import { randomUUID } from "node:crypto";
import * as fs from "node:fs";
import * as path from "node:path";
import {
	ASYNC_DIR,
	RESULTS_DIR,
	TEMP_ROOT_DIR,
	type AsyncJobState,
	type AsyncStatus,
	type NestedRouteInfo,
	type TurnBudgetState,
	type NestedRunSummary,
	type NestedRunState,
	type NestedStepSummary,
	type SubagentRunMode,
	type SubagentState,
} from "../../shared/types.ts";
import { isSafeNestedPathId, parseNestedPathEnv, sanitizeNestedPath, type NestedPathEntry } from "./nested-path.ts";
import {
	SUBAGENT_PARENT_CAPABILITY_TOKEN_ENV,
	SUBAGENT_PARENT_CHILD_INDEX_ENV,
	SUBAGENT_PARENT_CONTROL_INBOX_ENV,
	SUBAGENT_PARENT_DEPTH_ENV,
	SUBAGENT_PARENT_EVENT_SINK_ENV,
	SUBAGENT_PARENT_PATH_ENV,
	SUBAGENT_PARENT_ROOT_RUN_ID_ENV,
	SUBAGENT_PARENT_RUN_ID_ENV,
} from "./pi-args.ts";
import { writeAtomicJson } from "../../shared/atomic-json.ts";

export const NESTED_EVENTS_DIR = path.join(TEMP_ROOT_DIR, "nested-subagent-events");
const ROUTE_FILE = "route.json";
const REGISTRY_FILE = "registry.json";
const MAX_EVENT_BYTES = 64 * 1024;
const MAX_STEPS = 12;
const MAX_CHILDREN = 16;
const MAX_DEPTH = 3;

type NestedStatusEventType = "subagent.nested.started" | "subagent.nested.updated" | "subagent.nested.completed";
type NestedControlResultEventType = "subagent.nested.control-result";

export type NestedRoute = NestedRouteInfo;

export interface NestedEventRecord {
	type: NestedStatusEventType;
	ts: number;
	rootRunId: string;
	parentRunId: string;
	parentStepIndex?: number;
	capabilityToken: string;
	child: NestedRunSummary;
}

export interface NestedControlResultRecord {
	type: NestedControlResultEventType;
	ts: number;
	rootRunId: string;
	capabilityToken: string;
	requestId: string;
	targetRunId: string;
	ok: boolean;
	message: string;
}

export interface NestedControlRequestRecord {
	type: "subagent.nested.control-request";
	ts: number;
	rootRunId: string;
	capabilityToken: string;
	requestId: string;
	targetRunId: string;
	action: "interrupt" | "resume";
	message?: string;
}

export interface NestedRegistry {
	rootRunId: string;
	updatedAt: number;
	children: NestedRunSummary[];
	processedEvents: string[];
}

export function isSafeNestedId(value: unknown): value is string {
	return isSafeNestedPathId(value);
}

export function assertSafeNestedId(label: string, value: string): void {
	if (!isSafeNestedId(value)) throw new Error(`${label} must be a non-empty safe id token.`);
}

function assertSafeId(label: string, value: string): void {
	assertSafeNestedId(label, value);
}

function containedPath(base: string, candidate: string): boolean {
	const resolvedBase = path.resolve(base);
	const resolvedCandidate = path.resolve(candidate);
	return resolvedCandidate === resolvedBase || resolvedCandidate.startsWith(`${resolvedBase}${path.sep}`);
}

function commonRouteRoot(route: Pick<NestedRoute, "eventSink" | "controlInbox">): string {
	return path.dirname(path.resolve(route.eventSink));
}

function validateRouteShape(route: NestedRoute): void {
	assertSafeId("rootRunId", route.rootRunId);
	assertSafeId("capabilityToken", route.capabilityToken);
	if (!containedPath(NESTED_EVENTS_DIR, route.eventSink)) throw new Error("Nested event sink is outside the subagent nested event root.");
	if (!containedPath(NESTED_EVENTS_DIR, route.controlInbox)) throw new Error("Nested control inbox is outside the subagent nested event root.");
	if (commonRouteRoot(route) !== path.dirname(path.resolve(route.controlInbox))) throw new Error("Nested event sink and control inbox must share one route root.");
}

export function createNestedRoute(rootRunId: string): NestedRoute {
	assertSafeId("rootRunId", rootRunId);
	const capabilityToken = randomUUID();
	const routeRoot = path.join(NESTED_EVENTS_DIR, `${rootRunId}-${capabilityToken}`);
	const eventSink = path.join(routeRoot, "events");
	const controlInbox = path.join(routeRoot, "controls");
	fs.mkdirSync(eventSink, { recursive: true, mode: 0o700 });
	fs.mkdirSync(controlInbox, { recursive: true, mode: 0o700 });
	fs.writeFileSync(path.join(routeRoot, ROUTE_FILE), `${JSON.stringify({ rootRunId, capabilityToken, createdAt: Date.now() })}\n`, { mode: 0o600 });
	return { rootRunId, eventSink, controlInbox, capabilityToken };
}

export function resolveNestedRouteFromEnv(env: NodeJS.ProcessEnv = process.env): NestedRoute | undefined {
	const rootRunId = env[SUBAGENT_PARENT_ROOT_RUN_ID_ENV];
	const eventSink = env[SUBAGENT_PARENT_EVENT_SINK_ENV];
	const controlInbox = env[SUBAGENT_PARENT_CONTROL_INBOX_ENV];
	const capabilityToken = env[SUBAGENT_PARENT_CAPABILITY_TOKEN_ENV];
	if (!rootRunId || !eventSink || !controlInbox || !capabilityToken) return undefined;
	const route = { rootRunId, eventSink, controlInbox, capabilityToken };
	validateRouteShape(route);
	const routeFile = path.join(commonRouteRoot(route), ROUTE_FILE);
	const metadata = JSON.parse(fs.readFileSync(routeFile, "utf-8")) as { rootRunId?: unknown; capabilityToken?: unknown };
	if (metadata.rootRunId !== rootRunId || metadata.capabilityToken !== capabilityToken) {
		throw new Error("Nested event route metadata does not match the provided root id and capability token.");
	}
	return route;
}

