--- title: Active Component Import Verification — Check Which File Is Actually Rendered source: daily/2026-05-10.md updated: 2026-05-10 tags: [react, next.js, debugging, workflow] --- # Active Component Import Verification — Check Which File Is Actually Rendered ## The Pattern Before editing a component file, verify it is the one the app actually imports and renders. Editing the wrong file wastes multiple edit cycles with no visible change in the browser. ## The Bug (Shumiland Case Study) A project had two header files: - `src/components/Header.tsx` — unused legacy file - `src/components/HeaderClient.tsx` — the actual rendered component All edits went to `Header.tsx` because it was found first by glob. The app imports `HeaderClient.tsx` exclusively. The browser never changed. ## How to Verify Before Editing ```bash # Find who imports the component you want to change grep -r "import.*Header" src/ --include="*.tsx" --include="*.ts" # Or trace from the page/layout file downward grep -r "Header" src/app/ --include="*.tsx" ``` In Claude Code, use Grep to check the import chain: ``` pattern: "import.*Header|from.*Header" path: src/ ``` ## Rule **When a component name has multiple matching files, always grep for which one is imported before editing.** Common patterns that cause this: - `Header.tsx` vs `HeaderClient.tsx` (React Server Component split) - `Button.tsx` vs `ButtonBase.tsx` - `Layout.tsx` vs `RootLayout.tsx` - `index.tsx` barrel files that re-export a different file ## Cost of Getting This Wrong Each wasted edit cycle = reading the file, editing, checking browser, realizing nothing changed, investigating. In a long context window this compounds quickly and causes false conclusions ("the CSS must be wrong" when the file was never rendered at all).