shells: guard platform-specific pcsc tools

.codex/config.toml

@@ -0,0 +1,13 @@
+[mcp_servers.nixos]
+command = "mcp-nixos"
+startup_timeout_sec = 30
+tool_timeout_sec = 60
+required = false
+
+[mcp_servers.github]
+url = "https://api.githubcopilot.com/mcp/"
+bearer_token_env_var = "GITHUB_PERSONAL_ACCESS_TOKEN"
+http_headers = { X-MCP-Readonly = "true", X-MCP-Toolsets = "repos,pull_requests,actions" }
+startup_timeout_sec = 30
+tool_timeout_sec = 60
+required = false

.github/actions/check-nixos/action.yaml

@@ -1,27 +1,15 @@
 # Reference: https://github.com/ryoppippi/dotfiles/blob/main/.github/workflows/nix-build.yaml
-name: Check NixOS configurations
-description: Build every NixOS configuration and the Registry tests
+name: Build Linux checks
+description: Build every x86_64-linux flake check in parallel
 runs:
   using: composite
   steps:
-    - name: Build every NixOS configuration
+    - name: Build all Linux checks
       shell: bash
       run: |
         set -euo pipefail
-
-        mapfile -t hosts < <(
-          nix eval --raw .#nixosConfigurations \
-            --apply 'configs: builtins.concatStringsSep "\n" (builtins.attrNames configs)'
-        )
-
-        installables=(.#checks.x86_64-linux.registry)
-        for host in "${hosts[@]}"; do
-          installables+=(".#nixosConfigurations.${host}.config.system.build.toplevel")
-        done
-
-        nix build \
-          --keep-going \
-          --no-link \
-          --print-build-logs \
-          --show-trace \
-          "${installables[@]}"
+        nix run .#nix-fast-build -- \
+          --flake .#checks.x86_64-linux \
+          --skip-cached \
+          --no-nom \
+          --no-link

.github/actions/setup-nix/action.yaml

@@ -20,3 +20,4 @@ runs:
         primary-key: nix-${{ runner.os }}-${{ runner.arch }}-${{ hashFiles('flake.lock') }}
         restore-prefixes-first-match: nix-${{ runner.os }}-${{ runner.arch }}-
         gc-max-store-size-linux: 4G
+        gc-max-store-size-macos: 4G

.github/workflows/nixos.yaml

@@ -1,36 +1,50 @@
 # Reference: https://github.com/ryoppippi/dotfiles/blob/main/.github/workflows/nix-build.yaml
-name: "CI: NixOS"
+name: "CI: Nix"
 on:
   push:
     branches:
       - main
     paths:
+      - .gitignore
+      - AGENTS.md
+      - README.md
+      - "docs/**"
       - flake.nix
       - flake.lock
+      - ".codex/**"
+      - ".github/**"
+      - ".vscode/**"
       - "flake/**"
       - "hosts/**"
       - "libs/**"
       - "modules/**"
+      - "opencode.json"
       - "overlays/**"
+      - "scripts/**"
       - "shells/**"
+      - "skills/**"
       - "tests/**"
-      - ".github/actions/check-nixos/**"
-      - ".github/actions/setup-nix/**"
-      - ".github/workflows/nixos.yaml"
   pull_request:
     paths:
+      - .gitignore
+      - AGENTS.md
+      - README.md
+      - "docs/**"
       - flake.nix
       - flake.lock
+      - ".codex/**"
+      - ".github/**"
+      - ".vscode/**"
       - "flake/**"
       - "hosts/**"
       - "libs/**"
       - "modules/**"
+      - "opencode.json"
       - "overlays/**"
+      - "scripts/**"
       - "shells/**"
+      - "skills/**"
       - "tests/**"
-      - ".github/actions/check-nixos/**"
-      - ".github/actions/setup-nix/**"
-      - ".github/workflows/nixos.yaml"
   workflow_dispatch:
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
@@ -38,14 +52,153 @@ concurrency:
 permissions:
   contents: read
 jobs:
-  check:
-    name: Check all NixOS configurations
+  validate:
+    name: Plan, lint, and evaluate
     runs-on: ubuntu-latest
     timeout-minutes: 120
+    outputs:
+      build_linux: ${{ steps.plan.outputs.build_linux }}
+      build_darwin: ${{ steps.plan.outputs.build_darwin }}
+      nix_validation: ${{ steps.plan.outputs.nix_validation }}
     steps:
       - name: Checkout repository
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
+        with:
+          fetch-depth: 0
       - name: Setup Nix
         uses: ./.github/actions/setup-nix
-      - name: Check NixOS configurations
+      - name: Plan validation
+        id: plan
+        env:
+          PR_BASE_SHA: ${{ github.event.pull_request.base.sha }}
+          PUSH_BASE_SHA: ${{ github.event.before }}
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          case "${{ github.event_name }}" in
+            pull_request)
+              plan="$(nix run .#check -- plan --base "$PR_BASE_SHA" --json)"
+              ;;
+            push)
+              plan="$(nix run .#check -- plan --base "$PUSH_BASE_SHA" --json)"
+              ;;
+            *)
+              plan="$(nix run .#check -- plan --all-files --all-hosts --json)"
+              ;;
+          esac
+
+          printf '%s\n' "$plan"
+          nix_validation="$(jq -r '.requiresNixValidation' <<<"$plan")"
+
+          if [[ "${{ github.event_name }}" == "pull_request" ]]; then
+            build_linux="$(jq -r '.nativeBuildSystems["x86_64-linux"] // false' <<<"$plan")"
+            build_darwin="$(jq -r '.nativeBuildSystems["aarch64-darwin"] // false' <<<"$plan")"
+          else
+            build_linux="$nix_validation"
+            build_darwin="$nix_validation"
+          fi
+
+          {
+            echo "nix_validation=$nix_validation"
+            echo "build_linux=$build_linux"
+            echo "build_darwin=$build_darwin"
+          } >> "$GITHUB_OUTPUT"
+      - name: Run fast checks
+        env:
+          PR_BASE_SHA: ${{ github.event.pull_request.base.sha }}
+          PUSH_BASE_SHA: ${{ github.event.before }}
+        shell: bash
+        run: |
+          set +e
+          set -uo pipefail
+          case "${{ github.event_name }}" in
+            pull_request)
+              nix run .#check -- fast --base "$PR_BASE_SHA"
+              ;;
+            push)
+              nix run .#check -- fast --base "$PUSH_BASE_SHA"
+              ;;
+            *)
+              nix run .#check -- fast --all-files
+              ;;
+          esac
+          status=$?
+          if (( status != 0 )); then
+            git diff -- .
+            exit "$status"
+          fi
+      - name: Evaluate configurations
+        if: steps.plan.outputs.nix_validation == 'true' || github.event_name == 'workflow_dispatch'
+        env:
+          PR_BASE_SHA: ${{ github.event.pull_request.base.sha }}
+          PUSH_BASE_SHA: ${{ github.event.before }}
+        shell: bash
+        run: |
+          set -euo pipefail
+          case "${{ github.event_name }}" in
+            pull_request)
+              nix run .#check -- eval --base "$PR_BASE_SHA"
+              ;;
+            push)
+              nix run .#check -- eval --base "$PUSH_BASE_SHA" --all-systems
+              ;;
+            *)
+              nix run .#check -- eval --all-hosts --all-systems
+              ;;
+          esac
+  build-linux:
+    name: Build Linux checks
+    needs: validate
+    if: needs.validate.outputs.build_linux == 'true'
+    runs-on: ubuntu-latest
+    timeout-minutes: 180
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
+        with:
+          fetch-depth: 0
+      - name: Setup Nix
+        uses: ./.github/actions/setup-nix
+      - name: Build affected Linux checks
+        if: github.event_name == 'pull_request'
+        env:
+          PR_BASE_SHA: ${{ github.event.pull_request.base.sha }}
+        shell: bash
+        run: |
+          set -euo pipefail
+          nix run .#check -- build --base "$PR_BASE_SHA"
+      - name: Build all Linux checks
+        if: github.event_name != 'pull_request'
         uses: ./.github/actions/check-nixos
+  build-darwin:
+    name: Build Darwin checks
+    needs: validate
+    if: needs.validate.outputs.build_darwin == 'true'
+    runs-on: macos-15
+    timeout-minutes: 180
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
+        with:
+          fetch-depth: 0
+      - name: Setup Nix
+        uses: ./.github/actions/setup-nix
+      - name: Build affected Darwin checks
+        if: github.event_name == 'pull_request'
+        env:
+          PR_BASE_SHA: ${{ github.event.pull_request.base.sha }}
+        shell: bash
+        run: |
+          set -euo pipefail
+          nix run .#check -- build --base "$PR_BASE_SHA"
+      - name: Build all Darwin checks
+        if: github.event_name != 'pull_request'
+        shell: bash
+        run: |
+          set -euo pipefail
+          nix run .#nix-fast-build -- \
+            --flake .#checks.aarch64-darwin \
+            --skip-cached \
+            --no-nom \
+            --no-link

.github/workflows/update-flake.yaml

@@ -12,9 +12,11 @@ permissions:
   pull-requests: write
 jobs:
   update:
-    name: Update and validate flake inputs
+    name: Update and check Linux
     runs-on: ubuntu-latest
-    timeout-minutes: 120
+    timeout-minutes: 180
+    outputs:
+      changed: ${{ steps.update.outputs.changed }}
     steps:
       - name: Checkout repository
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
@@ -22,18 +24,76 @@ jobs:
         uses: ./.github/actions/setup-nix
       - name: Update flake inputs
         id: update
+        shell: bash
         run: |
+          set -euo pipefail
           nix flake update
           if git diff --quiet -- flake.lock; then
             echo 'changed=false' >> "$GITHUB_OUTPUT"
           else
             echo 'changed=true' >> "$GITHUB_OUTPUT"
           fi
-      - name: Check updated NixOS configurations
+      - name: Evaluate every flake system
+        if: steps.update.outputs.changed == 'true'
+        shell: bash
+        run: |
+          set -euo pipefail
+          nix flake check \
+            --no-build \
+            --all-systems \
+            --keep-going \
+            --show-trace
+      - name: Build Linux checks
         if: steps.update.outputs.changed == 'true'
         uses: ./.github/actions/check-nixos
-      - name: Create update pull request
+      - name: Upload updated lock file
         if: steps.update.outputs.changed == 'true'
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
+        with:
+          name: flake-lock
+          path: flake.lock
+          if-no-files-found: error
+  check-darwin:
+    name: Check Darwin
+    needs: update
+    if: needs.update.outputs.changed == 'true'
+    runs-on: macos-15
+    timeout-minutes: 180
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
+      - name: Download updated lock file
+        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4.3.0
+        with:
+          name: flake-lock
+          path: .
+      - name: Setup Nix
+        uses: ./.github/actions/setup-nix
+      - name: Build Darwin checks
+        shell: bash
+        run: |
+          set -euo pipefail
+          nix run .#nix-fast-build -- \
+            --flake .#checks.aarch64-darwin \
+            --skip-cached \
+            --no-nom \
+            --no-link
+  pull-request:
+    name: Create update pull request
+    needs:
+      - update
+      - check-darwin
+    if: needs.update.outputs.changed == 'true'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
+      - name: Download validated lock file
+        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4.3.0
+        with:
+          name: flake-lock
+          path: .
+      - name: Create update pull request
         uses: peter-evans/create-pull-request@5f6978faf089d4d20b00c7766989d076bb2fc7f1 # v8.1.1
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
@@ -45,4 +105,5 @@ jobs:
           body: |
             Automated update of `flake.lock`.
 
-            The updated inputs passed the Registry tests and a build of every NixOS configuration.
+            The updated inputs passed all-system evaluation and native builds of
+            the Linux and Darwin check sets.

.gitignore

@@ -1,4 +1,6 @@
 /*
+**/__pycache__/
+*.py[cod]
 
 !.gitignore
 !README.md
@@ -6,8 +8,10 @@
 !AGENTS.md
 !/docs/
 
-!.github/
+!/.codex/
+!/.github/
 !.gitea/
+!/.vscode/
 
 !.envrc
 
@@ -15,7 +19,9 @@
 
 !/flake.nix
 !/flake.lock
+!/opencode.json
 
+!/scripts/
 !/shells/
 !/flake/
 !/overlays/

.vscode/settings.json

@@ -0,0 +1,28 @@
+{
+  "nix.enableLanguageServer": true,
+  "nix.serverPath": "nixd",
+  "nix.serverSettings": {
+    "nixd": {
+      "formatting": {
+        "command": ["nixfmt"]
+      },
+      "nixpkgs": {
+        "expr": "import (builtins.getFlake (builtins.toString ./.)).inputs.nixpkgs { }"
+      },
+      "options": {
+        "nixos": {
+          "expr": "(builtins.getFlake (builtins.toString ./.)).nixosConfigurations.galleria.options"
+        },
+        "home-manager-nixos": {
+          "expr": "(builtins.getFlake (builtins.toString ./.)).nixosConfigurations.galleria.options.home-manager.users.type.getSubOptions []"
+        },
+        "darwin": {
+          "expr": "(builtins.getFlake (builtins.toString ./.)).darwinConfigurations.m2.options"
+        },
+        "home-manager-darwin": {
+          "expr": "(builtins.getFlake (builtins.toString ./.)).darwinConfigurations.m2.options.home-manager.users.type.getSubOptions []"
+        }
+      }
+    }
+  }
+}

README.md

@@ -1,3 +1,6 @@
 # moons14 dotfiles
 
-My NixOS + Home Manager configurations build with flake.
+My NixOS, nix-darwin, and Home Manager configurations built with flakes.
+
+See [Coding-agent validation](docs/coding-agents.md) for the non-activating,
+change-aware validation workflow used by Codex, OpenCode, and CI.

