apps/cli: Route studio_mobile_* bot replies to studio-mobile-client endpoint (PoC)

apps/cli/remote-session/config.ts

@@ -1,9 +1,25 @@
 import fs from 'fs';
+import { hostname } from 'os';
 import { readAuthToken } from '@studio/common/lib/shared-config';
 import { getRemoteSessionConfigPath } from '@studio/common/lib/well-known-paths';
 import { readFile, writeFile } from 'atomically';
 import { z } from 'zod';
 
+/**
+ * Sanitize the host's name down to the wpcom-friendly charset
+ * (`[a-z0-9_]`, max 32 chars) so it's safe to use as a `machine_id` cache key
+ * suffix without escaping. Falls back to `unknown_host` if `os.hostname()`
+ * yields nothing usable.
+ */
+function deriveMachineId(): string {
+	const sanitized = hostname()
+		.toLowerCase()
+		.replace( /[^a-z0-9_]/g, '_' )
+		.replace( /^_+|_+$/g, '' )
+		.slice( 0, 32 );
+	return sanitized || 'unknown_host';
+}
+
 export const remoteSessionConfigSchema = z.object( {
 	base_url: z.string().url().default( 'https://public-api.wordpress.com/wpcom/v2/telegram-bot' ),
 	// `token` is the only required field; if omitted everywhere, falls back to the
@@ -15,6 +31,14 @@ export const remoteSessionConfigSchema = z.object( {
 	// polled message back into the response.
 	bot: z.string().min( 1 ).optional(),
 	chat_id: z.number().int().optional(),
+	// Stable identifier for this CLI host, sent as `machine_id` on outbound
+	// replies to studio-mobile bots. Defaults to a sanitized `os.hostname()`;
+	// override via `STUDIO_REMOTE_MACHINE_ID` if multiple installs on the same
+	// host need to be distinguished (or to pin a friendly name for tests).
+	machine_id: z
+		.string()
+		.regex( /^[a-z0-9_]{1,32}$/, 'machine_id must match [a-z0-9_]{1,32}' )
+		.default( deriveMachineId ),
 	poll_interval_seconds: z.number().positive().default( 2 ),
 	long_poll_timeout_seconds: z.number().positive().default( 25 ),
 	max_message_chars: z.number().int().positive().max( 4096 ).default( 3800 ),
@@ -28,6 +52,7 @@ export interface RemoteSessionOverrides {
 	bot?: string;
 	chat_id?: number;
 	base_url?: string;
+	machine_id?: string;
 }
 
 export class RemoteSessionConfigError extends Error {
@@ -57,6 +82,9 @@ function readEnvOverrides(): RemoteSessionOverrides {
 			overrides.chat_id = parsed;
 		}
 	}
+	if ( process.env.STUDIO_REMOTE_MACHINE_ID ) {
+		overrides.machine_id = process.env.STUDIO_REMOTE_MACHINE_ID;
+	}
 	return overrides;
 }
 

apps/cli/remote-session/index.ts

@@ -9,7 +9,7 @@ import {
 import { installDaemonChildHooks, isDaemonChild } from 'cli/remote-session/daemon';
 import { RemoteSessionLogger } from 'cli/remote-session/logger';
 import { runPollLoop } from 'cli/remote-session/poll-loop';
-import { respondMessage } from 'cli/remote-session/telegram-client';
+import { respondMessage } from 'cli/remote-session/respond-router';
 
 export { RemoteSessionConfigError };
 

apps/cli/remote-session/media-streamer.ts

@@ -1,7 +1,7 @@
 import type { JsonEvent } from '@studio/common/ai/json-events';
 import type { RemoteSessionConfig } from 'cli/remote-session/config';
 import type { RemoteSessionLogger } from 'cli/remote-session/logger';
-import type { respondMessage } from 'cli/remote-session/telegram-client';
+import type { respondMessage } from 'cli/remote-session/respond-router';
 
 interface ValidMediaShare {
 	dataBase64: string;

apps/cli/remote-session/poll-loop.ts

@@ -5,15 +5,15 @@ import { type RemoteSessionConfig } from 'cli/remote-session/config';
 import { RemoteSessionLogger } from 'cli/remote-session/logger';
 import { MediaStreamer } from 'cli/remote-session/media-streamer';
 import { ProgressStreamer } from 'cli/remote-session/progress-streamer';
+import {
+	RemoteAuthError,
+	RemoteBadRequestError,
+	RemoteTransientError,
+} from 'cli/remote-session/remote-http';
 import { chunkReply, extractReply } from 'cli/remote-session/reply-formatter';
+import { respondMessage } from 'cli/remote-session/respond-router';
 import { clearSessionId, readStateForChat, writeSessionId } from 'cli/remote-session/state';
-import {
-	TelegramAuthError,
-	TelegramBadRequestError,
-	TelegramTransientError,
-	pollMessages,
-	respondMessage,
-} from 'cli/remote-session/telegram-client';
+import { pollMessages } from 'cli/remote-session/telegram-client';
 import { runTurn, type TurnOutcome, type TurnRunOptions } from 'cli/remote-session/turn-runner';
 
