[ xdebug ] Add `--experimental-devtools` option in PHP.wasm CLI #2408

mho22 · 2025-07-23T21:08:16Z

Motivation for the change, related issues

This pull request adds a --experimental-devtools option in php-wasm/cli.

Roadmap

Related issues and pull requests

Implementation details

Simple implementation of a Devtools option. It checks for a --experimental-devtools argument that starts the xdebug-to-cdp-bridge process.
Addition of external dependencies.

Testing Instructions

Create a xdebug.php PHP file at the root of the repository :

<?php

$test = 42;  // Set a breakpoint on this line

echo "Output!\n";

function test() {
	echo "Hello Xdebug World!\n";
}

test();

In WordPress-Playground repository

Run the php-wasm/cli command in a first terminal :

> nx run php-wasm-cli:dev --xdebug --experimental-devtools xdebug.php


Connect Chrome DevTools to CDP at:
devtools://devtools/bundled/inspector.html?ws=localhost:9229
...

Chrome connected! Initializing Xdebug receiver...
XDebug receiver running on port 9003
Running a PHP script with Xdebug enabled...
...

Output!
Hello Xdebug World!

In a non-related Playground project

Install dependencies

npm install @php-wasm/cli

Run the @php-wasm/cli command in a terminal :

> npx cli --xdebug --experimental-devtools xdebug.php


Connect Chrome DevTools to CDP at:
devtools://devtools/bundled/inspector.html?ws=localhost:9229
...

Chrome connected! Initializing Xdebug receiver...
XDebug receiver running on port 9003
Running a PHP script with Xdebug enabled...
...

Output!
Hello Xdebug World!

adamziel · 2025-07-23T21:12:29Z

Let's call the option --devtools to make it less about the protocol and more about the user journey

adamziel · 2025-07-23T21:31:03Z

This PR seems to only affect @php-wasm/cli, which is fine, but the title and description also talk about @wp-playground/cli – was something lost during rebasing?

mho22 · 2025-07-23T21:34:17Z

I'm currently working on getting it to run on wp-playground/cli. I just wanted to push my changes for php-wasm/cli and write the PR description for that part in the meantime.

mho22 · 2025-07-23T22:37:31Z

I get this error when trying to start the bridge inside wp-playground/run-cli.ts file :

> node --no-warnings --experimental-wasm-stack-switching --experimental-wasm-jspi --loader=./packages/meta/src/node-es-module-loader/loader.mts ./playground.ts

Starting a PHP server...
Setting up WordPress undefined
Resolved WordPress release URL: https://downloads.w.org/release/wordpress-6.8.2.zip
Fetching SQLite integration plugin...
Booting WordPress...
Booted!
Running the Blueprint...
Running the Blueprint – 100%
Finished running the blueprint
WordPress is running on http://127.0.0.1:58879
Connect Chrome DevTools to CDP at:
devtools://devtools/bundled/inspector.html?ws=localhost:9229

...

Chrome connected! Initializing Xdebug receiver...
XDebug receiver running on port 9003
Running a PHP script with Xdebug enabled...
[XDebug][send] stdout -c 1
[XDebug][send] stderr -c 1
[XDebug][received]] 493<?xml version="1.0" encoding="iso-8859-1"?>
<init xmlns="urn:debugger_protocol_v1" xmlns:xdebug="https://xdebug.org/dbgp/xdebug" fileuri="file:///internal/shared/auto_prepend_file.php" language="PHP" xdebug:language_version="8.4.10-dev" protocol_version="1.0" appid="42"><engine version="3.4.6-dev"><![CDATA[Xdebug]]></engine><author><![CDATA[Derick Rethans]]></author><url><![CDATA[https://xdebug.org]]></url><copyright><![CDATA[Copyright (c) 2002-2025 by Derick Rethans]]></copyright></init>
[XDebug][send] step_into undefined
[CDP][send] {"method":"Debugger.scriptParsed","params":{"scriptId":"1","url":"file:///internal/shared/auto_prepend_file.php","startLine":0,"startColumn":0,"executionContextId":1}}
[CDP][send] {"method":"Debugger.scriptParsed","params":{"scriptId":"1","url":"file:///internal/shared/auto_prepend_file.php","startLine":0,"startColumn":0,"executionContextId":1}}
[XDebug][received]] 192<?xml version="1.0" encoding="iso-8859-1"?>
<response xmlns="urn:debugger_protocol_v1" xmlns:xdebug="https://xdebug.org/dbgp/xdebug" command="stdout" transaction_id="1" success="1"></response>192<?xml version="1.0" encoding="iso-8859-1"?>
<response xmlns="urn:debugger_protocol_v1" xmlns:xdebug="https://xdebug.org/dbgp/xdebug" command="stderr" transaction_id="2" success="0"></response>311<?xml version="1.0" encoding="iso-8859-1"?>
<response xmlns="urn:debugger_protocol_v1" xmlns:xdebug="https://xdebug.org/dbgp/xdebug" command="step_into" transaction_id="3" status="break" reason="ok"><xdebug:message filename="file:///internal/shared/auto_prepend_file.php" lineno="3"></xdebug:message></response>
[XDebug][send] stack_get undefined
[XDebug][received]] 303<?xml version="1.0" encoding="iso-8859-1"?>
<response xmlns="urn:debugger_protocol_v1" xmlns:xdebug="https://xdebug.org/dbgp/xdebug" command="stack_get" transaction_id="4"><stack where="{main}" level="0" type="file" filename="file:///internal/shared/auto_prepend_file.php" lineno="3"></stack></response>
[CDP][send] {"method":"Debugger.paused","params":{"reason":"pause","callFrames":[{"callFrameId":"frame:0","functionName":"(anonymous)","location":{"scriptId":"1","lineNumber":2,"columnNumber":0},"scopeChain":[{"type":"local","object":{"objectId":"1","className":"Object","description":"Local"}},{"type":"global","object":{"objectId":"2","className":"Object","description":"Global"}}],"this":{"type":"object","className":"Object","description":"Object","objectId":"2"}}],"hitBreakpoints":[]}}
[CDP][received] {"id":42,"method":"Overlay.setPausedInDebuggerMessage","params":{"message":"Paused in debugger"}}
[CDP][send] {"id":42,"result":{}}
[CDP][received] {"id":43,"method":"Debugger.getScriptSource","params":{"scriptId":"1"}}
node:fs:443
    return binding.readFileUtf8(path, stringToFlags(options.flag));
                   ^

