feat: add validation to prevent secret names starting with GITHUB_

lib/config/__tests__/config.test.ts

@@ -105,6 +105,18 @@ describe('Configuration System', () => {
         result.warnings.some(warning => warning.includes('placeholder'))
       ).toBe(true)
     })
+
+    it('should fail validation with GITHUB_ prefix in variable names', () => {
+      process.env.GITHUB_SECRET = 'some-secret-value'
+
+      const result = validateConfiguration()
+      expect(result.success).toBe(false)
+      expect(
+        result.errors.some(error => 
+          error.includes('Secret names must not start with GITHUB_')
+        )
+      ).toBe(true)
+    })
   })
 
   describe('Environment-Specific Configuration', () => {

lib/config/env.ts

@@ -185,6 +185,16 @@ export type StagingEnvConfig = z.infer<typeof stagingEnvSchema>
 export function validateEnv(): EnvConfig {
   const env = process.env
 
+  // Check for reserved GITHUB_ prefix in environment variable names
+  const githubPrefixedVars = Object.keys(env).filter(key => key.startsWith('GITHUB_'))
+  if (githubPrefixedVars.length > 0) {
+    throw new Error(
+      `Environment validation failed:\nSecret names must not start with GITHUB_ as this prefix is reserved by GitHub.\n` +
+      `Found variables: ${githubPrefixedVars.join(', ')}\n\n` +
+      `Please rename these variables to use a different prefix.`
+    )
+  }
+
   // Choose schema based on environment (use APP_ENV for staging detection)
   const appEnv = env.APP_ENV || env.NODE_ENV
   let schema: z.ZodSchema