[bug]: "Failed to send command" when using "/quota" in the OpenCode Desktop

[klocus]

Pre-flight checks

• I searched existing issues and did not find a duplicate.
• I verified this on the current production released OpenCode version, or I explain why not below.

OpenCode version tested

1.15.13

opencode-quota version tested

3.8.6

Bug summary

When I use the /quota command in the desktop version of OpenCode, this error appears. In the CLI version, everything is fine.

Steps to reproduce

No response

Expected behavior

No response

Actual behavior

No response

Relevant logs/output

WARN  2026-06-03T12:12:37 +771ms service=weave url=http://127.0.0.1:52495/skill?directory=%2FUsers%2Fxxxx status=401 OpenCode /skill endpoint returned non-OK status — skills will not be loaded
WARN  2026-06-03T12:12:37 +74ms service=weave url=http://127.0.0.1:52495/skill?directory=%2FUsers%2Fxxxx%2FDocuments%2FWorkspaces%2FWebStorm%2Flab-ui-angular status=401 OpenCode /skill endpoint returned non-OK status — skills will not be loaded
ERROR 2026-06-03T12:12:38 +965ms service=plugin.copilot error=Missing key
  at ["data"][15]["capabilities"]["limits"]["max_context_window_tokens"] failed to fetch copilot models
ERROR 2026-06-03T12:12:39 +106ms service=plugin.copilot error=Missing key
  at ["data"][15]["capabilities"]["limits"]["max_context_window_tokens"] failed to fetch copilot models
ERROR 2026-06-03T12:12:39 +598ms service=mcp key=angular-cli command=["npx","-y","@angular/cli","mcp"] cwd=/Users/xxxx/Documents/Workspaces/WebStorm/lab-ui-angular error=MCP error -32000: Connection closed local mcp startup failed
WARN  2026-06-03T12:12:41 +1508ms service=weave url=http://127.0.0.1:52495/skill?directory=%2FUsers%2Fxxxx%2FDocuments%2FWorkspaces%2FWebStorm%2Flab-ui-angular status=401 OpenCode /skill endpoint returned non-OK status — skills will not be loaded
ERROR 2026-06-03T12:12:41 +288ms service=plugin.copilot error=Missing key
  at ["data"][15]["capabilities"]["limits"]["max_context_window_tokens"] failed to fetch copilot models
ERROR 2026-06-03T12:12:41 +565ms service=server ref=err_3ae3188f error=__QUOTA_COMMAND_HANDLED__ cause=Error: __QUOTA_COMMAND_HANDLED__
    at handled (file:///Users/xxxx/.cache/opencode/packages/@slkiser/opencode-quota@latest/node_modules/@slkiser/opencode-quota/dist/lib/command-handled.js:13:11)
    at injectCommandOutputAndHandle (file:///Users/xxxx/.cache/opencode/packages/@slkiser/opencode-quota@latest/node_modules/@slkiser/opencode-quota/dist/plugin.js:1094:9)
    at async handleQuotaSlashCommand (file:///Users/xxxx/.cache/opencode/packages/@slkiser/opencode-quota@latest/node_modules/@slkiser/opencode-quota/dist/plugin.js:1115:16)
    at async command.execute.before (file:///Users/xxxx/.cache/opencode/packages/@slkiser/opencode-quota@latest/node_modules/@slkiser/opencode-quota/dist/plugin.js:1289:28)
    at Plugin.trigger (file:///Applications/OpenCode.app/Contents/Resources/app.asar/out/main/chunks/node-CiOkNpBx.js:335631:21)
    at Plugin.trigger (definition) (file:///Applications/OpenCode.app/Contents/Resources/app.asar/out/main/chunks/node-CiOkNpBx.js:338844:36)
    at SessionPrompt.command (file:///Applications/OpenCode.app/Contents/Resources/app.asar/out/main/chunks/node-CiOkNpBx.js:458753:31)
    at SessionPrompt.command (definition) (file:///Applications/OpenCode.app/Contents/Resources/app.asar/out/main/chunks/node-CiOkNpBx.js:335550:36)
    at SessionHttpApi.command (file:///Applications/OpenCode.app/Contents/Resources/app.asar/out/main/chunks/node-CiOkNpBx.js:231608:30)
    at SessionHttpApi.command (definition) (file:///Applications/OpenCode.app/Contents/Resources/app.asar/out/main/chunks/node-CiOkNpBx.js:458751:36)
    at Server.listen (file:///Applications/OpenCode.app/Contents/Resources/app.asar/out/main/chunks/node-CiOkNpBx.js:459645:52)
    at Server.listen (definition) (file:///Applications/OpenCode.app/Contents/Resources/app.asar/out/main/chunks/node-CiOkNpBx.js:459768:33) failed

If not tested on current production OpenCode, explain why

No response

[slkiser]

Trying to fix this, it is related to e11e089 — “Add Effect-native core event system” in Opencode v1.15.0. In short when they re-factored EffectTS into events, they left out calculability for a prompt() call, see anomalyco/opencode#18554.

The only immediate fix I can suggest OpenCode to pin <v1.15.0 as a temporary workaround.

[slkiser]

Found a workaround which addresses the bug: using TUI Dialogs for the slash commands, coming out in v3.10.0

[sebastian-zarzycki-apzumi]

Actually, I am unable to see the commands registered in the desktop version at all. Running 3.10.1 and 1.17.7 for Opencode. I went through the standard initialization process, but nothing changed. The commands are working just fine in TUI.

[slkiser]

For web and desktop, there is not a clean solution without patching OpenCode.

TLDR:

There are a few fixes I can envision, including:

• Run a local sidecar proxy or reverse proxy in front of OpenCode web servers
• Have the LLM invoke the plugin API as a tool

True fix will be if anomalyco/opencode#18554 has its PR merged.

Cause:

This is because, in OpenCode v1.14.x–v1.15.x and above, i.e. 1.17.7, Web/Desktop custom slash commands always call client.session.command(...), which runs SessionPrompt.command(...) and eventually prompt(...).

plugin throws sentinel
> session.command fails
> HTTP BadRequest
> Web/Desktop shows Failed to send command

Proxy-based solution:
Since server plugins cannot stop that flow and return their own local output, the proxy has to intercept the request first.

PromptInput custom slash › client.session.command(...) › proxy intercepts › buildQuotaDialogCommandOutput(...) › upstream POST /session/:id/message with noReply: true › proxy returns 2xx JSON › app sees success › no model, no failed toast.

Problems with proxy-based: The reverse proxy in front of OpenCode web server might affect users, especially if they have remote deployments for OpenCode, so not sure if this is an acceptable fix.

Also would have to track and maintain auth, CORS, SSE, websocket/event streams, streaming responses, and non-quota routes safely.

[sebastian-zarzycki-apzumi]

I'm not sure I follow. Perhaps I was wrong to piggyback on this task, but my issue was that after installing the plugin for desktop OpenCode, I'm simply unable to trigger the quota commands - the commands are not registered / visible at all.

[slkiser]

@sebastian-zarzycki-apzumi I took out slash commands in recent versions of OpenCode quota for web/desktop.
This is because OpenCode 1.15.0 and above took out this feature anomalyco/opencode#18554.
This feature let me hide errors when injecting messages into OpenCode AND not send a message/tool call to the LLM.

In TUI, there is still a Dialog popup public API, which slash commands open now. Web/desktop doesn't have any public interfaces.