diff --git a/src/config/reserved-names.ts b/src/config/reserved-names.ts
index 657e5d78..25262265 100644
--- a/src/config/reserved-names.ts
+++ b/src/config/reserved-names.ts
@@ -9,6 +9,8 @@ export const RESERVED_PROFILE_NAMES = [
   'agy',
   'qwen',
   'iflow',
+  // Copilot API (GitHub Copilot proxy)
+  'copilot',
   // CLI commands and special names
   'default',
   'config',
diff --git a/src/config/unified-config-loader.ts b/src/config/unified-config-loader.ts
index 04394694..72f27ceb 100644
--- a/src/config/unified-config-loader.ts
+++ b/src/config/unified-config-loader.ts
@@ -14,6 +14,7 @@ import {
   isUnifiedConfig,
   createEmptyUnifiedConfig,
   UNIFIED_CONFIG_VERSION,
+  DEFAULT_COPILOT_CONFIG,
 } from './unified-config-types';
 import { isUnifiedConfigEnabled } from './feature-flags';
 
@@ -159,6 +160,16 @@ function mergeWithDefaults(partial: Partial<UnifiedConfig>): UnifiedConfig {
       // Legacy fields (keep for backwards compatibility during read)
       gemini: partial.websearch?.gemini,
     },
+    // Copilot config - strictly opt-in, merge with defaults
+    copilot: {
+      enabled: partial.copilot?.enabled ?? DEFAULT_COPILOT_CONFIG.enabled,
+      auto_start: partial.copilot?.auto_start ?? DEFAULT_COPILOT_CONFIG.auto_start,
+      port: partial.copilot?.port ?? DEFAULT_COPILOT_CONFIG.port,
+      account_type: partial.copilot?.account_type ?? DEFAULT_COPILOT_CONFIG.account_type,
+      rate_limit: partial.copilot?.rate_limit ?? DEFAULT_COPILOT_CONFIG.rate_limit,
+      wait_on_limit: partial.copilot?.wait_on_limit ?? DEFAULT_COPILOT_CONFIG.wait_on_limit,
+      model: partial.copilot?.model ?? DEFAULT_COPILOT_CONFIG.model,
+    },
   };
 }
 
@@ -302,6 +313,27 @@ function generateYamlWithComments(config: UnifiedConfig): string {
     lines.push('');
   }
 
+  // Copilot section (GitHub Copilot proxy)
+  if (config.copilot) {
+    lines.push('# ----------------------------------------------------------------------------');
+    lines.push('# Copilot: GitHub Copilot API proxy (via copilot-api)');
+    lines.push('# Uses your existing GitHub Copilot subscription with Claude Code.');
+    lines.push('#');
+    lines.push('# WARNING: This uses a reverse-engineered API. Use responsibly.');
+    lines.push('# Excessive automated usage may trigger GitHub abuse detection.');
+    lines.push('#');
+    lines.push('# Setup: npx copilot-api auth (authenticate with GitHub)');
+    lines.push('# Usage: ccs copilot (switch to copilot profile)');
+    lines.push('#');
+    lines.push('# Models: claude-opus-4-5-20250514, claude-sonnet-4-20250514, gpt-4.1, o3');
+    lines.push('# Account types: individual, business, enterprise');
+    lines.push('# ----------------------------------------------------------------------------');
+    lines.push(
+      yaml.dump({ copilot: config.copilot }, { indent: 2, lineWidth: -1, quotingType: '"' }).trim()
+    );
+    lines.push('');
+  }
+
   return lines.join('\n');
 }
 
diff --git a/src/config/unified-config-types.ts b/src/config/unified-config-types.ts
index 75cbfe31..0834ad48 100644
--- a/src/config/unified-config-types.ts
+++ b/src/config/unified-config-types.ts
@@ -13,8 +13,9 @@
  * Unified config version.
  * Version 2 = YAML unified format
  * Version 3 = WebSearch config with model configuration for Gemini/OpenCode
+ * Version 4 = Copilot API integration (GitHub Copilot proxy)
  */
-export const UNIFIED_CONFIG_VERSION = 3;
+export const UNIFIED_CONFIG_VERSION = 4;
 
 /**
  * Account configuration (formerly in profiles.json).
@@ -148,6 +149,36 @@ export interface WebSearchProvidersConfig {
   opencode?: OpenCodeWebSearchConfig;
 }
 
+/**
+ * Copilot API account type.
+ */
+export type CopilotAccountType = 'individual' | 'business' | 'enterprise';
+
+/**
+ * Copilot API configuration.
+ * Enables GitHub Copilot subscription usage via copilot-api proxy.
+ * Strictly opt-in - disabled by default.
+ *
+ * WARNING: This uses a reverse-engineered API. Excessive automated usage
+ * may trigger GitHub's abuse-detection systems.
+ */
+export interface CopilotConfig {
+  /** Enable Copilot integration (default: false) - must be explicitly enabled */
+  enabled: boolean;
+  /** Auto-start copilot-api daemon when using profile (default: false) */
+  auto_start: boolean;
+  /** Port for copilot-api proxy (default: 4141) */
+  port: number;
+  /** GitHub Copilot account type (default: individual) */
+  account_type: CopilotAccountType;
+  /** Rate limit in seconds between requests (null = no limit) */
+  rate_limit: number | null;
+  /** Wait instead of error when rate limit is hit (default: true) */
+  wait_on_limit: boolean;
+  /** Selected model (default: claude-opus-4-5-20250514) */
+  model: string;
+}
+
 /**
  * WebSearch configuration.
  * Uses CLI tools (Gemini CLI, Grok CLI, OpenCode) for third-party profiles.
@@ -183,7 +214,7 @@ export interface WebSearchConfig {
  * Stored in ~/.ccs/config.yaml
  */
 export interface UnifiedConfig {
-  /** Config version (2 for unified format) */
+  /** Config version (4 for copilot support) */
   version: number;
   /** Default profile name to use when none specified */
   default?: string;
@@ -197,6 +228,8 @@ export interface UnifiedConfig {
   preferences: PreferencesConfig;
   /** WebSearch configuration */
   websearch?: WebSearchConfig;
+  /** Copilot API configuration (GitHub Copilot proxy) */
+  copilot?: CopilotConfig;
 }
 
 /**
@@ -211,6 +244,20 @@ export interface SecretsConfig {
   profiles: Record<string, Record<string, string>>;
 }
 
+/**
+ * Default Copilot configuration.
+ * Strictly opt-in - disabled by default.
+ */
+export const DEFAULT_COPILOT_CONFIG: CopilotConfig = {
+  enabled: false,
+  auto_start: false,
+  port: 4141,
+  account_type: 'individual',
+  rate_limit: null,
+  wait_on_limit: true,
+  model: 'claude-opus-4-5-20250514',
+};
+
 /**
  * Create an empty unified config with defaults.
  */
@@ -253,6 +300,7 @@ export function createEmptyUnifiedConfig(): UnifiedConfig {
         },
       },
     },
+    copilot: { ...DEFAULT_COPILOT_CONFIG },
   };
 }