export function resolveInheritedNestedRouteFromEnv(env: NodeJS.ProcessEnv = process.env): NestedRoute | undefined {
	try {
		return resolveNestedRouteFromEnv(env);
	} catch (error) {
		console.error("Ignoring invalid nested subagent event route:", error);
		return undefined;
	}
}

export function resolveNestedParentAddressFromEnv(env: NodeJS.ProcessEnv = process.env): { parentRunId: string; parentStepIndex?: number; depth: number; path: NestedPathEntry[] } | undefined {
	const parentRunId = env[SUBAGENT_PARENT_RUN_ID_ENV];
	if (!isSafeNestedId(parentRunId)) return undefined;
	const rawIndex = env[SUBAGENT_PARENT_CHILD_INDEX_ENV];
	const parentStepIndex = rawIndex && /^\d+$/.test(rawIndex) ? Number(rawIndex) : undefined;
	const depth = Math.min(Math.max(1, clampNumber(Number(env[SUBAGENT_PARENT_DEPTH_ENV])) ?? 1), MAX_DEPTH);
	const parsedPath = parseNestedPathEnv(env[SUBAGENT_PARENT_PATH_ENV]);
	const nestedPath = parsedPath.length ? parsedPath : [{ runId: parentRunId, ...(parentStepIndex !== undefined ? { stepIndex: parentStepIndex } : {}) }];
	return { parentRunId, ...(parentStepIndex !== undefined ? { parentStepIndex } : {}), depth, path: nestedPath };
}

export function resolveNestedAsyncDir(rootRunId: string, run: NestedRunSummary): string | undefined {
	if (!run.asyncDir) return undefined;
	const resolved = path.resolve(run.asyncDir);
	const nestedRoot = path.resolve(TEMP_ROOT_DIR, "nested-subagent-runs", rootRunId, run.id);
	const relative = path.relative(nestedRoot, resolved);
	return resolved === nestedRoot || (!relative.startsWith("..") && !path.isAbsolute(relative)) ? resolved : undefined;
}

function clampNumber(value: unknown): number | undefined {
	return typeof value === "number" && Number.isFinite(value) ? value : undefined;
}

function stringValue(value: unknown, max = 512): string | undefined {
	return typeof value === "string" && value.length > 0 ? value.slice(0, max) : undefined;
}

function sanitizeTokenUsage(value: unknown): NestedRunSummary["totalTokens"] | undefined {
	if (!value || typeof value !== "object") return undefined;
	const raw = value as Record<string, unknown>;
	const input = clampNumber(raw.input);
	const output = clampNumber(raw.output);
	const total = clampNumber(raw.total);
	return input !== undefined && output !== undefined && total !== undefined
		? { input, output, total }
		: undefined;
}

function sanitizeCost(value: unknown): NestedRunSummary["totalCost"] | undefined {
	if (!value || typeof value !== "object") return undefined;
	const raw = value as Record<string, unknown>;
	const inputTokens = clampNumber(raw.inputTokens);
	const outputTokens = clampNumber(raw.outputTokens);
	const costUsd = clampNumber(raw.costUsd);
	return inputTokens !== undefined && outputTokens !== undefined && costUsd !== undefined
		? { inputTokens, outputTokens, costUsd }
		: undefined;
}

function sanitizeTurnBudget(value: unknown): TurnBudgetState | undefined {
	if (!value || typeof value !== "object") return undefined;
	const raw = value as Record<string, unknown>;
	const maxTurns = clampNumber(raw.maxTurns);
	const graceTurns = clampNumber(raw.graceTurns);
	const turnCount = clampNumber(raw.turnCount);
	const outcome = raw.outcome === "within-budget" || raw.outcome === "wrap-up-requested" || raw.outcome === "exceeded" ? raw.outcome : undefined;
	if (maxTurns === undefined || graceTurns === undefined || turnCount === undefined || !outcome) return undefined;
	return {
		maxTurns,
		graceTurns,
		turnCount,
		outcome,
		...(clampNumber(raw.wrapUpRequestedAtTurn) !== undefined ? { wrapUpRequestedAtTurn: clampNumber(raw.wrapUpRequestedAtTurn) } : {}),
		...(clampNumber(raw.exceededAtTurn) !== undefined ? { exceededAtTurn: clampNumber(raw.exceededAtTurn) } : {}),
	};
}

function sanitizeState(value: unknown, fallback: NestedRunState): NestedRunState {
	return value === "queued" || value === "running" || value === "complete" || value === "failed" || value === "paused"
		? value
		: fallback;
}

