/**
 * Hyperloop — Context-preserving sub-agent orchestrator
 *
 * The main agent stays lightweight and interactive. Heavy work is delegated
 * to background sub-agents that run in isolated Pi sessions, preserving
 * the main chat's context window.
 *
 * Key design:
 *   1. Main agent KEEPS all its tools (read, bash, edit, write) for quick inline work
 *   2. Heavy/complex tasks are offloaded to sub-agents via tools
 *   3. Sub-agents run asynchronously — main chat stays responsive
 *   4. Results stream back as follow-up messages when ready
 *   5. Auto-delegation: detects when a task should be offloaded (configurable)
 *   6. Sub-agents have persistent sessions for multi-turn continuations
 *   7. Live widget dashboard shows all running/completed agents
 *
 * Auto-delegation triggers:
 *   - "across all files", "entire codebase", "every file" → offload
 *   - Explicit multi-step plans with 5+ steps → offload
 *   - User says "background", "async", "offload" → offload
 *   - Main context > 70% full → suggest offloading
 *
 * Tools (available to LLM):
 *   hyperloop_spawn    — Spawn a sub-agent with a task
 *   hyperloop_continue — Continue a finished sub-agent's conversation
 *   hyperloop_status   — Check status of all sub-agents
 *   hyperloop_kill     — Kill/remove a sub-agent
 *   hyperloop_collect  — Collect results from finished sub-agents
 *
 * Commands:
 *   /hl              — Dashboard: show all sub-agents
 *   /hl spawn <task> — Manually spawn a sub-agent
 *   /hl kill <id>    — Kill a running sub-agent
 *   /hl clear        — Clear all sub-agents
 *   /hl auto on|off  — Toggle auto-delegation suggestions
 *   /hl mode <mode>  — Set mode: interactive (default), delegator, hybrid
 *
 * Modes:
 *   interactive — Main agent does everything, spawns sub-agents only when asked
 *   delegator   — Main agent primarily delegates, keeps minimal tools
 *   hybrid      — Main agent handles simple tasks inline, auto-offloads complex ones
 *
 * Usage: pi -e extensions/hyperloop.ts
 */

import type { AssistantMessage } from "@mariozechner/pi-ai";
import type { ExtensionAPI, ExtensionContext, ToolCallEvent } from "@mariozechner/pi-coding-agent";
import { DynamicBorder } from "@mariozechner/pi-coding-agent";
import { Container, Text, truncateToWidth, visibleWidth, type AutocompleteItem } from "@mariozechner/pi-tui";
import { Type } from "@sinclair/typebox";
import { spawn as cpSpawn, type ChildProcess } from "child_process";
import { existsSync, mkdirSync, readdirSync, readFileSync, unlinkSync } from "fs";
import { basename, join } from "path";
import { applyExtensionDefaults } from "./themeMap.ts";

// ── Constants ──────────────────────────────────────────────────────────────

const AGENT_TIMEOUT_MS = 10 * 60 * 1000; // 10 min per sub-agent
const WIDGET_THROTTLE_MS = 400;
const CONTEXT_WARN_PCT = 70;             // suggest offload above this
const MAX_RESULT_LENGTH = 12000;         // truncate sub-agent results

// ── Types ──────────────────────────────────────────────────────────────────

type AgentMode = "interactive" | "delegator" | "hybrid";
type SubStatus = "queued" | "running" | "done" | "error" | "killed";

interface SubAgent {
	id: number;
	status: SubStatus;
	task: string;
	role: string;               // "general", "scout", "builder", etc.
	tools: string;              // comma-separated tool list
	textChunks: string[];
	toolCount: number;
	elapsed: number;
	startTime: number;
	sessionFile: string;
	turnCount: number;
	proc?: ChildProcess;
	timer?: ReturnType<typeof setInterval>;
	exitCode?: number;
	// Context tracking
	inputTokens: number;
	outputTokens: number;
	cost: number;
}

interface AgentDef {
	name: string;
	description: string;
	tools: string;
	systemPrompt: string;
}

