feat: Add OpenRouter API request and response structures with tests

go.sum

@@ -0,0 +1,10 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
+github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

openrouter/openrouter-tool-calls.json

@@ -0,0 +1,35 @@
+{
+    "id": "gen-1738521823-zoQZYL4vJW8s167DSle",
+    "provider": "OpenAI",
+    "model": "openai/gpt-4o-2024-11-20",
+    "object": "chat.completion",
+    "created": 1738521823,
+    "system_fingerprint": "fp_e53e529995",
+    "choices": [
+      {
+        "logprobs": null,
+        "finish_reason": "tool_calls",
+        "native_finish_reason": "tool_calls",
+        "index": 0,
+        "message": {
+          "role": "assistant",
+          "content": "",
+          "tool_calls": [
+            {
+              "id": "call_vdkI1mqVvMFDYDtx22Q6MAQl",
+              "type": "function",
+              "function": {
+                "name": "get_train_fare",
+                "arguments": "{\"date\":\"2025-05-25\",\"destination\":\"New York City\",\"class\":\"standard\",\"origin\":\"Boston\",\"passengers\":1}"
+              }
+            }
+          ]
+        }
+      }
+    ],
+    "usage": {
+      "prompt_tokens": 2296,
+      "completion_tokens": 43,
+      "total_tokens": 2339
+    }
+  }

openrouter/openrouter_test.go

@@ -0,0 +1,41 @@
+package openrouter
+
+import (
+	"encoding/json"
+	"os"
+	"testing"
+
+	"github.com/presbrey/aichat"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestOpenRouterToolCalls(t *testing.T) {
+	b, err := os.ReadFile("openrouter-tool-calls.json")
+	assert.NoError(t, err)
+
+	resp := &Response{}
+	assert.NoError(t, json.Unmarshal(b, resp))
+
+	chat := &aichat.Chat{}
+	chat.AddMessage(resp.Choices[0].Message)
+
+	toolCallCount := 0
+	chat.RangePendingToolCalls(func(tc *aichat.ToolCallContext) error {
+		toolCallCount++
+		args, err := tc.Arguments()
+		assert.NoError(t, err)
+		assert.Equal(t, map[string]interface{}{
+			"class":       "standard",
+			"date":        "2025-05-25",
+			"destination": "New York City",
+			"origin":      "Boston",
+			"passengers":  float64(1),
+		}, args)
+		return tc.Return(map[string]any{
+			"foo": "bar",
+		})
+	})
+	assert.Equal(t, 1, toolCallCount)
+
+	assert.Equal(t, `{"foo":"bar"}`, chat.LastMessageByRole("tool").Content)
+}

openrouter/types.go

@@ -0,0 +1,84 @@
+package openrouter
+
+import "github.com/presbrey/aichat"
+
+// Request represents a chat completion request to the OpenRouter API
+type Request struct {
+	Messages       []*aichat.Message `json:"messages,omitempty"`
+	Prompt         string            `json:"prompt,omitempty"`
+	Model          string            `json:"model,omitempty"`
+	ResponseFormat *struct {
+		Type string `json:"type"`
+	} `json:"response_format,omitempty"`
+
+	Stop        interface{} `json:"stop,omitempty"` // string or []string
+	Stream      bool        `json:"stream,omitempty"`
+	MaxTokens   int         `json:"max_tokens,omitempty"`
+	Temperature float64     `json:"temperature,omitempty"`
+
+	Tools      any         `json:"tools,omitempty"`
+	ToolChoice interface{} `json:"tool_choice,omitempty"` // string or ToolChoice
+
+	Seed        int     `json:"seed,omitempty"`
+	TopP        float64 `json:"top_p,omitempty"`
+	TopK        int     `json:"top_k,omitempty"`
+	FreqPenalty float64 `json:"frequency_penalty,omitempty"`
+	PresPenalty float64 `json:"presence_penalty,omitempty"`
+	RepPenalty  float64 `json:"repetition_penalty,omitempty"`
+
+	LogitBias   map[int]float64 `json:"logit_bias,omitempty"`
+	TopLogprobs int             `json:"top_logprobs,omitempty"`
+
+	MinP float64 `json:"min_p,omitempty"`
+	TopA float64 `json:"top_a,omitempty"`
+
+	Prediction *struct {
+		Type    string `json:"type"`
+		Content string `json:"content"`
+	} `json:"prediction,omitempty"`
+	Transforms []string `json:"transforms,omitempty"`
+	Models     []string `json:"models,omitempty"`
+	Route      string   `json:"route,omitempty"`
+
+	IncludeReasoning bool `json:"include_reasoning,omitempty"`
+}
+
+// Response represents the API response structure
+type Response struct {
+	Error *struct {
+		Message string `json:"message"`
+		Code    int    `json:"code"`
+	} `json:"error,omitempty"`
+
+	UserID   string `json:"user_id,omitempty"`
+	ID       string `json:"id,omitempty"`
+	Provider string `json:"provider,omitempty"`
+	Model    string `json:"model,omitempty"`
+	Object   string `json:"object,omitempty"`
+	Created  int64  `json:"created,omitempty"`
+
+	SystemFingerprint string `json:"system_fingerprint,omitempty"`
+
+	Choices []struct {
+		LogProbs           interface{}     `json:"logprobs"`
+		FinishReason       string          `json:"finish_reason"`
+		NativeFinishReason string          `json:"native_finish_reason"`
+		Index              int             `json:"index"`
+		Message            *aichat.Message `json:"message"`
+	} `json:"choices,omitempty"`
+
+	Usage struct {
+		PromptTokens     int `json:"prompt_tokens"`
+		CompletionTokens int `json:"completion_tokens"`
+		TotalTokens      int `json:"total_tokens"`
+	} `json:"usage,omitempty"`
+}
+
+// ToolChoice represents the model's choice of tool usage
+type ToolChoice struct {
+	Type string `json:"type,omitempty"`
+
+	Function struct {
+		Name string `json:"name"`
+	} `json:"function,omitempty"`
+}