function sanitizeStep(input: unknown, depth: number): NestedStepSummary | undefined {
	if (!input || typeof input !== "object") return undefined;
	const raw = input as Record<string, unknown>;
	const agent = stringValue(raw.agent, 128);
	if (!agent) return undefined;
	const status = raw.status === "pending" || raw.status === "running" || raw.status === "complete" || raw.status === "completed" || raw.status === "failed" || raw.status === "paused"
		? raw.status
		: "pending";
	return {
		agent,
		status,
		...(stringValue(raw.sessionFile, 2048) ? { sessionFile: stringValue(raw.sessionFile, 2048) } : {}),
		...(raw.activityState === "active_long_running" || raw.activityState === "needs_attention" ? { activityState: raw.activityState } : {}),
		...(clampNumber(raw.lastActivityAt) !== undefined ? { lastActivityAt: clampNumber(raw.lastActivityAt) } : {}),
		...(stringValue(raw.currentTool, 128) ? { currentTool: stringValue(raw.currentTool, 128) } : {}),
		...(clampNumber(raw.currentToolStartedAt) !== undefined ? { currentToolStartedAt: clampNumber(raw.currentToolStartedAt) } : {}),
		...(stringValue(raw.currentPath, 2048) ? { currentPath: stringValue(raw.currentPath, 2048) } : {}),
		...(clampNumber(raw.turnCount) !== undefined ? { turnCount: clampNumber(raw.turnCount) } : {}),
		...(clampNumber(raw.toolCount) !== undefined ? { toolCount: clampNumber(raw.toolCount) } : {}),
		...(clampNumber(raw.startedAt) !== undefined ? { startedAt: clampNumber(raw.startedAt) } : {}),
		...(clampNumber(raw.endedAt) !== undefined ? { endedAt: clampNumber(raw.endedAt) } : {}),
		...(stringValue(raw.error, 1024) ? { error: stringValue(raw.error, 1024) } : {}),
		...(raw.timedOut === true ? { timedOut: true } : {}),
		...(sanitizeTurnBudget(raw.turnBudget) ? { turnBudget: sanitizeTurnBudget(raw.turnBudget) } : {}),
		...(raw.turnBudgetExceeded === true ? { turnBudgetExceeded: true } : {}),
		...(raw.wrapUpRequested === true ? { wrapUpRequested: true } : {}),
		...(depth < MAX_DEPTH && Array.isArray(raw.children) ? { children: raw.children.map((child) => sanitizeSummary(child, depth + 1)).filter((child): child is NestedRunSummary => Boolean(child)).slice(0, MAX_CHILDREN) } : {}),
	};
}

export function sanitizeSummary(input: unknown, depth = 0): NestedRunSummary | undefined {
	if (!input || typeof input !== "object") return undefined;
	const raw = input as Record<string, unknown>;
	if (!isSafeNestedId(raw.id) || !isSafeNestedId(raw.parentRunId)) return undefined;
	const pathParts = sanitizeNestedPath(raw.path);
	const steps = Array.isArray(raw.steps)
		? raw.steps.map((step) => sanitizeStep(step, depth + 1)).filter((step): step is NestedStepSummary => Boolean(step)).slice(0, MAX_STEPS)
		: undefined;
	const totalTokens = sanitizeTokenUsage(raw.totalTokens);
	const totalCost = sanitizeCost(raw.totalCost);
	return {
		id: raw.id,
		parentRunId: raw.parentRunId,
		...(clampNumber(raw.parentStepIndex) !== undefined ? { parentStepIndex: clampNumber(raw.parentStepIndex) } : {}),
		...(stringValue(raw.parentAgent, 128) ? { parentAgent: stringValue(raw.parentAgent, 128) } : {}),
		depth: Math.min(Math.max(0, clampNumber(raw.depth) ?? 0), MAX_DEPTH),
		path: pathParts,
		state: sanitizeState(raw.state, "running"),
		...(stringValue(raw.asyncDir, 2048) ? { asyncDir: stringValue(raw.asyncDir, 2048) } : {}),
		...(clampNumber(raw.pid) !== undefined && clampNumber(raw.pid)! > 0 && Number.isInteger(clampNumber(raw.pid)) ? { pid: clampNumber(raw.pid) } : {}),
		...(stringValue(raw.sessionId, 256) ? { sessionId: stringValue(raw.sessionId, 256) } : {}),
		...(stringValue(raw.sessionFile, 2048) ? { sessionFile: stringValue(raw.sessionFile, 2048) } : {}),
		...(stringValue(raw.intercomTarget, 256) ? { intercomTarget: stringValue(raw.intercomTarget, 256) } : {}),
		...(stringValue(raw.ownerIntercomTarget, 256) ? { ownerIntercomTarget: stringValue(raw.ownerIntercomTarget, 256) } : {}),
		...(stringValue(raw.leafIntercomTarget, 256) ? { leafIntercomTarget: stringValue(raw.leafIntercomTarget, 256) } : {}),
		...(raw.ownerState === "live" || raw.ownerState === "gone" || raw.ownerState === "unknown" ? { ownerState: raw.ownerState } : {}),
		...(stringValue(raw.controlInbox, 2048) ? { controlInbox: stringValue(raw.controlInbox, 2048) } : {}),
		...(stringValue(raw.capabilityToken, 128) ? { capabilityToken: stringValue(raw.capabilityToken, 128) } : {}),
		...(raw.mode === "single" || raw.mode === "parallel" || raw.mode === "chain" ? { mode: raw.mode } : {}),
		...(stringValue(raw.agent, 128) ? { agent: stringValue(raw.agent, 128) } : {}),
		...(Array.isArray(raw.agents) ? { agents: raw.agents.map((agent) => stringValue(agent, 128)).filter((agent): agent is string => Boolean(agent)).slice(0, MAX_STEPS) } : {}),
		...(clampNumber(raw.currentStep) !== undefined ? { currentStep: clampNumber(raw.currentStep) } : {}),
		...(clampNumber(raw.chainStepCount) !== undefined ? { chainStepCount: clampNumber(raw.chainStepCount) } : {}),
		...(raw.activityState === "active_long_running" || raw.activityState === "needs_attention" ? { activityState: raw.activityState } : {}),
		...(clampNumber(raw.lastActivityAt) !== undefined ? { lastActivityAt: clampNumber(raw.lastActivityAt) } : {}),
		...(stringValue(raw.currentTool, 128) ? { currentTool: stringValue(raw.currentTool, 128) } : {}),
		...(clampNumber(raw.currentToolStartedAt) !== undefined ? { currentToolStartedAt: clampNumber(raw.currentToolStartedAt) } : {}),
		...(stringValue(raw.currentPath, 2048) ? { currentPath: stringValue(raw.currentPath, 2048) } : {}),
		...(clampNumber(raw.turnCount) !== undefined ? { turnCount: clampNumber(raw.turnCount) } : {}),
		...(clampNumber(raw.toolCount) !== undefined ? { toolCount: clampNumber(raw.toolCount) } : {}),
		...(totalTokens ? { totalTokens } : {}),
		...(totalCost ? { totalCost } : {}),
		...(clampNumber(raw.startedAt) !== undefined ? { startedAt: clampNumber(raw.startedAt) } : {}),
		...(clampNumber(raw.endedAt) !== undefined ? { endedAt: clampNumber(raw.endedAt) } : {}),
		...(clampNumber(raw.lastUpdate) !== undefined ? { lastUpdate: clampNumber(raw.lastUpdate) } : {}),
		...(clampNumber(raw.timeoutMs) !== undefined ? { timeoutMs: clampNumber(raw.timeoutMs) } : {}),
		...(clampNumber(raw.deadlineAt) !== undefined ? { deadlineAt: clampNumber(raw.deadlineAt) } : {}),
		...(raw.timedOut === true ? { timedOut: true } : {}),
		...(sanitizeTurnBudget(raw.turnBudget) ? { turnBudget: sanitizeTurnBudget(raw.turnBudget) } : {}),
		...(raw.turnBudgetExceeded === true ? { turnBudgetExceeded: true } : {}),
		...(raw.wrapUpRequested === true ? { wrapUpRequested: true } : {}),
		...(stringValue(raw.error, 1024) ? { error: stringValue(raw.error, 1024) } : {}),
		...(steps && steps.length > 0 ? { steps } : {}),
		...(depth < MAX_DEPTH && Array.isArray(raw.children) ? { children: raw.children.map((child) => sanitizeSummary(child, depth + 1)).filter((child): child is NestedRunSummary => Boolean(child)).slice(0, MAX_CHILDREN) } : {}),
	};
}

