feat(sidebar): add dialogue selection and copying (#238)

src/preload-clipboard.test.ts

@@ -0,0 +1,46 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { runInNewContext } from 'node:vm';
+import { build } from 'esbuild';
+
+test('sidebar clipboard bridge writes exact text without renderer focus and rejects non-text input', async () => {
+  const result = await build({
+    entryPoints: ['src/preload.ts'],
+    bundle: true,
+    platform: 'node',
+    format: 'cjs',
+    external: ['electron'],
+    write: false,
+  });
+  const output = result.outputFiles[0];
+  assert.ok(output);
+  const writes: string[] = [];
+  let exposed: unknown;
+  runInNewContext(output.text, {
+    process: { argv: [] },
+    require: (name: string) => {
+      assert.equal(name, 'electron');
+      return {
+        ipcRenderer: { on: () => {} },
+        clipboard: { writeText: (text: string) => writes.push(text) },
+        contextBridge: {
+          exposeInMainWorld: (_name: string, api: unknown) => {
+            exposed = api;
+          },
+        },
+      };
+    },
+  });
+  assert.ok(
+    typeof exposed === 'object' && exposed !== null && 'copySubtitleSidebarSelection' in exposed,
+  );
+  const copy = exposed.copySubtitleSidebarSelection;
+  if (typeof copy !== 'function') throw new Error('Missing clipboard bridge');
+  const text = '最初の台詞\n二行目\n\n同じ台詞';
+  await copy(text);
+  assert.deepEqual(writes, [text]);
+  for (const value of [null, undefined, 42, { text }, ['台詞']]) {
+    await assert.rejects(async () => copy(value), /Subtitle selection must be text/);
+  }
+  assert.deepEqual(writes, [text]);
+});