diff --git a/package.json b/package.json
index 432d577..5b319ed 100644
--- a/package.json
+++ b/package.json
@@ -56,7 +56,7 @@
     "@dnd-kit/core": "^6.3.1",
     "@dnd-kit/sortable": "^10.0.0",
     "@dnd-kit/utilities": "^3.2.2",
-    "@tightknitai/slack-block-kit-validator": "^0.1.12",
+    "@tightknitai/slack-block-kit-validator": "^0.1.13",
     "@tiptap/extension-link": "^3.29.2",
     "@tiptap/react": "^3.29.2",
     "@tiptap/starter-kit": "^3.29.2",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 611be39..edf1c4e 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -22,8 +22,8 @@ importers:
         specifier: ^3.2.2
         version: 3.2.2(react@19.2.8)
       '@tightknitai/slack-block-kit-validator':
-        specifier: ^0.1.12
-        version: 0.1.12
+        specifier: ^0.1.13
+        version: 0.1.13
       '@tiptap/extension-link':
         specifier: ^3.29.2
         version: 3.29.2(@tiptap/core@3.29.2(@tiptap/pm@3.29.2))(@tiptap/pm@3.29.2)
@@ -1741,8 +1741,8 @@ packages:
     peerDependencies:
       '@testing-library/dom': '>=7.21.4'
 
-  '@tightknitai/slack-block-kit-validator@0.1.12':
-    resolution: {integrity: sha512-f+UNs6Mr/YoRrAHjm6cPidFLDwNkkq9dmdbMQNOktcqCVCl4cZy/uTVa+v1bNIk4++92RhxCTx3iPm2gG1jjPg==}
+  '@tightknitai/slack-block-kit-validator@0.1.13':
+    resolution: {integrity: sha512-Zxe+cgKnWSettBS5PCxGcNUR7GufZZlig9XXzf7FSxt6sYBc56eriEWE9Oub4MckSuCQTl8ds0NFsiMERTYkrg==}
     engines: {node: '>=20'}
 
   '@tiptap/core@3.29.2':
@@ -4892,7 +4892,7 @@ snapshots:
     dependencies:
       '@testing-library/dom': 10.4.1
 
-  '@tightknitai/slack-block-kit-validator@0.1.12':
+  '@tightknitai/slack-block-kit-validator@0.1.13':
     dependencies:
       ajv: 8.20.0
       ajv-formats: 3.0.1(ajv@8.20.0)
diff --git a/src/components/editors/actions-editor.tsx b/src/components/editors/actions-editor.tsx
index efe6239..a671330 100644
--- a/src/components/editors/actions-editor.tsx
+++ b/src/components/editors/actions-editor.tsx
@@ -5,7 +5,7 @@ import { Button } from '../../lib/ui/button';
 import { Input } from '../../lib/ui/input';
 import { Label } from '../../lib/ui/label';
 import { RadioGroup, RadioGroupItem } from '../../lib/ui/radio-group';
-import { EditorField } from './field';
+import { AdvancedIdField, EditorField } from './field';
 import type { BlockEditorProps } from './types';
 
 type ButtonStyle = 'default' | 'primary' | 'danger';
@@ -125,6 +125,14 @@ export function ActionsEditor({ block, onChange }: BlockEditorProps<ActionsBlock
                 ))}
               </RadioGroup>
             </EditorField>
+            <AdvancedIdField
+              label="Action ID"
+              help="Optional. Sent in the interaction payload so your app knows which button was clicked."
+              htmlFor={`btn-action-${idx}`}
+              value={el.action_id}
+              placeholder="e.g. approve_request"
+              onChange={(next) => updateButton(idx, { action_id: next })}
+            />
           </div>
         );
       })}
diff --git a/src/components/editors/block-editor.tsx b/src/components/editors/block-editor.tsx
index 5a3359f..c7c6bfb 100644
--- a/src/components/editors/block-editor.tsx
+++ b/src/components/editors/block-editor.tsx
@@ -33,6 +33,7 @@ import { ContextActionsEditor } from './context-actions-editor';
 import { ContextEditor } from './context-editor';
 import { DataVisualizationEditor } from './data-visualization-editor';
 import { DividerEditor } from './divider-editor';
+import { AdvancedIdField } from './field';
 import { HeaderEditor } from './header-editor';
 import { ImageEditor } from './image-editor';
 import { InputEditor } from './input-editor';
@@ -85,6 +86,14 @@ export function BlockEditor({
         </ul>
       ) : null}
       {dispatch(block, onChange)}
+      <AdvancedIdField
+        label="Block ID"
+        help="Optional. Unique within the message or view. Slack returns it in interaction payloads."
+        htmlFor="block-id"
+        value={block.block_id}
+        placeholder="e.g. approval_row"
+        onChange={(next) => onChange({ ...block, block_id: next })}
+      />
       {onDone ? (
         <div className="flex justify-end border-t pt-3">
           <Button type="button" size="sm" onClick={onDone}>
diff --git a/src/components/editors/card-editor.tsx b/src/components/editors/card-editor.tsx
index 159466c..bb9170c 100644
--- a/src/components/editors/card-editor.tsx
+++ b/src/components/editors/card-editor.tsx
@@ -8,7 +8,7 @@ import { Label } from '../../lib/ui/label';
 import { RadioGroup, RadioGroupItem } from '../../lib/ui/radio-group';
 import { Textarea } from '../../lib/ui/textarea';
 import type { CardBlock } from '../../types';
-import { EditorField } from './field';
+import { AdvancedIdField, EditorField } from './field';
 import type { BlockEditorProps } from './types';
 
