From e482d1ef943519aab59d35144cb2edc00e0f5330 Mon Sep 17 00:00:00 2001
From: leiserfg <leiserfg@gmail.com>
Date: Fri, 15 May 2026 09:31:58 +0200
Subject: [PATCH] Extract prek builtin hooks

---
 modules/pre-commit.nix | 48 +++++++++++++++++++++++++++++++++++-------
 1 file changed, 40 insertions(+), 8 deletions(-)

diff --git a/modules/pre-commit.nix b/modules/pre-commit.nix
index 75f71c11..b39c2fcf 100644
--- a/modules/pre-commit.nix
+++ b/modules/pre-commit.nix
@@ -36,7 +36,7 @@ let
         (builtins.attrValues enabledHooks);
     in
     if sortedHooks ? result then
-      builtins.map (value: value.raw) sortedHooks.result
+      sortedHooks.result
     else
       let
         getIds = builtins.map (value: value.id);
@@ -61,6 +61,33 @@ let
 
           ${prettyPrintCycle { indent = "  "; } sortedHooks.cycle}
       '';
+  _prekBuiltins =
+    if usingPrek then
+      builtins.filter (s: s != "") (builtins.split "\n" (
+        builtins.readFile (
+          pkgs.runCommand "prek-builtins.txt"
+            {
+              buildInputs = [ cfg.package ];
+              PREK_HOME = "/tmp/"; # This is to avoid prek trying to create ~/.cache/prek/
+            }
+            ''${lib.getExe cfg.package} util list-builtins > $out''
+        )
+      ))
+    else
+      [ ];
+
+  _is_builtin =
+    {
+      package,
+      name,
+      ...
+    }:
+    usingPrek && (package.pname == "pre-commit-hooks") && (builtins.elem name _prekBuiltins);
+
+  _partitioned = builtins.partition _is_builtin processedHooks;
+
+  builtinHooks = builtins.map (value: builtins.removeAttrs value.raw [ "entry" ]) _partitioned.right;
+  localHooks = builtins.map (value: value.raw) _partitioned.wrong;
 
   configFile =
     performAssertions (
@@ -455,13 +482,18 @@ in
 
     rawConfig =
       {
-        repos =
-          [
-            {
-              repo = "local";
-              hooks = processedHooks;
-            }
-          ];
+        repos = [
+          {
+            repo = "local";
+            hooks = localHooks;
+          }
+        ]
+        ++ lib.optionals (builtinHooks != [ ]) [
+          {
+            repo = "builtin";
+            hooks = builtinHooks;
+          }
+        ];
       } // lib.optionalAttrs (cfg.excludes != [ ]) {
         exclude = mergeExcludes cfg.excludes;
       } // lib.optionalAttrs (cfg.default_stages != [ ]) {