function parseRecord(content: string, route: NestedRoute): NestedEventRecord | undefined {
	if (Buffer.byteLength(content, "utf-8") > MAX_EVENT_BYTES) return undefined;
	let parsed: unknown;
	try {
		parsed = JSON.parse(content);
	} catch {
		return undefined;
	}
	if (!parsed || typeof parsed !== "object") return undefined;
	const raw = parsed as Record<string, unknown>;
	if (raw.type !== "subagent.nested.started" && raw.type !== "subagent.nested.updated" && raw.type !== "subagent.nested.completed") return undefined;
	if (raw.rootRunId !== route.rootRunId || raw.capabilityToken !== route.capabilityToken) return undefined;
	if (!isSafeNestedId(raw.parentRunId)) return undefined;
	const ts = clampNumber(raw.ts);
	if (ts === undefined) return undefined;
	const child = sanitizeSummary(raw.child);
	if (!child || child.id === route.rootRunId) return undefined;
	const routedChild: NestedRunSummary = {
		...child,
		controlInbox: route.controlInbox,
		capabilityToken: route.capabilityToken,
		ownerState: child.ownerState ?? "unknown",
	};
	return {
		type: raw.type,
		ts,
		rootRunId: route.rootRunId,
		parentRunId: raw.parentRunId,
		...(clampNumber(raw.parentStepIndex) !== undefined ? { parentStepIndex: clampNumber(raw.parentStepIndex) } : {}),
		capabilityToken: route.capabilityToken,
		child: routedChild,
	};
}

export function parseNestedEventRecords(content: string, route: NestedRoute): NestedEventRecord[] {
	if (!content.includes("\n")) {
		const record = parseRecord(content.trim(), route);
		return record ? [record] : [];
	}
	return content.split("\n")
		.slice(0, content.endsWith("\n") ? undefined : -1)
		.map((line) => line.trim() ? parseRecord(line, route) : undefined)
		.filter((event): event is NestedEventRecord => Boolean(event));
}

function terminal(state: NestedRunState): boolean {
	return state === "complete" || state === "failed" || state === "paused";
}

function mergeSummary(existing: NestedRunSummary | undefined, event: NestedEventRecord): NestedRunSummary {
	const incomingState = event.type === "subagent.nested.completed" && event.child.state === "running" ? "complete" : event.child.state;
	const incoming = { ...event.child, state: incomingState, lastUpdate: event.child.lastUpdate ?? event.ts };
	if (!existing) return incoming;
	const existingUpdate = existing.lastUpdate ?? 0;
	const incomingUpdate = incoming.lastUpdate ?? event.ts;
	if (incomingUpdate < existingUpdate) return existing;
	if (terminal(existing.state) && !terminal(incoming.state)) return existing;
	if (terminal(existing.state) && terminal(incoming.state) && incomingUpdate === existingUpdate) return existing;
	return { ...existing, ...incoming, state: incoming.state, lastUpdate: Math.max(existingUpdate, incomingUpdate) };
}

function attachChild(children: NestedRunSummary[], event: NestedEventRecord): NestedRunSummary[] {
	let updated = false;
	const walk = (items: NestedRunSummary[]): NestedRunSummary[] => items.map((item) => {
		if (item.id === event.parentRunId) {
			const existingChildren = item.children ?? [];
			const childIndex = existingChildren.findIndex((child) => child.id === event.child.id);
			const nextChild = mergeSummary(childIndex >= 0 ? existingChildren[childIndex] : undefined, event);
			const nextChildren = childIndex >= 0
				? existingChildren.map((child, index) => index === childIndex ? nextChild : child)
				: [...existingChildren, nextChild];
			updated = true;
			return { ...item, children: nextChildren.slice(0, MAX_CHILDREN), lastUpdate: Math.max(item.lastUpdate ?? 0, event.ts) };
		}
		if (!item.children?.length) return item;
		const nextChildren = walk(item.children);
		return nextChildren === item.children ? item : { ...item, children: nextChildren };
	});
	const next = walk(children);
	if (updated) return next;
	const childIndex = next.findIndex((child) => child.id === event.child.id);
	const nextChild = mergeSummary(childIndex >= 0 ? next[childIndex] : undefined, event);
	return childIndex >= 0
		? next.map((child, index) => index === childIndex ? nextChild : child)
		: [...next, nextChild].slice(0, MAX_CHILDREN);
}

