diff --git a/apps/api/app/admin/files.rb b/apps/api/app/admin/files.rb
index a3fef2b..622661c 100644
--- a/apps/api/app/admin/files.rb
+++ b/apps/api/app/admin/files.rb
@@ -152,6 +152,26 @@ ActiveAdmin.register_page "Files" do
     end
   end
 
+  # JSON API for AJAX file picker
+  page_action :list, method: :get do
+    service = FileManagerService.new
+    dir = params[:dir].to_s.presence || ""
+    begin
+      entries = service.list(dir)
+      render json: { entries: entries, dir: dir }
+    rescue ArgumentError => e
+      render json: { entries: [], dir: dir, error: e.message }
+    end
+  end
+
+  page_action :ajax_upload, method: :post do
+    service = FileManagerService.new
+    path = service.upload(params[:dir].to_s, params[:file])
+    render json: { ok: true, path: path }
+  rescue => e
+    render json: { ok: false, error: e.message }, status: 422
+  end
+
   page_action :upload, method: :post do
     service = FileManagerService.new
     service.upload(params[:dir].to_s, params[:file])
diff --git a/apps/api/app/assets/javascripts/active_admin.js b/apps/api/app/assets/javascripts/active_admin.js
index d60f0cc..bbe544d 100644
--- a/apps/api/app/assets/javascripts/active_admin.js
+++ b/apps/api/app/assets/javascripts/active_admin.js
@@ -2,6 +2,7 @@
 
 (function() {
   var PATH_FIELDS = ['html_folder_path', 'cartridge_path', 'source_path', 'docs_folder_path'];
+  var _pickerTarget = null;
 
   function addBrowseButtons() {
     PATH_FIELDS.forEach(function(fieldName) {
@@ -14,66 +15,207 @@
         btn.className = 'fm-browse-btn';
         btn.addEventListener('click', function(e) {
           e.preventDefault();
-          openFilePicker(input.id);
+          _pickerTarget = input;
+          openPicker('');
         });
         input.parentNode.insertBefore(btn, input.nextSibling);
       });
     });
   }
 
-  function openFilePicker(fieldId) {
-    // Backdrop
+  function openPicker(dir) {
+    closePicker();
     var overlay = document.createElement('div');
     overlay.className = 'fm-modal-overlay';
+    overlay.id = 'fm-picker-overlay';
     overlay.addEventListener('click', function(e) {
-      if (e.target === overlay) closeFilePicker();
+      if (e.target === overlay) closePicker();
     });
 
-    // Modal container
     var modal = document.createElement('div');
     modal.className = 'fm-modal';
 
-    // Close button
+    var header = document.createElement('div');
+    header.className = 'fm-modal-header';
+    header.innerHTML = '<span class="fm-modal-title">Select file or folder</span>';
     var closeBtn = document.createElement('button');
     closeBtn.className = 'fm-modal-close';
     closeBtn.innerHTML = '&times;';
-    closeBtn.addEventListener('click', closeFilePicker);
-    modal.appendChild(closeBtn);
+    closeBtn.addEventListener('click', closePicker);
+    header.appendChild(closeBtn);
+    modal.appendChild(header);
 
-    // Iframe
-    var iframe = document.createElement('iframe');
-    iframe.src = '/admin/files?picker=1&field=' + encodeURIComponent(fieldId);
-    iframe.className = 'fm-modal-iframe';
-    modal.appendChild(iframe);
+    var body = document.createElement('div');
+    body.className = 'fm-modal-body';
+    body.id = 'fm-picker-body';
+    body.innerHTML = '<div style="text-align:center;padding:40px;color:#999;">Loading...</div>';
+    modal.appendChild(body);
 
     overlay.appendChild(modal);
     document.body.appendChild(overlay);
     document.body.style.overflow = 'hidden';
 
