platform/src/servers/sidecar-client.ts

import type {
  SidecarCommand,
  SidecarEvent,
  SidecarState,
  ClaudeSpawnParams,
  ClaudeSpawnStreamingParams,
  ClaudeCodeResult,
  PiSpawnParams,
} from './sidecar/protocol';
import type { PiEvent } from './api/pi/types';
import type { Job, EnqueueParams } from './queue/types';

const SIDECAR_PORT = Number(process.env.SIDECAR_PORT ?? '5100');
const SIDECAR_URL = `ws://127.0.0.1:${SIDECAR_PORT}`;

const RECONNECT_DELAYS = [200, 500, 1000, 2000, 4000, 8000, 15000];

type PendingRequest = {
  resolve: (value: SidecarEvent) => void;
  reject: (error: Error) => void;
  timer: Timer;
};

type EventHandler = (event: SidecarEvent) => void;

let ws: WebSocket | null = null;
let connected = false;
let reconnectAttempt = 0;
let reconnectTimer: Timer | null = null;
const pending = new Map<string, PendingRequest>();
const eventHandlers = new Map<string, Set<EventHandler>>();
let cachedState: SidecarState | null = null;

// ── Connection management ──

function connect() {
  if (ws && (ws.readyState === WebSocket.CONNECTING || ws.readyState === WebSocket.OPEN)) return;

  try {
    ws = new WebSocket(SIDECAR_URL);
  } catch {
    scheduleReconnect();
    return;
  }

  ws.onopen = () => {
    connected = true;
    reconnectAttempt = 0;
    console.log('[sidecar-client] connected');

    // Sync state on connect
    sendCommand({ type: 'state:sync', id: nextId() }).then((res) => {
      if (res.type === 'state:sync') {
        cachedState = res.state;
        console.log('[sidecar-client] state synced');
      }
    }).catch(() => { /* best effort */ });
  };

  ws.onmessage = (event) => {
    try {
      const msg = JSON.parse(event.data as string) as SidecarEvent;

      // Check if this is a response to a pending request
      if ('id' in msg && msg.id && pending.has(msg.id)) {
        const req = pending.get(msg.id)!;
        pending.delete(msg.id);
        clearTimeout(req.timer);
        req.resolve(msg);
        return;
      }

      // Otherwise dispatch as event
      dispatchEvent(msg);
    } catch {
      // skip malformed messages
    }
  };

  ws.onclose = () => {
    connected = false;
    ws = null;
    rejectAllPending('WebSocket disconnected');
    scheduleReconnect();
  };

  ws.onerror = () => {
    // onclose will fire after this
  };
}

function scheduleReconnect() {
  if (reconnectTimer) return;
  const delay = RECONNECT_DELAYS[Math.min(reconnectAttempt, RECONNECT_DELAYS.length - 1)]!;
  reconnectAttempt++;
  reconnectTimer = setTimeout(() => {
    reconnectTimer = null;
    connect();
  }, delay);
}

function rejectAllPending(reason: string) {
  for (const [id, req] of pending) {
    clearTimeout(req.timer);
    req.reject(new Error(reason));
  }
  pending.clear();
}

// ── Event dispatch ──

function dispatchEvent(msg: SidecarEvent) {
  const handlers = eventHandlers.get(msg.type);
  if (handlers) {
    for (const handler of handlers) {
      try { handler(msg); } catch { /* ignore */ }
    }
  }
}

export function on(eventType: string, handler: EventHandler): () => void {
  if (!eventHandlers.has(eventType)) {
    eventHandlers.set(eventType, new Set());
  }
  eventHandlers.get(eventType)!.add(handler);
  return () => {
    eventHandlers.get(eventType)?.delete(handler);
  };
}

// ── Command sending ──

let idCounter = 0;
function nextId(): string {
  return `sc_${Date.now()}_${++idCounter}`;
}

const DEFAULT_TIMEOUT_MS = 30_000;
const LONG_TIMEOUT_MS = 6 * 60 * 1000; // 6 min for claude spawn

function sendCommand(cmd: SidecarCommand, timeoutMs = DEFAULT_TIMEOUT_MS): Promise<SidecarEvent> {
  return new Promise((resolve, reject) => {
    if (!ws || ws.readyState !== WebSocket.OPEN) {
      reject(new Error('Sidecar not connected'));
      return;
    }

    const timer = setTimeout(() => {
      pending.delete(cmd.id);
      reject(new Error(`Sidecar command ${cmd.type} timed out`));
    }, timeoutMs);

    pending.set(cmd.id, { resolve, reject, timer });
    ws.send(JSON.stringify(cmd));
  });
}

function sendFire(cmd: SidecarCommand): void {
  if (ws && ws.readyState === WebSocket.OPEN) {
    ws.send(JSON.stringify(cmd));
  }
}

