feat: add support for GitHub Models provider

- Introduced environment variable CLAUDE_CODE_USE_GITHUB to enable GitHub Models.
- Added checks for GITHUB_TOKEN or GH_TOKEN for authentication.
- Updated base URL handling to include GitHub Models default.
- Enhanced provider detection and error handling for GitHub Models.
- Updated relevant functions and components to accommodate the new provider.

src/services/api/client.ts

@@ -154,7 +154,10 @@ export async function getAnthropicClient({
       fetch: resolvedFetch,
     }),
   }
-  if (isEnvTruthy(process.env.CLAUDE_CODE_USE_OPENAI)) {
+  if (
+    isEnvTruthy(process.env.CLAUDE_CODE_USE_OPENAI) ||
+    isEnvTruthy(process.env.CLAUDE_CODE_USE_GITHUB)
+  ) {
     const { createOpenAIShimClient } = await import('./openaiShim.js')
     return createOpenAIShimClient({
       defaultHeaders,

src/services/api/openaiShim.ts

@@ -14,8 +14,15 @@
  *   OPENAI_BASE_URL=http://...        — base URL (default: https://api.openai.com/v1)
  *   OPENAI_MODEL=gpt-4o              — default model override
  *   CODEX_API_KEY / ~/.codex/auth.json — Codex auth for codexplan/codexspark
+ *
+ * GitHub Models (models.github.ai), OpenAI-compatible:
+ *   CLAUDE_CODE_USE_GITHUB=1         — enable GitHub inference (no need for USE_OPENAI)
+ *   GITHUB_TOKEN or GH_TOKEN         — PAT with models access (mapped to Bearer auth)
+ *   OPENAI_MODEL                     — optional; use github:copilot or openai/gpt-4.1 style IDs
  */
 
+import { isEnvTruthy } from '../../utils/envUtils.js'
+import { hydrateGithubModelsTokenFromSecureStorage } from '../../utils/githubModelsCredentials.js'
 import {
   codexStreamToAnthropic,
   collectCodexCompletedResponse,
@@ -30,6 +37,25 @@ import {
   resolveProviderRequest,
 } from './providerConfig.js'
 
+const GITHUB_MODELS_DEFAULT_BASE = 'https://models.github.ai/inference'
+const GITHUB_API_VERSION = '2022-11-28'
+const GITHUB_429_MAX_RETRIES = 3
+const GITHUB_429_BASE_DELAY_SEC = 1
+const GITHUB_429_MAX_DELAY_SEC = 32
+
+function isGithubModelsMode(): boolean {
+  return isEnvTruthy(process.env.CLAUDE_CODE_USE_GITHUB)
+}
+
+function formatRetryAfterHint(response: Response): string {
+  const ra = response.headers.get('retry-after')
+  return ra ? ` (Retry-After: ${ra})` : ''
+}
+
+function sleepMs(ms: number): Promise<void> {
+  return new Promise(resolve => setTimeout(resolve, ms))
+}
+
 // ---------------------------------------------------------------------------
 // Types — minimal subset of Anthropic SDK types we need to produce
 // ---------------------------------------------------------------------------
@@ -254,9 +280,7 @@ function normalizeSchemaForOpenAI(
 function convertTools(
   tools: Array<{ name: string; description?: string; input_schema?: Record<string, unknown> }>,
 ): OpenAITool[] {
-  const isGemini =
-    process.env.CLAUDE_CODE_USE_GEMINI === '1' ||
-    process.env.CLAUDE_CODE_USE_GEMINI === 'true'
+  const isGemini = isEnvTruthy(process.env.CLAUDE_CODE_USE_GEMINI)
 
   return tools
     .filter(t => t.name !== 'ToolSearchTool') // Not relevant for OpenAI
@@ -666,6 +690,12 @@ class OpenAIShimMessages {
       body.stream_options = { include_usage: true }
     }
 
+    const isGithub = isGithubModelsMode()
+    if (isGithub && body.max_completion_tokens !== undefined) {
+      body.max_tokens = body.max_completion_tokens
+      delete body.max_completion_tokens
+    }
+
     if (params.temperature !== undefined) body.temperature = params.temperature
     if (params.top_p !== undefined) body.top_p = params.top_p
 