-    window._fmOverlay = overlay;
+    loadDir(dir);
   }
 
-  function closeFilePicker() {
-    if (window._fmOverlay) {
-      window._fmOverlay.remove();
-      window._fmOverlay = null;
-      document.body.style.overflow = '';
+  function closePicker() {
+    var ov = document.getElementById('fm-picker-overlay');
+    if (ov) { ov.remove(); }
+    document.body.style.overflow = '';
+  }
+
+  function selectPath(absPath) {
+    if (_pickerTarget) {
+      _pickerTarget.value = absPath;
+      _pickerTarget.dispatchEvent(new Event('change', { bubbles: true }));
+    }
+    closePicker();
+  }
+
+  function loadDir(dir) {
+    var body = document.getElementById('fm-picker-body');
+    if (!body) return;
+    body.innerHTML = '<div style="text-align:center;padding:40px;color:#999;">Loading...</div>';
+
+    fetch('/admin/files/list?dir=' + encodeURIComponent(dir))
+      .then(function(r) { return r.json(); })
+      .then(function(data) { renderDir(data.entries || [], data.dir || ''); })
+      .catch(function(e) {
+        body.innerHTML = '<div style="color:red;padding:20px;">Error: ' + e.message + '</div>';
+      });
+  }
+
+  function renderDir(entries, dir) {
+    var body = document.getElementById('fm-picker-body');
+    if (!body) return;
+
+    var html = '';
+
+    // Breadcrumb
+    var parts = dir ? dir.split('/').filter(function(p){return p;}) : [];
+    html += '<div class="fm-breadcrumbs"><a href="#" data-dir="">softwares/</a>';
+    var acc = '';
+    for (var i = 0; i < parts.length; i++) {
+      acc = acc ? acc + '/' + parts[i] : parts[i];
+      html += '<a href="#" data-dir="' + esc(acc) + '">' + esc(parts[i]) + '/</a>';
+    }
+    html += '</div>';
+
+    // Upload bar
+    html += '<div class="fm-actions">';
+    html += '<input type="file" id="fm-picker-file" />';
+    html += '<button class="fm-btn" id="fm-picker-upload-btn">Upload</button>';
+    html += '</div>';
+
+    // Table
+    html += '<table class="fm-table"><thead><tr>';
+    html += '<th style="width:50px">Type</th><th>Name</th><th style="width:90px">Size</th>';
+    html += '<th style="width:80px"></th></tr></thead><tbody>';
+
+    // Parent dir
+    if (dir) {
+      var parentDir = dir.indexOf('/') >= 0 ? dir.substring(0, dir.lastIndexOf('/')) : '';
+      html += '<tr><td class="fm-type">DIR</td>';
+      html += '<td><a href="#" data-dir="' + esc(parentDir) + '">..</a></td>';
+      html += '<td></td><td></td></tr>';
+    }
+
+    for (var j = 0; j < entries.length; j++) {
+      var e = entries[j];
+      var absPath = '/softwares/' + e.path;
+      html += '<tr>';
+      html += '<td class="fm-type">' + (e.type === 'directory' ? 'DIR' : 'FILE') + '</td>';
+      html += '<td>';
+      if (e.type === 'directory') {
+        html += '<a href="#" data-dir="' + esc(e.path) + '">' + esc(e.name) + '</a>';
+      } else {
+        html += esc(e.name);
+      }
+      html += '</td>';
+      html += '<td>' + (e.size ? humanSize(e.size) : '') + '</td>';
+      html += '<td><a href="#" class="fm-btn fm-btn-select" data-select="' + esc(absPath) + '">Select</a></td>';
+      html += '</tr>';
+    }
+
+    html += '</tbody></table>';
+    body.innerHTML = html;
+
+    // Event delegation
+    body.addEventListener('click', handlePickerClick);
+  }
+
+  function handlePickerClick(e) {
+    var t = e.target;
+
+    // Navigate directory
+    if (t.tagName === 'A' && t.hasAttribute('data-dir')) {
+      e.preventDefault();
+      loadDir(t.getAttribute('data-dir'));
+      return;
+    }
+
+    // Select file/folder
+    if (t.hasAttribute('data-select')) {
+      e.preventDefault();
+      selectPath(t.getAttribute('data-select'));
+      return;
+    }
+
+    // Upload button
+    if (t.id === 'fm-picker-upload-btn') {
+      e.preventDefault();
+      var fileInput = document.getElementById('fm-picker-file');
+      if (!fileInput || !fileInput.files.length) { alert('Select a file first'); return; }
+
+      var breadcrumbs = document.querySelector('#fm-picker-body .fm-breadcrumbs');
+      var lastLink = breadcrumbs ? breadcrumbs.querySelectorAll('a') : [];
+      var currentDir = lastLink.length ? lastLink[lastLink.length - 1].getAttribute('data-dir') || '' : '';
+
+      var csrfToken = document.querySelector('meta[name="csrf-token"]');
+      var fd = new FormData();
+      fd.append('file', fileInput.files[0]);
+      fd.append('dir', currentDir);
+
+      t.textContent = 'Uploading...';
+      t.disabled = true;
+
+      fetch('/admin/files/ajax_upload', {
+        method: 'POST',
+        headers: csrfToken ? { 'X-CSRF-Token': csrfToken.getAttribute('content') } : {},
+        body: fd
+      })
+      .then(function(r) { return r.json(); })
+      .then(function(data) {
+        if (data.ok) {
+          loadDir(currentDir);
+        } else {
+          alert('Upload failed: ' + (data.error || 'unknown error'));
+          t.textContent = 'Upload';
+          t.disabled = false;
+        }
+      })
+      .catch(function(err) {
+        alert('Upload error: ' + err.message);
+        t.textContent = 'Upload';
+        t.disabled = false;
+      });
     }
   }
 