// ── Public API ──

export function isConnected(): boolean {
  return connected;
}

export function getCachedState(): SidecarState | null {
  return cachedState;
}

export async function syncState(): Promise<SidecarState> {
  const res = await sendCommand({ type: 'state:sync', id: nextId() });
  if (res.type === 'state:sync') {
    cachedState = res.state;
    return res.state;
  }
  throw new Error('Unexpected response');
}

export async function getProxySecret(): Promise<string> {
  if (cachedState?.proxySecret) return cachedState.proxySecret;
  const res = await sendCommand({ type: 'proxy:secret', id: nextId() });
  if (res.type === 'proxy:secret') return res.secret;
  throw new Error('Failed to get proxy secret');
}

export function getProxySecretSync(): string {
  return cachedState?.proxySecret ?? '';
}

// ── Claude Code ──

export async function spawnClaude(params: ClaudeSpawnParams): Promise<ClaudeCodeResult> {
  const res = await sendCommand({ type: 'claude:spawn', id: nextId(), params }, LONG_TIMEOUT_MS);
  if (res.type === 'claude:result') return res.result;
  if (res.type === 'claude:error') throw new Error(res.error);
  throw new Error('Unexpected response');
}

export async function spawnClaudeStreaming(params: ClaudeSpawnStreamingParams): Promise<void> {
  const res = await sendCommand({ type: 'claude:spawn-streaming', id: nextId(), params });
  if (res.type === 'claude:spawned') return;
  if (res.type === 'claude:error') throw new Error(res.error);
  throw new Error('Unexpected response');
}

export function killClaude(sessionKey: string): void {
  sendFire({ type: 'claude:kill', id: nextId(), sessionKey });
}

export function clearClaudeSession(sessionKey: string): void {
  sendFire({ type: 'claude:clear-session', id: nextId(), sessionKey });
}

export function onClaudeEvent(handler: (sessionKey: string, event: PiEvent) => void): () => void {
  return on('claude:event', (msg) => {
    if (msg.type === 'claude:event') {
      handler(msg.sessionKey, msg.event);
    }
  });
}

// ── Pi ──

export async function spawnPi(params: PiSpawnParams): Promise<void> {
  const res = await sendCommand({ type: 'pi:spawn', id: nextId(), params });
  if (res.type === 'pi:spawned') return;
  if (res.type === 'pi:error') throw new Error(res.error);
  throw new Error('Unexpected response');
}

export function sendPiPrompt(sessionId: string, prompt: string, requestId: string): void {
  sendFire({ type: 'pi:prompt', id: nextId(), sessionId, prompt, requestId });
}

export function abortPi(sessionId: string, requestId: string): void {
  sendFire({ type: 'pi:abort', id: nextId(), sessionId, requestId });
}

export function killPi(sessionId: string): void {
  sendFire({ type: 'pi:kill', id: nextId(), sessionId });
}

export function setPiThinking(sessionId: string, level: string): void {
  sendFire({ type: 'pi:set-thinking', id: nextId(), sessionId, level });
}

export function onPiEvent(handler: (sessionId: string, event: PiEvent) => void): () => void {
  return on('pi:event', (msg) => {
    if (msg.type === 'pi:event') {
      handler(msg.sessionId, msg.event);
    }
  });
}

// ── Queue ──

export async function enqueueJob(params: EnqueueParams): Promise<Job> {
  const res = await sendCommand({ type: 'queue:enqueue', id: nextId(), params });
  if (res.type === 'queue:enqueued') return res.job;
  if (res.type === 'queue:error') throw new Error(res.error);
  throw new Error('Unexpected response');
}

export async function cancelJob(jobId: string): Promise<Job | null> {
  const res = await sendCommand({ type: 'queue:cancel', id: nextId(), jobId });
  if (res.type === 'queue:cancelled') return res.job;
  if (res.type === 'queue:error') throw new Error(res.error);
  throw new Error('Unexpected response');
}

export async function listJobs(): Promise<Job[]> {
  const res = await sendCommand({ type: 'queue:list', id: nextId() });
  if (res.type === 'queue:list') return res.jobs;
  throw new Error('Unexpected response');
}

export async function getJob(jobId: string): Promise<Job | null> {
  const res = await sendCommand({ type: 'queue:get', id: nextId(), jobId });
  if (res.type === 'queue:get') return res.job;
  throw new Error('Unexpected response');
}

// ── Health check ──

export async function isSidecarAlive(): Promise<boolean> {
  try {
    const res = await fetch(`http://127.0.0.1:${SIDECAR_PORT}/`, { signal: AbortSignal.timeout(1000) });
    const text = await res.text();
    return text === 'process-sidecar';
  } catch {
    return false;
  }
}

// ── Init ──

export function initSidecarClient(): void {
  connect();
}