docs/coding-agents.md

@@ -0,0 +1,86 @@
+# Coding-agent workflow
+
+This repository exposes deterministic validation and narrowly scoped research
+tools for Codex, OpenCode, and editor agents. Live system activation is outside
+this workflow.
+
+## Validation commands
+
+Use task-owned paths during the edit loop:
+
+```console
+nix run .#check -- plan --paths modules/applications/example/home.nix --json
+nix run .#check -- fast --paths modules/applications/example/home.nix
+nix run .#check -- eval --paths modules/applications/example/home.nix
+nix run .#check -- build --paths modules/applications/example/home.nix
+nix run .#check -- all --paths modules/applications/example/home.nix
+```
+
+For a committed pull-request range, replace `--paths ...` with
+`--base <base-sha>`. `full` is reserved for CI, scheduled maintenance, or an
+explicit repository-wide audit:
+
+```console
+nix run .#check -- full
+```
+
+The stages have distinct meanings:
+
+- `plan` maps changed paths to Registry units, reverse `meta.includes`
+  dependencies, real hosts, and compatible build systems.
+- `fast` parses changed Nix files, validates JSON, TOML, Python, and Agent Skill
+  frontmatter, checks whitespace, and runs configured hooks only for the
+  selected files.
+- `eval` instantiates affected NixOS and nix-darwin configurations. Flake-wide,
+  validation-tool, shell, overlay, and test changes additionally evaluate every
+  flake system.
+- `build` realizes affected configurations supported by the current platform
+  with no result link. Incompatible targets remain evaluation-only until a
+  matching runner handles them.
+- `all` performs task-scoped file checks, all-system evaluation, and compatible
+  targeted builds.
+- `full` runs all-file hooks, all-system evaluation, and every check for the
+  current platform through `nix-fast-build`.
+
+The validation app constructs a filtered temporary `path:` flake from the
+committed `HEAD` tree and overlays only task-owned changed paths. This isolates
+unrelated worktree changes, makes new untracked Registry fragments visible to
+Nix without staging them, and avoids copying ignored state such as `.direnv`.
+
+None of these commands runs `nh os switch`, `nixos-rebuild switch`,
+`darwin-rebuild switch`, `home-manager switch`, or another activation command.
+The user performs activation separately.
+
+## Agent Skills
+
+Read `AGENTS.md` first. Use the repository skills as follows:
+
+- `validate-nix-change` controls validation scope and evidence.
+- `debug-nix-failure` classifies parse, evaluation, build, test, activation-log,
+  and runtime failures before proposing a correction.
+- `test-nixos-service` adds a `pkgs.testers.runNixOSTest` check when a build
+  cannot prove service behavior.
+- `update-flake-input` limits lock-file updates and validates them without
+  activating a host.
+- `add-application-or-service` preserves Registry ownership and delegates
+  validation to `validate-nix-change`.
+
+## MCP and language-server setup
+
+The development workload installs `mcp-nixos`, `nixd`, `nix-fast-build`, and
+`nix-tree`.
+
+Project-local Codex and OpenCode configuration exposes:
+
+- `mcp-nixos` for current NixOS, Home Manager, nix-darwin, package, and Nix
+  documentation queries;
+- GitHub's remote MCP endpoint for Codex and OpenCode in read-only mode,
+  restricted to repository, pull-request, and Actions toolsets.
+
+Set `GITHUB_PERSONAL_ACCESS_TOKEN` in the launching environment when GitHub MCP
+access is needed. Do not commit the token or put it in a Nix expression because
+that would expose it through source control or the Nix store.
+
+The workspace VS Code settings use `nixd` and expose option sets for the
+`galleria` NixOS configuration, its integrated Home Manager configuration, the
+`m2` nix-darwin configuration, and its integrated Home Manager configuration.

flake/default.nix

@@ -3,5 +3,6 @@
     ./formatter.nix
     ./git-hooks.nix
     ./registry.nix
+    ./validation.nix
   ];
 }

flake/git-hooks.nix

@@ -34,7 +34,9 @@
             ];
           };
 
+          actionlint.enable = true;
           deadnix.enable = true;
+          ruff.enable = true;
           statix.enable = true;
           shellcheck.enable = true;
         };

flake/registry.nix

@@ -25,11 +25,42 @@ let
     else
       { };
   configurations = dotfilesLib.hosts.mkConfigurations hostSpecs;
+
+  validationMetadata = {
+    schemaVersion = 1;
+
+    hosts = lib.mapAttrs (
+      name: spec:
+      let
+        isDarwin = lib.hasSuffix "-darwin" spec.system;
+      in
+      {
+        inherit (spec) system user;
+        kind = if isDarwin then "darwin" else "nixos";
+        homeManager = spec.homeManager or true;
+        selectedUnits = dotfilesLib.hosts.selectedUnits spec;
+        buildAttr =
+          if isDarwin then
+            "darwinConfigurations.${name}.system"
+          else
+            "nixosConfigurations.${name}.config.system.build.toplevel";
+      }
+    ) hostSpecs;
+
+    units = lib.mapAttrs (_id: unit: {
+      inherit (unit) id relativePath;
+      directory = "modules/${lib.concatStringsSep "/" unit.relativePath}";
+      includes = unit.meta.includes;
+      fragments = builtins.attrNames (lib.filterAttrs (_: value: value != null) unit.fragments);
+    }) dotfilesLib.registry.units;
+  };
 in
 {
   flake = {
     inherit (configurations) darwinConfigurations nixosConfigurations;
-    lib = dotfilesLib;
+    lib = dotfilesLib // {
+      inherit validationMetadata;
+    };
   };
 
   perSystem =
@@ -37,10 +68,9 @@ in
     let
       nixosChecks =
         lib.mapAttrs' (name: nixos: lib.nameValuePair "nixos-${name}" nixos.config.system.build.toplevel)
-          (
-            lib.filterAttrs (
-              _: nixos: nixos.pkgs.stdenv.hostPlatform.system == system
-            ) configurations.nixosConfigurations
+          (lib.filterAttrs (name: _: hostSpecs.${name}.system == system) configurations.nixosConfigurations);
+      darwinChecks = lib.mapAttrs' (name: darwin: lib.nameValuePair "darwin-${name}" darwin.system) (
+        lib.filterAttrs (name: _: hostSpecs.${name}.system == system) configurations.darwinConfigurations
       );
     in
     {
@@ -49,6 +79,7 @@ in
           inherit inputs lib pkgs;
         };
       }
-      // nixosChecks;
+      // nixosChecks
+      // darwinChecks;
     };
 }

flake/validation.nix

@@ -0,0 +1,51 @@
+_: {
+  perSystem =
+    { pkgs, config, ... }:
+    let
+      script = pkgs.writeText "dotfiles-check.py" (builtins.readFile ../scripts/dotfiles-check.py);
+      dotfilesCheck = pkgs.writeShellApplication {
+        name = "dotfiles-check";
+        runtimeInputs = [
+          pkgs.git
+          pkgs.nix
+          pkgs.python3
+        ];
+        text = ''
+          exec python3 ${script} "$@"
+        '';
+      };
+    in
+    {
+      apps = {
+        check = {
+          type = "app";
+          program = "${dotfilesCheck}/bin/dotfiles-check";
+        };
+        nix-fast-build = {
+          type = "app";
+          program = "${pkgs.nix-fast-build}/bin/nix-fast-build";
+        };
+      };
+
+      packages = {
+        dotfiles-check = dotfilesCheck;
+        inherit (pkgs) nix-fast-build;
+      };
+
+      devShells.validation = config.pre-commit.devShell;
+
+      checks = {
+        validation-tool =
+          pkgs.runCommand "dotfiles-check-self-test"
+            {
+              nativeBuildInputs = [ dotfilesCheck ];
+            }
+            ''
+              dotfiles-check self-test
+              touch "$out"
+            '';
+
+        dotnix-shell = config.devShells.dotnix;
+      };
+    };
+}

hosts/default.nix

@@ -104,6 +104,7 @@
       "interface.cli"
       "interface.labwc"
       "interface.niri"
+      "interface.wallpaperengine"
       "platform.intel-nvidia-desktop"
       "security.secrets"
       "security.secure-boot"

modules/applications/labwc/home.nix

@@ -102,8 +102,8 @@ in
           (action "W-q" "Close")
           (action "W-f" "ToggleMaximize")
           (action "W-c" "Iconify")
-          (action "W-Tab" "NextWindow")
-          (action "W-S-Tab" "PreviousWindow")
+          (execute "W-Tab" "window-overview")
+          (execute "W-S-Tab" "window-overview --reverse")
           (action "W-Up" "Lower")
           (action "W-Down" "Raise")
           (action "W-Left" "NextWindow")
@@ -125,7 +125,7 @@ in
           (execute "W-l" "loginctl lock-session")
           (execute "W-v" "vicinae vicinae://launch/clipboard/history?toggle=true")
           (execute "W-j" "nani-translate-primary")
-          (execute "W-S-j" "normcap-translate")
+          (execute "W-S-j" "nani-translate-ocr")
           (execute "W-C-j" "${lib.getExe' pkgs.xdg-utils "xdg-open"} naniapp://translate")
           (execute "W-space" "ghostty +toggle-quick-terminal")
           (execute "W-p" "wdisplays")

modules/applications/labwc/patches/remove-ext-workspace-output-on-destroy.patch

@@ -1,28 +1,103 @@
 From: Codex <[email protected]>
-Subject: [PATCH] output: remove destroyed output from ext-workspace group
+Subject: [PATCH] output: detach destroyed outputs from protocol handles
 
 The DRM backend destroys and recreates outputs when a session is paused and
-resumed. Remove the output from the ext-workspace group before wlroots
-finishes it, otherwise the group's output_bind listener remains attached and
-wlr_output_finish() aborts.
+resumed. Remove the output from the ext-workspace group and the foreign
+toplevel handles before wlroots finishes it. Both protocols attach bind
+listeners to the output; leaving either listener behind makes
+wlr_output_finish() abort.
 
 ---
- src/output.c | 3 +++
- 1 file changed, 3 insertions(+)
+ src/foreign-toplevel/foreign.c     | 14 ++++++++++++++
+ src/output.c                        |  6 ++++++
+ include/foreign-toplevel/foreign.h  |  2 ++
+ 3 files changed, 22 insertions(+)
 
 diff --git a/src/output.c b/src/output.c
-index 2eab8ec..f19c3ff 100644
+index 2eab8ec..6f6e7ef 100644
 --- a/src/output.c
 +++ b/src/output.c
-@@ -277,6 +277,9 @@ handle_output_destroy(struct wl_listener *listener, void *data)
+@@ -27,8 +27,9 @@
+ #include "common/macros.h"
+ #include "common/mem.h"
+ #include "common/scene-helpers.h"
+ #include "common/string-helpers.h"
+ #include "config/rcxml.h"
++#include "foreign-toplevel/foreign.h"
+ #include "labwc.h"
+ #include "layers.h"
+ #include "node.h"
+@@ -276,7 +277,15 @@ handle_output_destroy(struct wl_listener *listener, void *data)
+ 	struct output *output = wl_container_of(listener, output, destroy);
  	struct seat *seat = &server.seat;
  	regions_evacuate_output(output);
  	regions_destroy(seat, &output->regions);
 +	wlr_ext_workspace_group_handle_v1_output_leave(
 +		server.workspaces.ext_group, output->wlr_output);
++
++	struct view *view;
++	wl_list_for_each(view, &server.views, link) {
++		foreign_toplevel_remove_output(view->foreign_toplevel, output->wlr_output);
++	}
 +
  	if (seat->overlay.active.output == output) {
  		overlay_finish(seat);
  	}
+@@ -297,7 +305,6 @@ handle_output_destroy(struct wl_listener *listener, void *data)
+ 		output->workspace_osd = NULL;
+ 	}
+ 
+-	struct view *view;
+ 	wl_list_for_each(view, &server.views, link) {
+ 		if (view->output == output) {
+ 			view_on_output_destroy(view);
+diff --git a/include/foreign-toplevel/foreign.h b/include/foreign-toplevel/foreign.h
+index 69a340a..d8ec9b4 100644
+--- a/include/foreign-toplevel/foreign.h
++++ b/include/foreign-toplevel/foreign.h
+@@ -3,11 +3,14 @@
+ #define LABWC_FOREIGN_TOPLEVEL_H
+ 
+ struct view;
++struct wlr_output;
+ struct foreign_toplevel;
+ 
+ struct foreign_toplevel *foreign_toplevel_create(struct view *view);
+ void foreign_toplevel_set_parent(struct foreign_toplevel *toplevel,
+ 	struct foreign_toplevel *parent);
++void foreign_toplevel_remove_output(struct foreign_toplevel *toplevel,
++	struct wlr_output *output);
+ void foreign_toplevel_destroy(struct foreign_toplevel *toplevel);
+ 
+ #endif /* LABWC_FOREIGN_TOPLEVEL_H */
+diff --git a/src/foreign-toplevel/foreign.c b/src/foreign-toplevel/foreign.c
+index 7f1ec8d..0f628a3 100644
+--- a/src/foreign-toplevel/foreign.c
++++ b/src/foreign-toplevel/foreign.c
+@@ -1,4 +1,5 @@
+ // SPDX-License-Identifier: GPL-2.0-only
+ #include "foreign-toplevel/foreign.h"
++#include <wlr/types/wlr_foreign_toplevel_management_v1.h>
+ #include <assert.h>
+ #include "common/mem.h"
+@@ -34,6 +34,18 @@ foreign_toplevel_set_parent(struct foreign_toplevel *toplevel, struct foreign_to
+ 		parent ? &parent->wlr_toplevel : NULL);
+ }
+ 
++void
++foreign_toplevel_remove_output(struct foreign_toplevel *toplevel,
++	struct wlr_output *output)
++{
++	if (!toplevel || !toplevel->wlr_toplevel.handle) {
++		return;
++	}
++
++	wlr_foreign_toplevel_handle_v1_output_leave(
++		toplevel->wlr_toplevel.handle, output);
++}
++
+ void
+ foreign_toplevel_destroy(struct foreign_toplevel *toplevel)
+ {
 -- 
 2.51.0

modules/applications/linux-wallpaperengine/home/nixos.nix

@@ -61,6 +61,33 @@ let
     '';
   };
 