 /** Injected for tests. */
@@ -403,7 +403,7 @@ export async function runPollLoop( options: RunPollLoopOptions ): Promise< PollL
 				batch = await deps.poll( config, abortController.signal, { logger: deps.logger } );
 				backoffAttempt = 0;
 			} catch ( error ) {
-				if ( error instanceof TelegramAuthError ) {
+				if ( error instanceof RemoteAuthError ) {
 					deps.logger.error( 'Auth error; detaching', { status: error.status } );
 					if ( config.chat_id !== undefined ) {
 						await postBestEffort(
@@ -418,7 +418,7 @@ export async function runPollLoop( options: RunPollLoopOptions ): Promise< PollL
 					process.exitCode = 1;
 					break;
 				}
-				if ( error instanceof TelegramTransientError ) {
+				if ( error instanceof RemoteTransientError ) {
 					const delay = Math.min( 30_000, 1000 * Math.pow( 2, backoffAttempt ) );
 					deps.logger.warn( 'Transient poll error; backing off', {
 						status: error.status,
@@ -506,7 +506,7 @@ export async function runPollLoop( options: RunPollLoopOptions ): Promise< PollL
 							{ logger: deps.logger }
 						);
 					} catch ( error ) {
-						if ( error instanceof TelegramBadRequestError ) {
+						if ( error instanceof RemoteBadRequestError ) {
 							deps.logger.warn( 'Respond 4xx on /new ack', { status: error.status } );
 						} else {
 							throw error;
@@ -525,7 +525,7 @@ export async function runPollLoop( options: RunPollLoopOptions ): Promise< PollL
 						telemetryEnabled
 					);
 				} catch ( error ) {
-					if ( error instanceof TelegramAuthError ) {
+					if ( error instanceof RemoteAuthError ) {
 						deps.logger.error( 'Auth error during respond; detaching', {
 							status: error.status,
 						} );
@@ -534,7 +534,7 @@ export async function runPollLoop( options: RunPollLoopOptions ): Promise< PollL
 						process.exitCode = 1;
 						break batchLoop;
 					}
-					if ( error instanceof TelegramBadRequestError ) {
+					if ( error instanceof RemoteBadRequestError ) {
 						deps.logger.warn( 'Respond 4xx; dropping chunk', { status: error.status } );
 						continue;
 					}

apps/cli/remote-session/progress-streamer.ts

@@ -4,7 +4,7 @@ import type { AgentSessionEvent } from '@mariozechner/pi-coding-agent';
 import type { JsonEvent } from '@studio/common/ai/json-events';
 import type { RemoteSessionConfig } from 'cli/remote-session/config';
 import type { RemoteSessionLogger } from 'cli/remote-session/logger';
-import type { respondMessage } from 'cli/remote-session/telegram-client';
+import type { respondMessage } from 'cli/remote-session/respond-router';
 
 export interface ProgressTarget {
 	chatId: number;

apps/cli/remote-session/remote-http.ts

@@ -0,0 +1,84 @@
+/**
+ * Transport-layer primitives shared by the Telegram and studio-mobile clients
+ * — error classes, URL helpers, and fetch/backoff utilities. None of this
+ * knows about message shapes; it just gets bytes to and from the wpcom proxy.
+ */
+
+export class RemoteAuthError extends Error {
+	constructor( public readonly status: number ) {
+		super( `Remote server returned auth error (HTTP ${ status })` );
+		this.name = 'RemoteAuthError';
+	}
+}
+
+export class RemoteTransientError extends Error {
+	constructor(
+		message: string,
+		public readonly status?: number
+	) {
+		super( message );
+		this.name = 'RemoteTransientError';
+	}
+}
+
+export class RemoteBadRequestError extends Error {
+	constructor(
+		message: string,
+		public readonly status: number
+	) {
+		super( message );
+		this.name = 'RemoteBadRequestError';
+	}
+}
+
+export function assertSameHost( urlString: string, allowedHost: string ): void {
+	const u = new URL( urlString );
+	if ( u.host !== allowedHost ) {
+		throw new RemoteTransientError(
+			`Refusing to follow redirect to different host: ${ u.host } (allowed: ${ allowedHost })`
+		);
+	}
+}
+
+function normalizeBase( base: string ): URL {
+	// Ensure a trailing slash so relative path joins work predictably.
+	return new URL( base.endsWith( '/' ) ? base : `${ base }/` );
+}
+
+export function buildUrl( baseUrl: string, pathName: string ): string {
+	const base = normalizeBase( baseUrl );
+	const joined = new URL( pathName.replace( /^\//, '' ), base );
+	return joined.toString();
+}
+
+export async function safeReadText( response: Response ): Promise< string > {
+	try {
+		return await response.text();
+	} catch {
+		return '';
+	}
+}
+
+export async function backoff( attempt: number ): Promise< void > {
+	const baseMs = Math.min( 30_000, 500 * Math.pow( 2, attempt ) );
+	const jitter = Math.random() * 200;
+	await new Promise( ( resolve ) => setTimeout( resolve, baseMs + jitter ) );
+}
+
+export function composeSignals( a?: AbortSignal, b?: AbortSignal ): AbortSignal | undefined {
+	if ( ! a ) {
+		return b;
+	}
+	if ( ! b ) {
+		return a;
+	}
+	const controller = new AbortController();
+	const onAbort = () => controller.abort();
+	if ( a.aborted || b.aborted ) {
+		controller.abort();
+	} else {
+		a.addEventListener( 'abort', onAbort, { once: true } );
+		b.addEventListener( 'abort', onAbort, { once: true } );
+	}
+	return controller.signal;
+}