fix(cli): respect rsc: false and avoid adding 'use client' directive

[Juussticee]

Fix: Remove Stateful Regex Bug in transform-rsc (Fixes #8991)

Problem

The transformRsc function uses a global regex with .test() method, which maintains state in the regex's lastIndex property. This causes the directive removal to alternate between working and not working on successive component installations.

Symptom: When rsc: false is configured, components are installed inconsistently:

• Component 1: ✓ "use client" removed correctly
• Component 2: ✗ "use client" NOT removed (BUG)
• Component 3: ✓ "use client" removed correctly
• Component 4: ✗ "use client" NOT removed (BUG)
• Pattern: ✓ ✗ ✓ ✗ ✓ ✗ (alternating)

Root Cause

// BEFORE (Broken)
const directiveRegex = /^["']use client["']$/g  // Global flag + .test() = stateful!

if (first && directiveRegex.test(first.getText())) {  // State maintained in lastIndex
  first.remove()
}

On first call: .test() returns true, advances lastIndex to end
On second call: lastIndex is at end, .test() returns false (resets to 0 internally after match failure)
On third call: lastIndex is 0 again, .test() returns true
→ Alternating behavior

Solution

Replace the stateful regex with simple string comparison:

// AFTER (Fixed)
const text = first.getText().trim()
if (text === '"use client"' || text === "'use client'") {
  first.remove()
}

Advantages:

• No state management
• No regex parsing overhead
• Handles both quote styles
• Clearer intent and more maintainable

Changes Made

File: packages/shadcn/src/utils/transformers/transform-rsc.ts

• Removed: const directiveRegex = /^["']use client["']$/g
• Changed: Condition from regex test to string comparison
• Added: .trim() for whitespace handling
• Result: 6 lines modified

File: packages/shadcn/test/utils/transform-rsc.test.ts

• Added: Comprehensive regression test "transform rsc - sequential calls (regression test for [bug]: CLI ignores rsc: false setting and adds "use client" directive #8991)"
• Coverage: 5 sequential transformations with both quote styles
• Purpose: Prevents future regressions of stateful regex patterns

Testing

✅ Targeted test pass:

pnpm --filter shadcn test -- test/utils/transform-rsc.test.ts
✓ test/utils/transform-rsc.test.ts (2 tests)
  ✓ transform rsc
  ✓ transform rsc - sequential calls (regression test for #8991)

✅ Build success:

pnpm --filter shadcn build
→ No TypeScript errors
→ dist/ artifacts generated successfully

Impact Analysis

• Breaking Changes: None (API unchanged, only fixes broken behavior)
• Backward Compatibility: ✓ Full (only fixes when rsc: false is used)
• Side Effects: None (isolated to transform-rsc.ts; no other files affected)
• Dependencies: No new dependencies added
• Guidelines Compliance: Follows shadcn conventions (minimal, focused change)

Before & After

Before (Broken):

npx shadcn add accordion   → ✓ OK (no "use client")
npx shadcn add alert       → ✗ BROKEN (includes "use client" when it shouldn't)
npx shadcn add button      → ✓ OK (no "use client")
npx shadcn add card        → ✗ BROKEN (includes "use client" when it shouldn't)

After (Fixed):

npx shadcn add accordion   → ✓ OK (no "use client")
npx shadcn add alert       → ✓ OK (no "use client")
npx shadcn add button      → ✓ OK (no "use client")
npx shadcn add card        → ✓ OK (no "use client")

Related Issue

Fixes #8991: "CLI ignores rsc: false setting and adds "use client" directive"

Checklist

• [] Code follows project style guidelines
• [] TypeScript compiles without errors
• [] Tests added for regression prevention
• [] Existing tests still pass
• [] No new dependencies added
• [] Changes are minimal and focused
• [] Documentation updated (comments explain the fix)
• [] Backward compatible

[vercel]

@Juussticee is attempting to deploy a commit to the shadcn-pro Team on Vercel.

A member of the Team first needs to authorize it.