export function applyNestedEvent(registry: NestedRegistry, event: NestedEventRecord): NestedRegistry {
	return {
		...registry,
		updatedAt: Math.max(registry.updatedAt, event.ts),
		children: attachChild(registry.children, event),
	};
}

function registryPath(route: NestedRoute): string {
	return path.join(commonRouteRoot(route), REGISTRY_FILE);
}

export function findNestedRouteForRootId(rootRunId: string): NestedRoute | undefined {
	assertSafeId("rootRunId", rootRunId);
	let entries: string[];
	try {
		entries = fs.readdirSync(NESTED_EVENTS_DIR);
	} catch (error) {
		if ((error as NodeJS.ErrnoException).code === "ENOENT") return undefined;
		throw error;
	}
	for (const entry of entries) {
		if (!entry.startsWith(`${rootRunId}-`)) continue;
		const routeRoot = path.join(NESTED_EVENTS_DIR, entry);
		try {
			const metadata = JSON.parse(fs.readFileSync(path.join(routeRoot, ROUTE_FILE), "utf-8")) as { rootRunId?: unknown; capabilityToken?: unknown };
			if (metadata.rootRunId !== rootRunId || typeof metadata.capabilityToken !== "string") continue;
			const route = {
				rootRunId,
				eventSink: path.join(routeRoot, "events"),
				controlInbox: path.join(routeRoot, "controls"),
				capabilityToken: metadata.capabilityToken,
			};
			validateRouteShape(route);
			return route;
		} catch {
			continue;
		}
	}
	return undefined;
}

/**
 * Scan the nested-events directory once and index every route by its root run
 * id. Use this when resolving routes for many runs (e.g. listAsyncRuns) so the
 * cost is O(routes) total instead of O(runs * routes) from calling
 * findNestedRouteForRootId per run.
 */
export function buildNestedRouteIndex(): Map<string, NestedRoute> {
	let entries: string[];
	try {
		entries = fs.readdirSync(NESTED_EVENTS_DIR);
	} catch (error) {
		if ((error as NodeJS.ErrnoException).code === "ENOENT") return new Map();
		throw error;
	}
	const index = new Map<string, NestedRoute>();
	for (const entry of entries) {
		const routeRoot = path.join(NESTED_EVENTS_DIR, entry);
		try {
			const metadata = JSON.parse(fs.readFileSync(path.join(routeRoot, ROUTE_FILE), "utf-8")) as { rootRunId?: unknown; capabilityToken?: unknown };
			if (typeof metadata.rootRunId !== "string" || typeof metadata.capabilityToken !== "string") continue;
			if (index.has(metadata.rootRunId)) continue;
			const route: NestedRoute = {
				rootRunId: metadata.rootRunId,
				eventSink: path.join(routeRoot, "events"),
				controlInbox: path.join(routeRoot, "controls"),
				capabilityToken: metadata.capabilityToken,
			};
			validateRouteShape(route);
			index.set(metadata.rootRunId, route);
		} catch {
			continue;
		}
	}
	return index;
}

export function projectNestedRegistryForRoot(rootRunId: string): NestedRegistry | undefined {
	const route = findNestedRouteForRootId(rootRunId);
	return route ? projectNestedEvents(route) : undefined;
}

export function findNestedRun(children: NestedRunSummary[] | undefined, id: string): NestedRunSummary | undefined {
	if (!children?.length) return undefined;
	for (const child of children) {
		if (child.id === id) return child;
		const nested = findNestedRun(child.children, id) ?? findNestedRun(child.steps?.flatMap((step) => step.children ?? []), id);
		if (nested) return nested;
	}
	return undefined;
}

export interface NestedRunMatch {
	rootRunId: string;
	route: NestedRoute;
	run: NestedRunSummary;
}

export interface NestedRunResolutionScope {
	routes: NestedRoute[];
	descendantOf?: { parentRunId: string; parentStepIndex?: number };
}

function collectNestedRuns(children: NestedRunSummary[] | undefined, output: NestedRunSummary[] = []): NestedRunSummary[] {
	for (const child of children ?? []) {
		output.push(child);
		collectNestedRuns(child.children, output);
		collectNestedRuns(child.steps?.flatMap((step) => step.children ?? []), output);
	}
	return output;
}

function collectScopedNestedRuns(children: NestedRunSummary[] | undefined, scope: NestedRunResolutionScope["descendantOf"], output: NestedRunSummary[] = []): NestedRunSummary[] {
	if (!scope) return collectNestedRuns(children, output);
	for (const child of children ?? []) {
		if (child.parentRunId === scope.parentRunId && (scope.parentStepIndex === undefined || child.parentStepIndex === scope.parentStepIndex)) {
			collectNestedRuns([child], output);
			continue;
		}
		collectScopedNestedRuns(child.children, scope, output);
		collectScopedNestedRuns(child.steps?.flatMap((step) => step.children ?? []), scope, output);
	}
	return output;
}

function listNestedRoutes(): NestedRoute[] {
	let entries: string[];
	try {
		entries = fs.readdirSync(NESTED_EVENTS_DIR);
	} catch (error) {
		if ((error as NodeJS.ErrnoException).code === "ENOENT") return [];
		throw error;
	}
	const routes: NestedRoute[] = [];
	for (const entry of entries) {
		const routeRoot = path.join(NESTED_EVENTS_DIR, entry);
		try {
			const metadata = JSON.parse(fs.readFileSync(path.join(routeRoot, ROUTE_FILE), "utf-8")) as { rootRunId?: unknown; capabilityToken?: unknown };
			if (typeof metadata.rootRunId !== "string" || typeof metadata.capabilityToken !== "string") continue;
			const route = {
				rootRunId: metadata.rootRunId,
				eventSink: path.join(routeRoot, "events"),
				controlInbox: path.join(routeRoot, "controls"),
				capabilityToken: metadata.capabilityToken,
			};
			validateRouteShape(route);
			routes.push(route);
		} catch {
			continue;
		}
	}
	return routes;
}