Error: ENOENT: no such file or directory, open '/internal/shared/auto_prepend_file.php'

I had to treat how it finds the php files differently by using the playground's readFileAsText instead of a regular PHP instance [ one is a Promise while the other is a string ] :

if (args.devtools) {
	const bridge = await startBridge({ getPHPFile : async (path: string) => await playground!.readFileAsText(path) });

	bridge.start();
}

This meant refactoring the getPHPFile in start-bridge.ts file and xdebug-cdp-bridge.ts.

I successfully made the devtools and xdebug work together by breaking on auto_prepend_file file when running this command :

node --no-warnings --experimental-wasm-stack-switching --experimental-wasm-jspi --loader=./packages/meta/src/node-es-module-loader/loader.mts playground.ts

This is playground.ts

import { runCLI } from "./packages/playground/cli/src/run-cli";

const script = `
<?php

$test = 42;

echo "Output!\n";

function test() {
	echo "Hello Xdebug World!\n";
}

test();
`;

const cliServer = await runCLI( { php : '8.4', command : 'server', xdebug : true, devtools : true } );

cliServer.playground.writeFile( 'xdebug.php', script );

const result = await cliServer.playground.run( { scriptPath : `xdebug.php` } );

console.log( result.text );

This is not my xdebug.php script yet, but it is kinda cool. I should investigate further tomorrow.

adamziel · 2025-07-23T22:44:32Z

Nice! If changes for Playground CLI will take more than a day, let's split them into another PR and add the @php-wasm/cli option. I've just audited the devtools bridge and it seems to have some shortcomings we'll need to work on – maybe let's change the option name again to --experimental-devtools to make it very clear this is a work in progress.

mho22 · 2025-07-23T22:48:39Z

Ok! Let's split the pull request then. I am on it.

packages/php-wasm/cli/src/main.ts

) ## Motivation for the change, related issues This pull request adds a `--experimental-devtools` option in `wp-playground/cli`. [Roadmap](#2315) ## Related issues and pull requests - #2408 - #2402 - #2398 - #2346 - #2288 ## Implementation details - Simple implementation of a Devtools option. It checks for a `experimentalDevtools` argument that starts the `xdebug-to-cdp-bridge` process. - Changes the `StartBridgeConfig` `getPHPFile` property type from `(path: string) => string` to `(path: string) => Promise<string>` and adapt the related code. ## Testing Instructions ### In WordPress-Playground repository 1. Write a script like the following `cli.ts` : ```typescript import { runCLI } from "./packages/playground/cli/src/run-cli"; const script = ` <?php $test = 42; echo "Output!\n"; function test() { echo "Hello Xdebug World!\n"; } test(); `; const cliServer = await runCLI({command: 'server', xdebug: true, experimentalDevtools: true}); cliServer.playground.writeFile('xdebug.php', script); const result = await cliServer.playground.run({scriptPath: `xdebug.php`}); console.log(result.text); ``` 2. Run the following command : ``` > node --no-warnings --experimental-wasm-stack-switching --experimental-wasm-jspi --loader=./packages/meta/src/node-es-module-loader/loader.mts cli.ts Starting a PHP server... Setting up WordPress undefined Resolved WordPress release URL: https://downloads.w.org/release/wordpress-6.8.2.zip Fetching SQLite integration plugin... Booting WordPress... Booted! Running the Blueprint... Running the Blueprint – 100% Finished running the blueprint WordPress is running on http://127.0.0.1:61290 Connect Chrome DevTools to CDP at: devtools://devtools/bundled/inspector.html?ws=localhost:9229 ... Chrome connected! Initializing Xdebug receiver... XDebug receiver running on port 9003 Running a PHP script with Xdebug enabled... ``` ### In a non-related Playground project 1. Install dependencies ``` npm install @wp-playground/cli ``` 2. Write a script like the following `cli.ts` : ```typescript import { runCLI } from "@wp-playground/cli"; const script = ` <?php $test = 42; echo "Output!\n"; function test() { echo "Hello Xdebug World!\n"; } test(); `; const cliServer = await runCLI({command: 'server', xdebug: true, experimentalDevtools: true}); await cliServer.playground.writeFile(`xdebug.php`, script); const result = await cliServer.playground.run({scriptPath: `xdebug.php`}); console.log(result.text); ``` 3. Run command : ``` > node cli.js Starting a PHP server... Setting up WordPress undefined Resolved WordPress release URL: https://downloads.w.org/release/wordpress-6.8.2.zip Fetching SQLite integration plugin... Booting WordPress... Booted! Running the Blueprint... Running the Blueprint – 100% Finished running the blueprint WordPress is running on http://127.0.0.1:61859 Connect Chrome DevTools to CDP at: devtools://devtools/bundled/inspector.html?ws=localhost:9229 ... Chrome connected! Initializing Xdebug receiver... XDebug receiver running on port 9003 Running a PHP script with Xdebug enabled... ``` <img width="920" height="471" alt="screencapture" src="https://github.com/user-attachments/assets/b3548d0e-f824-41c4-9148-3e4f106b4116" /> Note: It will need 23 step overs before leaving the `auto_prepend_file.php` and entering the `xdebug.php` script.