+  mkVicinaeScript =
+    {
+      name,
+      title,
+      description,
+      command,
+      mode ? "compact",
+      message ? null,
+    }:
+    {
+      name = "vicinae/scripts/wallpaper-engine/${name}";
+      value = {
+        executable = true;
+        text = ''
+          #!${lib.getExe pkgs.bash}
+          # @vicinae.schemaVersion 1
+          # @vicinae.title ${title}
+          # @vicinae.description ${description}
+          # @vicinae.mode ${mode}
+          # @vicinae.icon 🖼️
+
+          ${lib.getExe controller} ${lib.escapeShellArg command}
+          ${lib.optionalString (message != null) "printf '%s\\n' ${lib.escapeShellArg message}"}
+        '';
+      };
+    };
+
   launcher = pkgs.writeShellApplication {
     name = "linux-wallpaperengine-launcher";
     runtimeInputs = [
@@ -115,6 +142,50 @@ assert lib.assertMsg (builtins.elem scaling [
     pkgs.linux-wallpaperengine
   ];
 
+  xdg.dataFile = builtins.listToAttrs [
+    (mkVicinaeScript {
+      name = "reload";
+      title = "Reload Wallpaper Engine";
+      description = "Restart the active Wallpaper Engine background";
+      command = "restart";
+      message = "Wallpaper Engine reloaded";
+    })
+    (mkVicinaeScript {
+      name = "next";
+      title = "Next Wallpaper Engine Wallpaper";
+      description = "Switch to the next configured Wallpaper Engine background";
+      command = "next";
+      message = "Switched to the next Wallpaper Engine wallpaper";
+    })
+    (mkVicinaeScript {
+      name = "previous";
+      title = "Previous Wallpaper Engine Wallpaper";
+      description = "Switch to the previous configured Wallpaper Engine background";
+      command = "previous";
+      message = "Switched to the previous Wallpaper Engine wallpaper";
+    })
+    (mkVicinaeScript {
+      name = "list";
+      title = "List Wallpaper Engine Wallpapers";
+      description = "Show the configured Wallpaper Engine backgrounds";
+      command = "list";
+      mode = "fullOutput";
+    })
+    (mkVicinaeScript {
+      name = "current";
+      title = "Current Wallpaper Engine Wallpaper";
+      description = "Show the active Wallpaper Engine background";
+      command = "current";
+    })
+    (mkVicinaeScript {
+      name = "stop";
+      title = "Stop Wallpaper Engine";
+      description = "Stop Wallpaper Engine for this session";
+      command = "stop";
+      message = "Wallpaper Engine stopped";
+    })
+  ];
+
   systemd.user.services = lib.optionalAttrs hasWallpapers {
     linux-wallpaperengine = {
       Unit = {

modules/applications/nani/home/nixos.nix

@@ -1,5 +1,78 @@
-_: {
+{ pkgs, ... }:
+let
+  tessdataBest = pkgs.runCommand "tessdata-best-jpn-eng-chi-sim" { } ''
+    mkdir -p "$out"
+    ln -s ${
+      pkgs.fetchurl {
+        url = "https://github.com/tesseract-ocr/tessdata_best/raw/main/jpn.traineddata";
+        hash = "sha256-Nr35rII/WRHmJMMNBVPokLirx8MaZbPvFNqUNljEC3k=";
+      }
+    } "$out/jpn.traineddata"
+    ln -s ${
+      pkgs.fetchurl {
+        url = "https://github.com/tesseract-ocr/tessdata_best/raw/main/eng.traineddata";
+        hash = "sha256-goCu0Hgv4nJXpo6hD+fvMkyg+Nhb0v0UXRwrVgvLZro=";
+      }
+    } "$out/eng.traineddata"
+    ln -s ${
+      pkgs.fetchurl {
+        url = "https://github.com/tesseract-ocr/tessdata_best/raw/main/chi_sim.traineddata";
+        hash = "sha256-T+8tEwbI6HYW1NPkxsZ/r11EvjNCKQz48vD246p+c1s=";
+      }
+    } "$out/chi_sim.traineddata"
+  '';
+
+  tesseract = pkgs.tesseract5.override {
+    tessdata = tessdataBest;
+  };
+
+  naniTranslatePrimary = pkgs.writeShellApplication {
+    name = "nani-translate-primary";
+
+    runtimeInputs = with pkgs; [
+      jq
+      wl-clipboard
+      xdg-utils
+    ];
+
+    text = ''
+      selected_text="$(wl-paste --primary --no-newline)" || exit 0
+      [ -n "$selected_text" ] || exit 0
+      encoded_text="$(printf '%s' "$selected_text" | jq -sRr @uri)"
+      exec xdg-open "naniapp://translate?source=$encoded_text"
+    '';
+  };
+
+  naniTranslateOcr = pkgs.writeShellApplication {
+    name = "nani-translate-ocr";
+
+    runtimeInputs = with pkgs; [
+      grim
+      jq
+      slurp
+      tesseract
+      xdg-utils
+    ];
+
+    text = ''
+      geometry="$(slurp)" || exit 0
+      captured_text="$(
+        grim -g "$geometry" - \
+          | tesseract stdin stdout -l jpn+eng+chi_sim --oem 1 --psm 6
+      )"
+      [ -n "$captured_text" ] || exit 0
+      encoded_text="$(printf '%s' "$captured_text" | jq -sRr @uri)"
+      exec xdg-open "naniapp://translate?source=$encoded_text"
+    '';
+  };
+in
+{
   programs.naniTranslateLinux.enable = true;
 
   xdg.mimeApps.defaultApplications."x-scheme-handler/naniapp" = "nani.desktop";
+
+  home.packages = [
+    naniTranslatePrimary
+    naniTranslateOcr
+  ];
 }

modules/applications/niri/home/nixos.nix

@@ -1,24 +1,8 @@
 { lib, pkgs, ... }:
 let
   keybindings = import ./keybindings.nix;
-  naniTranslatePrimary = pkgs.writeShellApplication {
-    name = "nani-translate-primary";
-    runtimeInputs = with pkgs; [
-      jq
-      wl-clipboard
-      xdg-utils
-    ];
-    text = ''
-      selected_text="$(wl-paste --primary --no-newline)" || exit 0
-      [ -n "$selected_text" ] || exit 0
-      encoded_text="$(printf '%s' "$selected_text" | jq -sRr @uri)"
-      exec xdg-open "naniapp://translate?source=$encoded_text"
-    '';
-  };
 in
 {
-  home.packages = [ naniTranslatePrimary ];
-
   programs.niri.settings = {
 
     binds = keybindings // {
@@ -57,6 +41,24 @@ in
         hotkey-overlay.title = "Move Window to Monitor Down";
       };
 
+      "Mod+Tab" = {
+        repeat = false;
+        action.spawn = [
+          "window-overview"
+          "--hold"
+        ];
+        hotkey-overlay.title = "Window Overview: Next";
+      };
+      "Mod+Shift+Tab" = {
+        repeat = false;
+        action.spawn = [
+          "window-overview"
+          "--hold"
+          "--reverse"
+        ];
+        hotkey-overlay.title = "Window Overview: Previous";
+      };
+
       "Print".action.spawn = [
         "screenshot"
         "region"
@@ -119,7 +121,7 @@ in
       };
       "Mod+Shift+J" = {
         repeat = false;
-        action.spawn = [ "normcap-translate" ];
+        action.spawn = [ "nani-translate-ocr" ];
         hotkey-overlay.title = "OCR and Translate with Nani";
       };
       "Mod+Ctrl+J" = {

modules/applications/noctalia/home.nix

@@ -18,6 +18,7 @@ let
       (oldAttrs: {
         patches = (oldAttrs.patches or [ ]) ++ [
           ./patches/window-switcher-labwc.patch
+          ./patches/taskbar-overview-hook.patch
         ];
       });
 

modules/applications/noctalia/meta.nix

@@ -2,6 +2,10 @@
 {
   description = "Noctalia Wayland desktop shell";
 
+  includes = [
+    "applications.window-overview"
+  ];
+
   imports = {
     nixos = [ inputs.noctalia.nixosModules.default ];
     home = [ inputs.noctalia.homeModules.default ];

modules/applications/noctalia/patches/taskbar-overview-hook.patch

@@ -0,0 +1,43 @@
+diff --git a/src/shell/bar/widgets/taskbar_widget.cpp b/src/shell/bar/widgets/taskbar_widget.cpp
+--- a/src/shell/bar/widgets/taskbar_widget.cpp
++++ b/src/shell/bar/widgets/taskbar_widget.cpp
+@@ -5,6 +5,7 @@
+ #include "compositors/workspace_backend.h"
+ #include "config/config_service.h"
+ #include "core/deferred_call.h"
++#include "core/process/process.h"
+ #include "i18n/i18n.h"
+ #include "render/core/color.h"
+ #include "render/core/renderer.h"
+@@ -36,6 +37,18 @@
+ 
+ namespace {
+ 
++  [[nodiscard]] bool launchTaskbarOverview(const std::string& appId) {
++    constexpr const char* command = "noctalia-taskbar-overview";
++    if (appId.empty() || !process::commandExists(command)) {
++      return false;
++    }
++    return process::runAsync({
++        command,
++        "--app-id",
++        appId.c_str(),
++    });
++  }
++
+   // Integer centering; optional odd spare pixel on the end side (right/bottom).
+   [[nodiscard]] float centeredOffset(float extent, float content, float inset = 0.0F, bool oddSpareOnEnd = true) {
+     const float inner = std::max(0.0F, extent - inset * 2.0F);
+@@ -373,6 +386,12 @@ void TaskbarWidget::activateOrLaunchPinned(const TaskModel& task) {
+     return;
+   }
+ 
++  const std::string overviewAppId =
++      !task.appId.empty() ? task.appId : (!task.desktopEntryId.empty() ? task.desktopEntryId : task.idLower);
++  if (launchTaskbarOverview(overviewAppId)) {
++    return;
++  }
++
+   const std::string cycleKey = !task.desktopEntryId.empty() ? task.desktopEntryId : task.idLower;
+   std::size_t& cursor = m_groupedAppCycleCursor[cycleKey];
+   if (cursor >= windows.size()) {

modules/applications/noctalia/patches/window-switcher-labwc.patch

@@ -24,56 +24,3 @@ diff --git a/src/shell/switcher/window_switcher.cpp b/src/shell/switcher/window_
          if (key.empty()) {
            continue;
          }
-diff --git a/src/shell/bar/widgets/taskbar_widget.cpp b/src/shell/bar/widgets/taskbar_widget.cpp
---- a/src/shell/bar/widgets/taskbar_widget.cpp
-+++ b/src/shell/bar/widgets/taskbar_widget.cpp
-@@ -5,6 +5,7 @@
- #include "compositors/workspace_backend.h"
- #include "config/config_service.h"
- #include "core/deferred_call.h"
-+#include "core/process/process.h"
- #include "i18n/i18n.h"
- #include "render/core/color.h"
- #include "render/core/renderer.h"
-@@ -36,6 +37,18 @@
- 
- namespace {
- 
-+  [[nodiscard]] bool launchTaskbarOverview(const std::string& appId) {
-+    constexpr const char* command = "noctalia-taskbar-overview";
-+    if (appId.empty() || !process::commandExists(command)) {
-+      return false;
-+    }
-+    return process::runAsync({
-+        command,
-+        "--app-id",
-+        appId.c_str(),
-+    });
-+  }
-+
-   // Integer centering; optional odd spare pixel on the end side (right/bottom).
-   [[nodiscard]] float centeredOffset(float extent, float content, float inset = 0.0F, bool oddSpareOnEnd = true) {
-     const float inner = std::max(0.0F, extent - inset * 2.0F);
-@@ -373,6 +386,12 @@ void TaskbarWidget::activateOrLaunchPinned(const TaskModel& task) {
-     return;
-   }
- 
-+  const std::string overviewAppId =
-+      !task.appId.empty() ? task.appId : (!task.desktopEntryId.empty() ? task.desktopEntryId : task.idLower);
-+  if (launchTaskbarOverview(overviewAppId)) {
-+    return;
-+  }
-+
-   const std::string cycleKey = !task.desktopEntryId.empty() ? task.desktopEntryId : task.idLower;
-   std::size_t& cursor = m_groupedAppCycleCursor[cycleKey];
-   if (cursor >= windows.size()) {
-@@ -792,6 +811,9 @@ void TaskbarWidget::create() {
-         }
-         if (data.button == BTN_LEFT) {
-           if (!cycleCandidates.empty()) {
-+            if (cycleCandidates.size() > 1 && launchTaskbarOverview(current->appId)) {
-+              return;
-+            }
-             std::size_t& cursor = m_groupedAppCycleCursor[cycleKey];
-             if (cursor >= cycleCandidates.size()) {
-               cursor = 0;

modules/applications/normcap/home/nixos.nix

@@ -1,44 +0,0 @@
-{ pkgs, ... }:
-let
-  normcap = pkgs.normcap.override {
-    tesseract4 = pkgs.tesseract4.override {
-      enableLanguages = [
-        "chi_sim"
-        "jpn"
-        "eng"
-      ];
-    };
-  };
-
-  normcapTranslate = pkgs.writeShellApplication {
-    name = "normcap-translate";
-
-    runtimeInputs = [
-      normcap
-      pkgs.jq
-      pkgs.xdg-utils
-    ];
-
-    text = ''
-      captured_text="$(
-        normcap \
-          --cli-mode \
-          --screenshot-handler grim \
-          --show-introduction False \
-          --update False \
-          --detect-codes False \
-          --notification False \
-          -l jpn eng chi_sim
-      )" || exit 0
-      [ -n "$captured_text" ] || exit 0
-      encoded_text="$(printf '%s' "$captured_text" | jq -sRr @uri)"
-      exec xdg-open "naniapp://translate?source=$encoded_text"
-    '';
-  };
-in
-{
-  home.packages = [
-    normcap
-    normcapTranslate
-  ];
-}

