diff --git a/engine/app/assets/stylesheets/coplan/application.css b/engine/app/assets/stylesheets/coplan/application.css
index a145536f..dba4f92d 100644
--- a/engine/app/assets/stylesheets/coplan/application.css
+++ b/engine/app/assets/stylesheets/coplan/application.css
@@ -2460,39 +2460,94 @@ body:has(.comment-toolbar) .main-content {
   margin-bottom: var(--space-md);
 }
 
-.attachments-upload {
+/* Drag-and-drop upload zone (see dropzone_controller.js). The whole inner
+   area is a <label>, so clicking anywhere opens the file picker; the real
+   input is visually hidden (not display:none, so it stays focusable). */
+.attachments-dropzone__inner {
   display: flex;
+  flex-direction: column;
   align-items: center;
-  gap: var(--space-sm);
-  flex-wrap: wrap;
+  gap: var(--space-xs);
+  padding: var(--space-xl) var(--space-lg);
+  border: 2px dashed var(--color-border-strong);
+  border-radius: var(--radius);
+  background: var(--color-surface-muted);
+  text-align: center;
+  cursor: pointer;
+  transition: border-color 0.15s, background 0.15s;
+}
+
+.attachments-dropzone__inner:hover,
+.attachments-dropzone--active .attachments-dropzone__inner {
+  border-color: var(--color-primary);
+  background: var(--color-primary-light);
+}
+
+.attachments-dropzone__inner:focus-within {
+  outline: 2px solid var(--color-primary);
+  outline-offset: 2px;
+}
+
+.attachments-dropzone--uploading .attachments-dropzone__inner {
+  opacity: 0.6;
+  pointer-events: none;
+}
+
+.attachments-dropzone__icon {
+  font-size: 1.75rem;
+  line-height: 1;
 }
 
-.attachments-upload__input {
+.attachments-dropzone__text {
   font-size: var(--text-sm);
+  color: var(--color-text);
 }
 
-.attachments-upload__hint {
-  margin: var(--space-xs) 0 0;
+.attachments-dropzone__browse {
+  color: var(--color-primary);
+  text-decoration: underline;
+}
+
+.attachments-dropzone__hint {
   font-size: 0.75rem;
   color: var(--color-text-muted);
 }
 
+.attachments-dropzone__input {
+  position: absolute;
+  width: 1px;
+  height: 1px;
+  padding: 0;
+  margin: -1px;
+  overflow: hidden;
+  clip: rect(0 0 0 0);
+  white-space: nowrap;
+  border: 0;
+}
+
 .attachments-list {
   list-style: none;
   padding: 0;
   margin: 0;
+  display: flex;
+  flex-direction: column;
+  gap: var(--space-sm);
 }
 
 .attachments-list__item {
   display: flex;
   align-items: center;
-  gap: var(--space-sm);
-  padding: var(--space-sm) 0;
-  border-bottom: 1px solid var(--color-border);
+  gap: var(--space-md);
+  padding: var(--space-sm) var(--space-md);
+  background: var(--color-surface);
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius);
+  transition: border-color 0.15s, box-shadow 0.15s;
 }
 
-.attachments-list__item:last-child {
-  border-bottom: none;
+.attachments-list__item:hover {
+  border-color: var(--color-border-strong);
+  box-shadow: var(--shadow);
 }
 
