biomejs · ematipico · Jan 4, 2026 · Dec 27, 2025 · Dec 27, 2025 · Dec 28, 2025
diff --git a/.changeset/free-cars-take.md b/.changeset/free-cars-take.md
@@ -0,0 +1,14 @@
+---
+"@biomejs/biome": patch
+---
+
+Added the nursery rule [`useUniqueEnumValueNames`](https://biomejs.dev/linter/rules/use-unique-enum-value-names/). Enforce unique enum value names.
+
+**Invalid:**
+
+```graphql
+enum A {
+  TEST
+  TesT
+}
+```
diff --git a/crates/biome_configuration/src/analyzer/linter/rules.rs b/crates/biome_configuration/src/analyzer/linter/rules.rs
diff --git a/crates/biome_diagnostics_categories/src/categories.rs b/crates/biome_diagnostics_categories/src/categories.rs
diff --git a/crates/biome_graphql_analyze/src/lint/nursery.rs b/crates/biome_graphql_analyze/src/lint/nursery.rs
@@ -7,8 +7,9 @@ pub mod no_empty_source;
 pub mod use_consistent_graphql_descriptions;
 pub mod use_deprecated_date;
 pub mod use_unique_argument_names;
+pub mod use_unique_enum_value_names;
 pub mod use_unique_field_definition_names;
 pub mod use_unique_graphql_operation_name;
 pub mod use_unique_input_field_names;
 pub mod use_unique_variable_names;
-declare_lint_group! { pub Nursery { name : "nursery" , rules : [self :: no_empty_source :: NoEmptySource , self :: use_consistent_graphql_descriptions :: UseConsistentGraphqlDescriptions , self :: use_deprecated_date :: UseDeprecatedDate , self :: use_unique_argument_names :: UseUniqueArgumentNames , self :: use_unique_field_definition_names :: UseUniqueFieldDefinitionNames , self :: use_unique_graphql_operation_name :: UseUniqueGraphqlOperationName , self :: use_unique_input_field_names :: UseUniqueInputFieldNames , self :: use_unique_variable_names :: UseUniqueVariableNames ,] } }
+declare_lint_group! { pub Nursery { name : "nursery" , rules : [self :: no_empty_source :: NoEmptySource , self :: use_consistent_graphql_descriptions :: UseConsistentGraphqlDescriptions , self :: use_deprecated_date :: UseDeprecatedDate , self :: use_unique_argument_names :: UseUniqueArgumentNames , self :: use_unique_enum_value_names :: UseUniqueEnumValueNames , self :: use_unique_field_definition_names :: UseUniqueFieldDefinitionNames , self :: use_unique_graphql_operation_name :: UseUniqueGraphqlOperationName , self :: use_unique_input_field_names :: UseUniqueInputFieldNames , self :: use_unique_variable_names :: UseUniqueVariableNames ,] } }
diff --git a/crates/biome_graphql_analyze/src/lint/nursery/use_unique_enum_value_names.rs b/crates/biome_graphql_analyze/src/lint/nursery/use_unique_enum_value_names.rs
@@ -0,0 +1,116 @@
+use std::collections::HashSet;
+
+use biome_analyze::{
+    Ast, Rule, RuleDiagnostic, RuleSource, context::RuleContext, declare_lint_rule,
+};
+use biome_console::markup;
+use biome_graphql_syntax::GraphqlEnumTypeDefinition;
+use biome_rowan::{AstNodeList, TextRange};
+use biome_rule_options::use_unique_enum_value_names::UseUniqueEnumValueNamesOptions;
+use biome_string_case::StrOnlyExtension;
+
+declare_lint_rule! {
+    /// Require all enum value names to be unique.
+    ///
+    /// A GraphQL enum type is only valid if all its values are uniquely named.
+    /// The enum value names are case insensitive, meaning `TEST` & `Test` are seen as the same enum value name.
+    ///
+    /// ## Examples
+    ///
+    /// ### Invalid
+    ///
+    /// ```graphql,expect_diagnostic
+    /// enum A {
+    ///   TEST
+    ///   OTHER
+    ///   TEST
+    /// }
+    /// ```
+    ///
+    /// ```graphql,expect_diagnostic
+    /// enum B {
+    ///   TEST
+    ///   TesT
+    /// }
+    /// ```
+    ///
+    /// ### Valid
+    ///
+    /// ```graphql
+    /// enum A {
+    ///   TEST
+    ///   OTHER
+    /// }
+    /// ```
+    ///
+    pub UseUniqueEnumValueNames {
+        version: "next",
+        name: "useUniqueEnumValueNames",
+        language: "graphql",
+        recommended: false,
+        sources: &[RuleSource::EslintGraphql("unique-enum-value-names").same()],
+    }
+}
+
+impl Rule for UseUniqueEnumValueNames {
+    type Query = Ast<GraphqlEnumTypeDefinition>;
+    type State = Vec<TextRange>;
+    type Signals = Option<Self::State>;
+    type Options = UseUniqueEnumValueNamesOptions;
+
+    fn run(ctx: &RuleContext<Self>) -> Self::Signals {
+        let node = ctx.query();
+        // We can't use TokenText (to minimize allocations) because of lowercasing and Cow can't be used in a HashSet
+        let mut found: HashSet<String> = HashSet::new();
+
+        let enum_values = node.enum_values()?;
+        let duplicates: Vec<TextRange> = enum_values
+            .values()
+            .iter()
+            .filter_map(|enum_value| {
+                if let Some(name) = enum_value.value().ok()
+                    && let Some(value_token) = name.value_token().ok()
+                {