modules/applications/normcap/meta.nix

@@ -1,7 +0,0 @@
-{
-  description = "NormCap OCR screen capture";
-
-  includes = [
-    "applications.nani"
-  ];
-}

modules/applications/vscode/home/common.nix

@@ -118,7 +118,7 @@ let
       ];
       userSettings = {
         "nix.enableLanguageServer" = true;
-        "nix.serverPath" = "nil";
+        "nix.serverPath" = "nixd";
         "nix.serverSettings" = {
           nixd = {
             formatting.command = [ "nixfmt" ];

modules/applications/window-overview/home/nixos.nix

@@ -0,0 +1,7 @@
+{ pkgs, ... }:
+let
+  windowOverview = pkgs.callPackage ../package.nix { };
+in
+{
+  home.packages = [ windowOverview ];
+}

modules/applications/window-overview/meta.nix

@@ -0,0 +1,7 @@
+{
+  description = "Fullscreen Wayland window overview with captured previews";
+
+  includes = [
+    "systems.wayland"
+  ];
+}

modules/applications/window-overview/package.nix

@@ -0,0 +1,77 @@
+{
+  lib,
+  fetchCrate,
+  libgbm,
+  libglvnd,
+  libxkbcommon,
+  jq,
+  makeWrapper,
+  pkg-config,
+  rustPlatform,
+  wayland,
+  wl-clipboard,
+}:
+rustPlatform.buildRustPackage rec {
+  pname = "window-overview";
+  version = "1.5.0";
+
+  src = fetchCrate {
+    pname = "wlr-chooser";
+    inherit version;
+    hash = "sha256-Jb59m1z+2G5istcbC0sg9jRVcC/bQh/OY0ny9OdTsdw=";
+  };
+
+  patches = [
+    ./patches/window-overview.patch
+    ./patches/niri-backend.patch
+  ];
+
+  cargoHash = "sha256-KBLgtS8ULrmsOf6BN5SlkVQyXB12utvr/KonnKnCTCM=";
+
+  nativeBuildInputs = [
+    makeWrapper
+    pkg-config
+  ];
+
+  buildInputs = [
+    libgbm
+    libglvnd
+    libxkbcommon
+    wayland
+  ];
+
+  cargoBuildFlags = [
+    "--bin"
+    "wlr-switcher"
+  ];
+
+  postInstall = ''
+    mv "$out/bin/wlr-switcher" "$out/bin/.window-overview-wrapped"
+    makeWrapper "$out/bin/.window-overview-wrapped" "$out/bin/window-overview" \
+      --add-flags "--layout grid" \
+      --prefix PATH : "${
+        lib.makeBinPath [
+          jq
+          wl-clipboard
+        ]
+      }" \
+      --prefix LD_LIBRARY_PATH : "${
+        lib.makeLibraryPath [
+          libgbm
+          libglvnd
+        ]
+      }:/run/opengl-driver/lib"
+    ln -s window-overview "$out/bin/noctalia-taskbar-overview"
+  '';
+
+  meta = {
+    description = "Fullscreen Wayland window overview with captured previews";
+    homepage = "https://github.com/sjourdois/wlr-utils";
+    license = with lib.licenses; [
+      asl20
+      mit
+    ];
+    mainProgram = "window-overview";
+    platforms = lib.platforms.linux;
+  };
+}

modules/applications/window-overview/patches/niri-backend.patch

@@ -0,0 +1,431 @@
+--- a/src/chooser_cli.rs
++++ b/src/chooser_cli.rs
+@@ -81,6 +81,7 @@
+         initial_cycle: None,
+         snapshot: false,
+         cycle_socket: None,
++        niri_backend: false,
+     };
+ 
+     match run_overlay(opts, t0) {
+--- a/src/lib.rs
++++ b/src/lib.rs
+@@ -65,7 +65,14 @@
+     // must connect, enumerate, and open sessions before any thumbnail appears.
+     let (tx, rx) = mpsc::channel();
+     let snapshot = opts.snapshot;
+-    std::thread::spawn(move || ui::capture_thread(tx, snapshot));
++    let niri_backend = opts.niri_backend;
++    std::thread::spawn(move || {
++        if niri_backend {
++            ui::niri_capture_thread(tx);
++        } else {
++            ui::capture_thread(tx, snapshot);
++        }
++    });
+     shell::tlog(t0, "capture-thread spawned");
+ 
+     let out: ui::Outcome = Arc::new(Mutex::new(None));
+--- a/src/switcher_cli.rs
++++ b/src/switcher_cli.rs
+@@ -88,6 +88,7 @@
+     let t0 = Instant::now();
+     let cli = Cli::parse();
+     i18n::init();
++    let niri_backend = std::env::var_os("NIRI_SOCKET").is_some();
+ 
+     if cli.doctor {
+         if let Err(e) = wlr_capture::doctor::report("wlr-switcher", env!("CARGO_PKG_VERSION")) {
+@@ -129,32 +130,50 @@
+         initial_cycle: Some(!cli.reverse),
+         snapshot: true,
+         cycle_socket: Some(cycle_socket),
++        niri_backend,
+     };
+ 
+     // Pre-flight: wlr-switcher switches *windows*, which need the foreign-toplevel
+     // capture source (wlroots >= 0.20 / Sway >= 1.12). On older compositors connect()
+     // now succeeds for screen-only capture, but there are no windows to offer — so say
+     // so clearly and exit, instead of showing an empty dimmed overlay (issue #1).
+-    match wl::Client::connect() {
+-        Ok(client) if !client.can_capture_windows() => {
+-            eprintln!("{}", tr!("capture-no-window"));
+-            std::process::exit(2);
+-        }
+-        Ok(_) => {}
+-        Err(e) => {
+-            eprintln!("{}", tr!("error", error = format!("{e:#}")));
+-            std::process::exit(2);
++    if !niri_backend {
++        match wl::Client::connect() {
++            Ok(client) if !client.can_capture_windows() => {
++                eprintln!("{}", tr!("capture-no-window"));
++                std::process::exit(2);
++            }
++            Ok(_) => {}
++            Err(e) => {
++                eprintln!("{}", tr!("error", error = format!("{e:#}")));
++                std::process::exit(2);
++            }
+         }
+     }
+ 
+     match run_overlay(opts, t0) {
+         Ok(Some(sel)) => {
+             // Focus the picked window (outputs aren't focusable, so ignore them).
+-            if sel.is_window
+-                && let Err(e) = wl::activate_window(&sel.app_id, &sel.title, sel.dup_index)
+-            {
+-                eprintln!("{}", tr!("error", error = format!("{e:#}")));
+-                std::process::exit(2);
++            if sel.is_window {
++                let result: anyhow::Result<()> = if niri_backend {
++                    let output = std::process::Command::new("niri")
++                        .args(["msg", "action", "focus-window", "--id", &sel.identifier])
++                        .output();
++                    match output {
++                        Ok(output) if output.status.success() => Ok(()),
++                        Ok(output) => Err(anyhow::anyhow!(
++                            "{}",
++                            String::from_utf8_lossy(&output.stderr).trim()
++                        )),
++                        Err(e) => Err(e.into()),
++                    }
++                } else {
++                    wl::activate_window(&sel.app_id, &sel.title, sel.dup_index).map_err(Into::into)
++                };
++                if let Err(e) = result {
++                    eprintln!("{}", tr!("error", error = format!("{e:#}")));
++                    std::process::exit(2);
++                }
+             }
+         }
+         Ok(None) => std::process::exit(1), // cancelled
+--- a/src/ui.rs
++++ b/src/ui.rs
+@@ -6,7 +6,9 @@
+ 
+ use crate::tr;
+ use std::collections::{HashMap, HashSet};
++use std::io::Write;
+ use std::path::PathBuf;
++use std::process::{Command, Stdio};
+ use std::sync::mpsc::{Receiver, Sender};
+ use std::sync::{Arc, Mutex};
+ use std::time::{Duration, Instant};
+@@ -366,6 +368,288 @@
+     }
+ }
+ 
++#[derive(Clone)]
++struct NiriWindow {
++    id: String,
++    app_id: String,
++    title: String,
++}
++
++enum ClipboardSnapshot {
++    Empty,
++    Content { mime: String, data: Vec<u8> },
++    Unavailable,
++}
++
++fn save_clipboard() -> ClipboardSnapshot {
++    let Ok(types) = Command::new("wl-paste").arg("--list-types").output() else {
++        return ClipboardSnapshot::Unavailable;
++    };
++    if !types.status.success() {
++        return ClipboardSnapshot::Empty;
++    }
++    let types = String::from_utf8_lossy(&types.stdout);
++    let offered: Vec<&str> = types.lines().filter(|line| !line.is_empty()).collect();
++    let Some(mime) = offered
++        .iter()
++        .copied()
++        .find(|mime| *mime == "text/plain;charset=utf-8")
++        .or_else(|| offered.first().copied())
++    else {
++        return ClipboardSnapshot::Empty;
++    };
++    let Ok(data) = Command::new("wl-paste")
++        .args(["--type", mime])
++        .output()
++    else {
++        return ClipboardSnapshot::Unavailable;
++    };
++    if !data.status.success() {
++        return ClipboardSnapshot::Unavailable;
++    }
++    ClipboardSnapshot::Content {
++        mime: mime.to_owned(),
++        data: data.stdout,
++    }
++}
++
++fn restore_clipboard(snapshot: ClipboardSnapshot) {
++    match snapshot {
++        ClipboardSnapshot::Empty => {
++            let _ = Command::new("wl-copy").arg("--clear").status();
++        }
++        ClipboardSnapshot::Content { mime, data } => {
++            let Ok(mut copy) = Command::new("wl-copy")
++                .args(["--type", &mime])
++                .stdin(Stdio::piped())
++                .spawn()
++            else {
++                return;
++            };
++            if let Some(mut stdin) = copy.stdin.take() {
++                let _ = stdin.write_all(&data);
++            }
++            let _ = copy.wait();
++        }
++        ClipboardSnapshot::Unavailable => {}
++    }
++}
++
++/// Decode one field emitted by jq's `@tsv` formatter. It escapes the only
++/// characters that would otherwise make the line-oriented transport ambiguous.
++fn unescape_tsv(value: &str) -> String {
++    let mut decoded = String::with_capacity(value.len());
++    let mut chars = value.chars();
++    while let Some(ch) = chars.next() {
++        if ch != '\\' {
++            decoded.push(ch);
++            continue;
++        }
++        match chars.next() {
++            Some('t') => decoded.push('\t'),
++            Some('r') => decoded.push('\r'),
++            Some('n') => decoded.push('\n'),
++            Some('\\') => decoded.push('\\'),
++            Some(other) => {
++                decoded.push('\\');
++                decoded.push(other);
++            }
++            None => decoded.push('\\'),
++        }
++    }
++    decoded
++}
++
++/// Ask niri for its toplevel list. niri does not implement the
++/// ext-image-copy-capture window protocol, so its IPC is the source of both the
++/// stable window id and the metadata used by this backend.
++fn niri_windows() -> Result<Vec<NiriWindow>, String> {
++    let response = Command::new("niri")
++        .args(["msg", "-j", "windows"])
++        .output()
++        .map_err(|e| format!("could not run niri msg: {e}"))?;
++    if !response.status.success() {
++        return Err(String::from_utf8_lossy(&response.stderr).trim().to_owned());
++    }
++
++    let mut jq = Command::new("jq")
++        .args([
++            "-r",
++            ".[] | [(.id | tostring), (.app_id // \"\"), (.title // \"\")] | @tsv",
++        ])
++        .stdin(Stdio::piped())
++        .stdout(Stdio::piped())
++        .stderr(Stdio::piped())
++        .spawn()
++        .map_err(|e| format!("could not run jq: {e}"))?;
++    jq.stdin
++        .take()
++        .ok_or_else(|| String::from("jq stdin was unavailable"))?
++        .write_all(&response.stdout)
++        .map_err(|e| format!("could not pass niri window list to jq: {e}"))?;
++    let output = jq
++        .wait_with_output()
++        .map_err(|e| format!("could not read jq output: {e}"))?;
++    if !output.status.success() {
++        return Err(String::from_utf8_lossy(&output.stderr).trim().to_owned());
++    }
++
++    let text = String::from_utf8(output.stdout)
++        .map_err(|e| format!("niri window list was not UTF-8: {e}"))?;
++    let mut windows = Vec::new();
++    for line in text.lines() {
++        let mut fields = line.splitn(3, '\t');
++        let Some(id) = fields.next() else { continue };
++        let Some(app_id) = fields.next() else { continue };
++        let Some(title) = fields.next() else { continue };
++        windows.push(NiriWindow {
++            id: id.to_owned(),
++            app_id: unescape_tsv(app_id),
++            title: unescape_tsv(title),
++        });
++    }
++    windows.sort_by(|a, b| {
++        a.app_id
++            .to_lowercase()
++            .cmp(&b.app_id.to_lowercase())
++            .then_with(|| a.title.to_lowercase().cmp(&b.title.to_lowercase()))
++    });
++    Ok(windows)
++}
++
++fn niri_window_source(w: &NiriWindow, dup_index: usize) -> Source {
++    let is_system = w.app_id.is_empty();
++    let (title, subtitle) = if is_system {
++        (w.title.clone(), String::new())
++    } else {
++        (w.app_id.clone(), w.title.clone())
++    };
++    Source {
++        key: w.id.clone(),
++        token: format!("Window: {}", w.id),
++        filter: format!("{} {}", w.app_id, w.title).to_lowercase(),
++        title,
++        subtitle,
++        is_window: true,
++        is_system,
++        app_id: w.app_id.clone(),
++        win_title: w.title.clone(),
++        dup_index,
++    }
++}
++
++/// Capture a static overview through niri's IPC. This is deliberately separate
++/// from the generic Wayland backend: niri can render any toplevel by id (even an
++/// occluded one), but does not advertise ext-image-copy-capture.
++pub fn niri_capture_thread(tx: Sender<Msg>) {
++    let windows = match niri_windows() {
++        Ok(windows) => windows,
++        Err(e) => {
++            eprintln!("niri overview backend: {e}");
++            return;
++        }
++    };
++
++    let mut dup: HashMap<(String, String), usize> = HashMap::new();
++    let mut current = Vec::with_capacity(windows.len());
++    for window in windows {
++        let e = dup
++            .entry((window.app_id.clone(), window.title.clone()))
++            .or_insert(0);
++        let source = niri_window_source(&window, *e);
++        *e += 1;
++        current.push((source, window));
++    }
++    if tx
++        .send(Msg::Sources(
++            current.iter().map(|(source, _)| source.clone()).collect(),
++        ))
++        .is_err()
++    {
++        return;
++    }
++
++    let capture_dir = wlr_capture::paths::runtime_dir().join(format!(
++        "window-overview-niri-{}",
++        std::process::id()
++    ));
++    if let Err(e) = std::fs::create_dir_all(&capture_dir) {
++        eprintln!("niri overview backend: could not create capture directory: {e}");
++        return;
++    }
++    // niri's screenshot action also sets the clipboard. Preserve the existing
++    // selection so opening the overview does not unexpectedly replace it.
++    let clipboard = save_clipboard();
++
++    for (source, window) in current {
++        if let Some(path) = icons::resolve(&window.app_id)
++            && let Some((w, h, rgba)) = icons::load(&path, 128)
++            && tx
++                .send(Msg::Icon {
++                    key: source.key.clone(),
++                    w: w as usize,
++                    h: h as usize,
++                    rgba,
++                })
++                .is_err()
++        {
++            break;
++        }
++
++        let path = capture_dir.join(format!("{}.png", window.id));
++        let command = Command::new("niri")
++            .args(["msg", "action", "screenshot-window", "--id"])
++            .arg(&window.id)
++            .args(["--write-to-disk", "true", "--show-pointer", "false", "--path"])
++            .arg(&path)
++            .output();
++        let Ok(output) = command else {
++            continue;
++        };
++        if !output.status.success() {
++            eprintln!(
++                "niri overview backend: could not capture window {}: {}",
++                window.id,
++                String::from_utf8_lossy(&output.stderr).trim()
++            );
++            continue;
++        }
++
++        // niri encodes PNGs off the compositor thread, after acknowledging the
++        // IPC action. Wait briefly for that completion without delaying the UI.
++        let mut bytes = None;
++        for _ in 0..200 {
++            match std::fs::read(&path) {
++                Ok(data) => {
++                    bytes = Some(data);
++                    break;
++                }
++                Err(_) => std::thread::sleep(Duration::from_millis(10)),
++            }
++        }
++        let Some(bytes) = bytes else { continue };
++        let Ok(image) = image::load_from_memory_with_format(&bytes, image::ImageFormat::Png) else {
++            continue;
++        };
++        let image = image.into_rgba8();
++        let (w, h, rgba) = thumbnail_rgba(image.width(), image.height(), image.into_raw());
++        if tx
++            .send(Msg::Thumb {
++                key: source.key,
++                w,
++                h,
++                rgba,
++            })
++            .is_err()
++        {
++            break;
++        }
++        let _ = std::fs::remove_file(path);
++    }
++    let _ = std::fs::remove_dir(capture_dir);
++    restore_clipboard(clipboard);
++}
++
+ /// Cheap content fingerprint of a frame (subsampled FNV-1a), to tell whether a
+ /// capture actually changed between rounds — used by the headless bench.
+ fn quick_hash(rgba: &[u8]) -> u64 {
+@@ -515,11 +799,14 @@
+ 
+ /// Downscale a capture to a thumbnail (max side `THUMB_MAX`), never upscaling.
+ fn thumbnail(img: wl::CapturedImage) -> (usize, usize, Vec<u8>) {
+-    let (w, h) = (img.width, img.height);
++    thumbnail_rgba(img.width, img.height, img.rgba)
++}
++
++fn thumbnail_rgba(w: u32, h: u32, rgba: Vec<u8>) -> (usize, usize, Vec<u8>) {
+     let scale = (THUMB_MAX as f32 / w as f32)
+         .min(THUMB_MAX as f32 / h as f32)
+         .min(1.0);
+-    let src = match image::RgbaImage::from_raw(w, h, img.rgba) {
++    let src = match image::RgbaImage::from_raw(w, h, rgba) {
+         Some(s) => s,
+         None => return (0, 0, Vec::new()),
+     };
+@@ -557,6 +844,9 @@
+     pub snapshot: bool,
+     /// Receives next/previous commands from repeated compositor keybind launches.
+     pub cycle_socket: Option<std::os::unix::net::UnixDatagram>,
++    /// Use niri's IPC for window enumeration and snapshots instead of the
++    /// ext-image-copy-capture protocol that niri does not implement.
++    pub niri_backend: bool,
+ }
+ 
+ pub struct App {

