fix: prevent @tailwindcss/upgrade from rewriting node_modules when run from subdirectory

[deepshekhardas]

Cherry-pick of PR #20329

[greptile-apps]

Confidence Score: 3/5

The CSS analysis path is correctly fixed, but the template migration path in index.ts uses the same unfixed pattern and could rewrite files inside ignored directories when the tool is run from a subdirectory.

The fix addresses the reported scenario but leaves an identical isGitIgnored call in index.ts at line 46 unfixed, which guards template file migration with the same potentially broken predicate when run from a subdirectory. The new integration test uses source(none) so this gap is not caught.

packages/@tailwindcss-upgrade/src/index.ts — the isGitIgnored call at line 46 needs the same gitRoot treatment applied in analyze.ts.

_{Reviews (1): Last reviewed commit: "update CHANGELOG" | Re-trigger Greptile}

[coderabbitai]

Walkthrough

The upgrade flow now passes its base directory into stylesheet analysis. Analysis resolves the Git repository root with git rev-parse --show-toplevel and uses it when checking ignored files, falling back to the base directory outside a repository. A regression test covers running the upgrade from a nested workspace directory with a root .gitignore, and the changelog documents the fix.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main fix: avoiding node_modules rewrites when running from a subdirectory.
Description check	✅ Passed	The description is related to the change set because it notes this is a cherry-pick of the same fix.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

⚔️ Resolve merge conflicts

• Resolve merge conflict in branch fix/upgrade-node-modules

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[coderabbitai]

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (2)

packages/@tailwindcss-upgrade/src/index.ts (2)

44-46: 🎯 Functional Correctness | 🟠 Major | ⚡ Quick win

Respect the repo-root .gitignore for template files.

The PR successfully updates analyze.ts to use gitRoot(base) so that the repository root's .gitignore rules are applied. However, isIgnored in this file is still initialized with { cwd: base }.

This means that when upgrading from a subpackage, template files that should be ignored by the root .gitignore (e.g., build outputs in a dist/ folder) will still be scanned and incorrectly migrated.

Update the initialization to match analyze.ts (and remember to add import { gitRoot } from './utils/git' to your imports):

🐛 Proposed fix

 async function run() {
   let base = process.cwd()
-  let isIgnored = await isGitIgnored({ cwd: base })
+  let isIgnored = await isGitIgnored({ cwd: gitRoot(base) ?? base })

---

105-106: 🎯 Functional Correctness | 🟠 Major | ⚡ Quick win

Filter discovered CSS files to respect repo-root ignores.

The globby call above uses gitignore: true, which resolves .gitignore files starting from cwd (base). When base is a subpackage, globby will not see the repository root's .gitignore.

Because analyze.ts seeds these initial stylesheets directly into its processing map without verifying them against isIgnored, any git-ignored CSS files (like dist/out.css) discovered here will be incorrectly mutated.

Filter the discovered files using the properly initialized isIgnored helper. It's best to apply this filter inside the if (files.length === 0) block to ensure that files explicitly passed as CLI arguments are still upgraded.

🐛 Proposed fix

         // gitignore: true will first search for all .gitignore including node_modules folders, this makes the initial search much faster
         ignore: ['**/node_modules/**'],
       })
+
+      files = files.filter((file) => {
+        try {
+          return !isIgnored(file)
+        } catch {
+          return false
+        }
+      })
     }

🧹 Nitpick comments (1)

integrations/upgrade/index.test.ts (1)

3405-3410: 📐 Maintainability & Code Quality | 🔵 Trivial | ⚡ Quick win

Add coverage for non-node_modules ignored files.

This test successfully verifies that @imported files inside node_modules are ignored. However, because node_modules is already hardcoded in the globby ignore list in index.ts (ignore: ['**/node_modules/**']), this test setup doesn't catch cases where other git-ignored files (like a dist/ folder containing generated CSS or HTML templates) are incorrectly discovered and processed when upgrading from a nested directory.

To ensure comprehensive coverage of the root .gitignore logic across both CSS discovery and template scanning, consider adding a dummy file in a dist/ directory, ignoring dist/ in this .gitignore, and asserting that the dist/ file remains unchanged.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 7c5d8ca8-d57a-443e-9993-c4886d7f58bf

📥 Commits

Reviewing files that changed from the base of the PR and between bdcd708 and eb97c9a.

📒 Files selected for processing (5)

• CHANGELOG.md
• integrations/upgrade/index.test.ts
• packages/@tailwindcss-upgrade/src/codemods/css/analyze.ts
• packages/@tailwindcss-upgrade/src/index.ts
• packages/@tailwindcss-upgrade/src/utils/git.ts