-  // Global callback for iframe to call directly (same-origin)
-  window.filePickerSelect = function(fieldId, path) {
-    var input = document.getElementById(fieldId);
-    if (input) {
-      input.value = path;
-      input.dispatchEvent(new Event('change', { bubbles: true }));
-    }
-    closeFilePicker();
-  };
+  function esc(s) {
+    var d = document.createElement('div');
+    d.textContent = s;
+    return d.innerHTML;
+  }
+
+  function humanSize(bytes) {
+    if (bytes < 1024) return bytes + ' B';
+    if (bytes < 1048576) return (bytes / 1024).toFixed(1) + ' KB';
+    return (bytes / 1048576).toFixed(1) + ' MB';
+  }
 
   document.addEventListener('DOMContentLoaded', addBrowseButtons);
 
-  // ActiveAdmin has_many dynamic rows
   if (typeof jQuery !== 'undefined') {
     jQuery(document).on('has_many_add:after', function() {
       setTimeout(addBrowseButtons, 50);
diff --git a/apps/api/app/assets/stylesheets/active_admin.scss b/apps/api/app/assets/stylesheets/active_admin.scss
index 3f100cf..6393299 100644
--- a/apps/api/app/assets/stylesheets/active_admin.scss
+++ b/apps/api/app/assets/stylesheets/active_admin.scss
@@ -39,12 +39,19 @@
   position: fixed; inset: 0; z-index: 9999; background: rgba(0,0,0,0.6); display: flex; align-items: center; justify-content: center;
 }
 .fm-modal {
-  position: relative; width: 90vw; max-width: 1000px; height: 80vh; background: #fff; border-radius: 8px; box-shadow: 0 20px 60px rgba(0,0,0,0.3); overflow: hidden;
+  position: relative; width: 90vw; max-width: 1000px; height: 80vh; background: #fff; border-radius: 8px; box-shadow: 0 20px 60px rgba(0,0,0,0.3); display: flex; flex-direction: column; overflow: hidden;
 }
+.fm-modal-header {
+  display: flex; align-items: center; justify-content: space-between; padding: 12px 16px; border-bottom: 1px solid #e0e0e0; background: #f8f8f8; flex-shrink: 0;
+}
+.fm-modal-title { font-weight: bold; font-size: 15px; color: #333; }
 .fm-modal-close {
-  position: absolute; top: 8px; right: 12px; z-index: 10; background: none; border: none; font-size: 28px; color: #666; cursor: pointer; line-height: 1;
+  background: none; border: none; font-size: 24px; color: #666; cursor: pointer; line-height: 1; padding: 0 4px;
   &:hover { color: #000; }
 }
-.fm-modal-iframe {
-  width: 100%; height: 100%; border: none;
+.fm-modal-body {
+  flex: 1; overflow-y: auto; padding: 16px;
+  .fm-breadcrumbs { margin-bottom: 12px; }
+  .fm-actions { margin-bottom: 12px; }
+  .fm-table { font-size: 13px; }
 }