diff --git a/src/services/api/claude.ts b/src/services/api/claude.ts
index 053bdb6c..1e924193 100644
--- a/src/services/api/claude.ts
+++ b/src/services/api/claude.ts
@@ -23,6 +23,7 @@ import { randomUUID } from 'crypto'
 import {
   getAPIProvider,
   isFirstPartyAnthropicBaseUrl,
+  isGithubNativeAnthropicMode,
 } from 'src/utils/model/providers.js'
 import {
   getAttributionHeader,
@@ -334,8 +335,13 @@ export function getPromptCachingEnabled(model: string): boolean {
   // Prompt caching is an Anthropic-specific feature. Third-party providers
   // do not understand cache_control blocks and strict backends (e.g. Azure
   // Foundry) reject or flag requests that contain them.
+  //
+  // Exception: when the GitHub provider is configured in native Anthropic API
+  // mode (CLAUDE_CODE_GITHUB_ANTHROPIC_API=1), requests are sent in Anthropic
+  // format, so cache_control blocks are supported.
   const provider = getAPIProvider()
-  if (provider !== 'firstParty' && provider !== 'bedrock' && provider !== 'vertex') {
+  const isNativeGithub = isGithubNativeAnthropicMode(model)
+  if (provider !== 'firstParty' && provider !== 'bedrock' && provider !== 'vertex' && !isNativeGithub) {
     return false
   }
 
diff --git a/src/services/api/client.ts b/src/services/api/client.ts
index dbeb8651..63d90e71 100644
--- a/src/services/api/client.ts
+++ b/src/services/api/client.ts
@@ -14,6 +14,7 @@ import { getSmallFastModel } from 'src/utils/model/model.js'
 import {
   getAPIProvider,
   isFirstPartyAnthropicBaseUrl,
+  isGithubNativeAnthropicMode,
 } from 'src/utils/model/providers.js'
 import { getProxyFetchOptions } from 'src/utils/proxy.js'
 import {
@@ -174,6 +175,25 @@ export async function getAnthropicClient({
       providerOverride,
     }) as unknown as Anthropic
   }
+  // GitHub provider in native Anthropic API mode: send requests in Anthropic
+  // format so cache_control blocks are honoured and prompt caching works.
+  // Requires the GitHub endpoint (OPENAI_BASE_URL) to support Anthropic's
+  // messages API — set CLAUDE_CODE_GITHUB_ANTHROPIC_API=1 to opt in.
+  if (isGithubNativeAnthropicMode(model)) {
+    const githubBaseUrl =
+      process.env.OPENAI_BASE_URL?.replace(/\/$/, '') ??
+      'https://api.githubcopilot.com'
+    const githubToken =
+      process.env.GITHUB_TOKEN ?? process.env.GH_TOKEN ?? ''
+    const nativeArgs: ConstructorParameters<typeof Anthropic>[0] = {
+      ...ARGS,
+      baseURL: githubBaseUrl,
+      authToken: githubToken,
+      // No apiKey — we authenticate via Bearer token (authToken)
+      apiKey: null,
+    }
+    return new Anthropic(nativeArgs)
+  }
   if (
     isEnvTruthy(process.env.CLAUDE_CODE_USE_OPENAI) ||
     isEnvTruthy(process.env.CLAUDE_CODE_USE_GITHUB) ||
diff --git a/src/utils/model/providers.test.ts b/src/utils/model/providers.test.ts
index a8e84069..6e18c98d 100644
--- a/src/utils/model/providers.test.ts
+++ b/src/utils/model/providers.test.ts
@@ -107,3 +107,60 @@ test('official OpenAI base URLs now keep provider detection on openai for aliase
   const { getAPIProvider } = await importFreshProvidersModule()
   expect(getAPIProvider()).toBe('openai')
 })
+
+// isGithubNativeAnthropicMode
+
+test('isGithubNativeAnthropicMode: false when CLAUDE_CODE_USE_GITHUB is not set', async () => {
+  clearProviderEnv()
+  process.env.OPENAI_MODEL = 'claude-sonnet-4-5'
+  const { isGithubNativeAnthropicMode } = await importFreshProvidersModule()
