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.

2 files changed, 263 insertions, 0 deletions

diff --git a/internal/llm/models/models.go b/internal/llm/models/models.go
index 5dd28359f..2c5e61d7e 100644
--- a/internal/llm/models/models.go
+++ b/internal/llm/models/models.go
@@ -86,4 +86,5 @@ func init() {
 	maps.Copy(SupportedModels, GeminiModels)
 	maps.Copy(SupportedModels, GroqModels)
 	maps.Copy(SupportedModels, AzureModels)
+	maps.Copy(SupportedModels, OpenRouterModels)
 }
diff --git a/internal/llm/models/openrouter.go b/internal/llm/models/openrouter.go
new file mode 100644
index 000000000..6fc2a2119
--- /dev/null
+++ b/internal/llm/models/openrouter.go
@@ -0,0 +1,262 @@
+package models
+
+const (
+	ProviderOpenRouter ModelProvider = "openrouter"
+
+	OpenRouterGPT41          ModelID = "openrouter.gpt-4.1"
+	OpenRouterGPT41Mini      ModelID = "openrouter.gpt-4.1-mini"
+	OpenRouterGPT41Nano      ModelID = "openrouter.gpt-4.1-nano"
+	OpenRouterGPT45Preview   ModelID = "openrouter.gpt-4.5-preview"
+	OpenRouterGPT4o          ModelID = "openrouter.gpt-4o"
+	OpenRouterGPT4oMini      ModelID = "openrouter.gpt-4o-mini"
+	OpenRouterO1             ModelID = "openrouter.o1"
+	OpenRouterO1Pro          ModelID = "openrouter.o1-pro"
+	OpenRouterO1Mini         ModelID = "openrouter.o1-mini"
+	OpenRouterO3             ModelID = "openrouter.o3"
+	OpenRouterO3Mini         ModelID = "openrouter.o3-mini"
+	OpenRouterO4Mini         ModelID = "openrouter.o4-mini"
+	OpenRouterGemini25Flash  ModelID = "openrouter.gemini-2.5-flash"
+	OpenRouterGemini25       ModelID = "openrouter.gemini-2.5"
+	OpenRouterClaude35Sonnet ModelID = "openrouter.claude-3.5-sonnet"
+	OpenRouterClaude3Haiku   ModelID = "openrouter.claude-3-haiku"
+	OpenRouterClaude37Sonnet ModelID = "openrouter.claude-3.7-sonnet"
+	OpenRouterClaude35Haiku  ModelID = "openrouter.claude-3.5-haiku"
+	OpenRouterClaude3Opus    ModelID = "openrouter.claude-3-opus"
+)
+
+var OpenRouterModels = map[ModelID]Model{
+	OpenRouterGPT41: {
+		ID:                 OpenRouterGPT41,
+		Name:               "OpenRouter – GPT 4.1",
+		Provider:           ProviderOpenRouter,
+		APIModel:           "openai/gpt-4.1",
+		CostPer1MIn:        OpenAIModels[GPT41].CostPer1MIn,
+		CostPer1MInCached:  OpenAIModels[GPT41].CostPer1MInCached,
+		CostPer1MOut:       OpenAIModels[GPT41].CostPer1MOut,
+		CostPer1MOutCached: OpenAIModels[GPT41].CostPer1MOutCached,
+		ContextWindow:      OpenAIModels[GPT41].ContextWindow,
+		DefaultMaxTokens:   OpenAIModels[GPT41].DefaultMaxTokens,
+	},
+	OpenRouterGPT41Mini: {
+		ID:                 OpenRouterGPT41Mini,
+		Name:               "OpenRouter – GPT 4.1 mini",
+		Provider:           ProviderOpenRouter,
+		APIModel:           "openai/gpt-4.1-mini",
+		CostPer1MIn:        OpenAIModels[GPT41Mini].CostPer1MIn,
+		CostPer1MInCached:  OpenAIModels[GPT41Mini].CostPer1MInCached,
+		CostPer1MOut:       OpenAIModels[GPT41Mini].CostPer1MOut,
+		CostPer1MOutCached: OpenAIModels[GPT41Mini].CostPer1MOutCached,
+		ContextWindow:      OpenAIModels[GPT41Mini].ContextWindow,
+		DefaultMaxTokens:   OpenAIModels[GPT41Mini].DefaultMaxTokens,
+	},
+	OpenRouterGPT41Nano: {
+		ID:                 OpenRouterGPT41Nano,
+		Name:               "OpenRouter – GPT 4.1 nano",
+		Provider:           ProviderOpenRouter,
+		APIModel:           "openai/gpt-4.1-nano",
+		CostPer1MIn:        OpenAIModels[GPT41Nano].CostPer1MIn,
