dsh-plugin-opencode-local

Why this exists

I wanted to use OpenCode's models in DeepSeek Harness through the OpenCode CLI installed on my own machine, the way T3 Code does. I couldn't find a DeepSeek Harness plugin that did that, so I built this one.

What it does

A DeepSeek Harness (DSH) plugin that adds an OpenCode (local) model provider. Every request is served by your own installed OpenCode, the same way T3 Code does it: one opencode serve on 127.0.0.1, started from your install with your own login and config, driven only through OpenCode's official clients.

• Your models: every model of every provider you are signed in to in OpenCode, plus OpenCode's own free models, with OpenCode's provider/model ids.
• Your login: the plugin never reads, copies or forwards auth.json or any credential. OpenCode uses its own.
• Your machine: all model traffic goes through your opencode process. The plugin makes no calls to opencode.ai or any other host, uses no proxies, and sets no custom headers or user agent.

Compatibility

DeepSeek Harness	0.2.x (tested on 0.2.1-rc.5)
DSH profiles	Desktop app and CLI/headless profiles
OpenCode	1.14.19 or newer, including 2.x
Platforms	Windows (tested end to end), Linux (CI); macOS should work but is untested
Node	22.19 or newer (DSH ships its own)

Restricted OpenCode tools (shell, file edits, web fetch) go through DSH's approval prompt; see Permission policy.

Install

1. Install OpenCode and check it runs:

   npm i -g opencode-ai     # or see https://opencode.ai/docs/#install
   opencode --version
   opencode auth login      # only for paid providers; the free models need no login
   

2. Add the plugin to DSH.

   • DSH desktop app: open the plugin manager and add dsh-plugin-opencode-local.

   • DSH CLI:

     dsh plugin --profile web add dsh-plugin-opencode-local
     

     Use the name of your own profile in place of web, for example desktop or headless.

   To try an unreleased version, build it (npm ci && npm pack) and add the .tgz file instead.

3. Restart DSH, open the model picker, and choose a model under OpenCode (local).

   

   The provider also shows up in Settings → Models, where Edit opens its settings:

   

The plugin has no install scripts and downloads nothing. If opencode can't be found, the first request tells you how to install it or where to point binaryPath.

Settings

In DSH under Settings → Models → OpenCode (local), or in your profile's cordis.patch.yml under dsh-plugin-opencode-local.

Setting	Default	What it does
binaryPath	opencode	Path or PATH name of your opencode executable.
serverUrl	empty	Attach to an opencode serve you already run (e.g. http://127.0.0.1:4096) instead of starting one.
serverPassword	empty	That server's password (OPENCODE_SERVER_PASSWORD for 1.x, OPENCODE_PASSWORD for 2.x).
cwd	empty	Working directory for OpenCode sessions. Empty uses the DSH conversation's working directory.
allowRestrictedTools	false	Allow the restricted tools (below) without asking.
askForApproval	true	Ask in DSH's approval prompt before a restricted tool runs. When off, they're rejected.
requestTimeoutMs	1800000	Upper bound for one turn, in ms. 0 means no limit.
modelRefreshSeconds	300	How often the model list is re-read from OpenCode.
showToolActivity	true	Show OpenCode's tool calls as short lines in the reply.
localSessionTitles	true	Make DSH session titles locally instead of spending a model request on them.

How it works

• One shared server. On the first request the plugin runs opencode --version, then opencode serve --hostname=127.0.0.1 --port=<free port> with your full environment and a new random password. It waits for the "listening" line and checks /global/health (1.x) or /api/info (2.x). If the server crashes it is restarted with backoff. When DSH stops or the plugin is disabled, the whole process group (or process tree on Windows) is killed.
• Sessions. Each DSH conversation gets its own OpenCode session in the conversation's working directory. Only the new message is sent each turn. If the DSH history no longer matches what OpenCode has seen (DSH restarted, a message was edited, the conversation was compacted, or a turn failed), a new session is created and seeded with the DSH transcript.
• Streaming. Text, reasoning, tool activity and token usage stream into DSH. Stopping a reply in DSH aborts the OpenCode run.
• Images. png, jpeg, gif and webp up to 20 MB are sent to models that accept images.

Permission policy

The same policy as T3 Code's default (non full-access) mode:

• Always allowed: question, read, glob, grep, lsp, todowrite, task, skill. Reading .env files still asks; .env.example doesn't.
• Restricted: bash (shell in 2.x), edit, webfetch, websearch, codesearch, external_directory, doom_loop, and anything not listed.

Restricted tools are configured as ask, never deny. (A deny rule makes OpenCode's free tier refuse requests with FreeTierError.) When OpenCode asks:

1. if allowRestrictedTools is on, it's allowed once;
2. otherwise, if DSH's approval prompt is available and askForApproval is on, you decide;
3. otherwise it's rejected, and the model gets a message saying the tool was not granted and not to retry.

For 1.x the policy is passed in OPENCODE_CONFIG_CONTENT (your own OPENCODE_CONFIG_CONTENT, if set, is kept and only its permission key replaced). For 2.x it's set as session permission rules. The plugin never uses --auto or allow-all.

OpenCode questions (the question tool) can't be shown in DSH, so they're declined and the model continues without an answer.

Errors

OpenCode's error message is shown as is.

OpenCode	DSH failure
HTTP 429, FreeUsageLimitError	RATE_LIMIT. The plugin doesn't retry it; wait and try again.
HTTP 401/403, FreeTierError, ProviderAuthError	AUTH
network errors, timeouts, lost connection to the local server	TRANSPORT (retried once by DSH)
HTTP 5xx	SERVER
<none> (OpenCode couldn't read the provider's reply)	a readable message with the HTTP status, as in T3 Code

Troubleshooting

• "OpenCode was not found". Install it (above), or set binaryPath to the full path. On Windows that's usually C:\Users\<you>\AppData\Roaming\npm\opencode.cmd.
• "OpenCode vX is too old". Run opencode upgrade or npm i -g opencode-ai@latest.
• No models in the picker. Run opencode models in a terminal. If that's empty too, sign in with opencode auth login. The list refreshes every modelRefreshSeconds.
• "database is locked". Another OpenCode process is busy with the same data directory. Try again, or attach to your running server with serverUrl.
• A tool keeps getting rejected. That's the policy. Approve it in DSH's prompt, or turn on allowRestrictedTools if you trust the model with your shell and files.
• Rate limits on free models. These come from OpenCode's free tier. The message is OpenCode's own; wait, or sign in to a provider with your own key.

The plugin never logs prompts, credentials or the server password. Server output shown in startup errors has the password removed.

Development

npm ci
npm run check   # typecheck, build to lib/, unit tests

The tests run against a fake opencode (test/fixtures/fake-opencode.mjs) that speaks both the 1.x and 2.x APIs.

Credits

• T3 Code inspired this plugin. The way it runs OpenCode follows T3 Code's OpenCode provider: starting your own opencode serve on 127.0.0.1, the permission policy, the OpenCode 1.x/2.x handling and the error messages. Parts are adapted from its code (MIT, © 2026 T3 Tools Inc.).
• @quonaro/dsh-plugin-opencode showed the DSH plugin shape and local session titles (MIT).

Details are in NOTICE.md.

License

MIT. See LICENSE.