feat: Fabric channel plugin for OpenClaw (Phase 1, B1)

OpenClaw channel plugin: defineChannelPluginEntry + createChatChannelPlugin.
Inbound via channel-turn kernel (wakeup -> admission: true=dispatch,
else drop+recordHistory). One Fabric socket per agent identity in the
plugin runtime (no sidecar). Center API-key agent auth. Tools:
fabric-register, create-{chat,work,report,discussion}-channel,
discussion-complete (post summary + close channel).

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

src/channel.ts

@@ -0,0 +1,63 @@
+import {
+  createChatChannelPlugin,
+  createChannelPluginBase,
+} from 'openclaw/plugin-sdk/channel-core';
+import type { OpenClawConfig } from 'openclaw/plugin-sdk/channel-core';
+
+export type ResolvedFabricAccount = {
+  accountId: string | null;
+  centerApiBase: string;
+  allowFrom: string[];
+  dmPolicy: string | undefined;
+};
+
+export function resolveFabricAccount(
+  cfg: OpenClawConfig,
+  accountId?: string | null,
+): ResolvedFabricAccount {
+  const section = (cfg.channels as Record<string, any>)?.['fabric'];
+  const centerApiBase: string | undefined = section?.centerApiBase;
+  if (!centerApiBase) throw new Error('fabric: channels.fabric.centerApiBase is required');
+  return {
+    accountId: accountId ?? null,
+    centerApiBase,
+    allowFrom: section?.allowFrom ?? [],
+    dmPolicy: section?.dmSecurity,
+  };
+}
+
+// Outbound is wired by the entry (it needs the identity registry + client to
+// post as the right agent). Channel-turn visible replies go through the
+// inbound adapter's delivery callback; this object owns config/security only.
+export function buildFabricChannelPlugin(
+  sendText: (params: { accountId?: string | null; to: string; text: string }) => Promise<{ messageId?: string }>,
+) {
+  return createChatChannelPlugin<ResolvedFabricAccount>({
+    base: createChannelPluginBase({
+      id: 'fabric',
+      setup: {
+        resolveAccount: resolveFabricAccount,
+        inspectAccount(cfg, accountId) {
+          const section = (cfg.channels as Record<string, any>)?.['fabric'];
+          const ok = Boolean(section?.centerApiBase);
+          return { enabled: ok, configured: ok, tokenStatus: ok ? 'available' : 'missing' };
+        },
+      },
+    }),
+    security: {
+      dm: {
+        channelKey: 'fabric',
+        resolvePolicy: (a) => a.dmPolicy,
+        resolveAllowFrom: (a) => a.allowFrom,
+        defaultPolicy: 'allowlist',
+      },
+    },
+    // Fabric replies thread by being posted into the same channel.
+    threading: { topLevelReplyToMode: 'channel' },
+    outbound: {
+      attachedResults: {
+        sendText: async (params) => sendText(params),
+      },
+    },
+  });
+}