From a14eb6cba0170454c4a3ae6cb6a98c1e2268c426 Mon Sep 17 00:00:00 2001
From: Carson McManus <carson.mcmanus1@gmail.com>
Date: Fri, 27 Feb 2026 12:14:17 -0500
Subject: [PATCH] fix(noVueDuplicateKeys): fix false positives when keys are
 defined in `watch`

---
 .changeset/quick-hands-show.md                |  5 ++++
 .../lint/correctness/no_vue_duplicate_keys.rs |  4 ++-
 .../noVueDuplicateKeys/valid-watch.vue        | 25 +++++++++++++++++
 .../noVueDuplicateKeys/valid-watch.vue.snap   | 27 +++++++++++++++++++
 4 files changed, 60 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/quick-hands-show.md
 create mode 100644 crates/biome_js_analyze/tests/specs/correctness/noVueDuplicateKeys/valid-watch.vue
 create mode 100644 crates/biome_js_analyze/tests/specs/correctness/noVueDuplicateKeys/valid-watch.vue.snap

diff --git a/.changeset/quick-hands-show.md b/.changeset/quick-hands-show.md
new file mode 100644
index 000000000000..095bc27a70fe
--- /dev/null
+++ b/.changeset/quick-hands-show.md
@@ -0,0 +1,5 @@
+---
+"@biomejs/biome": patch
+---
+
+Fixed [#9250](https://github.com/biomejs/biome/issues/9250): `noVueDuplicateKeys` will no longer flag keys under `watch`, preventing false positives.
diff --git a/crates/biome_js_analyze/src/lint/correctness/no_vue_duplicate_keys.rs b/crates/biome_js_analyze/src/lint/correctness/no_vue_duplicate_keys.rs
index 903e1207672b..16a461c9f69b 100644
--- a/crates/biome_js_analyze/src/lint/correctness/no_vue_duplicate_keys.rs
+++ b/crates/biome_js_analyze/src/lint/correctness/no_vue_duplicate_keys.rs
@@ -138,7 +138,9 @@ impl Rule for NoVueDuplicateKeys {
         let mut key_declarations: FxHashMap<String, Vec<VueDeclaration>> = FxHashMap::default();
 
         // Collect all declarations across all Vue component sections
-        for declaration in component.declarations(VueDeclarationCollectionFilter::all()) {
+        for declaration in component.declarations(
+            VueDeclarationCollectionFilter::all() ^ VueDeclarationCollectionFilter::Watcher,
+        ) {
             if let Some(name) = declaration.declaration_name() {
                 // Handle cases like `const { foo } = defineProps(...);`.
                 if let VueDeclaration::Setup(ref setup_decl) = declaration
diff --git a/crates/biome_js_analyze/tests/specs/correctness/noVueDuplicateKeys/valid-watch.vue b/crates/biome_js_analyze/tests/specs/correctness/noVueDuplicateKeys/valid-watch.vue
new file mode 100644
index 000000000000..6aff95ac0ee4
--- /dev/null
+++ b/crates/biome_js_analyze/tests/specs/correctness/noVueDuplicateKeys/valid-watch.vue
@@ -0,0 +1,25 @@
+<template>
+  <div>This is valid because this is how you declare watchers in Vue. The child keys of `watch` define which properties/variables to watch, and they are not declarations.</div>
+</template>
+
+<script>
+	export default {
+		name: 'QFormContainer',
+		props: {
+			formData: {
+				type: Object,
+				default: () => ({}),
+				validator: (val) => true
+			},
+		},
+		watch: {
+			formData: {
+				handler(newValue)
+				{
+					//do things
+				},
+				deep: true
+			}
+		}
+	}
+</script>
diff --git a/crates/biome_js_analyze/tests/specs/correctness/noVueDuplicateKeys/valid-watch.vue.snap b/crates/biome_js_analyze/tests/specs/correctness/noVueDuplicateKeys/valid-watch.vue.snap
new file mode 100644
index 000000000000..8ae731892fc6
--- /dev/null
+++ b/crates/biome_js_analyze/tests/specs/correctness/noVueDuplicateKeys/valid-watch.vue.snap
@@ -0,0 +1,27 @@
+---
+source: crates/biome_js_analyze/tests/spec_tests.rs
+expression: valid-watch.vue
+---
+# Input
+```ts
+	export default {
+		name: 'QFormContainer',
+		props: {
+			formData: {
+				type: Object,
+				default: () => ({}),
+				validator: (val) => true
+			},
+		},
+		watch: {
+			formData: {
+				handler(newValue)
+				{
+					//do things
+				},
+				deep: true
+			}
+		}
+	}
+
+```