fix: skip existing hosts on JSON and SSH config import (#1607)

* fix: skip existing hosts on JSON and SSH config import

Import (skip existing) only loaded existing hosts when overwriting, so
every host was created again. Always load them, and skip a match unless
overwrite is set. A skipped host still resolves as a jump host for the
hosts imported after it.

Fixes #1606

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* chore: use .js extension for test import

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

src/backend/tests/database/routes/host-import-terminal-settings.test.ts

@@ -36,12 +36,14 @@ vi.mock("../../../database/repositories/factory.js", () => ({
   }),
 }));
 import { registerHostBulkRoutes } from "../../../database/routes/host-bulk-routes.js";
-import { buildExportPayload } from "../../../../ui/sidebar/host-export-payload";
+import { buildExportPayload } from "../../../../ui/sidebar/host-export-payload.js";
 
 let handler: RequestHandler;
+let sshConfigHandler: RequestHandler;
 const router = {
   post: (path: string, ...handlers: RequestHandler[]) => {
     if (path === "/bulk-import") handler = handlers.at(-1)!;
+    if (path === "/ssh-config-import") sshConfigHandler = handlers.at(-1)!;
   },
   put: () => {},
   patch: () => {},
@@ -66,12 +68,13 @@ beforeEach(() => {
   vi.clearAllMocks();
   mocks.create.mockResolvedValue({ id: 71 });
   mocks.update.mockResolvedValue({ id: 19 });
-  mocks.list.mockResolvedValue([{ ...host, id: 19 }]);
+  mocks.list.mockResolvedValue([]);
 });
 
 it.each([false, true])(
   "carries plugin host settings through export selection and import (overwrite=%s)",
   async (overwrite) => {
+    if (overwrite) mocks.list.mockResolvedValue([{ ...host, id: 19 }]);
     const payload = buildExportPayload(
       { hosts: [host] },
       null,
@@ -168,6 +171,60 @@ it.each([20, "20"])(
   },
 );
 
+it("skips hosts that already exist when not overwriting", async () => {
+  mocks.list.mockResolvedValue([{ ...host, id: 19 }]);
+  const res = await importHosts([host]);
+  expect(res.json).toHaveBeenCalledWith(
+    expect.objectContaining({ success: 0, updated: 0, skipped: 1, failed: 0 }),
+  );
+  expect(mocks.create).not.toHaveBeenCalled();
+  expect(mocks.update).not.toHaveBeenCalled();
+  expect(mocks.applyPluginSettings).not.toHaveBeenCalled();
+});
+
+it("maps a skipped jump host reference to its existing destination ID", async () => {
+  mocks.list.mockResolvedValue([{ ...host, ip: "192.0.2.2", id: 801 }]);
+  const res = await importHosts([
+    { ...host, exportId: 10, jumpHosts: [{ hostId: 20 }] },
+    { ...host, ip: "192.0.2.2", exportId: 20 },
+  ]);
+  expect(res.json).toHaveBeenCalledWith(
+    expect.objectContaining({ success: 1, skipped: 1, failed: 0 }),
+  );
+  expect(mocks.create).toHaveBeenCalledTimes(1);
+  expect(mocks.update).not.toHaveBeenCalled();
+  expect(JSON.parse(mocks.create.mock.calls[0][1].jumpHosts)).toEqual([
+    { hostId: 801 },
+  ]);
+});
+
+it.each([
+  [false, { success: 0, updated: 0, skipped: 1 }],
+  [true, { success: 0, updated: 1, skipped: 0 }],
+])(
+  "SSH config import with an existing host (overwrite=%s)",
+  async (overwrite, counts) => {
+    mocks.list.mockResolvedValue([{ ...host, id: 19 }]);
+    const res = { json: vi.fn(), status: vi.fn().mockReturnThis() };
+    await sshConfigHandler(
+      {
+        userId: "user-1",
+        body: {
+          content: "Host web\n  HostName 192.0.2.1\n  User alice\n  Port 22\n",
+          overwrite,
+        },
+      } as unknown as Request,
+      res as unknown as Response,
+      vi.fn(),
+    );
+    expect(res.json).toHaveBeenCalledWith(
+      expect.objectContaining({ ...counts, failed: 0 }),
+    );
+    expect(mocks.create).not.toHaveBeenCalled();
+    expect(mocks.update).toHaveBeenCalledTimes(overwrite ? 1 : 0);
+  },
+);
+
 it.each([
   [{ ...host, jumpHosts: [{ hostId: 20 }] }],
   [{ ...host, jumpHosts: [{ hostId: "20" }] }],