feat(editing): pre-load a message into edit mode via editing.initialTarget

src/components/block-kitchen.tsx

@@ -14,7 +14,7 @@ import {
 } from '@dnd-kit/core';
 import { sortableKeyboardCoordinates } from '@dnd-kit/sortable';
 import { GripVertical } from 'lucide-react';
-import { useCallback, useMemo, useState } from 'react';
+import { useCallback, useEffect, useMemo, useState } from 'react';
 import { parseContainerBodyId } from '../lib/container-blocks';
 import { makeEmojiHook } from '../lib/custom-emoji-hook';
 import { buildVariantById, defaultPalette, type PaletteSection } from '../lib/default-blocks';
@@ -99,8 +99,22 @@ export function BlockKitchen(props: BlockKitchenProps) {
   const allowedSurfaces: readonly PreviewSurface[] =
     allowedSurfacesProp && allowedSurfacesProp.length > 0 ? allowedSurfacesProp : ['message'];
 
+  // A pre-loaded edit target (opt-in) carries its own blocks; they seed the
+  // draft and win over `initialBlocks`, which is the blank-canvas seed.
+  const seededBlocks = editing?.initialTarget?.blocks ?? initialBlocks;
+  // Mount-only: both props are read once at mount, so warn once.
+  // biome-ignore lint/correctness/useExhaustiveDependencies: intentional mount-only check
+  useEffect(() => {
+    if (editing?.initialTarget && initialBlocks) {
+      console.warn(
+        '[BlockKitchen] Both `initialBlocks` and `editing.initialTarget` were provided; ' +
+          'using the target’s blocks and ignoring `initialBlocks`.'
+      );
+    }
+  }, []);
+
   const { blocks, addBlock, addChild, updateBlock, removeBlock, duplicateBlock, reorderBlock, moveBlock, replaceAll } =
-    useBlockKitchenState({ initialBlocks, onChange });
+    useBlockKitchenState({ initialBlocks: seededBlocks, onChange });
 
   // Lookups for resolving a drop target: which ids are container children,
   // and which container each child belongs to. Recomputed when the tree
@@ -124,7 +138,7 @@ export function BlockKitchen(props: BlockKitchenProps) {
   // the current blocks as a new message (`sendOpen`).
   const [updateOpen, setUpdateOpen] = useState(false);
   const [loadOpen, setLoadOpen] = useState(false);
-  const [editTarget, setEditTarget] = useState<EditTarget | null>(null);
+  const [editTarget, setEditTarget] = useState<EditTarget | null>(() => editing?.initialTarget ?? null);
   // Edit mode only counts as active while `editing` is configured. If the host
   // toggles `editing` off mid-session, fall back to send-only without losing
   // the loaded target (it reactivates if `editing` returns).

src/types.ts

@@ -635,6 +635,14 @@ export interface EditingConfig {
    * entry only.
    */
   loadRecentMessages?: (channelId: string) => Promise<RecentMessage[]>;
+  /**
+   * Optional. Pre-load a message straight into edit mode at mount, skipping the
+   * load dialog. Same shape the host returns from {@link onLoadMessage} on
+   * success. Read once at mount (like {@link BlockKitchenProps.initialBlocks});
+   * changing it later needs a remount. When set, its `blocks` seed the draft and
+   * {@link BlockKitchenProps.initialBlocks} is ignored.
+   */
+  initialTarget?: Extract<LoadResult, { ok: true }>;
 }
 
 /**

test/block-kitchen-initial-target.test.tsx

@@ -0,0 +1,41 @@
+import { render, screen } from '@testing-library/react';
+import { afterEach, expect, it, vi } from 'vitest';
+import { BlockKitchen } from '../src/components/block-kitchen';
+import type { EditingConfig, LoadResult, SupportedBlock } from '../src/types';
+
+const baseProps = {
+  loadChannels: async () => [{ id: 'C1', name: 'general' }],
+  loadSendAsUserStatus: async () => ({ canSendAsUser: false }) as never,
+  onSend: async () => ({ ok: true }) as never
+};
+
+const target: Extract<LoadResult, { ok: true }> = {
+  ok: true,
+  channelId: 'C1',
+  channelName: 'general',
+  ts: '1699999999.000100',
+  blocks: [{ type: 'header', text: { type: 'plain_text', text: 'from target' } }] as SupportedBlock[],
+  editableVia: 'bot'
+};
+
+const editing: EditingConfig = {
+  onLoadMessage: async () => ({ ok: false, reason: 'n/a' }),
+  onUpdate: async () => ({ ok: true }),
+  initialTarget: target
+};
+
+afterEach(() => vi.restoreAllMocks());
+
+it('boots straight into edit mode when editing.initialTarget is provided', () => {
+  render(<BlockKitchen {...baseProps} editing={editing} />);
+  // The edit-mode banner only renders while a message is loaded.
+  expect(screen.getByText(/References an existing message in/i)).toBeTruthy();
+  expect(screen.getByText('#general')).toBeTruthy();
+});
+
+it('warns and prefers the target’s blocks when initialBlocks is also given', () => {
+  const warn = vi.spyOn(console, 'warn').mockImplementation(() => {});
+  render(<BlockKitchen {...baseProps} editing={editing} initialBlocks={[{ type: 'divider' }] as SupportedBlock[]} />);
+  expect(warn).toHaveBeenCalledOnce();
+  expect(warn.mock.calls[0][0]).toMatch(/ignoring `initialBlocks`/);
+});