// ── Agent Definitions (built-in roles) ─────────────────────────────────────

const BUILTIN_ROLES: AgentDef[] = [
	{
		name: "general",
		description: "General-purpose coding agent",
		tools: "read,bash,edit,write,grep,find,ls",
		systemPrompt: "You are a focused coding agent. Complete the given task efficiently. Be thorough but concise in your output.",
	},
	{
		name: "scout",
		description: "Fast recon and codebase exploration (read-only)",
		tools: "read,grep,find,ls",
		systemPrompt: "You are a scout agent. Investigate the codebase quickly and report findings concisely. Do NOT modify any files. Focus on structure, patterns, and key entry points.",
	},
	{
		name: "builder",
		description: "Implementation and code generation",
		tools: "read,write,edit,bash,grep,find,ls",
		systemPrompt: "You are a builder agent. Implement the requested changes thoroughly. Write clean, minimal code. Follow existing patterns in the codebase. Test your work when possible.",
	},
	{
		name: "reviewer",
		description: "Code review and quality analysis (read-only)",
		tools: "read,grep,find,ls",
		systemPrompt: "You are a reviewer agent. Analyze code for bugs, security issues, performance problems, and style inconsistencies. Be specific about line numbers and suggest fixes.",
	},
	{
		name: "tester",
		description: "Test writing and execution",
		tools: "read,write,edit,bash,grep,find,ls",
		systemPrompt: "You are a testing agent. Write and run tests for the specified code. Cover edge cases. Use the project's existing test framework and patterns.",
	},
];

// ── Auto-delegation patterns ───────────────────────────────────────────────

const OFFLOAD_PATTERNS = [
	/\b(across|entire|whole|every|all)\s+(files?|codebase|project|modules?|components?)\b/i,
	/\b(refactor|migrate|rewrite|overhaul)\s+(the\s+)?(entire|whole|full)\b/i,
	/\b(search|find|grep)\s+(and\s+)?(replace|update|change)\s+(across|in all|everywhere)\b/i,
	/\b(background|async|offload|delegate|spawn)\b/i,
	/\bstep\s+[5-9]\b/i,  // multi-step plan indicator
	/\b(in parallel|simultaneously|concurrently)\b/i,
];

function shouldSuggestOffload(prompt: string): boolean {
	return OFFLOAD_PATTERNS.some(p => p.test(prompt));
}

// ── Extension ──────────────────────────────────────────────────────────────

export default function hyperloop(pi: ExtensionAPI) {
	const agents: Map<number, SubAgent> = new Map();
	const activeProcesses: Set<ChildProcess> = new Set();
	let nextId = 1;
	let widgetCtx: any = null;
	let mode: AgentMode = "hybrid";
	let autoDelegate = true;
	let sessionDir = "";
	let customRoles: AgentDef[] = [];

	// ── Widget Throttle ────────────────────────────────────────────────────

	let widgetDirty = false;
	let widgetTimer: ReturnType<typeof setTimeout> | null = null;

	function scheduleWidget() {
		widgetDirty = true;
		if (widgetTimer) return;
		widgetTimer = setTimeout(() => {
			widgetTimer = null;
			if (widgetDirty) {
				widgetDirty = false;
				renderWidget();
			}
		}, WIDGET_THROTTLE_MS);
	}

	function flushWidget() {
		if (widgetTimer) {
			clearTimeout(widgetTimer);
			widgetTimer = null;
		}
		widgetDirty = false;
		renderWidget();
	}

	// ── Load custom roles from .pi/agents/ ─────────────────────────────────

	function loadCustomRoles(cwd: string) {
		const dirs = [
			join(cwd, ".pi", "agents"),
			join(cwd, "agents"),
		];
		customRoles = [];
		const seen = new Set(BUILTIN_ROLES.map(r => r.name));

		for (const dir of dirs) {
			if (!existsSync(dir)) continue;
			try {
				for (const file of readdirSync(dir)) {
					if (!file.endsWith(".md")) continue;
					const raw = readFileSync(join(dir, file), "utf-8");
					const match = raw.match(/^---\n([\s\S]*?)\n---\n([\s\S]*)$/);
					if (!match) continue;
					const fm: Record<string, string> = {};
					for (const line of match[1].split("\n")) {
						const idx = line.indexOf(":");
						if (idx > 0) fm[line.slice(0, idx).trim()] = line.slice(idx + 1).trim();
					}
					if (!fm.name || seen.has(fm.name)) continue;
					seen.add(fm.name);
					customRoles.push({
						name: fm.name,
						description: fm.description || "",
						tools: fm.tools || "read,grep,find,ls",
						systemPrompt: match[2].trim(),
					});
				}
			} catch {}
		}
	}

	function getAllRoles(): AgentDef[] {
		return [...BUILTIN_ROLES, ...customRoles];
	}

	function findRole(name: string): AgentDef {
		const all = getAllRoles();
		return all.find(r => r.name.toLowerCase() === name.toLowerCase()) || BUILTIN_ROLES[0];
	}

	// ── Session File Management ────────────────────────────────────────────

	function makeSessionFile(id: number): string {
		if (!existsSync(sessionDir)) mkdirSync(sessionDir, { recursive: true });
		return join(sessionDir, `hyperloop-${id}-${Date.now()}.jsonl`);
	}

