Dev server returns 404 at localhost:4567; all React Grab asks fail

[damien-schneider]

Running the React Grab dev script starts the server, but the UI returns 404 and any “ask” in the app fails.

➜ web git:(add-test-environments) ✗ npm run dev:react-grab

> @repo/web@0.0.0 dev:react-grab
> npx @react-grab/claude-code@latest

✿ React Grab 0.0.91 (Claude Code)
- Local:    http://localhost:4567

Steps to reproduce:

1. Install dependencies.
2. Run npx @react-grab/claude-code@latest.
3. Open http://localhost:4567/.
4. Use the app and trigger any ask.

• 404 on http://localhost:4567/.
• All asks fail in the app.

Environment:

• React Grab: 0.0.91 (Claude Code).
• Command used: npx @react-grab/claude-code@latest.

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🔗 Similar Issues

Possible Duplicates

• Agents integration doesn't works #45

Related Issues

• opencode integration not working #55
• Unable to make changes with OpenCode agent #77
• Error: Failed to spawn Claude Code process: spawn claude ENOENT when using agent mode with Next.js #64
• Next config setup not working #76

👤 Suggested Assignees

• inj-src
• emrosenf
• RafalFilipek
• brmdbr
• damien-schneider

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[tt-a1i]

the 404 on localhost:4567 is actually expected - it's an API server, not a web page. there's no root route defined, only /agent, /health, etc.

the real problem is probably that the server isn't actually starting. the cli spawns it in background with stdio: ignore, so if it crashes you won't see any error.

can you check if it's running?

curl http://localhost:4567/health
# should return {"status":"ok","provider":"claude"}

which claude
# needs to be installed for the server to work

my guess is claude cli isn't installed or not in PATH, so the server dies silently on first request.

[damien-schneider]

Thanks a lot for the quick reply!

My bad about the 404, you're right I well get the {"status":"ok","provider":"claude"}
And yeah, claude code is well installed with the latest version and which claude well shows me the Path.

But when using react-grab in the app pressing the enter key, I have this error after 2 seconds everytime.

It then says completed in 6.4 sec for example, often less, and then shows Error: Claude Code process exited with code 1 and it didn't do anything.

[tt-a1i]

server's fine, the issue is claude code failing during execution. stderr gets swallowed so can't see the actual error.

probably a cwd issue - try this:

REACT_GRAB_CWD=/path/to/your/react/project npx @react-grab/claude-code@latest

or test claude directly in your project dir: cd /your/project && claude --print "hello"

---

[damien-schneider]

I've tried with REACT_GRAB_CWD=/Users/...../project-name/ npx @react-grab/claude-code@latest and still the same. And when trying cd /Users/.... && claude --print "hello" I well get an answer.

[damien-schneider]

Using opencode works, but unfortunately do not have all the advantages of claude code hooks / config already existing. I'm switching to opencode before it evolves

[tt-a1i]

Thanks for testing — and totally fair to switch to opencode for now.

Since /health is returning OK, the local server is up. What’s actually failing is the Claude Code
subprocess exiting with code 1.

One problem on our side: the CLI starts the server detached with stdio: "ignore", and the SDK also
ignores Claude’s stderr by default — so right now we don’t get the real error message, only “exited
with code 1”.

If you’ve got 2 minutes, could you run this in your project folder and paste the output?

claude --permission-mode bypassPermissions --print "hello"

(react-grab sets permissionMode: "bypassPermissions" by default, so this is the closest “same config”
repro.)

If that succeeds, could you also try running the provider server in the foreground so we can actually
see stderr:

DEBUG=1 REACT_GRAB_CWD=/path/to/your/project
npx -p @react-grab/claude-code@0.0.91 node --input-type=module
-e "import { startServer } from '@react-grab/claude-code/server'; startServer().catch(console.error)"

Then reproduce one “ask” and paste whatever prints in that terminal.

Either way, thanks again — I can also open a PR to stop swallowing stderr (or add a foreground/
debug mode) so this is easier to diagnose next time.