 .attachments-list__icon {
diff --git a/engine/app/javascript/controllers/coplan/dropzone_controller.js b/engine/app/javascript/controllers/coplan/dropzone_controller.js
new file mode 100644
index 00000000..7ff8e0a4
--- /dev/null
+++ b/engine/app/javascript/controllers/coplan/dropzone_controller.js
@@ -0,0 +1,38 @@
+import { Controller } from "@hotwired/stimulus"
+
+// Drag-and-drop upload zone wrapping a visually-hidden file input. Files
+// upload immediately on selection or drop — there is no separate submit
+// button — so the controller sits on the <form> and posts via
+// requestSubmit(), letting Turbo handle the redirect.
+export default class extends Controller {
+  static targets = ["input", "text"]
+
+  dragOver(event) {
+    event.preventDefault()
+    this.element.classList.add("attachments-dropzone--active")
+  }
+
+  dragLeave(event) {
+    event.preventDefault()
+    this.element.classList.remove("attachments-dropzone--active")
+  }
+
+  drop(event) {
+    event.preventDefault()
+    this.element.classList.remove("attachments-dropzone--active")
+    if (!event.dataTransfer?.files?.length) return
+    this.inputTarget.files = event.dataTransfer.files
+    this.changed()
+  }
+
+  changed() {
+    const files = this.inputTarget.files
+    if (!files.length) return
+    if (this.hasTextTarget) {
+      this.textTarget.textContent =
+        files.length === 1 ? `Uploading ${files[0].name}…` : `Uploading ${files.length} files…`
+    }
+    this.element.classList.add("attachments-dropzone--uploading")
+    this.element.requestSubmit()
+  }
+}
diff --git a/engine/app/views/coplan/plans/_attachments.html.erb b/engine/app/views/coplan/plans/_attachments.html.erb
index 8604d833..99fc33e3 100644
--- a/engine/app/views/coplan/plans/_attachments.html.erb
+++ b/engine/app/views/coplan/plans/_attachments.html.erb
@@ -2,15 +2,26 @@
 <div class="attachments-section" id="plan-attachments">
   <% if can_edit %>
     <div class="attachments-section__header">
-      <%= form_with url: plan_attachments_path(plan), method: :post, multipart: true, class: "attachments-upload" do |f| %>
-        <%= f.file_field :files, multiple: true, name: "files[]", required: true, class: "attachments-upload__input",
-              accept: CoPlan::Plan::ATTACHMENT_CONTENT_TYPES.join(",") %>
-        <%= f.submit "Upload", class: "btn btn--primary btn--sm" %>
+      <%= form_with url: plan_attachments_path(plan), method: :post, multipart: true,
+            class: "attachments-dropzone",
+            data: {
+              controller: "coplan--dropzone",
+              action: "dragover->coplan--dropzone#dragOver dragleave->coplan--dropzone#dragLeave drop->coplan--dropzone#drop"
+            } do |f| %>
+        <label class="attachments-dropzone__inner">
+          <span class="attachments-dropzone__icon" aria-hidden="true">🖇️</span>
+          <span class="attachments-dropzone__text" data-coplan--dropzone-target="text">
+            <strong>Drag &amp; drop files here</strong> or <span class="attachments-dropzone__browse">browse</span>
+          </span>
+          <span class="attachments-dropzone__hint">
+            Up to <%= CoPlan::Plan::ATTACHMENT_MAX_BYTES / 1.megabyte %> MB per file ·
+            images, PDF, text/markdown/CSV/JSON, and ZIP
+          </span>
+          <%= f.file_field :files, multiple: true, name: "files[]", class: "attachments-dropzone__input",
+                accept: CoPlan::Plan::ATTACHMENT_CONTENT_TYPES.join(","),
+                data: { "coplan--dropzone-target": "input", action: "change->coplan--dropzone#changed" } %>
+        </label>
       <% end %>
-      <p class="attachments-upload__hint text-muted">
-        Up to <%= CoPlan::Plan::ATTACHMENT_MAX_BYTES / 1.megabyte %> MB per file.
-        Images, PDF, text/markdown/CSV/JSON, and ZIP files.
-      </p>
     </div>
   <% end %>
 
diff --git a/spec/requests/attachments_spec.rb b/spec/requests/attachments_spec.rb
index b6f86301..db9e391b 100644
--- a/spec/requests/attachments_spec.rb
+++ b/spec/requests/attachments_spec.rb
@@ -97,7 +97,7 @@
       expect(response.body).to include("diagram.png")
       expect(response.body).to include("disposition=attachment")
       # Viewers can't upload or delete.
-      expect(response.body).not_to include("attachments-upload")
+      expect(response.body).not_to include("attachments-dropzone")
     end
 
     it "shows the upload form to the plan author" do
@@ -105,7 +105,7 @@
       get plan_path(plan, tab: "attachments")
 
       expect(response).to have_http_status(:ok)
-      expect(response.body).to include("attachments-upload")
+      expect(response.body).to include("attachments-dropzone")
     end
   end
 end