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, 54 insertions, 32 deletions

diff --git a/opencode-schema.json b/opencode-schema.json
index 766ca0260..7d1dde213 100644
--- a/opencode-schema.json
+++ b/opencode-schema.json
@@ -49,23 +49,38 @@
             "gpt-4.1-mini",
             "azure.gpt-4.1-mini",
             "gemini-2.5",
-            "meta-llama/llama-4-scout-17b-16e-instruct"
+            "meta-llama/llama-4-scout-17b-16e-instruct",
+            "openrouter.deepseek-chat-free",
+            "openrouter.deepseek-r1-free",
+            "openrouter.gpt-4.1",
+            "openrouter.gpt-4.1-mini",
+            "openrouter.gpt-4.1-nano",
+            "openrouter.gpt-4.5-preview",
+            "openrouter.gpt-4o",
+            "openrouter.gpt-4o-mini",
+            "openrouter.o1",
+            "openrouter.o1-pro",
+            "openrouter.o1-mini",
+            "openrouter.o3",
+            "openrouter.o3-mini",
+            "openrouter.o4-mini",
+            "openrouter.gemini-2.5-flash",
+            "openrouter.gemini-2.5",
+            "openrouter.claude-3.5-sonnet",
+            "openrouter.claude-3-haiku",
+            "openrouter.claude-3.7-sonnet",
+            "openrouter.claude-3.5-haiku",
+            "openrouter.claude-3-opus"
           ],
           "type": "string"
         },
         "reasoningEffort": {
           "description": "Reasoning effort for models that support it (OpenAI, Anthropic)",
-          "enum": [
-            "low",
-            "medium",
-            "high"
-          ],
+          "enum": ["low", "medium", "high"],
           "type": "string"
         }
       },
-      "required": [
-        "model"
-      ],
+      "required": ["model"],
       "type": "object"
     }
   },
@@ -120,23 +135,38 @@
               "gpt-4.1-mini",
               "azure.gpt-4.1-mini",
               "gemini-2.5",
-              "meta-llama/llama-4-scout-17b-16e-instruct"
+              "meta-llama/llama-4-scout-17b-16e-instruct",
+              "openrouter.deepseek-chat-free",
+              "openrouter.deepseek-r1-free",
+              "openrouter.gpt-4.1",
+              "openrouter.gpt-4.1-mini",
+              "openrouter.gpt-4.1-nano",
+              "openrouter.gpt-4.5-preview",
+              "openrouter.gpt-4o",
+              "openrouter.gpt-4o-mini",
+              "openrouter.o1",
+              "openrouter.o1-pro",
+              "openrouter.o1-mini",
+              "openrouter.o3",
+              "openrouter.o3-mini",
+              "openrouter.o4-mini",
+              "openrouter.gemini-2.5-flash",
+              "openrouter.gemini-2.5",
+              "openrouter.claude-3.5-sonnet",
+              "openrouter.claude-3-haiku",
+              "openrouter.claude-3.7-sonnet",
+              "openrouter.claude-3.5-haiku",
+              "openrouter.claude-3-opus"
             ],
             "type": "string"
           },
           "reasoningEffort": {
             "description": "Reasoning effort for models that support it (OpenAI, Anthropic)",
-            "enum": [
-              "low",
-              "medium",
-              "high"
-            ],
+            "enum": ["low", "medium", "high"],
             "type": "string"
           }
         },
-        "required": [
-          "model"
-        ],
+        "required": ["model"],
         "type": "object"
       },
       "description": "Agent configurations",
@@ -182,9 +212,7 @@
           "type": "string"
         }
       },
-      "required": [
-        "directory"
-      ],
+      "required": ["directory"],
       "type": "object"
     },
     "debug": {
@@ -222,9 +250,7 @@
             "type": "object"
           }
         },
-        "required": [
-          "command"
-        ],
+        "required": ["command"],
         "type": "object"
       },
       "description": "Language Server Protocol configurations",
@@ -262,10 +288,7 @@
           "type": {
             "default": "stdio",
             "description": "Type of MCP server",
-            "enum": [
-              "stdio",
-              "sse"
-            ],
+            "enum": ["stdio", "sse"],
             "type": "string"
           },
           "url": {
@@ -273,9 +296,7 @@
             "type": "string"
           }
         },
-        "required": [
-          "command"
-        ],
+        "required": ["command"],
         "type": "object"
       },
       "description": "Model Control Protocol server configurations",
@@ -302,7 +323,8 @@
               "gemini",
               "groq",
               "bedrock",
-              "azure"
+              "azure",
+              "openrouter"
             ],
             "type": "string"
           }