@@ -715,6 +745,11 @@ class OpenAIShimMessages {
       }
     }
 
+    if (isGithub) {
+      headers.Accept = 'application/vnd.github.v3+json'
+      headers['X-GitHub-Api-Version'] = GITHUB_API_VERSION
+    }
+
     // Build the chat completions URL
     // Azure Cognitive Services / Azure OpenAI require a deployment-specific path
     // and an api-version query parameter.
@@ -737,19 +772,42 @@ class OpenAIShimMessages {
       chatCompletionsUrl = `${request.baseUrl}/chat/completions`
     }
 
-    const response = await fetch(chatCompletionsUrl, {
-      method: 'POST',
+    const fetchInit = {
+      method: 'POST' as const,
       headers,
       body: JSON.stringify(body),
       signal: options?.signal,
-    })
-
-    if (!response.ok) {
-      const errorBody = await response.text().catch(() => 'unknown error')
-      throw new Error(`OpenAI API error ${response.status}: ${errorBody}`)
     }
 
-    return response
+    const maxAttempts = isGithub ? GITHUB_429_MAX_RETRIES : 1
+    let response: Response | undefined
+    for (let attempt = 0; attempt < maxAttempts; attempt++) {
+      response = await fetch(chatCompletionsUrl, fetchInit)
+      if (response.ok) {
+        return response
+      }
+      if (
+        isGithub &&
+        response.status === 429 &&
+        attempt < maxAttempts - 1
+      ) {
+        await response.text().catch(() => {})
+        const delaySec = Math.min(
+          GITHUB_429_BASE_DELAY_SEC * 2 ** attempt,
+          GITHUB_429_MAX_DELAY_SEC,
+        )
+        await sleepMs(delaySec * 1000)
+        continue
+      }
+      const errorBody = await response.text().catch(() => 'unknown error')
+      const rateHint =
+        isGithub && response.status === 429 ? formatRetryAfterHint(response) : ''
+      throw new Error(
+        `OpenAI API error ${response.status}: ${errorBody}${rateHint}`,
+      )
+    }
+
+    throw new Error('OpenAI shim: request loop exited unexpectedly')
   }
 
   private _convertNonStreamingResponse(
@@ -759,7 +817,10 @@ class OpenAIShimMessages {
       choices?: Array<{
         message?: {
           role?: string
-          content?: string | null
+          content?:
+            | string
+            | null
+            | Array<{ type?: string; text?: string }>
           tool_calls?: Array<{
             id: string
             function: { name: string; arguments: string }
@@ -778,8 +839,25 @@ class OpenAIShimMessages {
     const choice = data.choices?.[0]
     const content: Array<Record<string, unknown>> = []
 
-    if (choice?.message?.content) {
-      content.push({ type: 'text', text: choice.message.content })
+    const rawContent = choice?.message?.content
+    if (typeof rawContent === 'string' && rawContent) {
+      content.push({ type: 'text', text: rawContent })
+    } else if (Array.isArray(rawContent) && rawContent.length > 0) {
+      const parts: string[] = []
+      for (const part of rawContent) {
+        if (
+          part &&
+          typeof part === 'object' &&
+          part.type === 'text' &&
+          typeof part.text === 'string'
+        ) {
+          parts.push(part.text)
+        }
+      }
+      const joined = parts.join('\n')
+      if (joined) {
+        content.push({ type: 'text', text: joined })
+      }
     }
 
     if (choice?.message?.tool_calls) {
@@ -838,12 +916,11 @@ export function createOpenAIShimClient(options: {
   maxRetries?: number
   timeout?: number
 }): unknown {
+  hydrateGithubModelsTokenFromSecureStorage()
+
   // When Gemini provider is active, map Gemini env vars to OpenAI-compatible ones
   // so the existing providerConfig.ts infrastructure picks them up correctly.
-  if (
-    process.env.CLAUDE_CODE_USE_GEMINI === '1' ||
-    process.env.CLAUDE_CODE_USE_GEMINI === 'true'
-  ) {
+  if (isEnvTruthy(process.env.CLAUDE_CODE_USE_GEMINI)) {
     process.env.OPENAI_BASE_URL ??=
       process.env.GEMINI_BASE_URL ??
       'https://generativelanguage.googleapis.com/v1beta/openai'
@@ -852,6 +929,10 @@ export function createOpenAIShimClient(options: {
     if (process.env.GEMINI_MODEL && !process.env.OPENAI_MODEL) {
       process.env.OPENAI_MODEL = process.env.GEMINI_MODEL
     }
+  } else if (isEnvTruthy(process.env.CLAUDE_CODE_USE_GITHUB)) {
+    process.env.OPENAI_BASE_URL ??= GITHUB_MODELS_DEFAULT_BASE
+    process.env.OPENAI_API_KEY ??=
+      process.env.GITHUB_TOKEN ?? process.env.GH_TOKEN ?? ''
   }
 
