Plugins: remove first-party legacy message discovery shims

src/plugin-sdk/agent-runtime.ts

@@ -23,15 +23,3 @@ export * from "../agents/vllm-defaults.js";
 // Intentional public runtime surface: channel plugins use ingress agent helpers directly.
 export * from "../agents/agent-command.js";
 export * from "../tts/tts.js";
-// Legacy channel action runtime re-exports. New bundled plugin code should use
-// local extension-owned modules instead of adding more public SDK surface here.
-export {
-  handleDiscordAction,
-  readDiscordParentIdParam,
-  isDiscordModerationAction,
-  readDiscordModerationCommand,
-} from "../../extensions/discord/runtime-api.js";
-export {
-  handleTelegramAction,
-  readTelegramButtons,
-} from "../../extensions/telegram/runtime-api.js";