feat(background): add background registry and status tool with tests

src/background-schema.ts

@@ -0,0 +1,35 @@
+import { StringEnum } from "@mariozechner/pi-ai";
+import { Type, type Static } from "@sinclair/typebox";
+
+export function createBackgroundAgentSchema(availableModels: readonly string[]) {
+  return Type.Object(
+    {
+      preset: Type.String({ description: "Subagent preset name to use for this task" }),
+      task: Type.String({ description: "Task to delegate to the child agent" }),
+      model: Type.Optional(
+        StringEnum(availableModels, {
+          description: "Optional child model override. Must be one of the currently available models.",
+        }),
+      ),
+      cwd: Type.Optional(Type.String({ description: "Optional working directory override" })),
+    },
+    { description: "Parameters for launching a background_agent run" },
+  );
+}
+
+export const BackgroundAgentSchema = createBackgroundAgentSchema([]);
+
+export function createBackgroundAgentStatusSchema() {
+  return Type.Object(
+    {
+      runId: Type.Optional(Type.String({ description: "Optional runId to query a single run" })),
+      includeCompleted: Type.Optional(Type.Boolean({ description: "Include completed/finished runs in listing" })),
+    },
+    { description: "Parameters for background_agent_status tool" },
+  );
+}
+
+export const BackgroundAgentStatusSchema = createBackgroundAgentStatusSchema();
+
+export type BackgroundAgentParams = Static<typeof BackgroundAgentSchema>;
+export type BackgroundAgentStatusParams = Static<typeof BackgroundAgentStatusSchema>;