export function findNestedRunMatchesById(id: string, options: { prefix?: boolean; scope?: NestedRunResolutionScope } = {}): NestedRunMatch[] {
	assertSafeId("id", id);
	const matches: NestedRunMatch[] = [];
	for (const route of options.scope?.routes ?? listNestedRoutes()) {
		try {
			const registry = projectNestedEvents(route);
			for (const run of collectScopedNestedRuns(registry.children, options.scope?.descendantOf)) {
				if (options.prefix ? run.id.startsWith(id) : run.id === id) matches.push({ rootRunId: route.rootRunId, route, run });
			}
		} catch {
			continue;
		}
	}
	return matches;
}

export function findNestedRunById(id: string): { rootRunId: string; run: NestedRunSummary } | undefined {
	const match = findNestedRunMatchesById(id)[0];
	return match ? { rootRunId: match.rootRunId, run: match.run } : undefined;
}

export function readNestedRegistry(route: NestedRoute): NestedRegistry {
	validateRouteShape(route);
	try {
		const parsed = JSON.parse(fs.readFileSync(registryPath(route), "utf-8")) as NestedRegistry;
		return {
			rootRunId: route.rootRunId,
			updatedAt: typeof parsed.updatedAt === "number" ? parsed.updatedAt : 0,
			children: Array.isArray(parsed.children) ? parsed.children.map((child) => sanitizeSummary(child)).filter((child): child is NestedRunSummary => Boolean(child)) : [],
			processedEvents: Array.isArray(parsed.processedEvents) ? parsed.processedEvents.filter((item): item is string => typeof item === "string") : [],
		};
	} catch (error) {
		if ((error as NodeJS.ErrnoException).code !== "ENOENT") throw error;
		return { rootRunId: route.rootRunId, updatedAt: 0, children: [], processedEvents: [] };
	}
}

export function projectNestedEvents(route: NestedRoute): NestedRegistry {
	validateRouteShape(route);
	let registry = readNestedRegistry(route);
	const seen = new Set(registry.processedEvents);
	let changed = false;
	let entries: string[] = [];
	try {
		entries = fs.readdirSync(route.eventSink).filter((entry) => entry.endsWith(".json") || entry.endsWith(".jsonl")).sort();
	} catch (error) {
		if ((error as NodeJS.ErrnoException).code !== "ENOENT") throw error;
	}
	for (const entry of entries) {
		if (seen.has(entry)) continue;
		const eventPath = path.join(route.eventSink, entry);
		if (!containedPath(route.eventSink, eventPath)) continue;
		let content: string;
		try {
			const stat = fs.statSync(eventPath);
			if (!stat.isFile() || stat.size > MAX_EVENT_BYTES) continue;
			content = fs.readFileSync(eventPath, "utf-8");
		} catch {
			continue;
		}
		for (const event of parseNestedEventRecords(content, route)) {
			registry = applyNestedEvent(registry, event);
			changed = true;
		}
		seen.add(entry);
		changed = true;
	}
	if (changed) {
		registry = { ...registry, processedEvents: [...seen].slice(-1000) };
		// Parent projection is the only writer to this sidecar registry. Child and
		// runner processes only create immutable event files, so parent status.json
		// remains owned by the existing runner writer and is never rewritten here.
		writeAtomicJson(registryPath(route), registry);
	}
	return registry;
}

function writeRouteRecord(dir: string, ts: number, payload: object): string {
	const content = `${JSON.stringify(payload)}\n`;
	if (Buffer.byteLength(content, "utf-8") > MAX_EVENT_BYTES) throw new Error("Nested route record exceeds the maximum size.");
	fs.mkdirSync(dir, { recursive: true, mode: 0o700 });
	const name = `${String(ts).padStart(13, "0")}-${randomUUID()}.json`;
	const tmp = path.join(dir, `.${name}.tmp`);
	const finalPath = path.join(dir, name);
	fs.writeFileSync(tmp, content, { mode: 0o600 });
	fs.renameSync(tmp, finalPath);
	return finalPath;
}

export function writeNestedEvent(route: NestedRoute, event: Omit<NestedEventRecord, "rootRunId" | "capabilityToken">): void {
	validateRouteShape(route);
	const record: NestedEventRecord = {
		...event,
		rootRunId: route.rootRunId,
		capabilityToken: route.capabilityToken,
	};
	const sanitized = parseRecord(JSON.stringify(record), route);
	if (!sanitized) throw new Error("Nested event record failed validation.");
	writeRouteRecord(route.eventSink, sanitized.ts, sanitized);
}

function parseControlRequest(content: string, route: NestedRoute): NestedControlRequestRecord | undefined {
	if (Buffer.byteLength(content, "utf-8") > MAX_EVENT_BYTES) return undefined;
	let parsed: unknown;
	try {
		parsed = JSON.parse(content);
	} catch {
		return undefined;
	}
	if (!parsed || typeof parsed !== "object") return undefined;
	const raw = parsed as Record<string, unknown>;
	if (raw.type !== "subagent.nested.control-request") return undefined;
	if (raw.rootRunId !== route.rootRunId || raw.capabilityToken !== route.capabilityToken) return undefined;
	if (!isSafeNestedId(raw.requestId) || !isSafeNestedId(raw.targetRunId)) return undefined;
	if (raw.action !== "interrupt" && raw.action !== "resume") return undefined;
	const ts = clampNumber(raw.ts);
	if (ts === undefined) return undefined;
	return {
		type: "subagent.nested.control-request",
		ts,
		rootRunId: route.rootRunId,
		capabilityToken: route.capabilityToken,
		requestId: raw.requestId,
		targetRunId: raw.targetRunId,
		action: raw.action,
		...(stringValue(raw.message, 16_000) ? { message: stringValue(raw.message, 16_000) } : {}),
	};
}

