feat(cli): add remote debugging port option

Adds a Chromium remote debugging port flag for preview and play.

The flag is only passed when launching an explicit browser/profile.

HyperFrames still does not own CDP automation.

packages/cli/src/commands/play.ts

@@ -13,7 +13,7 @@ import { resolve, dirname } from "node:path";
 import * as clack from "@clack/prompts";
 import { c } from "../ui/colors.js";
 import { resolveProject } from "../utils/project.js";
-import { openBrowser } from "../utils/openBrowser.js";
+import { openBrowser, parseRemoteDebuggingPort } from "../utils/openBrowser.js";
 
 export default defineCommand({
   meta: { name: "play", description: "Play a composition in a lightweight browser player" },
@@ -33,6 +33,10 @@ export default defineCommand({
       type: "string",
       description: "Chromium-compatible user data directory (requires --browser-path)",
     },
+    "remote-debugging-port": {
+      type: "string",
+      description: "Chromium remote debugging port (requires --browser-path and --user-data-dir)",
+    },
   },
   async run({ args }) {
     const project = resolveProject(args.dir);
@@ -44,6 +48,19 @@ export default defineCommand({
       process.exitCode = 1;
       return;
     }
+    // Validation: --remote-debugging-port requires --browser-path and --user-data-dir
+    if (args["remote-debugging-port"]) {
+      if (!args["browser-path"]) {
+        clack.log.error("--remote-debugging-port requires --browser-path");
+        process.exitCode = 1;
+        return;
+      }
+      if (!args["user-data-dir"]) {
+        clack.log.error("--remote-debugging-port requires --user-data-dir");
+        process.exitCode = 1;
+        return;
+      }
+    }
 
     // Resolve runtime path — same logic as studioServer.ts
     const runtimePath = resolveRuntimePath();
@@ -168,10 +185,22 @@ export default defineCommand({
     console.log();
     console.log(`  ${c.dim("Press Ctrl+C to stop")}`);
     console.log();
+    let remoteDebuggingPort: number | undefined;
+    if (args["remote-debugging-port"]) {
+      try {
+        remoteDebuggingPort = parseRemoteDebuggingPort(args["remote-debugging-port"]);
+      } catch (err) {
+        clack.log.error((err as Error).message);
+        process.exitCode = 1;
+        return;
+      }
+    }
+
     if (args.open) {
       void openBrowser(url, {
         browserPath: args["browser-path"] as string | undefined,
         userDataDir: args["user-data-dir"] as string | undefined,
+        remoteDebuggingPort,
       });
     }
 

packages/cli/src/commands/preview.ts

@@ -19,7 +19,7 @@ import { createRequire } from "node:module";
 import * as clack from "@clack/prompts";
 import { c } from "../ui/colors.js";
 import { isDevMode } from "../utils/env.js";
-import { openBrowser } from "../utils/openBrowser.js";
+import { openBrowser, parseRemoteDebuggingPort } from "../utils/openBrowser.js";
 import { lintProject } from "../utils/lintProject.js";
 import { formatLintFindings } from "../utils/lintFormat.js";
 import {
@@ -63,6 +63,10 @@ export default defineCommand({
       type: "string",
       description: "Chromium-compatible user data directory (requires --browser-path)",
     },
+    "remote-debugging-port": {
+      type: "string",
+      description: "Chromium remote debugging port (requires --browser-path and --user-data-dir)",
+    },
   },
   async run({ args }) {
     const startPort = parseInt(args.port ?? "3002", 10);
@@ -131,18 +135,53 @@ export default defineCommand({
       process.exitCode = 1;
       return;
     }
+    // Validation: --remote-debugging-port requires --browser-path and --user-data-dir
+    if (args["remote-debugging-port"]) {
+      if (!args["browser-path"]) {
+        clack.log.error("--remote-debugging-port requires --browser-path");
+        process.exitCode = 1;
+        return;
+      }
+      if (!args["user-data-dir"]) {
+        clack.log.error("--remote-debugging-port requires --user-data-dir");
+        process.exitCode = 1;
+        return;
+      }
+    }
 
     const noOpen = !args.open;
     const browserPath = args["browser-path"] as string | undefined;
     const userDataDir = args["user-data-dir"] as string | undefined;
+    let remoteDebuggingPort: number | undefined;
+    if (args["remote-debugging-port"]) {
+      try {
+        remoteDebuggingPort = parseRemoteDebuggingPort(args["remote-debugging-port"]);
+      } catch (err) {
+        clack.log.error((err as Error).message);
+        process.exitCode = 1;
+        return;
+      }
+    }
 
     if (isDevMode()) {
-      return runDevMode(dir, { projectName, noOpen, browserPath, userDataDir });
+      return runDevMode(dir, {
+        projectName,
+        noOpen,
+        browserPath,
+        userDataDir,
+        remoteDebuggingPort,
+      });
     }
 