+		CostPer1MInCached:  OpenAIModels[GPT41Nano].CostPer1MInCached,
+		CostPer1MOut:       OpenAIModels[GPT41Nano].CostPer1MOut,
+		CostPer1MOutCached: OpenAIModels[GPT41Nano].CostPer1MOutCached,
+		ContextWindow:      OpenAIModels[GPT41Nano].ContextWindow,
+		DefaultMaxTokens:   OpenAIModels[GPT41Nano].DefaultMaxTokens,
+	},
+	OpenRouterGPT45Preview: {
+		ID:                 OpenRouterGPT45Preview,
+		Name:               "OpenRouter – GPT 4.5 preview",
+		Provider:           ProviderOpenRouter,
+		APIModel:           "openai/gpt-4.5-preview",
+		CostPer1MIn:        OpenAIModels[GPT45Preview].CostPer1MIn,
+		CostPer1MInCached:  OpenAIModels[GPT45Preview].CostPer1MInCached,
+		CostPer1MOut:       OpenAIModels[GPT45Preview].CostPer1MOut,
+		CostPer1MOutCached: OpenAIModels[GPT45Preview].CostPer1MOutCached,
+		ContextWindow:      OpenAIModels[GPT45Preview].ContextWindow,
+		DefaultMaxTokens:   OpenAIModels[GPT45Preview].DefaultMaxTokens,
+	},
+	OpenRouterGPT4o: {
+		ID:                 OpenRouterGPT4o,
+		Name:               "OpenRouter – GPT 4o",
+		Provider:           ProviderOpenRouter,
+		APIModel:           "openai/gpt-4o",
+		CostPer1MIn:        OpenAIModels[GPT4o].CostPer1MIn,
+		CostPer1MInCached:  OpenAIModels[GPT4o].CostPer1MInCached,
+		CostPer1MOut:       OpenAIModels[GPT4o].CostPer1MOut,
+		CostPer1MOutCached: OpenAIModels[GPT4o].CostPer1MOutCached,
+		ContextWindow:      OpenAIModels[GPT4o].ContextWindow,
+		DefaultMaxTokens:   OpenAIModels[GPT4o].DefaultMaxTokens,
+	},
+	OpenRouterGPT4oMini: {
+		ID:                 OpenRouterGPT4oMini,
+		Name:               "OpenRouter – GPT 4o mini",
+		Provider:           ProviderOpenRouter,
+		APIModel:           "openai/gpt-4o-mini",
+		CostPer1MIn:        OpenAIModels[GPT4oMini].CostPer1MIn,
+		CostPer1MInCached:  OpenAIModels[GPT4oMini].CostPer1MInCached,
+		CostPer1MOut:       OpenAIModels[GPT4oMini].CostPer1MOut,
+		CostPer1MOutCached: OpenAIModels[GPT4oMini].CostPer1MOutCached,
+		ContextWindow:      OpenAIModels[GPT4oMini].ContextWindow,
+	},
+	OpenRouterO1: {
+		ID:                 OpenRouterO1,
+		Name:               "OpenRouter – O1",
+		Provider:           ProviderOpenRouter,
+		APIModel:           "openai/o1",
+		CostPer1MIn:        OpenAIModels[O1].CostPer1MIn,
+		CostPer1MInCached:  OpenAIModels[O1].CostPer1MInCached,
+		CostPer1MOut:       OpenAIModels[O1].CostPer1MOut,
+		CostPer1MOutCached: OpenAIModels[O1].CostPer1MOutCached,
+		ContextWindow:      OpenAIModels[O1].ContextWindow,
+		DefaultMaxTokens:   OpenAIModels[O1].DefaultMaxTokens,
+		CanReason:          OpenAIModels[O1].CanReason,
+	},
+	OpenRouterO1Pro: {
+		ID:                 OpenRouterO1Pro,
+		Name:               "OpenRouter – o1 pro",
+		Provider:           ProviderOpenRouter,
+		APIModel:           "openai/o1-pro",
+		CostPer1MIn:        OpenAIModels[O1Pro].CostPer1MIn,
+		CostPer1MInCached:  OpenAIModels[O1Pro].CostPer1MInCached,
+		CostPer1MOut:       OpenAIModels[O1Pro].CostPer1MOut,
+		CostPer1MOutCached: OpenAIModels[O1Pro].CostPer1MOutCached,
+		ContextWindow:      OpenAIModels[O1Pro].ContextWindow,
+		DefaultMaxTokens:   OpenAIModels[O1Pro].DefaultMaxTokens,
+		CanReason:          OpenAIModels[O1Pro].CanReason,
+	},
+	OpenRouterO1Mini: {
+		ID:                 OpenRouterO1Mini,
+		Name:               "OpenRouter – o1 mini",
+		Provider:           ProviderOpenRouter,
+		APIModel:           "openai/o1-mini",
