Fix private AI custom endpoints (#1299)

src/backend/ai/egress.ts

@@ -51,8 +51,7 @@ function normalizeHost(hostname: string): string {
 /**
  * True when the URL names a destination the SSRF guard would refuse. A bare
  * hostname that is not an IP literal (e.g. "ollama.internal") is treated as
- * private only if it is "localhost" -- anything else resolves through DNS and
- * is caught at connect time by the guard instead.
+ * private only if it is "localhost" -- anything else needs DNS resolution.
  */
 export function isPrivateDestination(rawUrl: string): boolean {
   let url: URL;
@@ -98,12 +97,18 @@ export function evaluateEgress(
 
   const host = normalizeHost(url.hostname);
   const isPrivate = isPrivateDestination(rawUrl);
+  const normalized = allowlist.map((entry) => entry.trim().toLowerCase());
+
+  // An explicitly allowlisted hostname may resolve to a private address. It
+  // must use the private fetch path; sending it through safeOutboundFetch
+  // would reject it after DNS resolution and make hostname allowlist entries
+  // ineffective. Only administrators can write this list.
+  if (normalized.includes(host)) {
+    return { allowed: true, isPrivate: true };
+  }
 
   if (!isPrivate) return { allowed: true, isPrivate: false };
 
-  const normalized = allowlist.map((entry) => entry.trim().toLowerCase());
-  if (normalized.includes(host)) return { allowed: true, isPrivate: true };
-
   return {
     allowed: false,
     isPrivate: true,

src/backend/tests/ai/egress.test.ts

@@ -61,6 +61,16 @@ describe("evaluateEgress", () => {
     expect(decision.isPrivate).toBe(true);
   });
 
+  it.each(["llm.internal", "host.docker.internal"])(
+    "routes allowlisted private DNS name %s through the private path",
+    (host) => {
+      expect(evaluateEgress(`http://${host}:8000/v1`, [host])).toEqual({
+        allowed: true,
+        isPrivate: true,
+      });
+    },
+  );
+
   it("matches the allowlist case-insensitively", () => {
     expect(
       evaluateEgress("http://LOCALHOST:11434", ["localhost"]).allowed,

src/ui/api/ai-api.ts

@@ -114,7 +114,11 @@ export async function probeAiModels(input: {
   baseUrl?: string | null;
   apiKey?: string | null;
   providerId?: number | null;
-}): Promise<{ models: string[]; source: "live" | "fallback" | "none" }> {
+}): Promise<{
+  models: string[];
+  source: "live" | "fallback" | "none";
+  warning?: string;
+}> {
   try {
     return (await authApi.post("/ai/probe-models", input)).data;
   } catch (error) {

src/ui/features/ai/AiProviderSettings.tsx

@@ -85,21 +85,24 @@ function AiProviderEditForm({
   const [models, setModels] = useState<string[]>([]);
   const [customModel, setCustomModel] = useState(false);
   const [detecting, setDetecting] = useState(false);
+  const [detectWarning, setDetectWarning] = useState<string | null>(null);
   const [saving, setSaving] = useState(false);
 
   const detectModels = useCallback(async () => {
     setDetecting(true);
+    setDetectWarning(null);
     try {
       const detected = await getAiProviderModels(provider.id);
       setModels(detected);
       setCustomModel(!!defaultModel && !detected.includes(defaultModel));
-    } catch {
+    } catch (error) {
       setModels([]);
       setCustomModel(true);
+      setDetectWarning(getErrorMessage(error, t("ai.modelDetectFailed")));
     } finally {
       setDetecting(false);
     }
-  }, [provider.id, defaultModel]);
+  }, [provider.id, defaultModel, t]);
 
   useEffect(() => {
     void detectModels();
@@ -203,6 +206,11 @@ function AiProviderEditForm({
             placeholder={t("ai.defaultModelPlaceholder")}
           />
         )}
+        {detectWarning && (
+          <p className="text-[11px] leading-snug text-destructive">
+            {detectWarning}
+          </p>
+        )}
       </div>
 
       <div className="flex gap-2">
@@ -269,8 +277,8 @@ export function AiProviderSettings({
         apiKey: apiKey.trim() || null,
       });
       setModels(result.models);
-      if (result.source === "fallback") {
-        setDetectWarning(t("ai.modelDetectFailed"));
+      if (result.source !== "live") {
+        setDetectWarning(result.warning || t("ai.modelDetectFailed"));
       }
       // Pick the first suggestion so the field is never left empty.
       setDefaultModel((current) => current || result.models[0] || "");

src/ui/tests/features/ai/AiProviderSettings.test.tsx

@@ -82,4 +82,17 @@ describe("AiProviderSettings", () => {
       screen.getByRole("combobox", { name: "ai.defaultModel" }),
     ).toBeTruthy();
   });
+
+  it("shows the provider error when refreshing models fails", async () => {
+    api.getAiProviderModels.mockRejectedValue(
+      new Error("Add llm.internal to the AI endpoint allowlist"),
+    );
+    render(<AiProviderSettings providers={[provider]} onChanged={() => {}} />);
+
+    fireEvent.click(screen.getByRole("button", { name: "ai.editProvider" }));
+
+    expect(
+      await screen.findByText("Add llm.internal to the AI endpoint allowlist"),
+    ).toBeTruthy();
+  });
 });