v2 phase 4: channel adapter interface, registry, and host wiring

ChannelAdapter interface with setup/deliver/teardown/setTyping lifecycle.
Self-registration pattern via channel-registry. Host wiring in index-v2
bridges inbound messages to routeInbound and outbound delivery to adapters.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/channels/adapter.ts

@@ -0,0 +1,79 @@
+/**
+ * v2 Channel Adapter interface.
+ *
+ * Channel adapters bridge NanoClaw with messaging platforms (Discord, Slack, etc.).
+ * Two patterns: native adapters (implement directly) or Chat SDK bridge (wrap a Chat SDK adapter).
+ */
+
+/** Configuration for a registered conversation (messaging group + agent wiring). */
+export interface ConversationConfig {
+  platformId: string;
+  agentGroupId: string;
+  triggerPattern?: string; // regex string (for native channels)
+  requiresTrigger: boolean;
+  sessionMode: 'shared' | 'per-thread';
+}
+
+/** Passed to the adapter at setup time. */
+export interface ChannelSetup {
+  /** Known conversations from central DB. */
+  conversations: ConversationConfig[];
+
+  /** Called when an inbound message arrives from the platform. */
+  onInbound(platformId: string, threadId: string | null, message: InboundMessage): void;
+
+  /** Called when the adapter discovers metadata about a conversation. */
+  onMetadata(platformId: string, name?: string, isGroup?: boolean): void;
+}
+
+/** Inbound message from adapter to host. */
+export interface InboundMessage {
+  id: string;
+  kind: 'chat' | 'chat-sdk';
+  content: unknown; // JS object — host will JSON.stringify before writing to session DB
+  timestamp: string;
+}
+
+/** Outbound message from host to adapter. */
+export interface OutboundMessage {
+  kind: string;
+  content: unknown; // parsed JSON from messages_out
+}
+
+/** Discovered conversation info (from syncConversations). */
+export interface ConversationInfo {
+  platformId: string;
+  name: string;
+  isGroup: boolean;
+}
+
+/** The v2 channel adapter contract. */
+export interface ChannelAdapter {
+  name: string;
+  channelType: string;
+
+  // Lifecycle
+  setup(config: ChannelSetup): Promise<void>;
+  teardown(): Promise<void>;
+  isConnected(): boolean;
+
+  // Outbound delivery
+  deliver(platformId: string, threadId: string | null, message: OutboundMessage): Promise<void>;
+
+  // Optional
+  setTyping?(platformId: string, threadId: string | null): Promise<void>;
+  syncConversations?(): Promise<ConversationInfo[]>;
+  updateConversations?(conversations: ConversationConfig[]): void;
+}
+
+/** Factory function that creates a channel adapter (returns null if credentials missing). */
+export type ChannelAdapterFactory = () => ChannelAdapter | null;
+
+/** Registration entry for a channel adapter. */
+export interface ChannelRegistration {
+  factory: ChannelAdapterFactory;
+  containerConfig?: {
+    mounts?: Array<{ hostPath: string; containerPath: string; readonly: boolean }>;
+    env?: Record<string, string>;
+  };
+}