From e423d13fca941aacafe98753a75a75589c71ef05 Mon Sep 17 00:00:00 2001
From: shulaoda <165626830+shulaoda@users.noreply.github.com>
Date: Sat, 4 Jul 2026 17:03:52 +0800
Subject: [PATCH] fix(migrate): emit a single --check when rewriting prettier
 scripts

---
 crates/vite_migration/src/prettier.rs       | 9 +++++++++
 crates/vite_migration/src/script_rewrite.rs | 9 ++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/crates/vite_migration/src/prettier.rs b/crates/vite_migration/src/prettier.rs
index db4ad7b0a1..d4505cb68d 100644
--- a/crates/vite_migration/src/prettier.rs
+++ b/crates/vite_migration/src/prettier.rs
@@ -225,6 +225,15 @@ mod tests {
             rewrite_prettier_script("prettier --check --list-different ."),
             "vp fmt --check ."
         );
+
+        // --list-different + --check (the other order) → still a single --check
+        assert_eq!(
+            rewrite_prettier_script("prettier --list-different --check ."),
+            "vp fmt --check ."
+        );
+
+        // two literal --check → still a single --check
+        assert_eq!(rewrite_prettier_script("prettier --check --check ."), "vp fmt --check .");
     }
 
     #[test]
diff --git a/crates/vite_migration/src/script_rewrite.rs b/crates/vite_migration/src/script_rewrite.rs
index 64cdd60144..753ed60f4c 100644
--- a/crates/vite_migration/src/script_rewrite.rs
+++ b/crates/vite_migration/src/script_rewrite.rs
@@ -497,7 +497,14 @@ fn strip_flags_from_suffix(
                     break;
                 }
                 if val == conv.dedup_flag {
-                    conversion_emitted[ci] = true;
+                    // Drop a duplicate if the target flag was already emitted;
+                    // otherwise keep this one and mark it emitted.
+                    if conversion_emitted[ci] {
+                        converted = true;
+                    } else {
+                        conversion_emitted[ci] = true;
+                    }
+                    break;
                 }
             }
             if converted {