feat: selectable pairing-notify provider (discord optional, add fabric)

Pairing-code delivery was hardwired to Discord DM (notifyBotToken +
adminUserId required). Make the provider config-selectable.

- core/config.ts: add notifyProvider ("discord"|"fabric", default
  "discord" for back-compat); discord fields required only for discord;
  add fabric block (centerApiBase/apiKey/guildNodeId/channelId) required
  only for fabric
- notifications/types.ts: neutral PairingNotificationService interface
  (DiscordNotificationService kept as back-compat alias)
- notifications/fabric.ts: post the pairing message to a Fabric channel
  (agent/login -> guild token -> POST messages); self-contained, no
  Fabric plugin dependency
- notifications/factory.ts: select provider from config
- core/runtime.ts: wire via factory
- openclaw.plugin.json: notifyProvider enum + fabric object; drop
  notifyBotToken/adminUserId from required (conditional in code)
- tests: fabric notifier + provider-selection config (80 passing)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/fabric-notification.test.ts

@@ -0,0 +1,109 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+import {
+  createFabricNotificationService,
+  type FabricFetch
+} from "../plugin/notifications/fabric.js";
+import { validateYonexusServerConfig } from "../plugin/core/config.js";
+
+const request = {
+  identifier: "client-a",
+  pairingCode: "PAIR-1234-CODE",
+  expiresAt: 1_710_000_300,
+  ttlSeconds: 300,
+  createdAt: 1_710_000_000
+};
+
+const fabricConfig = {
+  centerApiBase: "http://center.local/api",
+  apiKey: "fak_test",
+  guildNodeId: "guild-node-1",
+  channelId: "chan-1"
+};
+
+afterEach(() => {
+  vi.restoreAllMocks();
+});
+
+describe("Fabric notification service", () => {
+  it("logs in, resolves the guild token, and posts the pairing message", async () => {
+    const fetcher = vi
+      .fn<FabricFetch>()
+      .mockResolvedValueOnce({
+        ok: true,
+        status: 200,
+        json: async () => ({
+          user: { id: "u-1" },
+          guilds: [{ nodeId: "guild-node-1", endpoint: "http://guild.local" }],
+          guildAccessTokens: [{ guildNodeId: "guild-node-1", token: "gtok" }]
+        })
+      })
+      .mockResolvedValueOnce({ ok: true, status: 200, json: async () => ({}) });
+
+    const svc = createFabricNotificationService(fabricConfig, { fetcher });
+    const ok = await svc.sendPairingNotification(request);
+
+    expect(ok).toBe(true);
+    expect(fetcher).toHaveBeenCalledTimes(2);
+    expect(fetcher.mock.calls[0][0]).toBe("http://center.local/api/auth/agent/login");
+    expect(fetcher.mock.calls[1][0]).toBe(
+      "http://guild.local/api/channels/chan-1/messages"
+    );
+    const msgInit = fetcher.mock.calls[1][1]!;
+    expect(msgInit.headers?.Authorization).toBe("Bearer gtok");
+    expect(msgInit.body).toContain("PAIR-1234-CODE");
+  });
+
+  it("returns false when the notifier is not a member of the guild", async () => {
+    const fetcher = vi.fn<FabricFetch>().mockResolvedValueOnce({
+      ok: true,
+      status: 200,
+      json: async () => ({ user: { id: "u-1" }, guilds: [], guildAccessTokens: [] })
+    });
+
+    const svc = createFabricNotificationService(fabricConfig, { fetcher });
+    expect(await svc.sendPairingNotification(request)).toBe(false);
+  });
+
+  it("returns false when config is incomplete", async () => {
+    const fetcher = vi.fn<FabricFetch>();
+    const svc = createFabricNotificationService(
+      { ...fabricConfig, apiKey: "" },
+      { fetcher }
+    );
+    expect(await svc.sendPairingNotification(request)).toBe(false);
+    expect(fetcher).not.toHaveBeenCalled();
+  });
+});
+
+describe("notifyProvider config selection", () => {
+  it("defaults to discord and still requires discord fields", () => {
+    expect(() =>
+      validateYonexusServerConfig({ listenPort: 8080 })
+    ).toThrowError(/notifyBotToken is required/);
+  });
+
+  it("does not require discord fields when provider is fabric", () => {
+    const cfg = validateYonexusServerConfig({
+      followerIdentifiers: [],
+      listenPort: 8080,
+      notifyProvider: "fabric",
+      fabric: fabricConfig
+    });
+    expect(cfg.notifyProvider).toBe("fabric");
+    expect(cfg.fabric).toEqual(fabricConfig);
+    expect(cfg.notifyBotToken).toBeUndefined();
+  });
+
+  it("requires fabric fields when provider is fabric", () => {
+    expect(() =>
+      validateYonexusServerConfig({ listenPort: 8080, notifyProvider: "fabric" })
+    ).toThrowError(/fabric\.centerApiBase is required/);
+  });
+
+  it("rejects an unknown provider", () => {
+    expect(() =>
+      validateYonexusServerConfig({ listenPort: 8080, notifyProvider: "sms" })
+    ).toThrowError(/notifyProvider must be/);
+  });
+});