+                    let string = value_token.token_text().to_lowercase_cow().to_string();
+                    if found.insert(string) {
+                        return None;
+                    } else {
+                        let range = value_token.text_range();
+                        return Some(range);
+                    }
+                }
+
+                None
+            })
+            .collect();
+
+        if duplicates.is_empty() {
+            None
+        } else {
+            Some(duplicates)
+        }
+    }
+
+    fn diagnostic(_ctx: &RuleContext<Self>, state: &Self::State) -> Option<RuleDiagnostic> {
+        let mut diagnostic = RuleDiagnostic::new(
+            rule_category!(),
+            state.first()?,
+            markup! {
+               "Duplicate enum value name."
+            },
+        );
+
+        for range in &state[1..] {
+            diagnostic = diagnostic.detail(
+                range,
+                markup! {
+                    "Another duplicate enum value."
+                },
+            );
+        }
+
+        Some(diagnostic.note(markup! {
+            "A GraphQL enum type is only valid if all its values are uniquely named. Make sure to name every enum value differently."
+        }))
+    }
+}
diff --git a/crates/biome_graphql_analyze/tests/specs/nursery/useUniqueEnumValueNames/invalid.graphql b/crates/biome_graphql_analyze/tests/specs/nursery/useUniqueEnumValueNames/invalid.graphql
@@ -0,0 +1,8 @@
+# should generate diagnostics
+enum A {
+	TEST
+	OTHER
+	TesT
+	ANOTHER
+	Test
+}
diff --git a/...es/biome_graphql_analyze/tests/specs/nursery/useUniqueEnumValueNames/invalid.graphql.snap b/...es/biome_graphql_analyze/tests/specs/nursery/useUniqueEnumValueNames/invalid.graphql.snap
@@ -0,0 +1,49 @@
+---
+source: crates/biome_graphql_analyze/tests/spec_tests.rs
+expression: invalid.graphql
+---
+# Input
+```graphql
+# should generate diagnostics
+enum A {
+	TEST
+	OTHER
+	TesT
+	ANOTHER
+	Test
+}
+
+```
+
+# Diagnostics
+```
+invalid.graphql:4:7 lint/nursery/useUniqueEnumValueNames ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  i Duplicate enum value name.
+
+    2 │ enum A {
+    3 │ 	TEST
+  > 4 │ 	OTHER
+      │ 	     
+  > 5 │ 	TesT
+      │ 	^^^^
+    6 │ 	ANOTHER
+    7 │ 	Test
+
+  i Another duplicate enum value.
+
+    4 │ 	OTHER
+    5 │ 	TesT
+  > 6 │ 	ANOTHER
+      │ 	       
+  > 7 │ 	Test
+      │ 	^^^^
+    8 │ }
+    9 │ 
+
+  i A GraphQL enum type is only valid if all its values are uniquely named. Make sure to name every enum value differently.
+
+  i This rule belongs to the nursery group, which means it is not yet stable and may change in the future. Visit https://biomejs.dev/linter/#nursery for more information.
+
+
+```
diff --git a/crates/biome_graphql_analyze/tests/specs/nursery/useUniqueEnumValueNames/valid.graphql b/crates/biome_graphql_analyze/tests/specs/nursery/useUniqueEnumValueNames/valid.graphql
@@ -0,0 +1,6 @@
+# should not generate diagnostics
+enum A {
+	TEST
+	OTHER
+	ANOTHER
+}
diff --git a/crates/biome_graphql_analyze/tests/specs/nursery/useUniqueEnumValueNames/valid.graphql.snap b/crates/biome_graphql_analyze/tests/specs/nursery/useUniqueEnumValueNames/valid.graphql.snap
@@ -0,0 +1,14 @@
+---
+source: crates/biome_graphql_analyze/tests/spec_tests.rs
+expression: valid.graphql
+---
+# Input
+```graphql
+# should not generate diagnostics
+enum A {
+	TEST
+	OTHER
+	ANOTHER
+}
+
+```
diff --git a/crates/biome_rule_options/src/lib.rs b/crates/biome_rule_options/src/lib.rs
@@ -386,6 +386,7 @@ pub mod use_trim_start_end;
 pub mod use_unified_type_signatures;
 pub mod use_unique_argument_names;
 pub mod use_unique_element_ids;
+pub mod use_unique_enum_value_names;
 pub mod use_unique_field_definition_names;
 pub mod use_unique_graphql_operation_name;
 pub mod use_unique_input_field_names;

diff --git a/crates/biome_rule_options/src/use_unique_enum_value_names.rs b/crates/biome_rule_options/src/use_unique_enum_value_names.rs
@@ -0,0 +1,6 @@
+use biome_deserialize_macros::{Deserializable, Merge};
+use serde::{Deserialize, Serialize};
+#[derive(Default, Clone, Debug, Deserialize, Deserializable, Merge, Eq, PartialEq, Serialize)]
+#[cfg_attr(feature = "schema", derive(schemars::JsonSchema))]
+#[serde(rename_all = "camelCase", deny_unknown_fields, default)]
+pub struct UseUniqueEnumValueNamesOptions {}
diff --git a/justfile b/justfile
@@ -7,6 +7,8 @@ alias r := ready
 alias l := lint
 alias qt := test-quick
 
+set windows-powershell := true
+
 # Installs the tools needed to develop
 install-tools:
 	cargo install cargo-binstall

diff --git a/packages/@biomejs/backend-jsonrpc/src/workspace.ts b/packages/@biomejs/backend-jsonrpc/src/workspace.ts
diff --git a/packages/@biomejs/biome/configuration_schema.json b/packages/@biomejs/biome/configuration_schema.json