	// ── Widget Rendering ───────────────────────────────────────────────────

	function renderWidget() {
		if (!widgetCtx) return;

		if (agents.size === 0) {
			widgetCtx.ui.setWidget("hyperloop", undefined);
			return;
		}

		widgetCtx.ui.setWidget("hyperloop", (_tui: any, theme: any) => {
			const container = new Container();
			const content = new Text("", 0, 0);
			container.addChild(content);

			return {
				render(width: number): string[] {
					const lines: string[] = [];
					const modeLabel = mode === "hybrid" ? "⚡ hybrid"
						: mode === "delegator" ? "📡 delegator" : "💬 interactive";

					lines.push(
						theme.fg("dim", "─".repeat(width))
					);
					lines.push(
						theme.fg("accent", " ◉ Hyperloop") +
						theme.fg("dim", ` [${modeLabel}]`) +
						theme.fg("dim", ` · ${agents.size} agent${agents.size !== 1 ? "s" : ""}`) +
						(autoDelegate ? theme.fg("success", " · auto") : theme.fg("dim", " · manual"))
					);

					for (const [, agent] of agents) {
						const statusIcon = agent.status === "queued" ? "◌"
							: agent.status === "running" ? "●"
							: agent.status === "done" ? "✓"
							: agent.status === "killed" ? "⊘" : "✗";
						const statusColor = agent.status === "running" ? "accent"
							: agent.status === "done" ? "success"
							: agent.status === "queued" ? "dim" : "error";

						const elapsed = agent.status === "running"
							? Math.round((Date.now() - agent.startTime) / 1000)
							: Math.round(agent.elapsed / 1000);

						const taskPreview = agent.task.length > 50
							? agent.task.slice(0, 47) + "..."
							: agent.task;

						const turnLabel = agent.turnCount > 1 ? ` t${agent.turnCount}` : "";

						// Main status line
						lines.push(
							theme.fg(statusColor, `  ${statusIcon} #${agent.id}`) +
							theme.fg("dim", ` [${agent.role}${turnLabel}]`) +
							theme.fg("dim", ` ${elapsed}s`) +
							theme.fg("dim", ` · ${agent.toolCount} tools`) +
							(agent.cost > 0 ? theme.fg("warning", ` · $${agent.cost.toFixed(4)}`) : "")
						);

						// Task description
						lines.push(
							theme.fg("muted", `    ${taskPreview}`)
						);

						// Live output (last line) for running agents
						if (agent.status === "running" && agent.textChunks.length > 0) {
							const fullText = agent.textChunks.join("");
							const lastLine = fullText.split("\n").filter((l: string) => l.trim()).pop() || "";
							if (lastLine) {
								const trimmed = lastLine.length > width - 6
									? lastLine.slice(0, width - 9) + "..."
									: lastLine;
								lines.push(theme.fg("dim", `    → ${trimmed}`));
							}
						}
					}

					lines.push(theme.fg("dim", "─".repeat(width)));

					content.setText(lines.join("\n"));
					return container.render(width);
				},
				invalidate() { container.invalidate(); },
			};
		});
	}

	// ── Process JSON Stream from Sub-Agent ─────────────────────────────────

	function processLine(agent: SubAgent, line: string) {
		if (!line.trim()) return;
		try {
			const event = JSON.parse(line);
			if (event.type === "message_update") {
				const delta = event.assistantMessageEvent;
				if (delta?.type === "text_delta") {
					agent.textChunks.push(delta.delta || "");
					scheduleWidget();
				}
			} else if (event.type === "tool_execution_start") {
				agent.toolCount++;
				scheduleWidget();
			} else if (event.type === "message_end" || event.type === "agent_end") {
				const msg = event.message || (event.messages || []).reverse().find((m: any) => m.role === "assistant");
				if (msg?.usage) {
					agent.inputTokens = msg.usage.input || 0;
					agent.outputTokens = msg.usage.output || 0;
					agent.cost = msg.usage.cost?.total || 0;
					scheduleWidget();
				}
			}
		} catch {}
	}

	// ── Spawn Sub-Agent Process ────────────────────────────────────────────

	function spawnSubAgent(
		agent: SubAgent,
		prompt: string,
		ctx: ExtensionContext,
		isContinuation: boolean,
	): Promise<{ output: string; exitCode: number }> {
		agent.status = "running";
		agent.startTime = Date.now();
		scheduleWidget();

		const role = findRole(agent.role);

