refactor: add hook guards and test helpers

src/hooks/internal-hooks.ts

@@ -19,6 +19,12 @@ export type AgentBootstrapHookContext = {
   agentId?: string;
 };
 
+export type AgentBootstrapHookEvent = InternalHookEvent & {
+  type: "agent";
+  action: "bootstrap";
+  context: AgentBootstrapHookContext;
+};
+
 export interface InternalHookEvent {
   /** The type of event (command, session, agent, etc.) */
   type: InternalHookEventType;
@@ -159,3 +165,11 @@ export function createInternalHookEvent(
     messages: [],
   };
 }
+
+export function isAgentBootstrapEvent(event: InternalHookEvent): event is AgentBootstrapHookEvent {
+  if (event.type !== "agent" || event.action !== "bootstrap") return false;
+  const context = event.context as Partial<AgentBootstrapHookContext> | null;
+  if (!context || typeof context !== "object") return false;
+  if (typeof context.workspaceDir !== "string") return false;
+  return Array.isArray(context.bootstrapFiles);
+}