2018268 - Add debugging support to firefox-devtools-mcp

Status: ASSIGNED

(Developer Infrastructure :: Firefox MCP, task)

Comment 1

[Julian Descottes [:jdescottes]]

Going to start working on this now, as it seems to be the one of the most requested features.

Reviewing the current mcp + discussing with ochameau, there are 3 main options:

• A. leverage chrome JS execution already possible with the MCP and point Claude to Spidermonkey APIs
• B. add a webdriver bidi moz:-specific module for debugging
• C. allow BiDi to talk to RDP and/or devtools frontend

Option A is going to be challenging because we don't have a setup to directly run chrome JS in content process, so we would either need to teach Claude how to do that and have it inject JSWindowActors every time it needs to handle debugging.
Option C is probably not worth doing if we are talking to RDP actors, as it only provides a thin layer above spidemontkey apis. If instead we drive the frontend it would give access to more advanced features (setting breakpoints on URLs, sourcemaps etc), but this is 1/ heavy 2/ would imply having the devtools UI opened on the tab.
For now I'll start with option B, small BiDi module at least making it easier to run chrome privileged JS in content processes, but ideally just being a small wrapper on spidermonkey. If that's a dead end, I'll use some variant of option C.

Comment 2

[BugBot [:suhaib / :marco]]

The severity field is not set for this bug.
:marco, could you have a look please?

For more information, please visit BugBot documentation.

Comment 3

[Julian Descottes [:jdescottes]]

Once the modules for debugging have landed in BiDi, we can update the MCP to expose debugging, repurposing the bug to do that.

Comment 4

[BMO Github Automation]

Attachment: [mozilla/firefox-devtools-mcp] Bug 2018268 - fix: migrate script evaluation tools to WebDriver BiDi (#98)

Comment 5

[BMO Github Automation]

Attachment: [mozilla/firefox-devtools-mcp] Bug 2018268 - feature: expose firefox version number in get_firefox_info (#99)