OpenCode Integration

AVELIN API works seamlessly with OpenCode — a terminal-based AI coding tool that provides fast, context-aware code assistance directly in your terminal.

Why AVELIN + OpenCode? Get access to frontier coding models with 1M-token context windows for large codebases, automatic failover, and competitive pricing.

Quick Setup

Step 1: Get your AVELIN API key

Sign up at avelin.ai and generate an API key. It will look like sk-ave...xxxx.

Step 2: Install OpenCode

Prerequisites: Install Node.js (v18.0 or later).

npm install -g opencode-ai
opencode -v

Step 3: Configure OpenCode

Create the configuration file at ~/.config/opencode/opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "provider": {
    "avelin": {
      "npm": "@ai-sdk/anthropic",
      "name": "AVELIN AI",
      "options": {
        "baseURL": "https://api.avelin.ai",
        "apiKey": "sk-a...
      },
      "models": {
        "avelin-coding-pro": {
          "name": "Avelin Coding Plus",
          "options": {
            "thinking": {
              "type": "enabled",
              "budgetTokens": 32768
            }
          }
        },
        "avelin-coding-fast": {
          "name": "Avelin Coding",
          "options": {
            "thinking": {
              "type": "enabled",
              "budgetTokens": 32768
            }
          }
        },
        "avelin-coding-ultra": {
          "name": "Avelin Coding Architect",
          "options": {
            "thinking": {
              "type": "enabled",
              "budgetTokens": 32768
            }
          }
        },
        "avelin-fast": {
          "name": "Avelin Fast"
        }
      }
    }
  }
}

Step 4: Start OpenCode

opencode

OpenCode will automatically use AVELIN as the backend.

Primary Recommendation: avelin-coding-pro

For everyday coding tasks:

Featureavelin-coding-proWhy it matters for OpenCode
Context window1M tokensLarge codebases and multi-file refactors without context loss
Max output65K tokensGenerate large code files and comprehensive tests
Throughput~100 tokens/sec2× faster than standard tiers — faster feedback loops
ReasoningDeep step-by-step thinkingCatches subtle bugs, understands architectural impact
Tool callingFirst-class supportReliable file operations and command execution

Alternative Models

ModelWhen to use
avelin-coding-fastLighter coding tasks, quick questions — saves cost on simple work
avelin-coding-ultraSystem design, architecture reviews, security-sensitive refactors
avelin-fastQuick lookups and simple extractions — lowest cost, fastest response

Why AVELIN for OpenCode?

1. Cost Optimization

OpenCode sessions can be long with large context windows. AVELIN delivers frontier-tier coding quality at sustainable economics:

  • Prompt caching: ~80% cost reduction on repeated system prompts
  • Competitive pricing: Lower per-token costs than direct provider APIs
  • Pay-per-token: No subscription lock-in

2. Model Diversity

Access multiple frontier coding models through one API. AVELIN routes your requests to a diverse set of frontier models across multiple cloud providers, ensuring high availability and consistent quality. If one provider is slow or unavailable, your request automatically routes to the next best option.

3. Reliability

  • Automatic failover: If one provider is slow or down, AVELIN switches to another
  • Retry logic: Transient errors are handled automatically
  • 99.9% uptime: Enterprise-grade infrastructure

4. 1M Context Windows

OpenCode works best with large context. AVELIN's coding models support 1M tokens — load entire repositories without chunking.

Example Session

$ opencode

╭─ OpenCode ────────────────────────────────────╮
│ Model: avelin-coding-pro                    │
│ Provider: AVELIN (api.avelin.ai)            │
╰───────────────────────────────────────────────╯

You> Add input validation to the user registration endpoint.

OpenCode> I'll add comprehensive validation to the registration endpoint.
          Let me examine the current implementation...

[Reads routes/auth.js, models/User.js]

Here's my plan:
1. Add validation middleware using Joi
2. Validate email format, password strength, username uniqueness
3. Add error handling for validation failures
4. Write tests for valid and invalid inputs

Shall I proceed?

You> yes

OpenCode> [Creates middleware/validateRegistration.js]
          [Updates routes/auth.js to use validation]
          [Creates tests/auth.validation.test.js]

Done! I've added:
- Email format validation
- Password strength check (min 8 chars, uppercase, lowercase, number, special char)
- Username uniqueness check
- 8 passing tests covering valid and invalid cases

Run `npm test` to verify.

Advanced Configuration

Thinking Budget

The configuration includes budgetTokens: 32768 for thinking. This allocates tokens for the model's reasoning process:

  • Higher budget (32K+): Better for complex refactors, architecture decisions
  • Lower budget (8K): Faster responses for simple edits
  • Disabled: For quick questions where speed matters most
{
  "avelin-fast": {
    "name": "Avelin Fast",
    "options": {
      "thinking": {
        "type": "disabled"
      }
    }
  }
}

Model Switching

You can switch models on-the-fly in OpenCode:

opencode --model avelin-coding-ultra

Or set different models for different tasks in your config.

Troubleshooting

IssueSolution
"Provider not found"Ensure @ai-sdk/anthropic is specified in the npm field
"Model not available"Use a valid AVELIN model name from the Model Catalog
Slow first responseNormal — model thinks before responding. Streaming starts after reasoning completes.
Context too long errorsSet context_length: 1000000 in your configuration
API key errorsVerify your AVELIN API key is correct and active