 type ButtonStyle = 'default' | 'primary' | 'danger';
@@ -289,6 +289,14 @@ function ButtonsField({
                 ))}
               </RadioGroup>
             </EditorField>
+            <AdvancedIdField
+              label="Action ID"
+              help="Optional. Sent in the interaction payload so your app knows which button was clicked."
+              htmlFor={`${idPrefix}-btn-action-${idx}`}
+              value={btn.action_id}
+              placeholder="e.g. open_details"
+              onChange={(next) => update(idx, { action_id: next })}
+            />
           </div>
         );
       })}
diff --git a/src/components/editors/field.tsx b/src/components/editors/field.tsx
index 89fdd5e..3128911 100644
--- a/src/components/editors/field.tsx
+++ b/src/components/editors/field.tsx
@@ -1,4 +1,5 @@
 import type { ReactNode } from 'react';
+import { Input } from '../../lib/ui/input';
 import { Label } from '../../lib/ui/label';
 
 /**
@@ -30,3 +31,55 @@ export function EditorField({
     </div>
   );
 }
+
+/**
+ * Collapsed "Advanced" disclosure holding one identifier field
+ * (`block_id` on a block, `action_id` on an interactive element).
+ * These are plumbing the builder fills in automatically, so they stay
+ * out of the way until someone needs to pin one to a value their app
+ * matches on.
+ *
+ * Native `<details>`, so the open/closed state, the disclosure
+ * triangle, and keyboard behavior all come from the browser.
+ * @param props - field props
+ * @param props.label - the visible label (e.g. "Action ID")
+ * @param props.help - one-line helper text explaining the field
+ * @param props.htmlFor - id of the input, for a11y
+ * @param props.value - current identifier, if set
+ * @param props.placeholder - greyed-out example id
+ * @param props.onChange - called with the new id, or undefined when cleared
+ * @returns the rendered disclosure
+ */
+export function AdvancedIdField({
+  label,
+  help,
+  htmlFor,
+  value,
+  placeholder,
+  onChange
+}: {
+  label: string;
+  help: string;
+  htmlFor: string;
+  value: string | undefined;
+  placeholder: string;
+  onChange: (next: string | undefined) => void;
+}) {
+  return (
+    <details className="rounded-md border bg-muted/20 px-2.5 py-1.5">
+      <summary className="cursor-pointer text-[11px] font-medium text-muted-foreground hover:text-foreground">
+        Advanced
+      </summary>
+      <div className="pt-2 pb-1">
+        <EditorField label={label} help={help} htmlFor={htmlFor}>
+          <Input
+            id={htmlFor}
+            value={value ?? ''}
+            placeholder={placeholder}
+            onChange={(e) => onChange(e.target.value || undefined)}
+          />
+        </EditorField>
+      </div>
+    </details>
+  );
+}
diff --git a/src/components/editors/section-editor.tsx b/src/components/editors/section-editor.tsx
index 7f36a8b..02ac666 100644
--- a/src/components/editors/section-editor.tsx
+++ b/src/components/editors/section-editor.tsx
@@ -5,7 +5,7 @@ import { Label } from '../../lib/ui/label';
 import { RadioGroup, RadioGroupItem } from '../../lib/ui/radio-group';
 import { Textarea } from '../../lib/ui/textarea';
 import { EmojiTextInsertButton } from '../emoji/emoji-text-insert-button';
-import { EditorField } from './field';
+import { AdvancedIdField, EditorField } from './field';
 import type { BlockEditorProps } from './types';
 
