feat: add companion API and Android APK shell

apps/companion/src/config/companionConfig.ts

@@ -0,0 +1,61 @@
+import { existsSync } from 'node:fs';
+import { mkdir, readFile, writeFile } from 'node:fs/promises';
+import { homedir } from 'node:os';
+import { dirname, resolve } from 'node:path';
+import { randomBytes } from 'node:crypto';
+
+export type CompanionConfig = {
+  accessKey: string;
+  workspaceRoot: string;
+};
+
+export function getConfigPath(): string {
+  return process.env.HERMES_MOBILE_CONFIG ?? resolve(homedir(), '.config/hermes-mobile/companion.json');
+}
+
+export function getWorkspaceRoot(): string {
+  return resolve(process.env.HERMES_MOBILE_WORKSPACE_ROOT ?? process.cwd());
+}
+
+export function generateAccessKey(): string {
+  return `hm_${randomBytes(24).toString('base64url')}`;
+}
+
+export async function readCompanionConfig(): Promise<Partial<CompanionConfig>> {
+  const configPath = getConfigPath();
+
+  if (!existsSync(configPath)) {
+    return {};
+  }
+
+  const rawConfig = await readFile(configPath, 'utf8');
+  const parsedConfig = JSON.parse(rawConfig) as Partial<CompanionConfig>;
+
+  return parsedConfig;
+}
+
+export async function writeCompanionConfig(config: CompanionConfig): Promise<void> {
+  const configPath = getConfigPath();
+  await mkdir(dirname(configPath), { recursive: true });
+  await writeFile(configPath, `${JSON.stringify(config, null, 2)}\n`, { mode: 0o600 });
+}
+
+export async function ensureCompanionConfig(): Promise<CompanionConfig> {
+  const existingConfig = await readCompanionConfig();
+  const config: CompanionConfig = {
+    accessKey: existingConfig.accessKey || process.env.HERMES_MOBILE_ACCESS_KEY || generateAccessKey(),
+    workspaceRoot: resolve(existingConfig.workspaceRoot || getWorkspaceRoot()),
+  };
+
+  await writeCompanionConfig(config);
+  return config;
+}
+
+export async function getRuntimeConfig(): Promise<CompanionConfig> {
+  const existingConfig = await readCompanionConfig();
+
+  return {
+    accessKey: process.env.HERMES_MOBILE_ACCESS_KEY || existingConfig.accessKey || '',
+    workspaceRoot: resolve(process.env.HERMES_MOBILE_WORKSPACE_ROOT || existingConfig.workspaceRoot || process.cwd()),
+  };
+}