diff --git a/crates/ide/src/def/kind.rs b/crates/ide/src/def/kind.rs
new file mode 100644
index 0000000..056f074
--- /dev/null
+++ b/crates/ide/src/def/kind.rs
@@ -0,0 +1,76 @@
+use std::collections::HashMap;
+use std::sync::Arc;
+
+use smol_str::SmolStr;
+
+use crate::{DefDatabase, FileId, Module};
+
+use super::{BindingValue, Expr, NameId};
+
+/// Guessed kind of a nix file.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ModuleKind {
+    /// Uncatagorized or ambiguous.
+    Unknown,
+    /// Flake definition `flake.nix`.
+    FlakeNix {
+        /// Explicit inputs defined in top-level `inputs`.
+        explicit_inputs: HashMap<SmolStr, NameId>,
+        /// Implicit inputs introduced in the pat-parameter of `outputs`.
+        /// NB. `self` parameter is special and is excluded here.
+        param_inputs: HashMap<SmolStr, NameId>,
+    },
+}
+
+impl ModuleKind {
+    pub(crate) fn module_kind_query(db: &dyn DefDatabase, file_id: FileId) -> Arc<ModuleKind> {
+        let module = db.module(file_id);
+
+        // Check if it is the flake definition. This is always accurate.
+        if let Some(flake_info) = db.source_root_flake_info(db.file_source_root(file_id)) {
+            if flake_info.flake_file == file_id {
+                return Arc::new(parse_flake_nix(&module));
+            }
+        }
+
+        Arc::new(ModuleKind::Unknown)
+    }
+}
+
+fn parse_flake_nix(module: &Module) -> ModuleKind {
+    let mut explicit_inputs = HashMap::new();
+    let mut param_inputs = HashMap::new();
+    if let Expr::Attrset(flake_set) = &module[module.entry_expr()] {
+        for &(name_id, value) in flake_set.statics.iter() {
+            let BindingValue::Expr(value_expr) = value else { continue };
+            match &*module[name_id].text {
+                "inputs" => {
+                    let Expr::Attrset(inputs) = &module[value_expr] else { continue };
+                    explicit_inputs = inputs
+                        .statics
+                        .iter()
+                        .map(|&(input_name_id, _)| {
+                            (module[input_name_id].text.clone(), input_name_id)
+                        })
+                        .collect();
+                }
+                "outputs" => {
+                    let Expr::Lambda(_, Some(pat), _) = &module[value_expr] else { continue };
+                    param_inputs = pat
+                        .fields
+                        .iter()
+                        .filter_map(|&(name_id, _)| name_id)
+                        .map(|name_id| (module[name_id].text.clone(), name_id))
+                        // Exclude `self`.
+                        .filter(|(name, _)| name != "self")
+                        .collect();
+                }
+                _ => {}
+            }
+        }
+    }
+    ModuleKind::FlakeNix {
+        explicit_inputs,
+        param_inputs,
+    }
+}
diff --git a/crates/ide/src/def/mod.rs b/crates/ide/src/def/mod.rs
index 658de6d..5eb4a56 100644
--- a/crates/ide/src/def/mod.rs
+++ b/crates/ide/src/def/mod.rs
@@ -1,3 +1,4 @@
+mod kind;
 mod liveness;
 mod lower;
 mod nameres;
@@ -18,6 +19,7 @@ use std::ops;
 use std::sync::Arc;
 use syntax::Parse;
 
+pub use self::kind::ModuleKind;
 pub use self::liveness::LivenessCheckResult;
 pub use self::nameres::{
     ModuleScopes, NameReference, NameResolution, ResolveResult, ScopeData, ScopeId,
@@ -38,6 +40,7 @@ pub trait DefDatabase: SourceDatabase {
 
     fn source_map(&self, file_id: FileId) -> Arc<ModuleSourceMap>;
 
+    #[salsa::invoke(ModuleKind::module_kind_query)]
     fn module_kind(&self, file_id: FileId) -> Arc<ModuleKind>;
 
     #[salsa::invoke(Module::module_references_query)]
@@ -407,65 +410,3 @@ impl Bindings {
             .find_map(|&(name_id, value)| (module[name_id].text == name).then_some(value))
     }
 }
-
-/// Guessed kind of a nix file.
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub enum ModuleKind {
-    /// Uncatagorized or ambiguous.
-    Unknown,
-    /// Flake definition `flake.nix`.
-    FlakeNix {
-        /// Explicit inputs defined in top-level `inputs`.
-        explicit_inputs: HashMap<SmolStr, NameId>,
-        /// Implicit inputs introduced in the pat-parameter of `outputs`.
-        /// NB. `self` parameter is special and is excluded here.
-        param_inputs: HashMap<SmolStr, NameId>,
-    },
-}
-
-fn module_kind(db: &dyn DefDatabase, file_id: FileId) -> Arc<ModuleKind> {
-    let module = db.module(file_id);
-
-    // Check if it is the flake definition. This is always accurate.
-    if let Some(flake_info) = db.source_root_flake_info(db.file_source_root(file_id)) {
-        if flake_info.flake_file == file_id {
-            let mut explicit_inputs = HashMap::new();
-            let mut param_inputs = HashMap::new();
-            if let Expr::Attrset(flake_set) = &module[module.entry_expr()] {
-                for &(name_id, value) in flake_set.statics.iter() {
-                    let BindingValue::Expr(value_expr) = value else { continue };
-                    match &*module[name_id].text {
-                        "inputs" => {
-                            let Expr::Attrset(inputs) = &module[value_expr] else { continue };
-                            explicit_inputs = inputs
-                                .statics
-                                .iter()
-                                .map(|&(input_name_id, _)| {
-                                    (module[input_name_id].text.clone(), input_name_id)
-                                })
-                                .collect();
-                        }
-                        "outputs" => {
-                            let Expr::Lambda(_, Some(pat), _) = &module[value_expr] else { continue };
-                            param_inputs = pat
-                                .fields
-                                .iter()
-                                .filter_map(|&(name_id, _)| name_id)
-                                .map(|name_id| (module[name_id].text.clone(), name_id))
-                                // Exclude `self`.
-                                .filter(|(name, _)| name != "self")
-                                .collect();
-                        }
-                        _ => {}
-                    }
-                }
-            }
-            return Arc::new(ModuleKind::FlakeNix {
-                explicit_inputs,
-                param_inputs,
-            });
-        }
-    }
-
-    Arc::new(ModuleKind::Unknown)
-}