+		CostPer1MIn:        OpenAIModels[O1Mini].CostPer1MIn,
+		CostPer1MInCached:  OpenAIModels[O1Mini].CostPer1MInCached,
+		CostPer1MOut:       OpenAIModels[O1Mini].CostPer1MOut,
+		CostPer1MOutCached: OpenAIModels[O1Mini].CostPer1MOutCached,
+		ContextWindow:      OpenAIModels[O1Mini].ContextWindow,
+		DefaultMaxTokens:   OpenAIModels[O1Mini].DefaultMaxTokens,
+		CanReason:          OpenAIModels[O1Mini].CanReason,
+	},
+	OpenRouterO3: {
+		ID:                 OpenRouterO3,
+		Name:               "OpenRouter – o3",
+		Provider:           ProviderOpenRouter,
+		APIModel:           "openai/o3",
+		CostPer1MIn:        OpenAIModels[O3].CostPer1MIn,
+		CostPer1MInCached:  OpenAIModels[O3].CostPer1MInCached,
+		CostPer1MOut:       OpenAIModels[O3].CostPer1MOut,
+		CostPer1MOutCached: OpenAIModels[O3].CostPer1MOutCached,
+		ContextWindow:      OpenAIModels[O3].ContextWindow,
+		DefaultMaxTokens:   OpenAIModels[O3].DefaultMaxTokens,
+		CanReason:          OpenAIModels[O3].CanReason,
+	},
+	OpenRouterO3Mini: {
+		ID:                 OpenRouterO3Mini,
+		Name:               "OpenRouter – o3 mini",
+		Provider:           ProviderOpenRouter,
+		APIModel:           "openai/o3-mini-high",
+		CostPer1MIn:        OpenAIModels[O3Mini].CostPer1MIn,
+		CostPer1MInCached:  OpenAIModels[O3Mini].CostPer1MInCached,
+		CostPer1MOut:       OpenAIModels[O3Mini].CostPer1MOut,
+		CostPer1MOutCached: OpenAIModels[O3Mini].CostPer1MOutCached,
+		ContextWindow:      OpenAIModels[O3Mini].ContextWindow,
+		DefaultMaxTokens:   OpenAIModels[O3Mini].DefaultMaxTokens,
+		CanReason:          OpenAIModels[O3Mini].CanReason,
+	},
+	OpenRouterO4Mini: {
+		ID:                 OpenRouterO4Mini,
+		Name:               "OpenRouter – o4 mini",
+		Provider:           ProviderOpenRouter,
+		APIModel:           "openai/o4-mini-high",
+		CostPer1MIn:        OpenAIModels[O4Mini].CostPer1MIn,
+		CostPer1MInCached:  OpenAIModels[O4Mini].CostPer1MInCached,
+		CostPer1MOut:       OpenAIModels[O4Mini].CostPer1MOut,
+		CostPer1MOutCached: OpenAIModels[O4Mini].CostPer1MOutCached,
+		ContextWindow:      OpenAIModels[O4Mini].ContextWindow,
+		DefaultMaxTokens:   OpenAIModels[O4Mini].DefaultMaxTokens,
+		CanReason:          OpenAIModels[O4Mini].CanReason,
+	},
+	OpenRouterGemini25Flash: {
+		ID:                 OpenRouterGemini25Flash,
+		Name:               "OpenRouter – Gemini 2.5 Flash",
+		Provider:           ProviderOpenRouter,
+		APIModel:           "google/gemini-2.5-flash-preview:thinking",
+		CostPer1MIn:        GeminiModels[Gemini25Flash].CostPer1MIn,
+		CostPer1MInCached:  GeminiModels[Gemini25Flash].CostPer1MInCached,
+		CostPer1MOut:       GeminiModels[Gemini25Flash].CostPer1MOut,
+		CostPer1MOutCached: GeminiModels[Gemini25Flash].CostPer1MOutCached,
+		ContextWindow:      GeminiModels[Gemini25Flash].ContextWindow,
+		DefaultMaxTokens:   GeminiModels[Gemini25Flash].DefaultMaxTokens,
+	},
+	OpenRouterGemini25: {
+		ID:                 OpenRouterGemini25,
+		Name:               "OpenRouter – Gemini 2.5 Pro",
+		Provider:           ProviderOpenRouter,
+		APIModel:           "google/gemini-2.5-pro-preview-03-25",
+		CostPer1MIn:        GeminiModels[Gemini25].CostPer1MIn,
+		CostPer1MInCached:  GeminiModels[Gemini25].CostPer1MInCached,
+		CostPer1MOut:       GeminiModels[Gemini25].CostPer1MOut,
+		CostPer1MOutCached: GeminiModels[Gemini25].CostPer1MOutCached,
+		ContextWindow:      GeminiModels[Gemini25].ContextWindow,
