1// Package main implements a tool to fetch GitHub Copilot models and generate a Catwalk provider configuration.
2package main
3
4import (
5 "context"
6 "encoding/json"
7 "fmt"
8 "net/http"
9 "os"
10 "path/filepath"
11 "regexp"
12 "runtime"
13 "slices"
14 "strings"
15 "time"
16
17 "github.com/charmbracelet/catwalk/pkg/catwalk"
18)
19
20type Response struct {
21 Object string `json:"object"`
22 Data []Model `json:"data"`
23}
24
25type Model struct {
26 ID string `json:"id"`
27 Name string `json:"name"`
28 Version string `json:"version"`
29 Vendor string `json:"vendor"`
30 Preview bool `json:"preview"`
31 ModelPickerEnabled bool `json:"model_picker_enabled"`
32 Capabilities Capability `json:"capabilities"`
33 Policy *Policy `json:"policy,omitempty"`
34}
35
36type Capability struct {
37 Family string `json:"family"`
38 Type string `json:"type"`
39 Tokenizer string `json:"tokenizer"`
40 Limits Limits `json:"limits"`
41 Supports Supports `json:"supports"`
42}
43
44type Limits struct {
45 MaxContextWindowTokens int `json:"max_context_window_tokens,omitempty"`
46 MaxOutputTokens int `json:"max_output_tokens,omitempty"`
47 MaxPromptTokens int `json:"max_prompt_tokens,omitempty"`
48}
49
50type Supports struct {
51 ToolCalls bool `json:"tool_calls,omitempty"`
52 ParallelToolCalls bool `json:"parallel_tool_calls,omitempty"`
53 MaxThinkingBudget int `json:"max_thinking_budget,omitempty"`
54 MinThinkingBudget int `json:"min_thinking_budget,omitempty"`
55}
56
57type Policy struct {
58 State string `json:"state"`
59 Terms string `json:"terms"`
60}
61
62var versionedModelRegexp = regexp.MustCompile(`-\d{4}-\d{2}-\d{2}$`)
63
64func main() {
65 if err := run(); err != nil {
66 fmt.Fprintf(os.Stderr, "Error: %v\n", err)
67 os.Exit(1)
68 }
69}
70
71func run() error {
72 copilotModels, err := fetchCopilotModels()
73 if err != nil {
74 return err
75 }
76
77 // NOTE(@andreynering): Exclude versioned models and keep only the main version of each.
78 copilotModels = slices.DeleteFunc(copilotModels, func(m Model) bool {
79 return m.ID != m.Version || versionedModelRegexp.MatchString(m.ID) || strings.Contains(m.ID, "embedding")
80 })
81
82 catwalkModels := modelsToCatwalk(copilotModels)
83 slices.SortStableFunc(catwalkModels, func(a, b catwalk.Model) int {
84 return strings.Compare(a.ID, b.ID)
85 })
86
87 provider := catwalk.Provider{
88 ID: catwalk.InferenceProviderCopilot,
89 Name: "GitHub Copilot",
90 Models: catwalkModels,
91 APIEndpoint: "https://api.githubcopilot.com",
92 Type: catwalk.TypeOpenAICompat,
93 DefaultLargeModelID: "claude-sonnet-4.5",
94 DefaultSmallModelID: "claude-haiku-4.5",
95 }
96 data, err := json.MarshalIndent(provider, "", " ")
97 if err != nil {
98 return fmt.Errorf("unable to marshal json: %w", err)
99 }
100 if err := os.WriteFile("internal/providers/configs/copilot.json", data, 0o600); err != nil {
101 return fmt.Errorf("unable to write copilog.json: %w", err)
102 }
103 return nil
104}
105
106func fetchCopilotModels() ([]Model, error) {
107 ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
108 defer cancel()
109
110 req, err := http.NewRequestWithContext(
111 ctx,
112 "GET",
113 "https://api.githubcopilot.com/models",
114 nil,
115 )
116 if err != nil {
117 return nil, fmt.Errorf("unable to create request: %w", err)
118 }
119 req.Header.Set("Accept", "application/json")
120 req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", copilotToken()))
121
122 client := &http.Client{}
123 resp, err := client.Do(req)
124 if err != nil {
125 return nil, fmt.Errorf("unable to make http request: %w", err)
126 }
127 defer resp.Body.Close() //nolint:errcheck
128
129 if resp.StatusCode != http.StatusOK {
130 return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
131 }
132
133 var data Response
134 if err := json.NewDecoder(resp.Body).Decode(&data); err != nil {
135 return nil, fmt.Errorf("unable to unmarshal json: %w", err)
136 }
137 return data.Data, nil
138}
139
140func modelsToCatwalk(m []Model) []catwalk.Model {
141 models := make([]catwalk.Model, 0, len(m))
142 for _, model := range m {
143 models = append(models, modelToCatwalk(model))
144 }
145 return models
146}
147
148func modelToCatwalk(m Model) catwalk.Model {
149 canReason, reasoningLevels, defaultReasoning := detectReasoningCapabilities(m)
150
151 return catwalk.Model{
152 ID: m.ID,
153 Name: m.Name,
154 DefaultMaxTokens: int64(m.Capabilities.Limits.MaxOutputTokens),
155 ContextWindow: int64(m.Capabilities.Limits.MaxContextWindowTokens),
156 CanReason: canReason,
157 ReasoningLevels: reasoningLevels,
158 DefaultReasoningEffort: defaultReasoning,
159 }
160}
161
162func detectReasoningCapabilities(m Model) (canReason bool, levels []string, defaultLevel string) {
163 // Models with thinking budget (Claude, Gemini) support extended thinking without levels
164 if m.Capabilities.Supports.MaxThinkingBudget > 0 {
165 return true, nil, ""
166 }
167
168 // OpenAI o-series and GPT-5+ models support reasoning with effort levels
169 if strings.HasPrefix(m.ID, "o1") ||
170 strings.HasPrefix(m.ID, "o3") ||
171 strings.HasPrefix(m.ID, "o4") ||
172 strings.HasPrefix(m.ID, "gpt-5") {
173 return true, []string{"low", "medium", "high"}, "medium"
174 }
175
176 return false, nil, ""
177}
178
179func copilotToken() string {
180 if token := os.Getenv("COPILOT_TOKEN"); token != "" {
181 return token
182 }
183 return tokenFromDisk()
184}
185
186func tokenFromDisk() string {
187 data, err := os.ReadFile(tokenFilePath())
188 if err != nil {
189 return ""
190 }
191 var content map[string]struct {
192 User string `json:"user"`
193 OAuthToken string `json:"oauth_token"`
194 GitHubAppID string `json:"githubAppId"`
195 }
196 if err := json.Unmarshal(data, &content); err != nil {
197 return ""
198 }
199 if app, ok := content["github.com:Iv1.b507a08c87ecfe98"]; ok {
200 return app.OAuthToken
201 }
202 return ""
203}
204
205func tokenFilePath() string {
206 switch runtime.GOOS {
207 case "windows":
208 return filepath.Join(os.Getenv("LOCALAPPDATA"), "github-copilot/apps.json")
209 default:
210 return filepath.Join(os.Getenv("HOME"), ".config/github-copilot/apps.json")
211 }
212}