 type AccessoryKind = 'none' | 'button' | 'image' | 'other';
@@ -230,6 +230,14 @@ function ButtonAccessoryFields({ button, onChange }: { button: SlackButton; onCh
           ))}
         </RadioGroup>
       </EditorField>
+      <AdvancedIdField
+        label="Action ID"
+        help="Optional. Sent in the interaction payload so your app knows which button was clicked."
+        htmlFor="section-acc-btn-action"
+        value={button.action_id}
+        placeholder="e.g. learn_more"
+        onChange={(next) => onChange({ ...button, action_id: next })}
+      />
     </div>
   );
 }
diff --git a/test/block-editor-advanced.test.tsx b/test/block-editor-advanced.test.tsx
new file mode 100644
index 0000000..690ec98
--- /dev/null
+++ b/test/block-editor-advanced.test.tsx
@@ -0,0 +1,47 @@
+import { fireEvent, render, screen } from '@testing-library/react';
+import { describe, expect, it, vi } from 'vitest';
+import { BlockEditor } from '../src/components/editors/block-editor';
+import type { SupportedBlock } from '../src/types';
+
+const ACTIONS: SupportedBlock = {
+  type: 'actions',
+  elements: [
+    {
+      type: 'button',
+      text: { type: 'plain_text', text: 'Approve', emoji: true },
+      action_id: 'button_abc123'
+    }
+  ]
+};
+
+describe('BlockEditor advanced fields', () => {
+  it('edits the block_id', () => {
+    const onChange = vi.fn();
+    render(<BlockEditor block={{ type: 'divider' }} onChange={onChange} />);
+
+    fireEvent.change(screen.getByLabelText('Block ID'), { target: { value: 'approval_row' } });
+
+    expect(onChange).toHaveBeenCalledWith({ type: 'divider', block_id: 'approval_row' });
+  });
+
+  it('edits a button action_id', () => {
+    const onChange = vi.fn();
+    render(<BlockEditor block={ACTIONS} onChange={onChange} />);
+
+    fireEvent.change(screen.getByLabelText('Action ID'), { target: { value: 'approve_request' } });
+
+    expect(onChange).toHaveBeenCalledWith({
+      type: 'actions',
+      elements: [{ ...ACTIONS.elements[0], action_id: 'approve_request' }]
+    });
+  });
+
+  it('clearing an id drops the field so Slack generates one', () => {
+    const onChange = vi.fn();
+    render(<BlockEditor block={ACTIONS} onChange={onChange} />);
+
+    fireEvent.change(screen.getByLabelText('Action ID'), { target: { value: '' } });
+
+    expect(onChange.mock.calls[0][0].elements[0].action_id).toBeUndefined();
+  });
+});
diff --git a/test/duplicate-ids.test.ts b/test/duplicate-ids.test.ts
new file mode 100644
index 0000000..a656d45
--- /dev/null
+++ b/test/duplicate-ids.test.ts
@@ -0,0 +1,46 @@
+import { validateBlockKit } from '@tightknitai/slack-block-kit-validator';
+import { describe, expect, it } from 'vitest';
+import { groupValidatorErrors } from '../src/lib/error-grouping';
+import type { BuilderBlock, SupportedBlock } from '../src/types';
+
+/**
+ * The Advanced fields let people type `block_id` / `action_id` by hand, so the
+ * collisions the builder's generated ids used to make impossible are now one
+ * keystroke away. These assert the validator reports them and that the error
+ * lands on the offending block rather than in the general bucket.
+ */
+function validateAndGroup(blocks: SupportedBlock[]) {
+  const result = validateBlockKit(blocks, { target: 'blocks', surface: 'message' });
+  const builder: BuilderBlock[] = blocks.map((block, i) => ({ id: `blk-${i}`, block }));
+  return groupValidatorErrors(result.errors, builder);
+}
+
+const button = (text: string, action_id: string) =>
+  ({ type: 'button', text: { type: 'plain_text', text, emoji: true }, action_id }) as const;
+
+describe('duplicate id validation', () => {
+  it('flags two elements sharing an action_id inside one block', () => {
+    const grouped = validateAndGroup([{ type: 'actions', elements: [button('A', 'dup'), button('B', 'dup')] }]);
+
+    expect(grouped.byBlockId.get('blk-0')?.[0]).toMatch(/action_id must be unique within the block/);
+    expect(grouped.general).toEqual([]);
+  });
+
+  it('allows the same action_id in two different blocks', () => {
+    const grouped = validateAndGroup([
+      { type: 'actions', elements: [button('A', 'same')] },
+      { type: 'actions', elements: [button('B', 'same')] }
+    ]);
+
+    expect(grouped.total).toBe(0);
+  });
+
+  it('flags two blocks sharing a block_id', () => {
+    const grouped = validateAndGroup([
+      { type: 'section', text: { type: 'mrkdwn', text: 'one' }, block_id: 'dup' },
+      { type: 'section', text: { type: 'mrkdwn', text: 'two' }, block_id: 'dup' }
+    ]);
+
+    expect(grouped.byBlockId.get('blk-1')?.[0]).toMatch(/block_id must be unique/);
+  });
+});