+		DefaultMaxTokens:   GeminiModels[Gemini25].DefaultMaxTokens,
+	},
+	OpenRouterClaude35Sonnet: {
+		ID:                 OpenRouterClaude35Sonnet,
+		Name:               "OpenRouter – Claude 3.5 Sonnet",
+		Provider:           ProviderOpenRouter,
+		APIModel:           "anthropic/claude-3.5-sonnet",
+		CostPer1MIn:        AnthropicModels[Claude35Sonnet].CostPer1MIn,
+		CostPer1MInCached:  AnthropicModels[Claude35Sonnet].CostPer1MInCached,
+		CostPer1MOut:       AnthropicModels[Claude35Sonnet].CostPer1MOut,
+		CostPer1MOutCached: AnthropicModels[Claude35Sonnet].CostPer1MOutCached,
+		ContextWindow:      AnthropicModels[Claude35Sonnet].ContextWindow,
+		DefaultMaxTokens:   AnthropicModels[Claude35Sonnet].DefaultMaxTokens,
+	},
+	OpenRouterClaude3Haiku: {
+		ID:                 OpenRouterClaude3Haiku,
+		Name:               "OpenRouter – Claude 3 Haiku",
+		Provider:           ProviderOpenRouter,
+		APIModel:           "anthropic/claude-3-haiku",
+		CostPer1MIn:        AnthropicModels[Claude3Haiku].CostPer1MIn,
+		CostPer1MInCached:  AnthropicModels[Claude3Haiku].CostPer1MInCached,
+		CostPer1MOut:       AnthropicModels[Claude3Haiku].CostPer1MOut,
+		CostPer1MOutCached: AnthropicModels[Claude3Haiku].CostPer1MOutCached,
+		ContextWindow:      AnthropicModels[Claude3Haiku].ContextWindow,
+		DefaultMaxTokens:   AnthropicModels[Claude3Haiku].DefaultMaxTokens,
+	},
+	OpenRouterClaude37Sonnet: {
+		ID:                 OpenRouterClaude37Sonnet,
+		Name:               "OpenRouter – Claude 3.7 Sonnet",
+		Provider:           ProviderOpenRouter,
+		APIModel:           "anthropic/claude-3.7-sonnet",
+		CostPer1MIn:        AnthropicModels[Claude37Sonnet].CostPer1MIn,
+		CostPer1MInCached:  AnthropicModels[Claude37Sonnet].CostPer1MInCached,
+		CostPer1MOut:       AnthropicModels[Claude37Sonnet].CostPer1MOut,
+		CostPer1MOutCached: AnthropicModels[Claude37Sonnet].CostPer1MOutCached,
+		ContextWindow:      AnthropicModels[Claude37Sonnet].ContextWindow,
+		DefaultMaxTokens:   AnthropicModels[Claude37Sonnet].DefaultMaxTokens,
+		CanReason:          AnthropicModels[Claude37Sonnet].CanReason,
+	},
+	OpenRouterClaude35Haiku: {
+		ID:                 OpenRouterClaude35Haiku,
+		Name:               "OpenRouter – Claude 3.5 Haiku",
+		Provider:           ProviderOpenRouter,
+		APIModel:           "anthropic/claude-3.5-haiku",
+		CostPer1MIn:        AnthropicModels[Claude35Haiku].CostPer1MIn,
+		CostPer1MInCached:  AnthropicModels[Claude35Haiku].CostPer1MInCached,
+		CostPer1MOut:       AnthropicModels[Claude35Haiku].CostPer1MOut,
+		CostPer1MOutCached: AnthropicModels[Claude35Haiku].CostPer1MOutCached,
+		ContextWindow:      AnthropicModels[Claude35Haiku].ContextWindow,
+		DefaultMaxTokens:   AnthropicModels[Claude35Haiku].DefaultMaxTokens,
+	},
+	OpenRouterClaude3Opus: {
+		ID:                 OpenRouterClaude3Opus,
+		Name:               "OpenRouter – Claude 3 Opus",
+		Provider:           ProviderOpenRouter,
+		APIModel:           "anthropic/claude-3-opus",
+		CostPer1MIn:        AnthropicModels[Claude3Opus].CostPer1MIn,
+		CostPer1MInCached:  AnthropicModels[Claude3Opus].CostPer1MInCached,
+		CostPer1MOut:       AnthropicModels[Claude3Opus].CostPer1MOut,
+		CostPer1MOutCached: AnthropicModels[Claude3Opus].CostPer1MOutCached,
+		ContextWindow:      AnthropicModels[Claude3Opus].ContextWindow,
+		DefaultMaxTokens:   AnthropicModels[Claude3Opus].DefaultMaxTokens,
+	},
+}