chore: flatten src/ to root

utils/extraUsage.ts

@@ -0,0 +1,23 @@
+import { isClaudeAISubscriber } from './auth.js'
+import { has1mContext } from './context.js'
+
+export function isBilledAsExtraUsage(
+  model: string | null,
+  isFastMode: boolean,
+  isOpus1mMerged: boolean,
+): boolean {
+  if (!isClaudeAISubscriber()) return false
+  if (isFastMode) return true
+  if (model === null || !has1mContext(model)) return false
+
+  const m = model
+    .toLowerCase()
+    .replace(/\[1m\]$/, '')
+    .trim()
+  const isOpus46 = m === 'opus' || m.includes('opus-4-6')
+  const isSonnet46 = m === 'sonnet' || m.includes('sonnet-4-6')
+
+  if (isOpus46 && isOpus1mMerged) return false
+
+  return isOpus46 || isSonnet46
+}