modules/applications/window-overview/patches/window-overview.patch

@@ -0,0 +1,336 @@
+--- a/src/chooser_cli.rs
++++ b/src/chooser_cli.rs
+@@ -79,0 +80,4 @@
++        app_id_filter: None,
++        initial_cycle: None,
++        snapshot: false,
++        cycle_socket: None,
+--- a/src/lib.rs
++++ b/src/lib.rs
+@@ -33,3 +33,3 @@
+-/// Returns the held lock file (keep it alive), or `None` if another instance owns
+-/// it — sway processes its own keybinding even over our exclusive keyboard grab,
+-/// so re-pressing the bind would otherwise stack overlays.
++/// Returns the held lock and command socket for the first instance. Later
++/// invocations forward their requested cycle direction through the socket and
++/// return `None`, which also supports compositors that keep handling the binding.
+@@ -36 +36,3 @@
+-pub fn acquire_switch_lock() -> Option<std::fs::File> {
++pub fn acquire_switch_lock(
++    forward: bool,
++) -> Option<(std::fs::File, std::os::unix::net::UnixDatagram)> {
+@@ -38,0 +41 @@
++    let socket_path = dir.join("wlr-switcher.sock");
+@@ -45,2 +49,10 @@
+-    flock(&f, FlockOperation::NonBlockingLockExclusive).ok()?;
+-    Some(f)
++    if flock(&f, FlockOperation::NonBlockingLockExclusive).is_err() {
++        let socket = std::os::unix::net::UnixDatagram::unbound().ok()?;
++        let command = if forward { b"next" } else { b"prev" };
++        let _ = socket.send_to(command, socket_path);
++        return None;
++    }
++    let _ = std::fs::remove_file(&socket_path);
++    let socket = std::os::unix::net::UnixDatagram::bind(socket_path).ok()?;
++    socket.set_nonblocking(true).ok()?;
++    Some((f, socket))
+@@ -56 +68,2 @@
+-    std::thread::spawn(move || ui::capture_thread(tx));
++    let snapshot = opts.snapshot;
++    std::thread::spawn(move || ui::capture_thread(tx, snapshot));
+--- a/src/shell.rs
++++ b/src/shell.rs
+@@ -617,0 +618,3 @@
++        Keysym::plus | Keysym::KP_Add => Key::Plus,
++        Keysym::equal => Key::Equals,
++        Keysym::minus | Keysym::KP_Subtract => Key::Minus,
+--- a/src/switcher_cli.rs
++++ b/src/switcher_cli.rs
+@@ -75,0 +76,6 @@
++    /// Show only windows whose Wayland app-id exactly matches this value.
++    #[arg(long)]
++    app_id: Option<String>,
++    /// Select the previous window when the overview first opens.
++    #[arg(long)]
++    reverse: bool,
+@@ -96,2 +102,2 @@
+-    let _lock = match acquire_switch_lock() {
+-        Some(lock) => lock,
++    let (_lock, cycle_socket) = match acquire_switch_lock(!cli.reverse) {
++        Some(instance) => instance,
+@@ -121,0 +128,4 @@
++        app_id_filter: cli.app_id,
++        initial_cycle: Some(!cli.reverse),
++        snapshot: true,
++        cycle_socket: Some(cycle_socket),
+--- a/src/ui.rs
++++ b/src/ui.rs
+@@ -8,0 +9 @@
++use std::path::PathBuf;
+@@ -41,0 +43,32 @@
++const DEFAULT_OVERVIEW_SCALE: f32 = 0.85;
++const MIN_OVERVIEW_SCALE: f32 = 0.55;
++const MAX_OVERVIEW_SCALE: f32 = 1.0;
++
++fn overview_scale_path() -> Option<PathBuf> {
++    if let Some(path) = std::env::var_os("XDG_STATE_HOME") {
++        return Some(PathBuf::from(path).join("window-overview/scale"));
++    }
++    std::env::var_os("HOME")
++        .map(PathBuf::from)
++        .map(|path| path.join(".local/state/window-overview/scale"))
++}
++
++fn load_overview_scale() -> f32 {
++    overview_scale_path()
++        .and_then(|path| std::fs::read_to_string(path).ok())
++        .and_then(|value| value.trim().parse::<f32>().ok())
++        .unwrap_or(DEFAULT_OVERVIEW_SCALE)
++        .clamp(MIN_OVERVIEW_SCALE, MAX_OVERVIEW_SCALE)
++}
++
++fn save_overview_scale(scale: f32) {
++    let Some(path) = overview_scale_path() else {
++        return;
++    };
++    let Some(parent) = path.parent() else {
++        return;
++    };
++    if std::fs::create_dir_all(parent).is_ok() {
++        let _ = std::fs::write(path, format!("{scale:.2}\n"));
++    }
++}
+@@ -177 +210 @@
+-pub fn capture_thread(tx: Sender<Msg>) {
++pub fn capture_thread(tx: Sender<Msg>, snapshot: bool) {
+@@ -189,0 +223 @@
++    let mut captured: HashSet<String> = HashSet::new();
+@@ -236,0 +271 @@
++        captured.retain(|key| present.contains(key.as_str()));
+@@ -255 +290 @@
+-            if sessions.contains_key(&s.key) {
++            if sessions.contains_key(&s.key) || (snapshot && captured.contains(&s.key)) {
+@@ -295 +330,3 @@
+-            let Some(key) = by_id.get(&id) else { continue };
++            let Some(key) = by_id.get(&id).cloned() else {
++                continue;
++            };
+@@ -313,0 +351,6 @@
++            if snapshot {
++                captured.insert(key.clone());
++                sessions.remove(&key);
++                by_id.remove(&id);
++                client.close_session(&id);
++            }
+@@ -508,0 +552,8 @@
++    /// Exact Wayland app-id filter, used by taskbar launches.
++    pub app_id_filter: Option<String>,
++    /// Initial cycle direction. `None` leaves the first item selected.
++    pub initial_cycle: Option<bool>,
++    /// Capture each window once instead of continuously refreshing previews.
++    pub snapshot: bool,
++    /// Receives next/previous commands from repeated compositor keybind launches.
++    pub cycle_socket: Option<std::os::unix::net::UnixDatagram>,
+@@ -533,0 +585,5 @@
++    app_id_filter: Option<String>,
++    initial_forward: bool,
++    overview_scale: f32,
++    cycle_socket: Option<std::os::unix::net::UnixDatagram>,
++    queued_cycles: isize,
+@@ -567 +623 @@
+-            pending_initial_select: false,
++            pending_initial_select: opts.initial_cycle.is_some(),
+@@ -571,0 +628,5 @@
++            app_id_filter: opts.app_id_filter,
++            initial_forward: opts.initial_cycle.unwrap_or(true),
++            overview_scale: load_overview_scale(),
++            cycle_socket: opts.cycle_socket,
++            queued_cycles: 0,
+@@ -604 +665,4 @@
+-            return; // nothing to cycle yet; keep the pending initial jump
++            self.queued_cycles = self
++                .queued_cycles
++                .saturating_add(if forward { 1 } else { -1 });
++            return;
+@@ -639,0 +704,12 @@
++        loop {
++            let command = self.cycle_socket.as_ref().and_then(|socket| {
++                let mut buf = [0_u8; 8];
++                socket.recv(&mut buf).ok().map(|len| (buf, len))
++            });
++            match command {
++                Some((buf, len)) if &buf[..len] == b"next" => self.cycle(true),
++                Some((buf, len)) if &buf[..len] == b"prev" => self.cycle(false),
++                Some(_) => {}
++                None => break,
++            }
++        }
+@@ -698,0 +775,5 @@
++            .filter(|s| {
++                self.app_id_filter
++                    .as_ref()
++                    .is_none_or(|app_id| s.app_id.eq_ignore_ascii_case(app_id))
++            })
+@@ -713,2 +793,0 @@
+-        // Exposé covers the whole screen: dim almost to opaque so the real windows
+-        // behind are hidden (a client can't move them; this hides them instead).
+@@ -716 +795 @@
+-            c[3] = c[3].max(0.96);
++            c[3] = 0.5;
+@@ -734 +813,5 @@
+-                self.selected = if n > 1 { 1 } else { 0 };
++                self.selected = if n > 1 {
++                    if self.initial_forward { 1 } else { n - 1 }
++                } else {
++                    0
++                };
+@@ -737,0 +821,8 @@
++        if self.queued_cycles != 0 {
++            let n = self.visible().len();
++            if n > 0 {
++                self.selected = (self.selected as isize + self.queued_cycles)
++                    .rem_euclid(n as isize) as usize;
++                self.queued_cycles = 0;
++            }
++        }
+@@ -745 +836 @@
+-        let (esc, next, prev, enter) = ctx.input(|i| {
++        let (esc, next, prev, enter, zoom_in, zoom_out, wheel_zoom) = ctx.input(|i| {
+@@ -746,0 +838,8 @@
++            let wheel_zoom = i
++                .events
++                .iter()
++                .filter_map(|event| match event {
++                    egui::Event::MouseWheel { delta, .. } => Some(delta.y),
++                    _ => None,
++                })
++                .sum::<f32>();
+@@ -755,0 +855,3 @@
++                i.key_pressed(egui::Key::Plus) || i.key_pressed(egui::Key::Equals),
++                i.key_pressed(egui::Key::Minus),
++                wheel_zoom,
+@@ -771,0 +874,12 @@
++        if self.view == View::Grid && (zoom_in || zoom_out || wheel_zoom != 0.0) {
++            let delta = if zoom_in {
++                0.05
++            } else if zoom_out {
++                -0.05
++            } else {
++                wheel_zoom.signum() * 0.05
++            };
++            self.overview_scale =
++                (self.overview_scale + delta).clamp(MIN_OVERVIEW_SCALE, MAX_OVERVIEW_SCALE);
++            save_overview_scale(self.overview_scale);
++        }
+@@ -1020 +1134,5 @@
+-        let area = ctx.content_rect().shrink(24.0);
++        let full_area = ctx.content_rect().shrink(24.0);
++        let area = egui::Rect::from_center_size(
++            full_area.center(),
++            full_area.size() * self.overview_scale,
++        );
+@@ -1048,0 +1167 @@
++                    let selected = *i == self.selected;
+@@ -1062,9 +1181,3 @@
+-                        rect.size() * (0.86 + 0.14 * ease),
+-                    );
+-                    self.paint_expose_tile(
+-                        ui,
+-                        s,
+-                        scaled,
+-                        *i == self.selected,
+-                        resp.hovered(),
+-                        ease,
++                        rect.size()
++                            * (0.86 + 0.14 * ease)
++                            * if selected { 1.04 } else { 1.0 },
+@@ -1071,0 +1185 @@
++                    self.paint_expose_tile(ui, s, scaled, selected, resp.hovered(), ease);
+@@ -1077,0 +1192,8 @@
++        ui.painter().text(
++            egui::pos2(full_area.right(), full_area.top()),
++            egui::Align2::RIGHT_TOP,
++            format!("−  {:.0}%  +", self.overview_scale * 100.0),
++            egui::FontId::proportional(14.0),
++            self.theme.text_dim,
++        );
++
+@@ -1107 +1229,14 @@
+-        let white = egui::Color32::WHITE.gamma_multiply(a);
++        let accent = if s.is_window {
++            t.window_accent
++        } else {
++            t.screen_accent
++        };
++        let content_alpha = if selected || hovered { 1.0 } else { 0.55 };
++        let white = egui::Color32::WHITE.gamma_multiply(a * content_alpha);
++        if selected {
++            p.rect_filled(
++                rect.expand(8.0),
++                radius + 8.0,
++                fade(accent).gamma_multiply(0.35),
++            );
++        }
+@@ -1127,0 +1263,7 @@
++        if !selected && !hovered {
++            p.rect_filled(
++                rect,
++                radius,
++                egui::Color32::from_black_alpha(72).gamma_multiply(a),
++            );
++        }
+@@ -1136 +1278,5 @@
+-            egui::Color32::from_black_alpha(160).gamma_multiply(a),
++            if selected {
++                fade(accent).gamma_multiply(0.9)
++            } else {
++                egui::Color32::from_black_alpha(160).gamma_multiply(a)
++            },
+@@ -1175,9 +1321,22 @@
+-        let accent = if s.is_window {
+-            t.window_accent
+-        } else {
+-            t.screen_accent
+-        };
+-        let (sw, col) = if selected {
+-            (3.0, accent)
+-        } else if hovered {
+-            (2.0, accent)
++        if selected {
++            p.rect_stroke(
++                rect.expand(4.0),
++                radius + 4.0,
++                egui::Stroke::new(3.0, fade(egui::Color32::WHITE)),
++                egui::StrokeKind::Inside,
++            );
++            p.rect_stroke(
++                rect,
++                radius,
++                egui::Stroke::new(6.0, fade(accent)),
++                egui::StrokeKind::Inside,
++            );
++            let marker = egui::pos2(rect.right() - 18.0, rect.top() + 18.0);
++            p.circle_filled(marker, 13.0, fade(accent));
++            p.text(
++                marker,
++                egui::Align2::CENTER_CENTER,
++                "✓",
++                egui::FontId::proportional(18.0),
++                fade(egui::Color32::WHITE),
++            );
+@@ -1185,8 +1344,7 @@
+-            (1.0, t.thumb)
+-        };
+-        p.rect_stroke(
+-            rect,
+-            radius,
+-            egui::Stroke::new(sw, fade(col)),
+-            egui::StrokeKind::Inside,
+-        );
++            p.rect_stroke(
++                rect,
++                radius,
++                egui::Stroke::new(if hovered { 2.0 } else { 1.0 }, fade(accent)),
++                egui::StrokeKind::Inside,
++            );
++        }

