feat: ship the ssh terminal as a first-party in-process plugin

Adds a hardcoded process:transport-owner tier so the terminal can own its
WebSocket server and ssh2 clients, which cannot cross the worker boundary.

src/backend/tests/plugins/first-party.test.ts

@@ -0,0 +1,113 @@
+/**
+ * The first-party tier is the one place in the plugin system where code runs
+ * without the worker boundary, so the thing most worth testing is that it
+ * cannot be entered by a plugin that says it should be.
+ */
+
+import { describe, expect, it } from "vitest";
+import {
+  FIRST_PARTY_PLUGIN_IDS,
+  isFirstParty,
+  runsInProcess,
+  TRANSPORT_OWNER_CAPABILITY,
+} from "../../plugins/first-party.js";
+import {
+  parseManifest,
+  SUPPORTED_PLUGIN_API_VERSION,
+} from "../../plugins/manifest.js";
+
+function manifest(overrides: Record<string, unknown> = {}) {
+  return {
+    id: "sample-plugin",
+    name: "Sample Plugin",
+    version: "1.0.0",
+    description: "A plugin.",
+    author: { name: "Someone" },
+    license: "MIT",
+    category: "Productivity",
+    engine: { termix: ">=2.9.0", api: SUPPORTED_PLUGIN_API_VERSION },
+    capabilities: {
+      backend: true,
+      frontend: false,
+      electron: false,
+      platforms: ["linux"],
+    },
+    permissions: [] as string[],
+    sidecars: [],
+    ...overrides,
+  };
+}
+
+describe("first-party allowlist", () => {
+  it("contains only ssh-terminal", () => {
+    expect([...FIRST_PARTY_PLUGIN_IDS]).toEqual(["ssh-terminal"]);
+  });
+
+  it("recognises ssh-terminal and nothing else", () => {
+    expect(isFirstParty("ssh-terminal")).toBe(true);
+    expect(isFirstParty("ssh-terminal-pro")).toBe(false);
+    expect(isFirstParty("community-plugin")).toBe(false);
+    expect(isFirstParty("")).toBe(false);
+  });
+});
+
+describe("runsInProcess", () => {
+  it("requires both the allowlist and the declared capability", () => {
+    expect(runsInProcess("ssh-terminal", [TRANSPORT_OWNER_CAPABILITY])).toBe(
+      true,
+    );
+
+    // On the list but not asking for it: stays in a worker, so the manifest
+    // remains an honest description of what the plugin does.
+    expect(runsInProcess("ssh-terminal", ["hosts.read"])).toBe(false);
+
+    // Asking for it but not on the list.
+    expect(
+      runsInProcess("community-plugin", [TRANSPORT_OWNER_CAPABILITY]),
+    ).toBe(false);
+
+    expect(runsInProcess("community-plugin", ["hosts.read"])).toBe(false);
+  });
+});
+
+describe("manifest gate on the reserved capability", () => {
+  it("refuses the capability for a plugin that is not first-party", () => {
+    const { manifest: parsed, errors } = parseManifest(
+      manifest({ permissions: [TRANSPORT_OWNER_CAPABILITY] }),
+    );
+
+    expect(parsed).toBeUndefined();
+    expect(errors).toHaveLength(1);
+    expect(errors[0]).toContain(TRANSPORT_OWNER_CAPABILITY);
+    expect(errors[0]).toContain("reserved for first-party plugins");
+  });
+
+  it("refuses it even when mixed in with ordinary permissions", () => {
+    const { manifest: parsed } = parseManifest(
+      manifest({
+        permissions: ["hosts.read", TRANSPORT_OWNER_CAPABILITY, "storage.own"],
+      }),
+    );
+    expect(parsed).toBeUndefined();
+  });
+
+  it("allows it for ssh-terminal", () => {
+    const { manifest: parsed, errors } = parseManifest(
+      manifest({
+        id: "ssh-terminal",
+        permissions: [TRANSPORT_OWNER_CAPABILITY],
+      }),
+    );
+
+    expect(errors).toEqual([]);
+    expect(parsed?.id).toBe("ssh-terminal");
+  });
+
+  it("still accepts an ordinary manifest that never mentions it", () => {
+    const { manifest: parsed, errors } = parseManifest(
+      manifest({ permissions: ["hosts.read"] }),
+    );
+    expect(errors).toEqual([]);
+    expect(parsed?.id).toBe("sample-plugin");
+  });
+});