     // If @hyperframes/studio is installed locally, use Vite for full HMR
     if (hasLocalStudio(dir)) {
-      return runLocalStudioMode(dir, { projectName, noOpen, browserPath, userDataDir });
+      return runLocalStudioMode(dir, {
+        projectName,
+        noOpen,
+        browserPath,
+        userDataDir,
+        remoteDebuggingPort,
+      });
     }
 
     const forceNew = !!args["force-new"];
@@ -152,6 +191,7 @@ export default defineCommand({
       noOpen,
       browserPath,
       userDataDir,
+      remoteDebuggingPort,
     });
   },
 });
@@ -161,7 +201,13 @@ export default defineCommand({
  */
 async function runDevMode(
   dir: string,
-  options?: { projectName?: string; noOpen?: boolean; browserPath?: string; userDataDir?: string },
+  options?: {
+    projectName?: string;
+    noOpen?: boolean;
+    browserPath?: string;
+    userDataDir?: string;
+    remoteDebuggingPort?: number;
+  },
 ): Promise<void> {
   // Find monorepo root by navigating from packages/cli/src/commands/
   const thisFile = fileURLToPath(import.meta.url);
@@ -231,6 +277,7 @@ async function runDevMode(
         openBrowser(urlToOpen, {
           browserPath: options?.browserPath,
           userDataDir: options?.userDataDir,
+          remoteDebuggingPort: options?.remoteDebuggingPort,
         });
       }
 
@@ -294,7 +341,13 @@ function hasLocalStudio(dir: string): boolean {
  */
 async function runLocalStudioMode(
   dir: string,
-  options?: { projectName?: string; noOpen?: boolean; browserPath?: string; userDataDir?: string },
+  options?: {
+    projectName?: string;
+    noOpen?: boolean;
+    browserPath?: string;
+    userDataDir?: string;
+    remoteDebuggingPort?: number;
+  },
 ): Promise<void> {
   const req = createRequire(join(dir, "package.json"));
   const studioPkgPath = dirname(req.resolve("@hyperframes/studio/package.json"));
@@ -346,6 +399,7 @@ async function runLocalStudioMode(
         openBrowser(`${url}#project/${pName}`, {
           browserPath: options?.browserPath,
           userDataDir: options?.userDataDir,
+          remoteDebuggingPort: options?.remoteDebuggingPort,
         });
       }
     }
@@ -396,6 +450,7 @@ async function runEmbeddedMode(
     noOpen?: boolean;
     browserPath?: string;
     userDataDir?: string;
+    remoteDebuggingPort?: number;
   },
 ): Promise<void> {
   const { createStudioServer, loadPreviewServerBuildSignature, resolveStudioBundle } =
@@ -458,6 +513,7 @@ async function runEmbeddedMode(
       openBrowser(`${url}#project/${pName}`, {
         browserPath: options?.browserPath,
         userDataDir: options?.userDataDir,
+        remoteDebuggingPort: options?.remoteDebuggingPort,
       });
     }
     return;
@@ -482,6 +538,7 @@ async function runEmbeddedMode(
     openBrowser(`${url}#project/${pName}`, {
       browserPath: options?.browserPath,
       userDataDir: options?.userDataDir,
+      remoteDebuggingPort: options?.remoteDebuggingPort,
     });
   }
 

packages/cli/src/utils/openBrowser.test.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect } from "vitest";
-import { buildBrowserArgs } from "./openBrowser.js";
+import { buildBrowserArgs, parseRemoteDebuggingPort } from "./openBrowser.js";
 