modules/profiles/README.md

@@ -30,6 +30,7 @@ required on every supported host.
 | `interface.linux-desktop`            | NixOS with Home Manager                       |
 | `interface.labwc`                    | NixOS with Home Manager                       |
 | `interface.niri`                     | NixOS with Home Manager                       |
+| `interface.wallpaperengine`          | NixOS with Home Manager                       |
 | `platform.nixos`                     | NixOS                                         |
 | `platform.desktop`                   | Physical NixOS desktop                        |
 | `platform.intel-nvidia-desktop`      | Intel/NVIDIA physical NixOS desktop           |
@@ -58,6 +59,10 @@ selects labwc. A daily-use macOS development machine can combine
 `interface.macos`, `workload.development`, and `workload.personal`. Hardware
 support does not implicitly select an interface or workload.
 
+`interface.wallpaperengine` is an opt-in Linux desktop appearance profile. It
+enables Wallpaper Engine and disables Noctalia's wallpaper surface, so hosts
+without this profile retain Noctalia's configured wallpaper.
+
 `workload.personal` provides Pear Desktop on both NixOS and macOS. Home Manager
 enables performance improvements, synced lyrics, tracker blocking, the album
 color theme, and custom output-device selection while preserving user-owned

modules/profiles/interface/linux-desktop/home.nix

@@ -4,8 +4,6 @@
     pkgs.playerctl
   ];
 
-  programs.noctalia.settings.wallpaper.enabled = false;
-
   xdg.userDirs = {
     enable = true;
     createDirectories = true;

modules/profiles/interface/linux-desktop/meta.nix

@@ -11,9 +11,8 @@
     "applications.ghostty"
     "applications.gtk"
     "applications.loupe"
-    "applications.linux-wallpaperengine"
     "applications.nautilus"
-    "applications.normcap"
+    "applications.nani"
     "applications.papers"
     "applications.qalculate-gtk"
     "applications.resources"

modules/profiles/interface/wallpaperengine/home.nix

@@ -0,0 +1,3 @@
+{
+  programs.noctalia.settings.wallpaper.enabled = false;
+}

modules/profiles/interface/wallpaperengine/meta.nix

@@ -0,0 +1,7 @@
+{
+  description = "Wallpaper Engine backgrounds for Linux desktop sessions";
+
+  includes = [
+    "applications.linux-wallpaperengine"
+  ];
+}

modules/profiles/workload/development/home.nix

@@ -3,7 +3,10 @@
   home.packages = with pkgs; [
     bind
     bun
-    nil
+    mcp-nixos
+    nix-fast-build
+    nix-tree
+    nixd
     python312
     uv
   ];

opencode.json

@@ -0,0 +1,23 @@
+{
+  "$schema": "https://opencode.ai/config.json",
+  "mcp": {
+    "nixos": {
+      "type": "local",
+      "command": ["mcp-nixos"],
+      "enabled": true,
+      "timeout": 30000
+    },
+    "github": {
+      "type": "remote",
+      "url": "https://api.githubcopilot.com/mcp/",
+      "enabled": true,
+      "oauth": false,
+      "headers": {
+        "Authorization": "Bearer {env:GITHUB_PERSONAL_ACCESS_TOKEN}",
+        "X-MCP-Readonly": "true",
+        "X-MCP-Toolsets": "repos,pull_requests,actions"
+      },
+      "timeout": 30000
+    }
+  }
+}