		// Use a cheaper model for sub-agents to save cost
		const model = ctx.model
			? `${ctx.model.provider}/${ctx.model.id}`
			: "anthropic/claude-sonnet-4-6";

		const args = [
			"--mode", "json",
			"-p",
			"--no-extensions",
			"--no-skills",
			"--model", model,
			"--tools", role.tools,
			"--thinking", "low",
			"--append-system-prompt", role.systemPrompt,
			"--session", agent.sessionFile,
		];

		if (isContinuation) {
			args.push("-c");
		}

		args.push(prompt);

		return new Promise((resolve) => {
			let resolved = false;
			const safeResolve = (val: { output: string; exitCode: number }) => {
				if (resolved) return;
				resolved = true;
				resolve(val);
			};

			const proc = cpSpawn("pi", args, {
				stdio: ["ignore", "pipe", "pipe"],
				env: { ...process.env },
			});

			agent.proc = proc;
			activeProcesses.add(proc);

			agent.timer = setInterval(() => {
				agent.elapsed = Date.now() - agent.startTime;
				scheduleWidget();
			}, 1000);

			const timeout = setTimeout(() => {
				try { proc.kill("SIGTERM"); } catch {}
				setTimeout(() => { try { proc.kill("SIGKILL"); } catch {} }, 3000);
			}, AGENT_TIMEOUT_MS);

			let buffer = "";

			proc.stdout!.setEncoding("utf-8");
			proc.stdout!.on("data", (chunk: string) => {
				buffer += chunk;
				const lines = buffer.split("\n");
				buffer = lines.pop() || "";
				for (const line of lines) processLine(agent, line);
			});

			proc.stderr!.setEncoding("utf-8");
			proc.stderr!.on("data", () => {});

			proc.on("close", (code) => {
				clearTimeout(timeout);
				activeProcesses.delete(proc);
				agent.proc = undefined;
				if (agent.timer) clearInterval(agent.timer);
				agent.elapsed = Date.now() - agent.startTime;
				agent.exitCode = code ?? 1;

				if (buffer.trim()) processLine(agent, buffer);

				const timedOut = agent.elapsed >= AGENT_TIMEOUT_MS;
				agent.status = timedOut ? "error" : (code === 0 ? "done" : "error");
				flushWidget();

				const output = agent.textChunks.join("");
				safeResolve({ output, exitCode: code ?? 1 });
			});

			proc.on("error", (err) => {
				clearTimeout(timeout);
				activeProcesses.delete(proc);
				agent.proc = undefined;
				if (agent.timer) clearInterval(agent.timer);
				agent.status = "error";
				flushWidget();
				safeResolve({ output: `Error: ${err.message}`, exitCode: 1 });
			});
		});
	}

	// ── Fire-and-forget spawn (delivers result as follow-up) ───────────────

	function spawnAndDeliver(agent: SubAgent, prompt: string, ctx: ExtensionContext, isContinuation: boolean) {
		spawnSubAgent(agent, prompt, ctx, isContinuation).then(({ output, exitCode }) => {
			const status = exitCode === 0 ? "✓ done" : "✗ error";
			const elapsed = Math.round(agent.elapsed / 1000);
			const turnLabel = agent.turnCount > 1 ? ` (Turn ${agent.turnCount})` : "";

			const truncated = output.length > MAX_RESULT_LENGTH
				? output.slice(0, MAX_RESULT_LENGTH) + "\n\n... [truncated — full output in sub-agent session]"
				: output;

			ctx.ui.notify(
				`Sub-agent #${agent.id} [${agent.role}] ${status} in ${elapsed}s`,
				exitCode === 0 ? "info" : "error",
			);

			pi.sendMessage({
				customType: "hyperloop-result",
				content: `**Sub-agent #${agent.id}** [${agent.role}]${turnLabel} — ${status} in ${elapsed}s | ${agent.toolCount} tool calls | $${agent.cost.toFixed(4)}\n\n${truncated}`,
				display: true,
			}, { deliverAs: "followUp", triggerTurn: true });
		});
	}

	// ── LLM Tools ──────────────────────────────────────────────────────────

	pi.registerTool({
		name: "hyperloop_spawn",
		label: "Spawn Sub-Agent",
		description: `Spawn a background sub-agent to execute a task without consuming main chat context. The sub-agent runs asynchronously — you can continue chatting while it works. Results are delivered automatically when finished.

Available roles: ${BUILTIN_ROLES.map(r => `${r.name} (${r.description})`).join(", ")}. Custom roles from .pi/agents/*.md are also available.

