更新摘要锚点支持 CI 兜底

- 摘要锚点优先取渠道清单 commit，缺失时回退 CI 传入的上一次成功构建 COMMIT_HASH
- Jenkins 构建阶段解析上一次成功构建的 COMMIT_HASH 并注入 AGC_UPDATE_PREVIOUS_COMMIT，读取失败保持为空
- 新增锚点优先级与非法值忽略的定向用例
- 技术方案补充锚点兜底说明

apps/ai-game-creator-shell/scripts/build-release.mjs

@@ -196,9 +196,21 @@ async function readRemoteChannelManifest(channel = resolveReleaseChannel()) {
   return fetchManifest(updateManifestUrl(channel), 'OSS 渠道清单');
 }
 
+/**
+ * 摘要锚点：上次发布对应的提交。
+ *
+ * 首选渠道清单里的 `commit`（发布产物自己的事实来源）；清单缺该字段时（首次启用
+ * 摘要、或更换渠道后清单还没带过 commit）回退到 CI 传入的 `AGC_UPDATE_PREVIOUS_COMMIT`
+ * —— 它是上一次成功构建的 COMMIT_HASH，同样指向用户拿到的那个版本。
+ */
 export async function resolvePreviousReleaseCommit(
   channel = resolveReleaseChannel(),
+  { override = process.env.AGC_UPDATE_PREVIOUS_COMMIT } = {},
 ) {
+  const explicit = override?.trim();
+  if (explicit && /^[0-9a-f]{7,40}$/u.test(explicit)) {
+    return explicit;
+  }
   const manifest = await readRemoteChannelManifest(channel);
   const commit =
     typeof manifest?.commit === 'string' ? manifest.commit.trim() : '';

apps/ai-game-creator-shell/scripts/build-release.test.mjs

@@ -22,6 +22,7 @@ import {
   formatReleaseNotes,
   nextPatchVersion,
   resolveManifestPlatformKeys,
+  resolvePreviousReleaseCommit,
   resolveReleaseChannel,
   resolveRemoteHighWaterVersion,
   selectReleaseArtifact,
@@ -241,6 +242,41 @@ test('version high water ignores the windows migration pointer for other channel
   );
 });
 
+test('release notes anchor prefers the explicit commit and falls back to the manifest', async () => {
+  await withStubbedFetch(
+    () => jsonResponse({ version: '0.1.61', commit: 'abcdef1234567890' }),
+    async () => {
+      assert.equal(
+        await resolvePreviousReleaseCommit('dev-win', {
+          override: '6017d46088c04199e99cf89f347b12d67591475e',
+        }),
+        '6017d46088c04199e99cf89f347b12d67591475e',
+      );
+      // 覆盖值非法时忽略，继续用清单里的 commit。
+      assert.equal(
+        await resolvePreviousReleaseCommit('dev-win', {
+          override: 'not-a-sha',
+        }),
+        'abcdef1234567890',
+      );
+      assert.equal(
+        await resolvePreviousReleaseCommit('dev-win', { override: '  ' }),
+        'abcdef1234567890',
+      );
+    },
+  );
+
+  await withStubbedFetch(
+    () => jsonResponse({ version: '0.1.61' }),
+    async () => {
+      assert.equal(
+        await resolvePreviousReleaseCommit('dev-win', { override: undefined }),
+        null,
+      );
+    },
+  );
+});
+
 test('release upload forces overwrite for artifact, signature and channel pointers', () => {
   const source = readFileSync(
     new URL('./release-upload.mjs', import.meta.url),