feat(downloads): 多下载器路由:默认下载器、站点指定下载器、别名

照 MP(chain/download/submission.py:明确指定 or 站点下载器 or 默认):
- 迁移 0063:downloader_instance.is_default(至多一个,唯一索引)、site.downloader_instance_id
- pickInstance:明确指定 > 站点指定 > 默认 > 第一个可用;自动下载(gates)与手动下载共用
- 设置:下载器名称改称别名,新增「设为默认下载器」;站点编辑新增「下载器」选择
- 测试 downloader-routing.test.ts

Co-Authored-By: Claude Opus 5.5 <[email protected]>

apps/server/src/modules/acquisition-organize/services/acquisition.ts

@@ -40,6 +40,7 @@ import {
   hostPathOf,
   type InstanceTopology,
   loadInstances,
+  pickInstance,
   recordCandidate,
 } from "./common.ts";
 import { autoFillCheck, type ForceFill } from "./evaluate-autofill.ts";
@@ -894,9 +895,10 @@ async function gates(
   const blocked = await automationBlock(d);
   if (blocked) return { ok: false, reasons: [blocked], rejected: [] };
   const sp = (sub?.params ?? {}) as { downloaderInstanceId?: string; downloadSavePath?: string };
-  const wanted = sp.downloaderInstanceId;
-  const insts = (await loadInstances(d.ctx.db)).filter((t) => t.savePath && (!wanted || t.inst.id === wanted));
-  const inst = insts[0];
+  const inst = await pickInstance(d.ctx.db, await loadInstances(d.ctx.db), {
+    explicitId: sp.downloaderInstanceId,
+    siteId: rel.site_id,
+  });
   if (!inst?.savePath) return { ok: false, reasons: ["no_downloader_instance"], rejected: [] };
   // 订阅指定的保存路径:本机路径经下载器路径映射换成下载器侧路径;本来就是下载器侧路径的原样用
   let savePath = inst.savePath;

apps/server/src/modules/acquisition-organize/services/common.ts

@@ -216,6 +216,31 @@ export interface InstanceTopology {
   category: string | null;
 }
 
+/**
+ * 选下载器(照 MP):明确指定(订阅 / 手动)> 站点指定 > 默认下载器 > 第一个有保存目录的。
+ * 明确指定但不可用时返回 undefined(不悄悄换别的);站点指定的不可用时回落默认。
+ */
+export async function pickInstance(
+  exec: Exec,
+  insts: readonly InstanceTopology[],
+  opts: { explicitId?: string | undefined; siteId?: string | null | undefined },
+): Promise<InstanceTopology | undefined> {
+  const usable = insts.filter((t) => t.savePath);
+  if (opts.explicitId) return usable.find((t) => t.inst.id === opts.explicitId);
+  if (opts.siteId) {
+    const site = await exec
+      .selectFrom("site")
+      .select("downloader_instance_id")
+      .where("id", "=", opts.siteId)
+      .executeTakeFirst();
+    const hit = site?.downloader_instance_id
+      ? usable.find((t) => t.inst.id === site.downloader_instance_id)
+      : undefined;
+    if (hit) return hit;
+  }
+  return usable.find((t) => t.inst.is_default) ?? usable[0];
+}
+
 export async function loadInstances(
   exec: Exec,
   opts: { enabledOnly?: boolean; ids?: string[] } = {},

apps/server/src/modules/acquisition-organize/services/manual-acquisition.ts

@@ -4,7 +4,7 @@ import { ApiException } from "../../../http/errors.ts";
 import type { ServerContext } from "../../types.ts";
 import { hashJson, jsonb, toApi } from "../util.ts";
 import { subscriptionSavePath } from "./acquisition.ts";
-import { enqueueTracked, loadInstances } from "./common.ts";
+import { enqueueTracked, loadInstances, pickInstance } from "./common.ts";
 
 /** Manual choice is a one-off plan, independent of subscription filters and slots. */
 export async function planManualAcquisition(
@@ -32,8 +32,10 @@ export async function planManualAcquisition(
     };
   if (entityId && !(await db.selectFrom("media_entity").select("id").where("id", "=", entityId).executeTakeFirst()))
     throw new ApiException("not_found", "作品不存在");
-  const instances = await loadInstances(db, body.downloaderInstanceId ? { ids: [body.downloaderInstanceId] } : {});
-  const topo = instances.find((i) => i.savePath);
+  const topo = await pickInstance(db, await loadInstances(db), {
+    explicitId: body.downloaderInstanceId,
+    siteId: rel.site_id,
+  });
   if (!topo?.savePath) throw new ApiException("precondition_failed", "没有可用的下载器或保存目录");
   const replacementIds = body.importMode === "replace" ? [...new Set(body.replacementAssetIds)] : [];
   if (body.importMode === "replace" && (!entityId || replacementIds.length === 0))

apps/server/src/modules/auth-settings/instances-routes.ts

@@ -262,8 +262,15 @@ export function registerInstanceRoutes(app: ModuleApp, ctx: ServerContext) {
       throw new ApiException("validation_failed", "API Key 认证需要填写 API Key");
     return { ...curSettings, ...(next.settings ?? {}), authKind };
   };
+  /** 默认下载器至多一个:设新的之前先取消旧的 */
+  const clearDefault = (exceptId?: string) => {
+    let q = ctx.db.updateTable("downloader_instance").set({ is_default: false }).where("is_default", "=", true);
+    if (exceptId) q = q.where("id", "!=", exceptId);
+    return q.execute();
+  };
   endpoint(app, DL.create, async ({ body, actor }) => {
     const { credential: rawCredential, authKind, ...rest } = body;
+    if (rest.isDefault) await clearDefault();
     const credential = secretInput(rawCredential) ?? undefined;
     const settings = dlAuth(authKind, { ...rest, ...(credential ? { credential } : {}) });
     const keep = authKind !== "none" && credential;
@@ -291,6 +298,7 @@ export function registerInstanceRoutes(app: ModuleApp, ctx: ServerContext) {
     const { credential: rawCredential, authKind, ...rest } = body;
     const credential = secretInput(rawCredential);
     const cur = await getRow("downloader_instance", params.id);
+    if (rest.isDefault) await clearDefault(params.id);
     const curAuth = ((cur.settings ?? {}) as Record<string, unknown>).authKind;
     if (credential === null && (authKind ?? curAuth) === "api_key")
       throw new ApiException("validation_failed", "API Key 认证不能清除 API Key；不用认证时把认证方式改为无认证");