 describe("buildBrowserArgs", () => {
   it("returns only the URL when no options are given", () => {
@@ -37,4 +37,80 @@ describe("buildBrowserArgs", () => {
       }),
     ).toEqual(["--user-data-dir=C:\\Documents and Settings\\profile", "http://localhost:3002"]);
   });
+
+  it("prepends --remote-debugging-port before the URL", () => {
+    expect(
+      buildBrowserArgs("http://localhost:3002", {
+        browserPath: "/usr/bin/chromium",
+        userDataDir: "/tmp/hf-profile",
+        remoteDebuggingPort: 9222,
+      }),
+    ).toEqual([
+      "--user-data-dir=/tmp/hf-profile",
+      "--remote-debugging-port=9222",
+      "http://localhost:3002",
+    ]);
+  });
+
+  it("includes all flags together", () => {
+    expect(
+      buildBrowserArgs("http://localhost:3002", {
+        browserPath: "/usr/bin/chromium",
+        userDataDir: "/tmp/hf-profile",
+        remoteDebuggingPort: 9222,
+      }),
+    ).toEqual([
+      "--user-data-dir=/tmp/hf-profile",
+      "--remote-debugging-port=9222",
+      "http://localhost:3002",
+    ]);
+  });
+});
+
+describe("parseRemoteDebuggingPort", () => {
+  it("returns undefined for undefined", () => {
+    expect(parseRemoteDebuggingPort(undefined)).toBeUndefined();
+  });
+
+  it("returns undefined for empty string", () => {
+    expect(parseRemoteDebuggingPort("")).toBeUndefined();
+  });
+
+  it("parses a valid port number", () => {
+    expect(parseRemoteDebuggingPort("9222")).toBe(9222);
+  });
+
+  it("parses port 1 (minimum)", () => {
+    expect(parseRemoteDebuggingPort("1")).toBe(1);
+  });
+
+  it("parses port 65535 (maximum)", () => {
+    expect(parseRemoteDebuggingPort("65535")).toBe(65535);
+  });
+
+  it("rejects 0", () => {
+    expect(() => parseRemoteDebuggingPort("0")).toThrow(
+      "--remote-debugging-port must be an integer between 1 and 65535",
+    );
+  });
+
+  it("rejects negative numbers", () => {
+    expect(() => parseRemoteDebuggingPort("-1")).toThrow();
+  });
+
+  it("rejects non-numeric input", () => {
+    expect(() => parseRemoteDebuggingPort("abc")).toThrow();
+  });
+
+  it("rejects trailing non-digits (no parseInt leakage)", () => {
+    expect(() => parseRemoteDebuggingPort("9222abc")).toThrow();
+  });
+
+  it("rejects numbers above 65535", () => {
+    expect(() => parseRemoteDebuggingPort("70000")).toThrow();
+  });
+
+  it("rejects decimals", () => {
+    expect(() => parseRemoteDebuggingPort("22.5")).toThrow();
+  });
 });

packages/cli/src/utils/openBrowser.ts

@@ -3,6 +3,30 @@ import { spawn } from "node:child_process";
 export interface OpenBrowserOptions {
   browserPath?: string;
   userDataDir?: string;
+  remoteDebuggingPort?: number;
+}
+
+/**
+ * Validate and parse a --remote-debugging-port value.
+ * Returns the port number or undefined if not provided.
+ * Throws if the value is not a valid integer in 1..65535.
+ */
+export function parseRemoteDebuggingPort(value: unknown): number | undefined {
+  if (value === undefined || value === null || value === "") return undefined;
+
+  const text = String(value);
+
+  if (!/^\d+$/.test(text)) {
+    throw new Error("--remote-debugging-port must be an integer between 1 and 65535");
+  }
+
+  const port = Number(text);
+
+  if (!Number.isInteger(port) || port < 1 || port > 65535) {
+    throw new Error("--remote-debugging-port must be an integer between 1 and 65535");
+  }
+
+  return port;
 }
 
 /**
@@ -15,6 +39,9 @@ export function buildBrowserArgs(url: string, options: OpenBrowserOptions): stri
   if (options.userDataDir) {
     args.push(`--user-data-dir=${options.userDataDir}`);
   }
+  if (options.remoteDebuggingPort !== undefined) {
+    args.push(`--remote-debugging-port=${options.remoteDebuggingPort}`);
+  }
   args.push(url);
   return args;
 }
@@ -24,6 +51,7 @@ export function buildBrowserArgs(url: string, options: OpenBrowserOptions): stri
  *
  * - browserPath: spawn the given binary directly (enables Chromium flags)
  * - userDataDir: passed as --user-data-dir (requires browserPath)
+ * - remoteDebuggingPort: passed as --remote-debugging-port (requires browserPath + userDataDir)
  * - otherwise: fall back to the `open` package (default browser)
  */
 export function openBrowser(url: string, options: OpenBrowserOptions = {}): void {