Testing wrangler dev on Major Cloud-Based AI Coding Agents

What is Cloudflare Workers

Cloudflare Workers is a serverless execution environment that runs JavaScript/TypeScript on Cloudflare's edge network to process requests.
Because it is a runtime based on V8 Isolates rather than Node.js, it features extremely small cold starts and operates with low latency near Points of Presence (PoPs) worldwide.

For data persistence and integration with surrounding services, you can use managed services such as KV / R2 / D1 / Queues / Durable Objects. It is also advantageous in terms of cost.

Development is done using the official CLI, wrangler.
When debugging locally, using wrangler dev launches a local preview runtime (based on Miniflare), allowing you to verify configurations in an environment close to production while reproducing the behavior of standard Web APIs such as fetch / Request / Response.

How to debug with Web-based AI coding agents

It is common and perfectly fine to run wrangler dev in an editor or terminal installed on a local PC.
On the other hand, I verified whether the same can be achieved from "Web-based AI coding agents" that run entirely within the browser.

Web agents are subject to the constraints of browser sandboxes and permission models, so they may not work in the following respects:

• Running long-running processes
• Opening local ports and running a server
• Command execution backend (Does it really run locally?)

Therefore, I actually verified whether wrangler dev could be started from the browser and if the local preview could be reached for the three major AI coding agents.

AI coding agents tested this time

• Claude Code on Web
  The Web version of Claude Code that became available on 2025-10-21. I have started using it a bit.

• Codex Web
  The Web version of Codex, which has been highly evaluated since the GPT-5.0 generation. I have been using this primarily since October.

• Jules
  Google's AI coding agent, which became a formal version on 2025/8/6. Although it is the most minor among the three, I have high expectations for its growth in the Gemini 3.0 generation and beyond. I have been using it since the ̠ version in May, but recently Codex's quality has been good, so my usage frequency has decreased slightly.

Results

Agent	wrangler dev Local Startup
Claude Code on Web	OK
Codex Web	OK
Jules	OK

The results showed that wrangler dev worked for all three.
Below is the screen from Claude Code.

Moreover, all of them were running locally, not remotely.

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Thoughts

I had assumed it wasn't possible, but the results were surprising—especially Jules.
I wonder if it's been possible from the start or if it became possible at some point...

With this, Cloudflare Worker development can be completed within web-based AI coding agents.
Since I just found this out myself, I want to think about ways to utilize it.