);
-      if (node.children) node.children.forEach((child) => renderNode(child, depth + 1));
     };
 
-    renderNode(rootNode, 0);
+    renderNode(rootNode, 0, true);
   }
 
-  renderFileTabs(openPaths, activePath, dirtyPaths, onTabClick, onCloseTab, onRenameTab) {
+  renderFileTabs(openPaths, activePath, dirtyPaths, onTabClick, onCloseTab, onRenameTab, reviewTab = null) {
     this.el.fileTabs.innerHTML = "";
     for (const path of openPaths) {
       const tab = document.createElement("div");
@@ -177,6 +328,21 @@ export class AppView {
       tab.append(openBtn, closeBtn);
       this.el.fileTabs.appendChild(tab);
     }
+
+    if (reviewTab?.visible) {
+      const tab = document.createElement("div");
+      tab.className = `tab-item ${reviewTab.active ? "active" : ""}`;
+      tab.title = "Ревью изменений";
+
+      const openBtn = document.createElement("button");
+      openBtn.className = "tab-main";
+      openBtn.textContent = "Ревью";
+      openBtn.title = "Ревью изменений";
+      openBtn.onclick = () => reviewTab.onClick?.();
+
+      tab.append(openBtn);
+      this.el.fileTabs.appendChild(tab);
+    }
   }
 
   #formatTabLabel(path) {
@@ -269,4 +435,21 @@ export class AppView {
     }
     this.el.fileEditor.classList.toggle("hidden", !visible);
   }
+
+  #expandSelectedPathParents(selectedPath) {
+    if (!selectedPath) return;
+    const parts = String(selectedPath)
+      .split("/")
+      .filter(Boolean);
+    if (parts.length <= 1) return;
+    for (let i = 1; i < parts.length; i += 1) {
+      this.expandedTreeDirs.add(parts.slice(0, i).join("/"));
+    }
+  }
+
+  async #renderMermaid(renderVersion) {
+    if (!this.mermaidRenderer) return;
+    if (renderVersion !== this.markdownRenderVersion) return;
+    await this.mermaidRenderer.render(this.el.mdPreview);
+  }
 }
diff --git a/styles.css b/styles.css
index 9298802..b86eae5 100644
--- a/styles.css
+++ b/styles.css
@@ -318,6 +318,9 @@ textarea {
 .md-toggle {
   position: static;
   z-index: 0;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
   width: var(--top-control-btn-h);
   min-width: var(--top-control-btn-h);
   height: var(--top-control-btn-h);
@@ -327,6 +330,7 @@ textarea {
   line-height: 1;
   background: #163057;
   flex-shrink: 0;
+  text-align: center;
 }
 
 .md-toggle.active {
@@ -409,6 +413,21 @@ textarea {
   color: #81b9ff;
 }
 
+.md-preview .mermaid {
+  margin: 10px 0;
+  padding: 8px;
+  border: 1px solid var(--line);
+  border-radius: 6px;
+  background: #081427;
+  overflow: auto;
+}
+
+.md-preview .mermaid-error {
+  color: #ffd7d7;
+  font-family: "IBM Plex Mono", "Consolas", monospace;
+  white-space: pre-wrap;
+}
+
 .editor-footer {
   margin-top: 8px;
   border: 1px solid var(--line);
@@ -432,12 +451,55 @@ textarea {
   white-space: nowrap;
 }
 
+.rag-status {
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+  color: var(--muted);
+  font-size: 12px;
+  flex-shrink: 0;
+  white-space: nowrap;
+}
+
+.rag-dot {
+  width: 10px;
+  height: 10px;
+  border-radius: 999px;
+  border: 1px solid #315685;
+  box-shadow: 0 0 0 1px #0f2343 inset;
+}
+
+.rag-red {
+  background: #cf4b57;
+}
+
+.rag-yellow {
+  background: #d7b84d;
+}
+
+.rag-green {
+  background: #49c47c;
+}
+
 .editor-actions {
   display: flex;
   gap: 8px;
   flex-shrink: 0;
 }
 
+.tree-footer {
+  display: grid;
+  grid-template-rows: 1fr 1fr;
+  align-items: center;
+  justify-items: start;
+  row-gap: 0;
+}
+
+.tree-footer-line {
+  width: 100%;
+  min-width: 0;
+}
+
 .chat-wrap,
 .review-wrap {
   display: flex;
@@ -451,7 +513,12 @@ textarea {
 
 .review-wrap {
   flex: 1;
-  margin-top: 8px;
+  margin-top: 0;
+}
+
+.editor-review {
+  flex: 1;
+  min-height: 0;
 }
 
 .chat-log,
@@ -466,6 +533,9 @@ textarea {
   flex: 1;
   min-height: 0;
   overflow: auto;
+  display: flex;
+  flex-direction: column;
+  justify-content: flex-end;
 }
 
 .chat-entry {
@@ -475,6 +545,12 @@ textarea {
   white-space: pre-wrap;
 }
 
+.chat-entry:last-child {
+  margin-bottom: 0;
+  padding-bottom: 0;
+  border-bottom: none;
+}
+
 .chat-form {
   margin-top: 8px;
   display: grid;
@@ -521,6 +597,7 @@ textarea {
 .diff-view {
   overflow: auto;
   min-height: 120px;
+  flex: 1;
 }
 
 .diff-line {
@@ -543,12 +620,81 @@ textarea {
 .tree-item {
   padding: 2px 4px;
   cursor: pointer;
+  user-select: none;
 }
 
 .tree-item:hover {
   background: #133056;
 }
 
+.tree-item-dir {
+  color: var(--muted);
+}
+
+.indexing-modal {
+  position: fixed;
+  inset: 0;
+  z-index: 9999;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  background: rgba(4, 10, 20, 0.78);
+  backdrop-filter: blur(2px);
+}
+
+.indexing-card {
+  width: min(640px, calc(100vw - 40px));
+  border: 1px solid var(--line);
+  border-radius: 10px;
+  padding: 16px;
+  background: linear-gradient(180deg, #112648 0%, #0c1a33 100%);
+  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.4);
+}
+
+.indexing-card h3 {
+  margin: 0 0 12px;
+  font-size: 18px;
+  color: var(--text);
+}
+
+.indexing-row {
+  display: grid;
+  grid-template-columns: 130px 1fr;
+  gap: 8px;
+  margin-bottom: 8px;
+  min-height: 20px;
+}
+
+.indexing-label {
+  color: var(--muted);
+  font-size: 13px;
+}
+
+.indexing-value {
+  min-width: 0;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  color: var(--text);
+  font-size: 13px;
+}
+
+.indexing-progress {
+  margin-top: 8px;
+  height: 8px;
+  border: 1px solid var(--line);
+  border-radius: 999px;
+  background: #0b1830;
+  overflow: hidden;
+}
+
+.indexing-progress-bar {
+  height: 100%;
+  width: 0%;
+  background: linear-gradient(90deg, #2f5f99 0%, #4fa0ff 100%);
+  transition: width 0.2s ease;
+}
+
 @media (max-width: 1100px) {
   .layout {
     grid-template-columns: 1fr;