From b4e1daad3bcd434cf09a42fd0014c5d239c7ceed Mon Sep 17 00:00:00 2001
From: awwpotato <awwpotato@voidq.com>
Date: Wed, 30 Jul 2025 07:12:40 -0700
Subject: [PATCH] ci: request subsystem maintainers review (#1053)

Link: https://github.com/nix-community/stylix/pull/1053

Co-authored-by: NAHO <90870942+trueNAHO@users.noreply.github.com>
Reviewed-by: Daniel Thwaites <danth@danth.me>
Reviewed-by: Matt Sturgeon <matt@sturgeon.me.uk>
Reviewed-by: NAHO <90870942+trueNAHO@users.noreply.github.com>
---
 .github/workflows/request-reviewers.yml | 81 +++++++++++++++++++++++++
 flake/dev/default.nix                   |  3 +-
 flake/dev/subsystem-maintainers.nix     | 17 ++++++
 flake/propagated-packages.nix           |  1 +
 4 files changed, 101 insertions(+), 1 deletion(-)
 create mode 100644 .github/workflows/request-reviewers.yml
 create mode 100644 flake/dev/subsystem-maintainers.nix

diff --git a/.github/workflows/request-reviewers.yml b/.github/workflows/request-reviewers.yml
new file mode 100644
index 00000000..98d2387e
--- /dev/null
+++ b/.github/workflows/request-reviewers.yml
@@ -0,0 +1,81 @@
+---
+name: Request Reviewers
+
+on:
+  pull_request_target:
+    types: [opened, ready_for_review, reopened, synchronize]
+    paths:
+      - 'modules/'
+
+jobs:
+  request-reviewers:
+    runs-on: ubuntu-24.04
+    if: vars.APP_ID
+    steps:
+      - uses: actions/checkout@v4.2.2
+        with:
+          ref: ${{ github.base_ref }}
+
+      - uses: cachix/install-nix-action@v31
+
+      - uses: cachix/cachix-action@v16
+        with:
+          name: nix-community
+          authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
+        continue-on-error: true
+
+      - uses: actions/create-github-app-token@v2
+        id: app-token
+        with:
+          app-id: ${{ vars.APP_ID }}
+          private-key: ${{ secrets.APP_PRIVATE_KEY }}
+          permission-contents: read
+          permission-pull-requests: write
+
+      - run: nix build .#subsystem-maintainers
+
+      - id: get-reviewers
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          MAX_REVIEWERS: 5
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+        run: |
+          printf \
+            'reviewers=%s\n' \
+            "$(
+              gh pr diff --name-only "$PR_NUMBER" |
+                jq \
+                  --argjson max_reviewers "$MAX_REVIEWERS" \
+                  --raw-input \
+                  --raw-output \
+                  --slurp \
+                  --slurpfile maintainers result '
+                    ($maintainers[0] | keys_unsorted) as $subsystems |
+                    split("\n") as $changed_files |
+                    [
+                      $changed_files[] as $changed_file |
+                      (
+                        $maintainers[0][
+                          $subsystems[] |
+                          select(
+                            . as $subsystem |
+                            $changed_file |
+                            startswith($subsystem)
+                          )
+                        ]
+                      )[]
+                    ] |
+                    unique |
+                    if length <= $max_reviewers then
+                      . | join(",")
+                    else
+                      ""
+                    end
+                  '
+            )" \
+            >>"$GITHUB_OUTPUT"
+
+      - uses: AveryCameronUofR/add-reviewer-gh-action@1.0.3
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          reviewers: ${{ steps.get-reviewers.outputs.reviewers }}
diff --git a/flake/dev/default.nix b/flake/dev/default.nix
index 953bcdd2..18075861 100644
--- a/flake/dev/default.nix
+++ b/flake/dev/default.nix
@@ -4,7 +4,8 @@
     ./dev-shell.nix
     ./packages.nix
     ./pre-commit.nix
-    ./treefmt.nix
     ./public-and-dev-version-consistency.nix
+    ./subsystem-maintainers.nix
+    ./treefmt.nix
   ];
 }
diff --git a/flake/dev/subsystem-maintainers.nix b/flake/dev/subsystem-maintainers.nix
new file mode 100644
index 00000000..d978f386
--- /dev/null
+++ b/flake/dev/subsystem-maintainers.nix
@@ -0,0 +1,17 @@
+{ lib, ... }:
+{
+  perSystem =
+    { pkgs, ... }:
+    {
+      packages.subsystem-maintainers = pkgs.writeText "subsystem-maintainers" (
+        lib.pipe ../../stylix/meta.nix [
+          (lib.flip pkgs.callPackage { })
+          (lib.mapAttrs (
+            _: meta: map (maintainer: maintainer.github) (meta.maintainers or [ ])
+          ))
+          (lib.mapAttrs' (name: lib.nameValuePair "modules/${name}/"))
+          builtins.toJSON
+        ]
+      );
+    };
+}
diff --git a/flake/propagated-packages.nix b/flake/propagated-packages.nix
index 215458de..ebc2a75b 100644
--- a/flake/propagated-packages.nix
+++ b/flake/propagated-packages.nix
@@ -24,6 +24,7 @@
         {
           inherit (config.partitions.dev.module.flake.packages.${system})
             all-maintainers
+            subsystem-maintainers
             ;
         }
         (lib.mkIf pkgs.stdenv.hostPlatform.isLinux (