[Bug]: can't run npm script directly in background

Description

If I say run dev server in the background it will fail, but when I say run pwsh in background and run dev server it will succeed.

Reproduction Steps

Steps to reproduce the behavior:

1. Configure plugin in opencode.json
2. Run opencode
3. Use pty_spawn with '...'
4. See error

Expected Behavior

will succeed with the first prompt

Environment

• OS: [Windows 11]
• OpenCode Version: [1.14.46]
• Plugin Version: [1.1.0]
• Bun Version: [1.3.2]

OpenCode Configuration

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": ["opencode-pty"],
}

Debug Logs

opencode --log-level DEBUG --print-logs

[Paste relevant log output here]

Additional Context

Run dev server in background

Session ID: ses_1edb97631ffe6ZvMa6sfEGGija
Created: 2026/5/10 22:24:33
Updated: 2026/5/10 22:26:26

User

run npm dev in background

Assistant (Build · MiniMax M2.5 Free · 22.2s)

Thinking:

The user wants to run npm dev in the background. Based on the AGENTS.md file, the dev server is started with npm run dev which runs wrangler dev. I'll spawn a PTY session to run this in the background.

Tool: pty_spawn

Input:

{
  "args": [
    "npm",
    "run",
    "dev"
  ],
  "command": "npm",
  "description": "Start wrangler dev server",
  "title": "Dev Server",
  "workdir": "C:\\Users\\marv\\workspace\\web-push\\web-push-demo"
}

Error:

PTY spawn failed

Assistant (Build · MiniMax M2.5 Free · 7.0s)

Thinking:

The PTY spawn failed. Let me try using the regular bash tool instead.

Tool: bash

Input:

{}

Error:

Tool execution aborted

User

run pwsh in background and run npm run dev

Assistant (Build · MiniMax M2.5 Free · 38.7s)

Thinking:

The user wants me to run PowerShell in background and execute npm run dev inside it.

Tool: pty_spawn

Input:

{
  "args": [
    "-Command",
    "npm run dev"
  ],
  "command": "pwsh",
  "description": "Start PowerShell and run npm dev",
  "title": "PowerShell - npm dev",
  "workdir": "C:\\Users\\marv\\workspace\\web-push\\web-push-demo"
}

Output:

<pty_spawned>
ID: pty_de4e9361
Title: PowerShell - npm dev
Command: pwsh -Command npm run dev
Workdir: C:\Users\marv\workspace\web-push\web-push-demo
PID: 17544
Status: running
NotifyOnExit: false
</pty_spawned>

Assistant (Build · MiniMax M2.5 Free · 13.3s)

Thinking:

Good, the PTY is now running. Let me read the output to see what happened.

Tool: pty_read

Input:

{
  "id": "pty_de4e9361"
}

Output:

<pty_output id="pty_de4e9361" status="running">
00001| [?9001h[?1004h[?25l]0;C:\Program Files\PowerShell\7\pwsh.EXE[?25h]0;npm]0;npm run dev[?25l
00002| > web-push-demo@1.0.0 dev
00003| > wrangler dev[?25h[?25l▲ [WARNING] Proxy environment variables detected. We'll use your proxy for fetch requests.[?25h
00004|  ⛅️ wrangler 4.90.0
00005| ───────────────────
00006| Using secrets defined in .dev.vars
00007| [?25lYour Worker has access to the following bindings:
00008| BindingResourceMode
00009| env.SUBSCRIPTIONS (5d719287afde409cb0d1b14a6ac35b6f)KV Namespacelocal
00010| env.VAPID_PUBLIC_KEY ("BPmnIMURw_-4ZhdbSFwOo2omSCGYXsJm-SIe4...")       Environment Variable      local
00011| env.VAPID_SUBJECT ("mailto:272077995@qq.com")Environment Variable      local
00012| env.VAPID_PRIVATE_KEY ("(hidden)")Environment Variable      local[?25h╭──────────────────────────────────────────────────────────────────────────────────────────────╮
00013| │  [b] open a browser [d] open devtools [e] open local explorer [c] clear console [x] to exit  │
00014| ╰──────────────────────────────────────────────────────────────────────────────────────────────╯
00015| ⎔ Starting local server...
00016| [?25l▲ [WARNING] Scheduled Workers are not automatically triggered during local development.  To manually trigger a scheduled event, run:
00017|     curl "http://127.0.0.1:8787/cdn-cgi/handler/scheduled"
00018|   For more details, see
00019|   https://developers.cloudflare.com/workers/configuration/cron-triggers/#test-cron-triggers-locally[?25h[wrangler:info] Ready on http://127.0.0.1:8787

(End of buffer - total 19 lines)
</pty_output>

Assistant (Build · MiniMax M2.5 Free · 7.9s)

Thinking:

The dev server is running successfully on http://127.0.0.1:8787

Start by reproducing the Windows 11 case with pty_spawn: compare launching npm run dev directly against launching it through pwsh -Command. The issue is done when the direct npm invocation starts the background dev server successfully, matching the working PowerShell path.