adamziel and others added 14 commits July 22, 2025 16:18

XDebug <-> CDP bridge

07a90a2

Correct lint errors and warnings

57496d4

Correct merge conflicts with unneeded file index.ts

877d80e

Implement build based on other packages

a48da90

Corrected errors crashing built package

66a81e0

Correct error related to tests

587fee5

Focus on repository first xdebug bridge usage

90d601e

Switch statSync to lstatSync

8ff09a8

Improve help section

ee31029

Correct merge conflicts with trunk

14f2216

Correct merge conflicts with trunk

eaa48e4

Implement package building files and commands

3b7cb6c

Reorganize files for next step

84caeae

Add --cdp option in @php-wasm/cli

f7a006b

mho22 requested a review from a team as a code owner July 23, 2025 21:08

mho22 changed the title ~~[ xdebug ] Add --cdp option in php-wasm CLI and wp-playground CLI~~ [ xdebug ] Add --cdp option in php-wasm CLI and wp-playground CLI Jul 23, 2025

mho22 mentioned this pull request Jul 22, 2025

[ php-wasm ] Follow-up on Xdebug #2315

Open

11 tasks

adamziel added [Type] Enhancement New feature or request [Package][@wp-playground] CLI Release Highlight labels Jul 23, 2025

mho22 added 2 commits July 23, 2025 23:15

Merge branch 'trunk' into add-cdp-option-in-cli

32dbfa5

rename --cdp to --devtools

b947aea

mho22 changed the title ~~[ xdebug ] Add --cdp option in php-wasm CLI and wp-playground CLI~~ [ xdebug ] Add --devtools option in php-wasm CLI and wp-playground CLI Jul 23, 2025

mho22 added [Focus] Developer Tools [Package][@php-wasm] CLI labels Jul 23, 2025

mho22 mentioned this pull request Jul 23, 2025

Support Xdebug #314

Open

Add --devtools option in @php-wasm/cli and @wp-playground/cli

d531989

mho22 changed the title ~~[ xdebug ] Add --devtools option in php-wasm CLI and wp-playground CLI~~ [ xdebug ] Add --devtools option in php-wasm CLI Jul 23, 2025

mho22 changed the title ~~[ xdebug ] Add --devtools option in php-wasm CLI~~ [ xdebug ] Add --experimental-devtools option in php-wasm CLI Jul 23, 2025

Add --experimental-devtools option in @php-wasm/cli

e55cf92

mho22 added [Aspect] Browser [Type] Developer Experience and removed [Package][@wp-playground] CLI labels Jul 23, 2025

Reset missed code from playground/cli

9595443

adamziel reviewed Jul 24, 2025

View reviewed changes

packages/php-wasm/cli/src/main.ts Outdated Show resolved Hide resolved

Update main.ts

3ff2adf

adamziel merged commit a064680 into trunk Jul 24, 2025
23 of 25 checks passed

adamziel deleted the add-cdp-option-in-cli branch July 24, 2025 08:10

mho22 mentioned this pull request Jul 24, 2025

[ xdebug ] Add --experimental-devtools option in Playground CLI #2411

Merged

mho22 added the XDebug label Jul 24, 2025

mho22 changed the title ~~[ xdebug ] Add --experimental-devtools option in php-wasm CLI~~ [ xdebug ] Add --experimental-devtools option in PHP.wasm CLI Nov 26, 2025

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