function parseControlResult(content: string, route: NestedRoute): NestedControlResultRecord | undefined {
	if (Buffer.byteLength(content, "utf-8") > MAX_EVENT_BYTES) return undefined;
	let parsed: unknown;
	try {
		parsed = JSON.parse(content);
	} catch {
		return undefined;
	}
	if (!parsed || typeof parsed !== "object") return undefined;
	const raw = parsed as Record<string, unknown>;
	if (raw.type !== "subagent.nested.control-result") return undefined;
	if (raw.rootRunId !== route.rootRunId || raw.capabilityToken !== route.capabilityToken) return undefined;
	if (!isSafeNestedId(raw.requestId) || !isSafeNestedId(raw.targetRunId)) return undefined;
	const ts = clampNumber(raw.ts);
	if (ts === undefined || typeof raw.ok !== "boolean") return undefined;
	return {
		type: "subagent.nested.control-result",
		ts,
		rootRunId: route.rootRunId,
		capabilityToken: route.capabilityToken,
		requestId: raw.requestId,
		targetRunId: raw.targetRunId,
		ok: raw.ok,
		message: stringValue(raw.message, 16_000) ?? (raw.ok ? "Control request completed." : "Control request failed."),
	};
}

export function writeNestedControlRequest(route: NestedRoute, request: Omit<NestedControlRequestRecord, "type" | "rootRunId" | "capabilityToken">): string {
	validateRouteShape(route);
	assertSafeId("requestId", request.requestId);
	assertSafeId("targetRunId", request.targetRunId);
	const record: NestedControlRequestRecord = {
		type: "subagent.nested.control-request",
		...request,
		rootRunId: route.rootRunId,
		capabilityToken: route.capabilityToken,
	};
	const sanitized = parseControlRequest(JSON.stringify(record), route);
	if (!sanitized) throw new Error("Nested control request failed validation.");
	return writeRouteRecord(route.controlInbox, sanitized.ts, sanitized);
}

export function readNestedControlRequests(route: NestedRoute): Array<NestedControlRequestRecord & { filePath: string }> {
	validateRouteShape(route);
	let entries: string[] = [];
	try {
		entries = fs.readdirSync(route.controlInbox).filter((entry) => entry.endsWith(".json")).sort();
	} catch (error) {
		if ((error as NodeJS.ErrnoException).code !== "ENOENT") throw error;
	}
	const requests: Array<NestedControlRequestRecord & { filePath: string }> = [];
	for (const entry of entries) {
		const filePath = path.join(route.controlInbox, entry);
		if (!containedPath(route.controlInbox, filePath)) continue;
		try {
			const stat = fs.statSync(filePath);
			if (!stat.isFile() || stat.size > MAX_EVENT_BYTES) continue;
			const request = parseControlRequest(fs.readFileSync(filePath, "utf-8"), route);
			if (request) requests.push({ ...request, filePath });
		} catch {
			continue;
		}
	}
	return requests;
}

export function writeNestedControlResult(route: NestedRoute, result: Omit<NestedControlResultRecord, "type" | "rootRunId" | "capabilityToken">): void {
	validateRouteShape(route);
	assertSafeId("requestId", result.requestId);
	assertSafeId("targetRunId", result.targetRunId);
	const record: NestedControlResultRecord = {
		type: "subagent.nested.control-result",
		...result,
		rootRunId: route.rootRunId,
		capabilityToken: route.capabilityToken,
	};
	const sanitized = parseControlResult(JSON.stringify(record), route);
	if (!sanitized) throw new Error("Nested control result failed validation.");
	writeRouteRecord(route.eventSink, sanitized.ts, sanitized);
}

export function readNestedControlResults(route: NestedRoute): NestedControlResultRecord[] {
	validateRouteShape(route);
	let entries: string[] = [];
	try {
		entries = fs.readdirSync(route.eventSink).filter((entry) => entry.endsWith(".json") || entry.endsWith(".jsonl")).sort();
	} catch (error) {
		if ((error as NodeJS.ErrnoException).code !== "ENOENT") throw error;
	}
	const results: NestedControlResultRecord[] = [];
	for (const entry of entries) {
		const eventPath = path.join(route.eventSink, entry);
		if (!containedPath(route.eventSink, eventPath)) continue;
		try {
			const stat = fs.statSync(eventPath);
			if (!stat.isFile() || stat.size > MAX_EVENT_BYTES) continue;
			const content = fs.readFileSync(eventPath, "utf-8");
			const lines = content.includes("\n") ? content.split("\n").filter((line) => line.trim()) : [content];
			for (const line of lines) {
				const result = parseControlResult(line, route);
				if (result) results.push(result);
			}
		} catch {
			continue;
		}
	}
	return results;
}

export function nestedRouteEnv(route: NestedRoute): Record<string, string> {
	return {
		[SUBAGENT_PARENT_EVENT_SINK_ENV]: route.eventSink,
		[SUBAGENT_PARENT_CONTROL_INBOX_ENV]: route.controlInbox,
		[SUBAGENT_PARENT_ROOT_RUN_ID_ENV]: route.rootRunId,
		[SUBAGENT_PARENT_CAPABILITY_TOKEN_ENV]: route.capabilityToken,
	};
}

export function attachRootChildrenToSteps<T extends { children?: NestedRunSummary[]; index?: number }>(rootRunId: string, steps: T[] | undefined, children: NestedRunSummary[] | undefined): void {
	if (!steps?.length) return;
	for (const step of steps) {
		step.children = undefined;
	}
	if (!children?.length) return;
	for (const child of children) {
		if (child.parentRunId !== rootRunId || child.parentStepIndex === undefined) continue;
		const step = steps.find((candidate, index) => (candidate.index ?? index) === child.parentStepIndex);
		if (!step) continue;
		step.children ??= [];
		step.children = [...step.children.filter((existing) => existing.id !== child.id), child].slice(0, MAX_CHILDREN);
	}
}

export function updateAsyncJobNestedProjection(job: AsyncJobState): void {
	if (!job.nestedRoute) return;
	const registry = projectNestedEvents(job.nestedRoute);
	job.nestedChildren = registry.children;
	attachRootChildrenToSteps(job.asyncId, job.steps, registry.children);
}

