[Performance] Optimize outputDebug to skip expensive work when disabled

.jules/bolt.md

@@ -0,0 +1,3 @@
+## 2025-05-14 - Optimize outputDebug to skip expensive string construction
+**Learning:** outputDebug always constructs a timestamped message even when debug logging is disabled. This involves calling `new Date().toISOString()` and string concatenation, which is wasteful in the hot path of logging.
+**Action:** Add an early return in `outputDebug` using `shouldOutput('debug')` to skip work when not in verbose mode.

packages/cli-kit/src/public/node/output.ts

@@ -313,6 +313,8 @@ export function outputCompleted(content: OutputMessage, logger: Logger = console
  */
 export function outputDebug(content: OutputMessage, logger: Logger = consoleWarn): void {
   if (isUnitTest()) collectLog('debug', content)
+  if (!shouldOutput('debug')) return
+
   const message = colors.gray(stringifyMessage(content))
   outputWhereAppropriate('debug', logger, `${new Date().toISOString()}: ${message}`)
 }