Use this for:
- Complex multi-file operations that would flood the context
- Long-running tasks (tests, builds, migrations)
- Parallel independent tasks (spawn multiple)
- When context usage is high and you need to preserve it`,
		promptGuidelines: [
			"Spawn sub-agents for heavy/multi-file work to preserve main context",
			"Use role='scout' for exploration, 'builder' for implementation, 'reviewer' for code review, 'tester' for tests",
			"You can spawn multiple sub-agents in parallel for independent tasks",
			"Sub-agent results are delivered automatically — continue chatting while they work",
		],
		parameters: Type.Object({
			task: Type.String({ description: "Complete task description. Be specific — the sub-agent has no context from this conversation." }),
			role: Type.Optional(Type.String({ description: "Agent role: general, scout, builder, reviewer, tester, or custom role name. Default: general" })),
		}),

		async execute(_callId, params, _signal, onUpdate, ctx) {
			widgetCtx = ctx;
			const task = params.task;
			const role = params.role || "general";

			const id = nextId++;
			const agent: SubAgent = {
				id,
				status: "queued",
				task,
				role,
				tools: findRole(role).tools,
				textChunks: [],
				toolCount: 0,
				elapsed: 0,
				startTime: Date.now(),
				sessionFile: makeSessionFile(id),
				turnCount: 1,
				inputTokens: 0,
				outputTokens: 0,
				cost: 0,
			};
			agents.set(id, agent);

			if (onUpdate) {
				onUpdate({
					content: [{ type: "text", text: `Spawning sub-agent #${id} [${role}]...` }],
					details: { id, role, task, status: "spawning" },
				});
			}

			// Fire and forget — result delivered via sendMessage
			spawnAndDeliver(agent, task, ctx, false);

			return {
				content: [{ type: "text", text: `Sub-agent #${id} [${role}] spawned and running in background. You'll receive results automatically when it finishes. Continue chatting normally.` }],
				details: { id, role, task, status: "running" },
			};
		},

		renderCall(args, theme) {
			const role = (args as any).role || "general";
			const task = (args as any).task || "";
			const preview = task.length > 55 ? task.slice(0, 52) + "..." : task;
			return new Text(
				theme.fg("toolTitle", theme.bold("hyperloop_spawn ")) +
				theme.fg("accent", `[${role}] `) +
				theme.fg("muted", preview),
				0, 0,
			);
		},

		renderResult(result, options, theme) {
			const d = result.details as any;
			if (!d) return undefined;
			if (options.isPartial || d.status === "spawning") {
				return new Text(theme.fg("accent", `● #${d.id} [${d.role}]`) + theme.fg("dim", " spawning..."), 0, 0);
			}
			return new Text(
				theme.fg("success", `◉ #${d.id}`) +
				theme.fg("dim", ` [${d.role}] running in background`),
				0, 0,
			);
		},
	});

	pi.registerTool({
		name: "hyperloop_continue",
		label: "Continue Sub-Agent",
		description: "Continue a finished sub-agent's conversation with follow-up instructions. The sub-agent retains its full conversation history.",
		parameters: Type.Object({
			id: Type.Number({ description: "Sub-agent ID to continue" }),
			prompt: Type.String({ description: "Follow-up instructions" }),
		}),

		async execute(_callId, params, _signal, _onUpdate, ctx) {
			widgetCtx = ctx;
			const agent = agents.get(params.id);
			if (!agent) {
				return { content: [{ type: "text", text: `No sub-agent #${params.id} found.` }], details: undefined };
			}
			if (agent.status === "running") {
				return { content: [{ type: "text", text: `Sub-agent #${params.id} is still running. Wait for it to finish.` }], details: undefined };
			}

			agent.textChunks = [];
			agent.toolCount = 0;
			agent.elapsed = 0;
			agent.turnCount++;

			spawnAndDeliver(agent, params.prompt, ctx, true);

			return {
				content: [{ type: "text", text: `Sub-agent #${params.id} continuing (Turn ${agent.turnCount}). Results will be delivered when ready.` }],
				details: undefined,
			};
		},
	});

	pi.registerTool({
		name: "hyperloop_status",
		label: "Sub-Agent Status",
		description: "Check status of all sub-agents.",
		parameters: Type.Object({}),

		async execute() {
			if (agents.size === 0) {
				return { content: [{ type: "text", text: "No sub-agents." }], details: undefined };
			}

			const lines: string[] = [];
			for (const [, a] of agents) {
				const elapsed = a.status === "running"
					? Math.round((Date.now() - a.startTime) / 1000)
					: Math.round(a.elapsed / 1000);
				const turnLabel = a.turnCount > 1 ? ` (Turn ${a.turnCount})` : "";
				lines.push(
					`#${a.id} [${a.role}${turnLabel}] ${a.status.toUpperCase()} — ${elapsed}s, ${a.toolCount} tools, $${a.cost.toFixed(4)}`,
					`  Task: ${a.task}`,
				);
			}

			return { content: [{ type: "text", text: lines.join("\n") }], details: undefined };
		},
	});

