feat: Add support for OpenRouter (#92)

* Add support for OpenRouter as a new model provider

- Introduced `ProviderOpenRouter` in the `models` package.
- Added OpenRouter-specific models, including `GPT41`, `GPT41Mini`, `GPT4o`, and others, with their configurations and costs.
- Updated `generateSchema` to include OpenRouter as a provider.
- Added OpenRouter-specific environment variable handling (`OPENROUTER_API_KEY`) in `config.go`.
- Implemented default model settings for OpenRouter agents in `setDefaultModelForAgent`.
- Updated `getProviderAPIKey` to retrieve the OpenRouter API key.
- Extended `SupportedModels` to include OpenRouter models.
- Added OpenRouter client initialization in the `provider` package.
- Modified `processGeneration` to handle `FinishReasonUnknown` in addition to `FinishReasonToolUse`.

* [feature/openrouter-provider] Add new models and provider to schema

- Added "deepseek-chat-free" and "deepseek-r1-free" to the list of supported models in `opencode-schema.json`.

* [feature/openrouter-provider] Add OpenRouter provider support and integrate new models

- Updated README.md to include OpenRouter as a supported provider and its configuration details.
- Added `OPENROUTER_API_KEY` to environment variable configuration.
- Introduced OpenRouter-specific models in `internal/llm/models/openrouter.go` with mappings to existing cost and token configurations.
- Updated `internal/config/config.go` to set default models for OpenRouter agents.
- Extended `opencode-schema.json` to include OpenRouter models in the schema definitions.
- Refactored model IDs and names to align with OpenRouter naming conventions.

* [feature/openrouter-provider] Refactor finish reason handling and tool call logic in agent and OpenAI provider

- Simplified finish reason check in `agent.go` by removing redundant variable assignment.
- Updated `openai.go` to override the finish reason to `FinishReasonToolUse` when tool calls are present.
- Ensured consistent finish reason handling in both `send` and `stream` methods of the OpenAI provider.

[feature/openrouter-provider] Refactor finish reason handling and tool call logic in agent and OpenAI provider

- Simplified finish reason check in `agent.go` by removing redundant variable assignment.
- Updated `openai.go` to override the finish reason to `FinishReasonToolUse` when tool calls are present.
- Ensured consistent finish reason handling in both `send` and `stream` methods of the OpenAI provider.

* **[feature/openrouter-provider] Add support for custom headers in OpenAI client configuration**

- Introduced a new `extraHeaders` field in the `openaiOptions` struct to allow specifying additional HTTP headers.
- Added logic in `newOpenAIClient` to apply `extraHeaders` to the OpenAI client configuration.
- Implemented a new option function `WithOpenAIExtraHeaders` to set custom headers in `openaiOptions`.
- Updated the OpenRouter provider configuration in `NewProvider` to include default headers (`HTTP-Referer` and `X-Title`) for OpenRouter API requests.

* Update OpenRouter model config and remove unsupported models

* [feature/openrouter-provider] Update OpenRouter models and default configurations

- Added new OpenRouter models: `claude-3.5-sonnet`, `claude-3-haiku`, `claude-3.7-sonnet`, `claude-3.5-haiku`, and `claude-3-opus` in `openrouter.go`.
- Updated default agent models in `config.go`:
  - `agents.coder.model` now uses `claude-3.7-sonnet`.
  - `agents.task.model` now uses `claude-3.7-sonnet`.
  - `agents.title.model` now uses `claude-3.5-haiku`.
- Updated `opencode-schema.json` to include the new models in the allowed list for schema validation.
- Adjusted logic in `setDefaultModelForAgent` to reflect the new default models.

* [feature/openrouter-provider] Remove unused ProviderEvent emission in stream function

The changes remove the emission of a `ProviderEvent` with type `EventContentStop` in the `stream` function of the `openaiClient` implementation. This event was sent upon successful stream completion but is no longer used.

1 files changed, 39 insertions, 0 deletions

diff --git a/internal/config/config.go b/internal/config/config.go
index 9aa22bd4e..22781e189 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -267,6 +267,15 @@ func setProviderDefaults() {
 		return
 	}
 
+	// OpenRouter configuration
+	if apiKey := os.Getenv("OPENROUTER_API_KEY"); apiKey != "" {
+		viper.SetDefault("providers.openrouter.apiKey", apiKey)
+		viper.SetDefault("agents.coder.model", models.OpenRouterClaude37Sonnet)
+		viper.SetDefault("agents.task.model", models.OpenRouterClaude37Sonnet)
+		viper.SetDefault("agents.title.model", models.OpenRouterClaude35Haiku)
+		return
+	}
+
 	// AWS Bedrock configuration
 	if hasAWSCredentials() {
 		viper.SetDefault("agents.coder.model", models.BedrockClaude37Sonnet)
@@ -527,6 +536,8 @@ func getProviderAPIKey(provider models.ModelProvider) string {
 		return os.Getenv("GROQ_API_KEY")
 	case models.ProviderAzure:
 		return os.Getenv("AZURE_OPENAI_API_KEY")
+	case models.ProviderOpenRouter:
+		return os.Getenv("OPENROUTER_API_KEY")
 	case models.ProviderBedrock:
 		if hasAWSCredentials() {
 			return "aws-credentials-available"
@@ -578,6 +589,34 @@ func setDefaultModelForAgent(agent AgentName) bool {
 		return true
 	}
 
+	if apiKey := os.Getenv("OPENROUTER_API_KEY"); apiKey != "" {
+		var model models.ModelID
+		maxTokens := int64(5000)
+		reasoningEffort := ""
+
+		switch agent {
+		case AgentTitle:
+			model = models.OpenRouterClaude35Haiku
+			maxTokens = 80
+		case AgentTask:
+			model = models.OpenRouterClaude37Sonnet
+		default:
+			model = models.OpenRouterClaude37Sonnet
+		}
+
+		// Check if model supports reasoning
+		if modelInfo, ok := models.SupportedModels[model]; ok && modelInfo.CanReason {
+			reasoningEffort = "medium"
+		}
+
+		cfg.Agents[agent] = Agent{
+			Model:           model,
+			MaxTokens:       maxTokens,
+			ReasoningEffort: reasoningEffort,
+		}
+		return true
+	}
+
 	if apiKey := os.Getenv("GEMINI_API_KEY"); apiKey != "" {
 		var model models.ModelID
 		maxTokens := int64(5000)