   const beta = new OpenAIShimBeta({

src/services/api/providerConfig.github.test.ts

@@ -0,0 +1,41 @@
+import { afterEach, expect, test } from 'bun:test'
+
+import {
+  DEFAULT_GITHUB_MODELS_API_MODEL,
+  normalizeGithubModelsApiModel,
+  resolveProviderRequest,
+} from './providerConfig.js'
+
+const originalUseGithub = process.env.CLAUDE_CODE_USE_GITHUB
+
+afterEach(() => {
+  if (originalUseGithub === undefined) {
+    delete process.env.CLAUDE_CODE_USE_GITHUB
+  } else {
+    process.env.CLAUDE_CODE_USE_GITHUB = originalUseGithub
+  }
+})
+
+test.each([
+  ['copilot', DEFAULT_GITHUB_MODELS_API_MODEL],
+  ['github:copilot', DEFAULT_GITHUB_MODELS_API_MODEL],
+  ['', DEFAULT_GITHUB_MODELS_API_MODEL],
+  ['github:gpt-4o', 'gpt-4o'],
+  ['gpt-4o', 'gpt-4o'],
+  ['github:copilot?reasoning=high', DEFAULT_GITHUB_MODELS_API_MODEL],
+] as const)('normalizeGithubModelsApiModel(%s) -> %s', (input, expected) => {
+  expect(normalizeGithubModelsApiModel(input)).toBe(expected)
+})
+
+test('resolveProviderRequest applies GitHub normalization when CLAUDE_CODE_USE_GITHUB=1', () => {
+  process.env.CLAUDE_CODE_USE_GITHUB = '1'
+  const r = resolveProviderRequest({ model: 'github:gpt-4o' })
+  expect(r.resolvedModel).toBe('gpt-4o')
+  expect(r.transport).toBe('chat_completions')
+})
+
+test('resolveProviderRequest leaves model unchanged without GitHub flag', () => {
+  delete process.env.CLAUDE_CODE_USE_GITHUB
+  const r = resolveProviderRequest({ model: 'github:gpt-4o' })
+  expect(r.resolvedModel).toBe('github:gpt-4o')
+})

src/services/api/providerConfig.ts

@@ -2,8 +2,12 @@ import { existsSync, readFileSync } from 'node:fs'
 import { homedir } from 'node:os'
 import { join } from 'node:path'
 
+import { isEnvTruthy } from '../../utils/envUtils.js'
+
 export const DEFAULT_OPENAI_BASE_URL = 'https://api.openai.com/v1'
 export const DEFAULT_CODEX_BASE_URL = 'https://chatgpt.com/backend-api/codex'
+/** Default GitHub Models API model when user selects copilot / github:copilot */
+export const DEFAULT_GITHUB_MODELS_API_MODEL = 'openai/gpt-4.1'
 
 const CODEX_ALIAS_MODELS: Record<
   string,
@@ -171,6 +175,20 @@ export function isCodexBaseUrl(baseUrl: string | undefined): boolean {
   }
 }
 
+/**
+ * Normalize user model string for GitHub Models inference (models.github.ai).
+ * Mirrors runtime devsper `github._normalize_model_id`.
+ */
+export function normalizeGithubModelsApiModel(requestedModel: string): string {
+  const noQuery = requestedModel.split('?', 1)[0] ?? requestedModel
+  const segment =
+    noQuery.includes(':') ? noQuery.split(':', 2)[1]!.trim() : noQuery.trim()
+  if (!segment || segment.toLowerCase() === 'copilot') {
+    return DEFAULT_GITHUB_MODELS_API_MODEL
+  }
+  return segment
+}
+
 export function resolveProviderRequest(options?: {
   model?: string
   baseUrl?: string
@@ -192,10 +210,16 @@ export function resolveProviderRequest(options?: {
       ? 'codex_responses'
       : 'chat_completions'
 
+  const resolvedModel =
+    transport === 'chat_completions' &&
+    isEnvTruthy(process.env.CLAUDE_CODE_USE_GITHUB)
+      ? normalizeGithubModelsApiModel(requestedModel)
+      : descriptor.baseModel
+
   return {
     transport,
     requestedModel,
-    resolvedModel: descriptor.baseModel,
+    resolvedModel,
     baseUrl:
       (rawBaseUrl ??
         (transport === 'codex_responses'