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Opencode Desktop configuration

Step-by-step instructions to configure OpenCode Desktop on Windows to use the ElettraGateway LLM gateway (https://llm-api-gw.elettra.eu/v1) and its models.

Prerequisites

  • Windows 10/11 with OpenCode Desktop installed (v2.x)
  • An ElettraGateway API key (sk-...)
  • A plain-text editor (Notepad, Notepad++, VS Code…)

All steps below are for your Windows user account. <you> means your Windows user name, e.g. C:\Users\name.surname\....

Step 1 — Create the configuration file opencode.jsonc

OpenCode reads its global configuration from:

C:\Users\<you>\.config\opencode\opencode.jsonc

Create the folder and the file if they do not exist yet:

Paste the following content into opencode.jsonc and save it:

{
  "$schema": "https://opencode.ai/config.json",
  "provider": {
    "elettragateway": {
      "name": "ElettraGateway",
      "npm": "@ai-sdk/openai-compatible",
      "options": {
        "baseURL": "https://llm-api-gw.elettra.eu/v1"
      },
      "models": {
        "balanced": {
          "name": "balanced",
          "limit": {
            "context": 262144,
            "input": 262144,
            "output": 100000
          },
          "modalities": {
            "input": ["text", "image"]
          }
        },
        "top": {
          "name": "top",
          "limit": {
            "context": 1000000,
            "input": 1000000,
            "output": 100000
          },
          "modalities": {
            "input": ["text", "image"]
          }
        },
        "fast": {
          "name": "fast",
          "limit": {
            "context": 131000,
            "input": 131000,
            "output": 100000
          }
        }
      }
    }
  }
}

What this does

  • Registers a custom, OpenAI-compatible provider named ElettraGateway pointing at the gateway URL.
  • Declares the available models and their context limits (limit.context, limit.input, limit.output) — this is what OpenCode uses for context accounting.
  • modalities.input: ["text", "image"] marks the models that accept images.

Tip: keep the API key out of this file (see Step 2). If you prefer a single file, you can instead put it under options as `"apiKey": "sk-...".

Step 2 — Register your API key

C:\Users\<you>\.local\share\opencode\auth.json

Create it with this content (replace the key with your own):

{
  "elettragateway": {
    "type": "api",
    "key": "sk-YOUR-KEY-HERE"
  }
}

Step 3 — Start (or reload) OpenCode Desktop

Launch OpenCode Desktop.

If the app was already running while you edited opencode.jsonc, please restart it.

Step 4 — Enable the models

The desktop app keeps its own list of which models appear in the model picker. Models that are not enabled there are hidden, even when they are correctly configured.

  1. Click on the "three rows icon" (see screenshot), select File -> Settings. opencode_file_settings.png
  2. Go to Providers — "Choose which models appear in model picker". Settings → Provider: verify that ElettraGateway appears as a model provider.
  3. Go to Models — "Choose which models appear in model picker".
  4. Switch off everything not belonging to ElettraGateway, switch on the ElettraGateway models (top, balanced, `fast), or use Enable all models. Settings → Models: enable the models that appear in the pickerg

Step 5 — Testing

  1. Go back to the main Opencode Desktop window clicking on the "back to app" on the top left corner.
  2. The main screen presents 3 elements:
  • a: the selection box, allowing to switch between the build/plan phase; start in plan mode to analyse and plan the work, switch to build to actually edit existing files, perform actions, etc.
  • b: when clicked, the model selection box allow you choose betweent the configured models
  • c: Opencode utilise "workspaces" to organise the work. A workspace is an existing folder in the filesystem. Opencode will edit, write new files within that folder and will not asks for permissions. annotated_session.pngPick one of the ElettraGateway models, e.g. top or balanced.
  1. Send a test prompt and check that a reply arrives.

Model picker showing the ElettraGateway models

Troubleshooting

Symptom Cause / fix
Only some models appear in the picker Step 4: the model is disabled in Settings → Models (models not listed there are hidden by default).
No ElettraGateway provider at all opencode.jsonc not found or not valid JSON/JSONC. Check the path from Step 1 and validate the syntax (a missing } or a trailing comma breaks the whole file).
401 / "API key required" errors The key is missing or wrong — re-check auth.json (Step 2) or the apiKey field.
Changes to opencode.jsonc seem ignored Use /reload in the app, or restart it. Config is merged from the global file plus any opencode.json(c) in the project folder.
Still stuck Inspect the logs: C:\Users\<you>\.local\share\opencode\log\opencode.log (background service) and C:\Users\<you>\AppData\Roaming\ai.opencode.desktop\logs\ (app). Look for configuration normalization diagnostic warnings — they point to malformed config.

Appendix — where things live

What Path
Global configuration (providers, models) C:\Users\<you>\.config\opencode\opencode.jsonc
CLI/TUI settings (not used by the desktop) C:\Users\<you>\.config\opencode\cli.json
API keys / credentials C:\Users\<you>\.local\share\opencode\auth.json
Sessions database C:\Users\<you>\.local\share\opencode\opencode.db
Service log C:\Users\<you>\.local\share\opencode\log\opencode.log
Desktop app GUI settings (model visibility, layout, tabs) C:\Users\<you>\AppData\Roaming\ai.opencode.desktop\drafts.sqlite
Desktop app logs C:\Users\<you>\AppData\Roaming\ai.opencode.desktop\logs\

Appendix — useful keyboard shortcuts

Action Shortcut
Open settings Ctrl+,
Choose model Ctrl+'
New session Ctrl+T / Ctrl+N
Open project Ctrl+O
Toggle terminal `Ctrl+``
Command palette search everything (Settings → Search everything)