+  expect(isGithubNativeAnthropicMode()).toBe(false)
+})
+
+test('isGithubNativeAnthropicMode: true for bare claude- model via OPENAI_MODEL', async () => {
+  clearProviderEnv()
+  process.env.CLAUDE_CODE_USE_GITHUB = '1'
+  process.env.OPENAI_MODEL = 'claude-sonnet-4-5'
+  const { isGithubNativeAnthropicMode } = await importFreshProvidersModule()
+  expect(isGithubNativeAnthropicMode()).toBe(true)
+})
+
+test('isGithubNativeAnthropicMode: true for github:copilot:claude- compound format', async () => {
+  clearProviderEnv()
+  process.env.CLAUDE_CODE_USE_GITHUB = '1'
+  process.env.OPENAI_MODEL = 'github:copilot:claude-sonnet-4'
+  const { isGithubNativeAnthropicMode } = await importFreshProvidersModule()
+  expect(isGithubNativeAnthropicMode()).toBe(true)
+})
+
+test('isGithubNativeAnthropicMode: true when resolvedModel is a claude- model', async () => {
+  clearProviderEnv()
+  process.env.CLAUDE_CODE_USE_GITHUB = '1'
+  process.env.OPENAI_MODEL = 'github:copilot'
+  const { isGithubNativeAnthropicMode } = await importFreshProvidersModule()
+  expect(isGithubNativeAnthropicMode('claude-haiku-4-5')).toBe(true)
+})
+
+test('isGithubNativeAnthropicMode: false for generic github:copilot alias', async () => {
+  clearProviderEnv()
+  process.env.CLAUDE_CODE_USE_GITHUB = '1'
+  process.env.OPENAI_MODEL = 'github:copilot'
+  const { isGithubNativeAnthropicMode } = await importFreshProvidersModule()
+  expect(isGithubNativeAnthropicMode()).toBe(false)
+})
+
+test('isGithubNativeAnthropicMode: false for non-Claude model', async () => {
+  clearProviderEnv()
+  process.env.CLAUDE_CODE_USE_GITHUB = '1'
+  process.env.OPENAI_MODEL = 'gpt-4o'
+  const { isGithubNativeAnthropicMode } = await importFreshProvidersModule()
+  expect(isGithubNativeAnthropicMode()).toBe(false)
+})
+
+test('isGithubNativeAnthropicMode: false for github:copilot:gpt- model', async () => {
+  clearProviderEnv()
+  process.env.CLAUDE_CODE_USE_GITHUB = '1'
+  process.env.OPENAI_MODEL = 'github:copilot:gpt-4o'
+  const { isGithubNativeAnthropicMode } = await importFreshProvidersModule()
+  expect(isGithubNativeAnthropicMode()).toBe(false)
+})
diff --git a/src/utils/model/providers.ts b/src/utils/model/providers.ts
index 55675cd6..aed15e55 100644
--- a/src/utils/model/providers.ts
+++ b/src/utils/model/providers.ts
@@ -45,6 +45,24 @@ export function getAPIProvider(): APIProvider {
 export function usesAnthropicAccountFlow(): boolean {
   return getAPIProvider() === 'firstParty'
 }
+
+/**
+ * Returns true when the GitHub provider should use Anthropic's native API
+ * format instead of the OpenAI-compatible shim.
+ *
+ * Enabled when CLAUDE_CODE_USE_GITHUB=1 and the model string contains "claude-"
+ * anywhere (handles bare names like "claude-sonnet-4" and compound formats like
+ * "github:copilot:claude-sonnet-4" or any future provider-prefixed variants).
+ *
+ * api.githubcopilot.com supports Anthropic native format for Claude models,
+ * enabling prompt caching via cache_control blocks which significantly reduces
+ * per-turn token costs by caching the system prompt and tool definitions.
+ */
+export function isGithubNativeAnthropicMode(resolvedModel?: string): boolean {
+  if (!isEnvTruthy(process.env.CLAUDE_CODE_USE_GITHUB)) return false
+  const model = resolvedModel?.trim() || process.env.OPENAI_MODEL?.trim() || ''
+  return model.toLowerCase().includes('claude-')
+}
 function isCodexModel(): boolean {
   return shouldUseCodexTransport(
     process.env.OPENAI_MODEL || '',