/** * EngineSpec: a self-contained description of each inference backend, inspired * by exo-spark's EngineSpec pattern. Each backend owns its command building, * process detection, health endpoint, install action, and binary probing, * rather than scattering these concerns across backend-builder, * process-utilities, runtime-targets, and runtime-info. */import type { ChildProcess } from "node:child_process";import type { Config } from "../../config/env";import type { Recipe, ProcessInfo } from "../models/types";import type {  EngineBackend,  RuntimeBackendInfo,  RuntimeUpgradeResult,} from "@local-studio/contracts/system";import type { InstallProgressUpdate } from "./runtimes/managed-venv"; export type { InstallProgressUpdate }; export interface InstallOptions {  config: Config;  version?: string | undefined;  pythonPath?: string | null | undefined;  preferBundled?: boolean | undefined;  createManagedVenv?: boolean | undefined;  onProgress?: ((update: InstallProgressUpdate) => void) | undefined;  onSpawn?: ((child: ChildProcess) => void) | undefined;}import { vllmSpec } from "./specs/vllm-spec";import { sglangSpec } from "./specs/sglang-spec";import { llamacppSpec } from "./specs/llamacpp-spec";import { mlxSpec } from "./specs/mlx-spec"; export interface BinaryProbeResult {  installed: boolean;  version: string | null;  binaryPath: string | null;  pythonPath?: string | null;  message?: string;} export interface ConfigHelpResult {  config: string | null;  error: string | null;} export interface EngineSpec {  readonly id: EngineBackend;   /** Health endpoint path appended to the inference base URL for readiness checks. */  readonly healthPath: string;   /** CLI binary name in the venv bin directory (e.g. "vllm", "sglang"). Null for engines without a CLI binary. */  readonly cliBinary: string | null;   /**   * Build the full command array (including binary) to serve a recipe.   * Replaces the per-backend functions in backend-builder.ts.   */  buildCommand: (recipe: Recipe, config: Config) => string[];   /**   * Managed venv package spec for install/update (e.g. "sglang[all]", "vllm", "mlx-lm").   * Replaces managedPackageSpec in engine-jobs.ts.   */  managedPackageSpec: (version?: string | null) => string;   /**   * Idempotent install of this backend into a target Python (when pythonPath is   * given) or the controller-owned managed venv (when it is not). Short-circuits   * when the backend is already present. Replaces the per-backend upgrade   * branches in engine-jobs.ts and runtime-upgrade.ts.   */  install: (options: InstallOptions) => Promise<RuntimeUpgradeResult>;   /**   * Detect whether a process's args represent this engine's serve invocation.   * Replaces the per-backend checks in process-utilities.detectBackend.   */  detectInvocation: (args: string[]) => boolean;   /** Extract the model path from a running process's args. */  extractModelPath: (args: string[]) => string | null;   /** Extract the served model name from a running process's args. */  extractServedModelName: (args: string[]) => string | null;   /** Probe a CLI binary for version/install info. Undefined if the engine has no CLI binary. */  probeBinary?: (binary: string) => Promise<BinaryProbeResult>;   /** Engine-specific Python path resolver for venv discovery. */  resolvePythonPath?: (config: Config) => string | null;   /** Get detailed runtime info (async). Replaces the sync functions in runtime-info.ts. */  getRuntimeInfo?: (    config: Config,    runningProcess?: Pick<ProcessInfo, "pid" | "backend"> | null,  ) => Promise<RuntimeBackendInfo>;   /** Get config help (--help output) for the recipe editor's command tab. */  getConfigHelp?: (config: Config) => Promise<ConfigHelpResult>;} const SPECS: Record<EngineBackend, EngineSpec> = {  vllm: vllmSpec,  sglang: sglangSpec,  llamacpp: llamacppSpec,  mlx: mlxSpec,}; export const getEngineSpec = (backend: EngineBackend): EngineSpec => SPECS[backend]; export const ALL_ENGINE_SPECS: readonly EngineSpec[] = Object.values(SPECS); /** Detect which engine a running process belongs to, or null if unrecognized. */export const detectEngineFromArguments = (args: string[]): EngineBackend | null => {  for (const spec of ALL_ENGINE_SPECS) {    if (spec.detectInvocation(args)) return spec.id;  }  return null;}; export { vllmSpec, sglangSpec, llamacppSpec, mlxSpec };