scripts/dotfiles-check.py

@@ -0,0 +1,526 @@
+#!/usr/bin/env python3
+"""Change-aware, non-activating validation for this Nix dotfiles repository."""
+
+from __future__ import annotations
+
+import argparse
+from collections import defaultdict, deque
+from contextlib import contextmanager
+import io
+import json
+import os
+from pathlib import Path, PurePosixPath
+import shutil
+import subprocess
+import sys
+import tarfile
+import tempfile
+import tomllib
+from typing import Any, Iterator, Sequence
+
+GLOBAL_FILES = {"flake.nix", "flake.lock", "hosts/default.nix"}
+GLOBAL_PREFIXES = ("flake/", "libs/", "overlays/")
+FULL_EVAL_PREFIXES = GLOBAL_PREFIXES + ("scripts/", "shells/", "tests/")
+FULL_BUILD_PREFIXES = GLOBAL_PREFIXES + ("scripts/", "shells/", "tests/")
+DOC_SUFFIXES = (".md", ".png", ".jpg", ".jpeg", ".webp")
+
+
+class ValidationError(RuntimeError):
+    pass
+
+
+def command_text(command: Sequence[str]) -> str:
+    return " ".join(json.dumps(part) if any(c.isspace() for c in part) else part for part in command)
+
+
+def run(
+    command: Sequence[str],
+    *,
+    cwd: Path,
+    capture: bool = False,
+    check: bool = True,
+    input_text: str | None = None,
+) -> subprocess.CompletedProcess[str]:
+    print(f"+ {command_text(command)}", file=sys.stderr)
+    return subprocess.run(
+        list(command),
+        cwd=cwd,
+        check=check,
+        text=True,
+        input=input_text,
+        stdout=subprocess.PIPE if capture else None,
+        stderr=subprocess.PIPE if capture else None,
+    )
+
+
+def git(root: Path, *args: str, check: bool = True) -> str:
+    return run(["git", *args], cwd=root, capture=True, check=check).stdout
+
+
+def repo_root() -> Path:
+    return Path(run(["git", "rev-parse", "--show-toplevel"], cwd=Path.cwd(), capture=True).stdout.strip()).resolve()
+
+
+def normalize(root: Path, raw: str) -> str:
+    candidate = Path(raw)
+    absolute = candidate.resolve() if candidate.is_absolute() else (root / candidate).resolve()
+    try:
+        return absolute.relative_to(root).as_posix()
+    except ValueError as error:
+        raise ValidationError(f"path escapes repository root: {raw}") from error
+
+
+def nonempty_lines(value: str) -> list[str]:
+    return [line for line in value.splitlines() if line]
+
+
+def tracked_paths(root: Path) -> set[str]:
+    return set(nonempty_lines(git(root, "ls-files")))
+
+
+def untracked_paths(root: Path) -> set[str]:
+    return set(nonempty_lines(git(root, "ls-files", "--others", "--exclude-standard")))
+
+
+def expand_paths(root: Path, raw_paths: Sequence[str], available: set[str]) -> list[str]:
+    result: set[str] = set()
+    for raw in raw_paths:
+        relative = normalize(root, raw)
+        target = root / relative
+        if target.is_dir():
+            prefix = f"{relative.rstrip('/')}/" if relative else ""
+            result.update(path for path in available if path.startswith(prefix))
+        else:
+            result.add(relative)
+    return sorted(result)
+
+
+def collect_paths(root: Path, args: argparse.Namespace) -> tuple[list[str], set[str]]:
+    tracked = tracked_paths(root)
+    untracked = untracked_paths(root)
+    if args.paths:
+        paths = expand_paths(root, args.paths, tracked | untracked)
+    elif args.all_files:
+        paths = sorted(tracked)
+    elif args.base:
+        paths = nonempty_lines(
+            git(root, "diff", "--name-only", "--no-renames", "--diff-filter=ACMRTUXBD", f"{args.base}...HEAD", "--")
+        )
+    else:
+        paths = nonempty_lines(git(root, "diff", "--name-only", "--no-renames", "--diff-filter=ACMRTUXBD", "HEAD", "--"))
+        paths += sorted(untracked)
+    return sorted(set(paths)), untracked
+
+
+def remove_path(path: Path) -> None:
+    if path.is_symlink() or path.is_file():
+        path.unlink()
+    elif path.is_dir():
+        shutil.rmtree(path)
+
+
+@contextmanager
+def flake_reference(root: Path, changed: Sequence[str]) -> Iterator[str]:
+    """Create a clean HEAD snapshot and overlay only task-owned worktree paths."""
+    with tempfile.TemporaryDirectory(prefix="dotfiles-flake-") as temporary:
+        source = Path(temporary) / "source"
+        source.mkdir()
+        archive = subprocess.run(
+            ["git", "archive", "--format=tar", "HEAD"],
+            cwd=root,
+            check=True,
+            stdout=subprocess.PIPE,
+        ).stdout
+        with tarfile.open(fileobj=io.BytesIO(archive), mode="r:") as tar:
+            tar.extractall(source, filter="data")
+        for relative in changed:
+            src, dst = root / relative, source / relative
+            remove_path(dst)
+            if src.is_symlink():
+                dst.parent.mkdir(parents=True, exist_ok=True)
+                dst.symlink_to(os.readlink(src))
+            elif src.is_file():
+                dst.parent.mkdir(parents=True, exist_ok=True)
+                shutil.copy2(src, dst)
+        yield f"path:{source}"
+
+
+def load_metadata(root: Path, reference: str) -> dict[str, Any]:
+    result = run(
+        ["nix", "eval", "--json", "--show-trace", f"{reference}#lib.validationMetadata"],
+        cwd=root,
+        capture=True,
+    )
+    metadata = json.loads(result.stdout)
+    if metadata.get("schemaVersion") != 1:
+        raise ValidationError("unsupported validation metadata schema")
+    return metadata
+
+
+def reverse_dependencies(units: dict[str, Any]) -> dict[str, set[str]]:
+    result: dict[str, set[str]] = defaultdict(set)
+    for unit_id, unit in units.items():
+        for dependency in unit.get("includes", []):
+            result[dependency].add(unit_id)
+    return result
+
+
+def users_of(unit_id: str, reverse: dict[str, set[str]]) -> set[str]:
+    result, queue = {unit_id}, deque([unit_id])
+    while queue:
+        for dependent in reverse.get(queue.popleft(), set()):
+            if dependent not in result:
+                result.add(dependent)
+                queue.append(dependent)
+    return result
+
+
+def owner_for(path: str, units: dict[str, Any]) -> str | None:
+    matches = []
+    for unit_id, unit in units.items():
+        directory = unit["directory"].rstrip("/")
+        if path == directory or path.startswith(f"{directory}/"):
+            matches.append((len(directory), unit_id))
+    return max(matches)[1] if matches else None
+
+
+def path_classes(path: str, unit: dict[str, Any]) -> set[str]:
+    directory = unit["directory"].rstrip("/")
+    relative = path[len(directory) :].lstrip("/")
+    if relative == "nixos.nix" or relative == "home/nixos.nix":
+        return {"nixos"}
+    if relative == "darwin.nix" or relative == "home/darwin.nix":
+        return {"darwin"}
+    if relative == "meta.nix":
+        return {"nixos", "darwin"}
+    if relative in {"common.nix", "home.nix", "home/common.nix"}:
+        return {"nixos", "darwin"}
+    fragments = set(unit.get("fragments", []))
+    classes: set[str] = set()
+    if fragments & {"common", "nixos", "home", "homeCommon", "homeNixos"}:
+        classes.add("nixos")
+    if fragments & {"common", "darwin", "home", "homeCommon", "homeDarwin"}:
+        classes.add("darwin")
+    return classes or {"nixos", "darwin"}
+
+
+def is_docs_only(path: str) -> bool:
+    return path.endswith(DOC_SUFFIXES)
+
+
+def plan(metadata: dict[str, Any], paths: Sequence[str], *, all_hosts: bool = False) -> dict[str, Any]:
+    hosts: dict[str, Any] = metadata["hosts"]
+    units: dict[str, Any] = metadata["units"]
+    reverse = reverse_dependencies(units)
+    affected_units: set[str] = set()
+    unit_classes: dict[str, set[str]] = defaultdict(set)
+    affected_hosts = {"nixos": set(), "darwin": set()}
+    global_change = all_hosts
+    requires_full_eval = False
+    requires_full_build = False
+    requires_nix = False
+
+    for path in paths:
+        if path in GLOBAL_FILES or path.startswith(GLOBAL_PREFIXES):
+            global_change = True
+            requires_nix = True
+        if path.startswith(FULL_EVAL_PREFIXES) or path in GLOBAL_FILES:
+            requires_full_eval = True
+        if path.startswith(FULL_BUILD_PREFIXES) or path in {"flake.nix", "flake.lock"}:
+            requires_full_build = True
+        if path.endswith(".nix") or path == "flake.lock":
+            requires_nix = True
+        if path == "scripts/dotfiles-check.py":
+            requires_nix = requires_full_eval = requires_full_build = True
+
+        if path.startswith("hosts/") and path != "hosts/default.nix":
+            parts = PurePosixPath(path).parts
+            if len(parts) > 1 and parts[1] in hosts:
+                affected_hosts[hosts[parts[1]]["kind"]].add(parts[1])
+                requires_nix = True
+
+        owner = owner_for(path, units)
+        if owner:
+            classes = path_classes(path, units[owner])
+            for unit_id in users_of(owner, reverse):
+                affected_units.add(unit_id)
+                unit_classes[unit_id].update(classes)
+            requires_nix = requires_nix or not is_docs_only(path)
+        elif path.startswith("modules/") and not is_docs_only(path):
+            global_change = True
+            requires_nix = True
+
+    if global_change:
+        for name, host in hosts.items():
+            affected_hosts[host["kind"]].add(name)
+    else:
+        for name, host in hosts.items():
+            selected = set(host["selectedUnits"])
+            if any(unit_id in selected and host["kind"] in unit_classes[unit_id] for unit_id in affected_units):
+                affected_hosts[host["kind"]].add(name)
+
+    synthetic = {"nixos": set(), "darwin": set()}
+    for unit_id in affected_units:
+        for kind in unit_classes[unit_id]:
+            if not any(unit_id in hosts[name]["selectedUnits"] for name in affected_hosts[kind]):
+                synthetic[kind].add(unit_id)
+
+    systems = sorted({host["system"] for host in hosts.values()})
+    native_systems = {system: False for system in systems}
+    if requires_full_build:
+        native_systems = {system: requires_nix for system in systems}
+    else:
+        for kind, names in affected_hosts.items():
+            for name in names:
+                native_systems[hosts[name]["system"]] = True
+        for kind, unit_ids in synthetic.items():
+            if unit_ids:
+                candidates = sorted(host["system"] for host in hosts.values() if host["kind"] == kind)
+                if candidates:
+                    native_systems[candidates[0]] = True
+
+    return {
+        "schemaVersion": 1,
+        "paths": sorted(paths),
+        "affectedUnits": sorted(affected_units),
+        "affectedHosts": {kind: sorted(names) for kind, names in affected_hosts.items()},
+        "syntheticUnits": {kind: sorted(names) for kind, names in synthetic.items()},
+        "requiresNixValidation": requires_nix,
+        "requiresFullEvaluation": requires_full_eval,
+        "requiresFullNativeBuild": requires_full_build,
+        "nativeBuildSystems": native_systems,
+    }
+
+
+def render_plan(value: dict[str, Any], reference: str) -> None:
+    print(f"flake: {reference}")
+    print("paths:", ", ".join(value["paths"]) or "(none)")
+    print("units:", ", ".join(value["affectedUnits"]) or "(none)")
+    for kind in ("nixos", "darwin"):
+        print(f"{kind} hosts:", ", ".join(value["affectedHosts"][kind]) or "(none)")
+        print(f"{kind} synthetic:", ", ".join(value["syntheticUnits"][kind]) or "(none)")
+    print("full evaluation:", value["requiresFullEvaluation"])
+    print("full native build:", value["requiresFullNativeBuild"])
+
+
+def validate_skill(path: Path) -> None:
+    text = path.read_text()
+    if not text.startswith("---\n"):
+        raise ValidationError(f"missing Skill frontmatter: {path}")
+    try:
+        frontmatter = text.split("---\n", 2)[1]
+        name = next(line.split(":", 1)[1].strip() for line in frontmatter.splitlines() if line.startswith("name:"))
+    except (IndexError, StopIteration) as error:
+        raise ValidationError(f"invalid Skill frontmatter: {path}") from error
+    if name != path.parent.name:
+        raise ValidationError(f"Skill name {name!r} does not match directory {path.parent.name!r}")
+
+
+def static_checks(root: Path, paths: Sequence[str], untracked: set[str]) -> None:
+    for relative in paths:
+        path = root / relative
+        if not path.is_file():
+            continue
+        if relative.endswith(".nix"):
+            run(["nix-instantiate", "--parse", str(path)], cwd=root, capture=True)
+        elif relative.endswith(".json"):
+            json.loads(path.read_text())
+        elif relative.endswith(".toml"):
+            tomllib.loads(path.read_text())
+        elif relative.endswith(".py"):
+            compile(path.read_text(), relative, "exec")
+        if path.name == "SKILL.md":
+            validate_skill(path)
+        if relative in untracked:
+            for number, line in enumerate(path.read_text(errors="replace").splitlines(), 1):
+                if line.rstrip() != line:
+                    raise ValidationError(f"trailing whitespace: {relative}:{number}")
+
+    diff_paths = [path for path in paths if path not in untracked]
+    if diff_paths:
+        run(["git", "diff", "--check", "HEAD", "--", *diff_paths], cwd=root)
+
+
+def run_fast(root: Path, reference: str, paths: Sequence[str], untracked: set[str], *, all_files: bool) -> None:
+    static_checks(root, paths, untracked)
+    command = ["nix", "develop", f"{reference}#validation", "--command", "pre-commit", "run"]
+    command += ["--all-files"] if all_files else (["--files", *paths] if paths else [])
+    if paths or all_files:
+        run(command, cwd=root)
+
+
+def selection_module_expr(unit_id: str) -> str:
+    quoted = json.dumps(unit_id)
+    return f"(flake.lib.registry.mkSelectionModule [ {quoted} ])"
+
+
+def synthetic_expr(reference: str, host_name: str, host: dict[str, Any], unit_id: str, *, drv_path: bool) -> str:
+    selection = selection_module_expr(unit_id)
+    modules = [selection]
+    if host.get("homeManager", True):
+        user = json.dumps(host["user"])
+        modules.append(f"{{ home-manager.users.{user}.imports = [ {selection} ]; }}")
+    base = f"flake.{('darwinConfigurations' if host['kind'] == 'darwin' else 'nixosConfigurations')}.{json.dumps(host_name)}"
+    output = "extended.system" if host["kind"] == "darwin" else "extended.config.system.build.toplevel"
+    if drv_path:
+        output += ".drvPath"
+    return f'''let
+  flake = builtins.getFlake {json.dumps(reference)};
+  base = {base};
+  extended = base.extendModules {{ modules = [ {' '.join(modules)} ]; }};
+in {output}'''
+
+
+def representative_host(metadata: dict[str, Any], kind: str, current_system: str | None = None) -> tuple[str, dict[str, Any]] | None:
+    candidates = [(name, host) for name, host in metadata["hosts"].items() if host["kind"] == kind]
+    if current_system:
+        candidates = [item for item in candidates if item[1]["system"] == current_system]
+    return sorted(candidates)[0] if candidates else None
+
+
+def host_drv_attr(reference: str, host: dict[str, Any]) -> str:
+    return f"{reference}#{host['buildAttr']}.drvPath"
+
+
+def run_eval(
+    root: Path,
+    reference: str,
+    metadata: dict[str, Any],
+    value: dict[str, Any],
+    *,
+    all_systems: bool,
+) -> None:
+    if all_systems or value["requiresFullEvaluation"]:
+        run(["nix", "flake", "check", reference, "--no-build", "--all-systems", "--keep-going", "--show-trace"], cwd=root)
+        return
+    for kind in ("nixos", "darwin"):
+        for name in value["affectedHosts"][kind]:
+            run(["nix", "eval", "--raw", "--show-trace", host_drv_attr(reference, metadata["hosts"][name])], cwd=root)
+        representative = representative_host(metadata, kind)
+        if representative:
+            name, host = representative
+            for unit_id in value["syntheticUnits"][kind]:
+                run(["nix", "eval", "--raw", "--impure", "--show-trace", "--expr", synthetic_expr(reference, name, host, unit_id, drv_path=True)], cwd=root)
+
+
+def current_system(root: Path) -> str:
+    return run(["nix", "eval", "--raw", "--impure", "--expr", "builtins.currentSystem"], cwd=root, capture=True).stdout.strip()
+
+
+def run_full_native(root: Path, reference: str, system: str) -> None:
+    run(
+        ["nix", "run", f"{reference}#nix-fast-build", "--", "--flake", f"{reference}#checks.{system}", "--skip-cached", "--no-nom", "--no-link"],
+        cwd=root,
+    )
+
+
+def run_build(root: Path, reference: str, metadata: dict[str, Any], value: dict[str, Any]) -> None:
+    system = current_system(root)
+    if value["requiresFullNativeBuild"]:
+        run_full_native(root, reference, system)
+        return
+
+    installables: list[str] = []
+    for kind in ("nixos", "darwin"):
+        for name in value["affectedHosts"][kind]:
+            host = metadata["hosts"][name]
+            if host["system"] == system:
+                installables.append(f"{reference}#{host['buildAttr']}")
+            else:
+                print(f"skip incompatible build: {name} ({host['system']})", file=sys.stderr)
+    for check in ("registry", "validation-tool"):
+        installables.append(f"{reference}#checks.{system}.{check}")
+    if installables:
+        run(["nix", "build", "--no-link", "--keep-going", "--print-build-logs", *sorted(set(installables))], cwd=root)
+
+    for kind in ("nixos", "darwin"):
+        representative = representative_host(metadata, kind, system)
+        if representative:
+            name, host = representative
+            for unit_id in value["syntheticUnits"][kind]:
+                run(["nix", "build", "--no-link", "--impure", "--expr", synthetic_expr(reference, name, host, unit_id, drv_path=False)], cwd=root)
+
+
+def self_test() -> None:
+    metadata = {
+        "schemaVersion": 1,
+        "units": {
+            "applications.foo": {"directory": "modules/applications/foo", "includes": [], "fragments": ["home", "homeNixos"]},
+            "applications.dormant": {"directory": "modules/applications/dormant", "includes": [], "fragments": ["home"]},
+            "profiles.workload.dev": {"directory": "modules/profiles/workload/dev", "includes": ["applications.foo"], "fragments": ["meta"]},
+        },
+        "hosts": {
+            "linux": {"kind": "nixos", "system": "x86_64-linux", "user": "test", "homeManager": True, "selectedUnits": ["profiles.workload.dev"], "buildAttr": "nixosConfigurations.linux.config.system.build.toplevel"},
+            "mac": {"kind": "darwin", "system": "aarch64-darwin", "user": "test", "homeManager": True, "selectedUnits": ["profiles.workload.dev"], "buildAttr": "darwinConfigurations.mac.system"},
+        },
+    }
+    nixos = plan(metadata, ["modules/applications/foo/home/nixos.nix"])
+    assert nixos["affectedHosts"] == {"nixos": ["linux"], "darwin": []}
+    assert nixos["affectedUnits"] == ["applications.foo", "profiles.workload.dev"]
+    common = plan(metadata, ["modules/applications/foo/home.nix"])
+    assert common["affectedHosts"] == {"nixos": ["linux"], "darwin": ["mac"]}
+    dormant = plan(metadata, ["modules/applications/dormant/home.nix"])
+    assert dormant["syntheticUnits"] == {"nixos": ["applications.dormant"], "darwin": ["applications.dormant"]}
+    global_value = plan(metadata, ["flake.nix"])
+    assert global_value["requiresFullEvaluation"] and global_value["requiresFullNativeBuild"]
+    docs = plan(metadata, ["modules/profiles/README.md"])
+    assert not docs["requiresNixValidation"]
+    print("dotfiles-check self-test passed")
+
+
+def parser() -> argparse.ArgumentParser:
+    result = argparse.ArgumentParser(description=__doc__)
+    result.add_argument("command", choices=("plan", "fast", "eval", "build", "all", "full", "self-test"))
+    result.add_argument("--paths", nargs="+", help="Explicit task-owned repository paths")
+    result.add_argument("--base", help="Compare BASE...HEAD")
+    result.add_argument("--all-files", action="store_true", help="Check every tracked file")
+    result.add_argument("--all-hosts", action="store_true", help="Validate every registered host")
+    result.add_argument("--all-systems", action="store_true", help="Evaluate every flake system")
+    result.add_argument("--json", action="store_true", help="Emit the plan as JSON")
+    return result
+
+
+def main() -> int:
+    args = parser().parse_args()
+    if args.command == "self-test":
+        self_test()
+        return 0
+    selectors = sum(bool(value) for value in (args.paths, args.base, args.all_files))
+    if selectors > 1:
+        raise ValidationError("use only one of --paths, --base, or --all-files")
+    if args.command == "full":
+        if selectors or args.all_hosts or args.all_systems:
+            raise ValidationError("full is exhaustive and accepts no scope flags")
+        args.all_files = args.all_hosts = args.all_systems = True
+
+    root = repo_root()
+    paths, untracked = collect_paths(root, args)
+    with flake_reference(root, paths) as reference:
+        metadata = load_metadata(root, reference)
+        value = plan(metadata, paths, all_hosts=args.all_hosts)
+        if args.command == "plan":
+            print(json.dumps(value, ensure_ascii=False, indent=2, sort_keys=True)) if args.json else render_plan(value, reference)
+            return 0
+        if args.command in {"fast", "all", "full"}:
+            run_fast(root, reference, paths, untracked, all_files=args.all_files)
+        if args.command in {"eval", "all", "full"} and value["requiresNixValidation"]:
+            run_eval(root, reference, metadata, value, all_systems=args.all_systems or args.command in {"all", "full"})
+        if args.command in {"build", "all"} and value["requiresNixValidation"]:
+            run_build(root, reference, metadata, value)
+        if args.command == "full":
+            run_full_native(root, reference, current_system(root))
+    return 0
+
+
+if __name__ == "__main__":
+    try:
+        raise SystemExit(main())
+    except ValidationError as error:
+        print(f"error: {error}", file=sys.stderr)
+        raise SystemExit(2) from error
+    except subprocess.CalledProcessError as error:
+        if error.stdout:
+            print(error.stdout, file=sys.stderr, end="")
+        if error.stderr:
+            print(error.stderr, file=sys.stderr, end="")
+        raise SystemExit(error.returncode) from error

