chore(vendor): import pi 0.85.1

Imported as a linear vendor commit so forge rebases do not replay the upstream root tree.

git-subtree-dir: third_party/pi

git-subtree-split: d981de1229ef899957bbe968bc8dcda02a21f477

third_party/pi/packages/coding-agent/src/experimental/services/agent-controller.ts

@@ -0,0 +1,54 @@
+import { type Context, defineService } from "@earendil-works/chord";
+
+export interface AgentPromptImage {
+	type: "image";
+	data: string;
+	mimeType: string;
+}
+
+export interface AgentPromptRequest {
+	message: string;
+	images: AgentPromptImage[] | null;
+}
+
+export interface AgentOperationError {
+	code: string;
+	message: string;
+}
+
+export type AgentOperationResponse =
+	| { accepted: true; operationId: string; error: AgentOperationError | null }
+	| { accepted: false; operationId: string | null; error: AgentOperationError };
+
+export type AgentQueueResponse =
+	| { accepted: true; entryId: string; error: null }
+	| { accepted: false; entryId: null; error: AgentOperationError };
+
+export interface AgentCompactionRequest {
+	customInstructions: string | null;
+}
+
+export interface AgentNavigationRequest {
+	targetId: string | null;
+	summarize: boolean;
+	label: string | null;
+	customInstructions: string | null;
+}
+
+/** Presentation-safe command facade over the worker-owned main AgentLane. */
+export interface AgentController {
+	prompt(request: AgentPromptRequest, context: Context): Promise<AgentOperationResponse>;
+	requestAbort(operationId: string, context: Context): Promise<void>;
+	steer(request: AgentPromptRequest, context: Context): Promise<AgentQueueResponse>;
+	followUp(request: AgentPromptRequest, context: Context): Promise<AgentQueueResponse>;
+	nextRun(request: AgentPromptRequest, context: Context): Promise<AgentQueueResponse>;
+	cancelQueued(
+		entryId: string,
+		context: Context,
+	): Promise<{ outcome: "cancelled" | "already_consumed" | "not_found" }>;
+	resume(context: Context): Promise<AgentOperationResponse>;
+	compact(request: AgentCompactionRequest, context: Context): Promise<AgentOperationResponse>;
+	navigate(request: AgentNavigationRequest, context: Context): Promise<AgentOperationResponse>;
+}
+
+export const AgentController = defineService<AgentController>("pi.agent-controller");