export function updateForegroundNestedProjection(control: SubagentState["foregroundControls"] extends Map<string, infer T> ? T : never): void {
	if (!control.nestedRoute) return;
	const registry = projectNestedEvents(control.nestedRoute);
	control.nestedChildren = registry.children;
}

export function hasLiveNestedDescendants(children: NestedRunSummary[] | undefined): boolean {
	if (!children?.length) return false;
	for (const child of children) {
		if (!terminal(child.state)) return true;
		if (hasLiveNestedDescendants(child.children)) return true;
		if (hasLiveNestedDescendants(child.steps?.flatMap((step) => step.children ?? []))) return true;
	}
	return false;
}

export function nestedSummaryFromAsyncStatus(status: AsyncStatus, asyncDir: string, fallback: { id: string; parentRunId: string; parentStepIndex?: number; depth: number; path?: Array<{ runId: string; stepIndex?: number; agent?: string }>; mode?: SubagentRunMode; ts: number }): NestedRunSummary {
	return {
		id: status.runId || fallback.id,
		parentRunId: fallback.parentRunId,
		...(fallback.parentStepIndex !== undefined ? { parentStepIndex: fallback.parentStepIndex } : {}),
		depth: fallback.depth,
		path: fallback.path ?? [{ runId: fallback.parentRunId, ...(fallback.parentStepIndex !== undefined ? { stepIndex: fallback.parentStepIndex } : {}) }],
		asyncDir,
		...(status.pid ? { pid: status.pid } : {}),
		...(status.sessionId ? { sessionId: status.sessionId } : {}),
		mode: status.mode ?? fallback.mode,
		state: status.state,
		...(status.currentStep !== undefined ? { currentStep: status.currentStep } : {}),
		...(status.chainStepCount !== undefined ? { chainStepCount: status.chainStepCount } : {}),
		...(status.activityState ? { activityState: status.activityState } : {}),
		...(status.lastActivityAt !== undefined ? { lastActivityAt: status.lastActivityAt } : {}),
		...(status.currentTool ? { currentTool: status.currentTool } : {}),
		...(status.currentToolStartedAt !== undefined ? { currentToolStartedAt: status.currentToolStartedAt } : {}),
		...(status.currentPath ? { currentPath: status.currentPath } : {}),
		...(status.turnCount !== undefined ? { turnCount: status.turnCount } : {}),
		...(status.toolCount !== undefined ? { toolCount: status.toolCount } : {}),
		...(status.totalTokens ? { totalTokens: status.totalTokens } : {}),
		...(status.timeoutMs !== undefined ? { timeoutMs: status.timeoutMs } : {}),
		...(status.deadlineAt !== undefined ? { deadlineAt: status.deadlineAt } : {}),
		...(status.timedOut !== undefined ? { timedOut: status.timedOut } : {}),
		...(status.turnBudget ? { turnBudget: status.turnBudget } : {}),
		...(status.turnBudgetExceeded !== undefined ? { turnBudgetExceeded: status.turnBudgetExceeded } : {}),
		...(status.wrapUpRequested !== undefined ? { wrapUpRequested: status.wrapUpRequested } : {}),
		...(status.error ? { error: status.error } : {}),
		...(status.startedAt !== undefined ? { startedAt: status.startedAt } : { startedAt: fallback.ts }),
		...(status.endedAt !== undefined ? { endedAt: status.endedAt } : {}),
		lastUpdate: status.lastUpdate ?? fallback.ts,
		...(status.sessionFile ? { sessionFile: status.sessionFile } : {}),
		...(status.steps?.length ? { steps: status.steps.map((step) => ({
			agent: step.agent,
			status: step.status,
			...(step.sessionFile ? { sessionFile: step.sessionFile } : {}),
			...(step.activityState ? { activityState: step.activityState } : {}),
			...(step.lastActivityAt !== undefined ? { lastActivityAt: step.lastActivityAt } : {}),
			...(step.currentTool ? { currentTool: step.currentTool } : {}),
			...(step.currentToolStartedAt !== undefined ? { currentToolStartedAt: step.currentToolStartedAt } : {}),
			...(step.currentPath ? { currentPath: step.currentPath } : {}),
			...(step.turnCount !== undefined ? { turnCount: step.turnCount } : {}),
			...(step.toolCount !== undefined ? { toolCount: step.toolCount } : {}),
			...(step.startedAt !== undefined ? { startedAt: step.startedAt } : {}),
			...(step.endedAt !== undefined ? { endedAt: step.endedAt } : {}),
			...(step.error ? { error: step.error } : {}),
			...(step.timedOut !== undefined ? { timedOut: step.timedOut } : {}),
			...(step.turnBudget ? { turnBudget: step.turnBudget } : {}),
			...(step.turnBudgetExceeded !== undefined ? { turnBudgetExceeded: step.turnBudgetExceeded } : {}),
			...(step.wrapUpRequested !== undefined ? { wrapUpRequested: step.wrapUpRequested } : {}),
		})).slice(0, MAX_STEPS) } : {}),
	};
}

export function nestedArtifactEnv(rootRunId: string, parentRunId: string): Record<string, string> {
	return {
		SELESAI_SUBAGENT_NESTED_ROOT_RUN_ID: rootRunId,
		SELESAI_SUBAGENT_NESTED_PARENT_RUN_ID: parentRunId,
	};
}

export function isTopLevelAsyncDir(asyncDir: string): boolean {
	const resolved = path.resolve(asyncDir);
	return containedPath(ASYNC_DIR, resolved) && !containedPath(path.join(TEMP_ROOT_DIR, "nested-subagent-runs"), resolved);
}

export function nestedResultsPath(rootRunId: string, id: string): string {
	assertSafeId("rootRunId", rootRunId);
	assertSafeId("id", id);
	return path.join(RESULTS_DIR, "nested", rootRunId, `${id}.json`);
}