	pi.registerTool({
		name: "hyperloop_kill",
		label: "Kill Sub-Agent",
		description: "Kill a running sub-agent or remove a finished one.",
		parameters: Type.Object({
			id: Type.Number({ description: "Sub-agent ID" }),
		}),

		async execute(_callId, params) {
			const agent = agents.get(params.id);
			if (!agent) {
				return { content: [{ type: "text", text: `No sub-agent #${params.id} found.` }], details: undefined };
			}

			if (agent.proc && agent.status === "running") {
				try { agent.proc.kill("SIGTERM"); } catch {}
				agent.status = "killed";
			}
			if (agent.timer) clearInterval(agent.timer);

			if (widgetCtx) widgetCtx.ui.setWidget(`sub-${params.id}`, undefined);
			agents.delete(params.id);
			flushWidget();

			return { content: [{ type: "text", text: `Sub-agent #${params.id} removed.` }], details: undefined };
		},
	});

	pi.registerTool({
		name: "hyperloop_collect",
		label: "Collect Results",
		description: "Collect and summarize results from all finished sub-agents. Useful after spawning multiple parallel agents.",
		parameters: Type.Object({}),

		async execute() {
			const finished = Array.from(agents.values()).filter(a => a.status === "done" || a.status === "error");
			if (finished.length === 0) {
				const running = Array.from(agents.values()).filter(a => a.status === "running");
				if (running.length > 0) {
					return { content: [{ type: "text", text: `${running.length} sub-agent(s) still running. Wait for them to finish.` }], details: undefined };
				}
				return { content: [{ type: "text", text: "No sub-agent results to collect." }], details: undefined };
			}

			const parts: string[] = [];
			let totalCost = 0;
			for (const a of finished) {
				const output = a.textChunks.join("");
				const truncated = output.length > 6000
					? output.slice(0, 6000) + "\n... [truncated]"
					: output;
				const status = a.status === "done" ? "✓" : "✗";
				parts.push(`## ${status} Sub-agent #${a.id} [${a.role}] — ${Math.round(a.elapsed / 1000)}s\nTask: ${a.task}\n\n${truncated}`);
				totalCost += a.cost;
			}

			return {
				content: [{
					type: "text",
					text: `Collected ${finished.length} results (total cost: $${totalCost.toFixed(4)})\n\n${parts.join("\n\n---\n\n")}`,
				}],
				details: undefined,
			};
		},
	});

	// ── Auto-Delegation (hybrid mode) ──────────────────────────────────────

	pi.on("before_agent_start", async (event, ctx) => {
		if (!autoDelegate || mode === "interactive") return;

		// Check context pressure
		const usage = ctx.getContextUsage();
		if (usage && usage.percent && usage.percent > CONTEXT_WARN_PCT) {
			ctx.ui.setStatus("hyperloop-warn", `⚠️ Context ${Math.round(usage.percent)}% — consider offloading heavy tasks`);
		} else {
			ctx.ui.setStatus("hyperloop-warn", undefined);
		}

		// In hybrid mode, nudge the system prompt to encourage delegation
		if (mode === "hybrid" || mode === "delegator") {
			const shouldOffload = shouldSuggestOffload(event.prompt);
			const contextHigh = usage && usage.percent && usage.percent > CONTEXT_WARN_PCT;

			if (shouldOffload || contextHigh) {
				const roles = getAllRoles().map(r => `${r.name}: ${r.description}`).join("\n");
				return {
					systemPrompt: event.systemPrompt + `\n\n## Hyperloop Sub-Agent System
You have access to a sub-agent system (hyperloop_spawn, hyperloop_continue, hyperloop_status, hyperloop_kill, hyperloop_collect).

**The current task appears complex or context-heavy.** Consider spawning sub-agents for:
- Multi-file operations (use role="builder")
- Codebase exploration (use role="scout")
- Code review (use role="reviewer")
- Test writing (use role="tester")
- Any task that would generate lots of context

${contextHigh ? `⚠️ CONTEXT IS ${Math.round(usage!.percent!)}% FULL — strongly prefer sub-agents for any significant work.\n` : ""}
Available roles:\n${roles}

Sub-agents run in background. You can spawn multiple in parallel. Results auto-deliver as follow-up messages. Keep your main responses concise.`,
				};
			}
		}
	});

