feat(pi): fetch and refresh upstream model lists, searchable model picker

- POST /pi/upstreams/{id}/models/refresh calls the provider's model list
  endpoint (OpenAI-shaped /models, Anthropic /v1/models, Google
  /v1beta/models, OpenRouter /api/v1/models; Radius via pi-ai refresh),
  normalizes {id, displayName, contextWindow, supportsVision,
  supportsTools, pricing} and stores it in pi_upstream.models (0044)
- GET .../models returns {source, fetchedAt, models[]}: remote merged
  with the static catalog (remote first); failures (401/network/
  unsupported) fall back to static with a one-line error
- POST /pi/models/probe for trying credentials before creating
- wizard and edit drawer: fetch button, searchable dropdown with
  vision/tool tags, manual id, source line; default upstream needs a model
- tests: mock /models, 401, network failure; smoke step; runbook

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

apps/web/app/components/settings/pi-upstreams.tsx

@@ -7,6 +7,7 @@ import {
   usePiProviders,
   usePiUpstreamModels,
   usePiUpstreams,
+  useRefreshPiModels,
   useRemovePiUpstream,
   useUpdatePiUpstream,
 } from "~/api/pi.ts";
@@ -22,6 +23,7 @@ import { formatDateTime } from "~/lib/utils.ts";
 import { PiOAuthLogin } from "./pi-oauth.tsx";
 import {
   AUTH_LABEL,
+  ModelFetchBar,
   ModelInput,
   providerName,
   THINKING_LABEL,
@@ -113,6 +115,7 @@ function UpstreamDrawer({
   const remove = useRemovePiUpstream();
   const logout = useLogoutPiOAuth();
   const models = usePiUpstreamModels(upstream?.id ?? null);
+  const refresh = useRefreshPiModels();
   const [deleting, setDeleting] = useState(false);
   const [v, setV] = useState(() => ({
     name: upstream?.name ?? "",
@@ -139,6 +142,16 @@ function UpstreamDrawer({
     v.enabled !== upstream.enabled ||
     envFields.some((f) => (v.env[f.name] ?? "") !== (upstream.extra.env?.[f.name] ?? ""));
 
+  // 获取用已保存的配置:凭证或端点改了没保存时先保存
+  const fetchBlocked =
+    upstream.authKind !== "none" && !custom && !upstream.hasCredential
+      ? upstream.authKind === "oauth"
+        ? "登录后可获取"
+        : "先配置 API Key"
+      : v.apiKey.trim() || v.baseUrl !== (upstream.baseUrl ?? "")
+        ? "先保存 API Key / Base URL 再获取"
+        : null;
+
   const save = async (e: React.FormEvent) => {
     e.preventDefault();
     const env = Object.fromEntries(Object.entries(v.env).filter(([, x]) => x.trim()));
@@ -166,8 +179,16 @@ function UpstreamDrawer({
   };
 
   const makeDefault = async () => {
+    const model = v.model.trim();
+    if (!model) {
+      setErrors((e) => ({ ...e, defaultModel: "设为默认上游前先选默认模型" }));
+      return;
+    }
     try {
-      await update.mutateAsync({ id: upstream.id, body: { makeDefault: true } });
+      await update.mutateAsync({
+        id: upstream.id,
+        body: { makeDefault: true, ...(model !== (upstream.defaultModel ?? "") ? { defaultModel: model } : {}) },
+      });
       toast.success(`${upstream.name}已设为默认上游`);
     } catch (err) {
       toast.error(errorMessage(err, "设置失败"));
@@ -294,15 +315,27 @@ function UpstreamDrawer({
             label="默认模型"
             htmlFor="pu-model"
             error={errors.defaultModel}
-            hint={models.data?.refreshError ? `模型列表刷新失败：${models.data.refreshError}` : "可从列表选，也可手填"}
+            hint="可从列表选，也可手填"
             className="sm:col-span-2"
           >
+            <ModelFetchBar
+              data={models.data}
+              pending={refresh.isPending}
+              onFetch={() =>
+                refresh.mutate(upstream.id, { onError: (err) => toast.error(errorMessage(err, "获取失败")) })
+              }
+              disabledReason={fetchBlocked}
+            />
             <ModelInput
               id="pu-model"
               value={v.model}
-              onChange={(x) => setV((s) => ({ ...s, model: x }))}
-              models={models.data?.items ?? []}
+              onChange={(x) => {
+                setV((s) => ({ ...s, model: x }));
+                setErrors(({ defaultModel: _, ...rest }) => rest);
+              }}
+              models={models.data?.models ?? []}
               disabled={pending}
+              invalid={!!errors.defaultModel}
             />
           </FormField>
           {showThinking ? (