	// ── /hl Command ────────────────────────────────────────────────────────

	pi.registerCommand("hl", {
		description: "Hyperloop controls: /hl [spawn|kill|clear|auto|mode]",
		getArgumentCompletions: (prefix: string): AutocompleteItem[] | null => {
			const items = [
				{ value: "spawn ", label: "spawn <task> — Spawn a sub-agent" },
				{ value: "kill ", label: "kill <id> — Kill a sub-agent" },
				{ value: "clear", label: "clear — Remove all sub-agents" },
				{ value: "auto on", label: "auto on — Enable auto-delegation" },
				{ value: "auto off", label: "auto off — Disable auto-delegation" },
				{ value: "mode interactive", label: "mode interactive — Manual only" },
				{ value: "mode hybrid", label: "mode hybrid — Smart auto-offload" },
				{ value: "mode delegator", label: "mode delegator — Prefer delegation" },
			];
			return items.filter(i => i.value.startsWith(prefix));
		},

		async handler(args, ctx) {
			widgetCtx = ctx;
			const parts = (args || "").trim().split(/\s+/);
			const sub = parts[0]?.toLowerCase();

			if (!sub || sub === "status") {
				// Show dashboard
				const modeLabel = mode === "hybrid" ? "⚡ hybrid" : mode === "delegator" ? "📡 delegator" : "💬 interactive";
				const autoLabel = autoDelegate ? "on" : "off";
				const agentList = agents.size === 0
					? "  No sub-agents"
					: Array.from(agents.values()).map(a => {
						const elapsed = a.status === "running"
							? Math.round((Date.now() - a.startTime) / 1000)
							: Math.round(a.elapsed / 1000);
						return `  #${a.id} [${a.role}] ${a.status} — ${elapsed}s, ${a.toolCount} tools, $${a.cost.toFixed(4)}\n    ${a.task}`;
					}).join("\n");

				const usage = ctx.getContextUsage();
				const pct = usage?.percent ? Math.round(usage.percent) : "?";

				pi.sendMessage({
					customType: "hyperloop-dashboard",
					content: `\n◉ Hyperloop Dashboard\n  Mode: ${modeLabel} | Auto: ${autoLabel} | Context: ${pct}%\n  Agents: ${agents.size}\n\n${agentList}\n\n  Commands: /hl spawn|kill|clear|auto|mode`,
					display: true,
				});
				return;
			}

			if (sub === "spawn") {
				const task = parts.slice(1).join(" ").trim();
				if (!task) {
					ctx.ui.notify("Usage: /hl spawn <task>", "error");
					return;
				}

				const id = nextId++;
				const agent: SubAgent = {
					id,
					status: "queued",
					task,
					role: "general",
					tools: BUILTIN_ROLES[0].tools,
					textChunks: [],
					toolCount: 0,
					elapsed: 0,
					startTime: Date.now(),
					sessionFile: makeSessionFile(id),
					turnCount: 1,
					inputTokens: 0,
					outputTokens: 0,
					cost: 0,
				};
				agents.set(id, agent);
				spawnAndDeliver(agent, task, ctx, false);
				ctx.ui.notify(`Sub-agent #${id} spawned`, "info");
				return;
			}

			if (sub === "kill") {
				const id = parseInt(parts[1], 10);
				if (isNaN(id)) {
					ctx.ui.notify("Usage: /hl kill <id>", "error");
					return;
				}
				const agent = agents.get(id);
				if (!agent) {
					ctx.ui.notify(`No sub-agent #${id}`, "error");
					return;
				}
				if (agent.proc) try { agent.proc.kill("SIGTERM"); } catch {}
				if (agent.timer) clearInterval(agent.timer);
				agents.delete(id);
				flushWidget();
				ctx.ui.notify(`Sub-agent #${id} killed`, "info");
				return;
			}

			if (sub === "clear") {
				for (const [, a] of agents) {
					if (a.proc) try { a.proc.kill("SIGTERM"); } catch {}
					if (a.timer) clearInterval(a.timer);
				}
				agents.clear();
				nextId = 1;
				flushWidget();
				ctx.ui.notify("All sub-agents cleared", "info");
				return;
			}

			if (sub === "auto") {
				const val = parts[1]?.toLowerCase();
				if (val === "on") { autoDelegate = true; ctx.ui.notify("Auto-delegation ON", "info"); }
				else if (val === "off") { autoDelegate = false; ctx.ui.notify("Auto-delegation OFF", "info"); }
				else ctx.ui.notify("Usage: /hl auto on|off", "error");
				return;
			}

			if (sub === "mode") {
				const val = parts[1]?.toLowerCase() as AgentMode;
				if (["interactive", "delegator", "hybrid"].includes(val)) {
					mode = val;
					ctx.ui.notify(`Mode: ${val}`, "info");
					flushWidget();
				} else {
					ctx.ui.notify("Usage: /hl mode interactive|hybrid|delegator", "error");
				}
				return;
			}

			ctx.ui.notify("Unknown command. Try: /hl spawn|kill|clear|auto|mode", "error");
		},
	});

	// ── Session Lifecycle ──────────────────────────────────────────────────

	pi.on("session_start", async (_event, ctx) => {
		applyExtensionDefaults(import.meta.url, ctx);
		widgetCtx = ctx;
		sessionDir = join(ctx.cwd, ".pi", "agent-sessions", "hyperloop");

		loadCustomRoles(ctx.cwd);

		// Clean up any previous agents
		for (const [, a] of agents) {
			if (a.proc) try { a.proc.kill("SIGTERM"); } catch {}
			if (a.timer) clearInterval(a.timer);
		}
		agents.clear();
		nextId = 1;

		// Footer
		ctx.ui.setFooter((_tui, theme, footerData) => {
			const unsub = footerData.onBranchChange(() => _tui.requestRender());
			return {
				dispose: unsub,
				invalidate() {},
				render(width: number): string[] {
					const model = ctx.model?.id || "no-model";
					const usage = ctx.getContextUsage();
					const pct = usage?.percent ?? 0;
					const filled = Math.round(pct / 10) || 1;
					const bar = "#".repeat(filled) + "-".repeat(10 - filled);

					const running = Array.from(agents.values()).filter(a => a.status === "running").length;
					const total = agents.size;
					const modeIcon = mode === "hybrid" ? "⚡" : mode === "delegator" ? "📡" : "💬";

					let tokIn = 0, tokOut = 0, cost = 0;
					for (const entry of ctx.sessionManager.getBranch()) {
						if (entry.type === "message" && entry.message.role === "assistant") {
							const m = entry.message as AssistantMessage;
							tokIn += m.usage.input;
							tokOut += m.usage.output;
							cost += m.usage.cost.total;
						}
					}
					// Add sub-agent costs
					for (const [, a] of agents) cost += a.cost;

					const fmt = (n: number) => n < 1000 ? `${n}` : `${(n / 1000).toFixed(1)}k`;

					const l1Left =
						theme.fg("dim", ` ${model} `) +
						theme.fg("warning", "[") +
						theme.fg("success", "#".repeat(filled)) +
						theme.fg("dim", "-".repeat(10 - filled)) +
						theme.fg("warning", "]") +
						theme.fg("dim", " ") +
						theme.fg("accent", `${Math.round(pct)}%`);

					const l1Right =
						theme.fg("success", `${fmt(tokIn)}`) +
						theme.fg("dim", " in ") +
						theme.fg("accent", `${fmt(tokOut)}`) +
						theme.fg("dim", " out ") +
						theme.fg("warning", `$${cost.toFixed(4)}`) +
						theme.fg("dim", " ");

					const pad1 = " ".repeat(Math.max(1, width - visibleWidth(l1Left) - visibleWidth(l1Right)));
					const line1 = truncateToWidth(l1Left + pad1 + l1Right, width, "");

					const dir = basename(ctx.cwd);
					const branch = footerData.getGitBranch();
					const l2Left =
						theme.fg("dim", ` ${dir}`) +
						(branch ? theme.fg("dim", " ") + theme.fg("warning", "(") + theme.fg("success", branch) + theme.fg("warning", ")") : "") +
						theme.fg("dim", ` · ${modeIcon} ${mode}`);

					const agentStatus = total > 0
						? (running > 0
							? theme.fg("accent", `● ${running} running`) + theme.fg("dim", ` / ${total} total `)
							: theme.fg("dim", `${total} agents `))
						: theme.fg("dim", "no agents ");

					const pad2 = " ".repeat(Math.max(1, width - visibleWidth(l2Left) - visibleWidth(agentStatus)));
					const line2 = truncateToWidth(l2Left + pad2 + agentStatus, width, "");

					return [line1, line2];
				},
			};
		});

		const roles = getAllRoles().map(r => r.name).join(", ");
		ctx.ui.notify(
			`◉ Hyperloop active [${mode} mode]\n` +
			`Roles: ${roles}\n` +
			`/hl — Dashboard & controls`,
			"info",
		);
	});

	// ── Cleanup ────────────────────────────────────────────────────────────

	function killAll() {
		for (const proc of activeProcesses) {
			try { proc.kill("SIGTERM"); } catch {}
		}
		setTimeout(() => {
			for (const proc of activeProcesses) {
				try { proc.kill("SIGKILL"); } catch {}
			}
		}, 3000);
	}

	pi.on("session_shutdown", async () => { killAll(); });
	process.on("exit", killAll);
	process.on("SIGINT", () => { killAll(); process.exit(0); });
	process.on("SIGTERM", () => { killAll(); process.exit(0); });
}