shells/dotnix.nix

@@ -3,15 +3,22 @@ _: {
     {
       pkgs,
       config,
+      lib,
       ...
     }:
     {
       devShells.dotnix = pkgs.mkShell {
         packages = [
           config.treefmt.build.wrapper
+          config.packages.dotfiles-check
 
+          pkgs.actionlint
           pkgs.git
           pkgs.gitleaks
+          pkgs.mcp-nixos
+          pkgs.nix-fast-build
+          pkgs.nix-tree
+          pkgs.nixd
           pkgs.pre-commit
 
           # sops-nix / age
@@ -22,6 +29,8 @@ _: {
           # YubiKey for sops editing
           pkgs.age-plugin-yubikey
           pkgs.yubikey-manager
+        ]
+        ++ lib.optionals (lib.meta.availableOn pkgs.stdenv.hostPlatform pkgs.pcsc-tools) [
           pkgs.pcsc-tools
         ];
 

skills/add-application-or-service/SKILL.md

@@ -95,26 +95,33 @@ points cannot express the requirement.
 
 ### 4. Prove the change
 
-Run the validation matrix in
-[references/review-checklist.md](references/review-checklist.md). At minimum:
+Invoke the `validate-nix-change` skill and use the task-owned files as its
+explicit path set. At minimum:
 
-1. Format the task-owned files with the repository formatter and run
-   `git diff --check`.
-2. Inspect the complete task diff for accidental files, duplication, leaked
+1. Inspect `nix run .#check -- plan --paths <task-path>... --json` and confirm
+   the reported units, host classes, and real hosts are correct.
+2. Run `nix run .#check -- fast --paths <task-path>...` during the edit loop.
+3. Inspect the complete task diff for accidental files, duplication, leaked
    secrets, forced values, direct enable assignments, and unrelated rewrites.
-3. Run `nix flake check`.
-4. Run `pre-commit run --all-files`.
-5. Evaluate every affected real host without switching it. For a
-   cross-platform unit or profile, evaluate both NixOS and nix-darwin even if
-   only one class changed. Build an affected configuration with `--no-link`
-   when the current platform can build it.
-6. Verify selection as well as syntax: confirm that the expected package,
+4. Run `nix run .#check -- all --paths <task-path>...` after the structure is
+   complete. This evaluates every flake system and builds affected targets for
+   the current platform without activation.
+5. Verify selection as well as syntax: confirm that the expected package,
    program, service, group, cask, or external module appears in the resulting
    configuration.
+6. Add a `pkgs.testers.runNixOSTest` check through the `test-nixos-service`
+   skill when service startup or another runtime contract cannot be proved by
+   evaluation and a system build.
+
+Use `nix run .#check -- full` only for CI, scheduled maintenance, or an explicit
+repository-wide audit. These commands never activate the live system. Do not
+run `nh os switch`, `nixos-rebuild switch`, `darwin-rebuild switch`,
+`home-manager switch`, or an equivalent activation command as validation.
 
 If a command is unavailable, blocked by the environment, or fails for a
-pre-existing reason, diagnose it and report the exact gap. Never silently skip
-a required check or weaken the implementation to make a check pass.
+pre-existing reason, invoke the `debug-nix-failure` skill, diagnose it, and
+report the exact gap. Never silently skip a required check or weaken the
+implementation to make a check pass.
 
 ### 5. Audit before completion
 

skills/add-application-or-service/references/review-checklist.md

@@ -72,56 +72,47 @@ user-owned mutable state unless the requested policy explicitly owns it.
 
 ## Validation matrix
 
-Run checks from the repository root and keep the exact results for the handoff.
-Do not switch or activate a live system merely to validate a change.
+Use the `validate-nix-change` skill and run checks from the repository root.
+Keep exact results for the handoff. The validation app never switches or
+activates a live system.
 
 ### Always
 
-1. Format task-owned files. If the worktree contains unrelated user changes,
-   pass only task-owned paths to the configured formatter when supported.
-2. Run `git diff --check`.
-3. Review `git status --short`, `git diff --stat`, and the complete `git diff`.
-4. Run `nix flake check`.
-5. Run `pre-commit run --all-files`.
+1. Run `nix run .#check -- plan --paths <task-path>... --json` and inspect the
+   affected units and hosts.
+2. Run `nix run .#check -- fast --paths <task-path>...` during implementation.
+3. Review `git status --short`, `git diff --stat`, and the complete task diff.
+4. Run `nix run .#check -- all --paths <task-path>...` before handoff. It runs
+   all-system evaluation and compatible targeted builds without activation.
+5. Reserve `nix run .#check -- full` for CI, scheduled maintenance, or an
+   explicit repository-wide audit.
+
+Do not run `nh os switch`, `nixos-rebuild switch`, `darwin-rebuild switch`,
+`home-manager switch`, or an equivalent activation command.
 
 ### NixOS or Home Manager on NixOS
 
-- Evaluate each affected host's system toplevel derivation.
-- Build at least one affected NixOS configuration with `--no-link` when the
-  current system supports it.
+- Confirm that the validation plan includes each affected real NixOS host.
+- Build affected NixOS configurations with `--no-link` through the validation
+  app when the current system supports them.
 - Inspect the resulting option that proves selection: for example
   `environment.systemPackages`, the user's `home.packages`,
   `systemd.services`, `users.users.<name>.extraGroups`, or the upstream
   `programs`/`services` option.
 
-Typical build shape:
-
-```sh
-nix build .#nixosConfigurations.<host>.config.system.build.toplevel --no-link
-```
-
 ### nix-darwin or Home Manager on Darwin
 
-- Evaluate every affected Darwin host even when running on Linux.
+- Confirm that every affected Darwin host is evaluated even when running on
+  Linux.
 - Inspect `homebrew.casks` or `homebrew.brews` for Homebrew-backed additions.
 - Evaluate the relevant Home Manager program or package option.
-- Build a Darwin configuration only on a compatible Darwin builder; otherwise
-  report that build as an explicit runtime-validation gap.
-
-Typical evaluation shapes:
-
-```sh
-nix eval --raw .#darwinConfigurations.<host>.system.drvPath
-nix eval --json .#darwinConfigurations.<host>.config.homebrew.casks
-```
-
-Confirm the exact output attribute against the current flake before using a
-command; do not paste these shapes blindly.
+- Build a Darwin configuration only on a compatible Darwin runner or builder;
+  otherwise report the build as an explicit platform gap.
 
 ### Profiles and cross-platform changes
 
-- Determine transitive selection through `meta.includes`, not only direct
-  mentions.
+- Confirm transitive selection through `meta.includes`, not only direct
+  mentions. The validation plan computes reverse dependency closure.
 - Evaluate every real host selecting the changed profile.
 - Evaluate both host classes for a cross-platform profile, even if only one
   current fragment changed.
@@ -134,6 +125,8 @@ command; do not paste these shapes blindly.
 ### Runtime-dependent behavior
 
 Evaluation and builds cannot prove GUI appearance, credentials, network access,
-hardware behavior, or successful daemon interaction. State the precise manual
-post-activation check needed for those behaviors. Never describe evaluation as
+hardware behavior, successful daemon interaction, or reboot state. For
+reusable NixOS behavior, use the `test-nixos-service` skill and add a
+`pkgs.testers.runNixOSTest` check. State the precise manual post-activation check
+needed for physical hardware or external systems. Never describe evaluation as
 a runtime test.

skills/debug-nix-failure/SKILL.md

@@ -0,0 +1,63 @@
+---
+name: debug-nix-failure
+description: Diagnose failures from parsing, Nix module evaluation, derivation builds, flake checks, NixOS tests, or Home Manager activation logs without changing the live system. Use when `nix run .#check`, `nix flake check`, `nix build`, CI, or a user-provided activation log fails.
+---
+
+# Debug a Nix Failure
+
+Classify the failure before changing code. Preserve the original command,
+complete error, first causal frame, and affected attribute. Never run a live
+switch or activation to reproduce a validation failure.
+
+## Identify the failing layer
+
+- **Parse or format:** syntax location, malformed string, unmatched delimiter,
+  or formatter-owned rewrite.
+- **Static analysis:** dead binding, suspicious expression, ShellCheck finding,
+  secret scan, or workflow lint.
+- **Module evaluation:** missing option, wrong type, assertion, infinite
+  recursion, conflicting definitions, Registry selection, or unsupported host
+  class.
+- **Derivation instantiation/build:** missing dependency, hash mismatch, patch
+  failure, compiler/test failure, sandbox violation, or unsupported platform.
+- **NixOS test:** failed unit, timeout, command assertion, network readiness, or
+  reboot state.
+- **Activation/runtime:** filesystem conflict, activation script, systemd unit,
+  hardware, credential, or external-service behavior. Diagnose only from logs
+  supplied by the user unless they explicitly request a non-switch inspection
+  command.
+
+## Reproduce the narrowest failing operation
+
+Start with the stage and paths reported by the validation app:
+
+```sh
+nix run .#check -- plan --paths <task-path>... --json
+nix run .#check -- fast --paths <task-path>...
+nix run .#check -- eval --paths <task-path>...
+nix run .#check -- build --paths <task-path>...
+```
+
+For a single attribute, use `nix eval --show-trace` on its `drvPath` before a
+build. For a failed derivation, retain `--print-build-logs` and inspect
+`nix log <drv-path>` when the summary omits the causal lines.
+
+## Read traces selectively
+
+1. Find the first repository-owned frame or option path.
+2. Separate the immediate failure from wrapper frames in `modules.nix`,
+   `lib.evalModules`, or flake-parts.
+3. Inspect the option declaration and every definition contributing to it.
+4. Confirm package and option names against locked inputs, not memory.
+5. Check whether the failure reproduces on the base revision before calling it
+   task-owned.
+
+Do not respond to a type or ownership error with import-order changes,
+`lib.mkForce`, global arguments, or an overlay unless repository evidence shows
+that those mechanisms are the correct owner.
+
+## Finish with a bounded diagnosis
+
+Report the failing layer, root cause, minimal correction, rerun command, and any
+remaining platform or runtime gap. Include enough of the error to identify it,
+but do not paste large unrelated logs.

skills/test-nixos-service/SKILL.md

@@ -0,0 +1,64 @@
+---
+name: test-nixos-service
+description: Add or extend a non-activating NixOS VM or container test for service startup, sockets, timers, permissions, firewall behavior, reboot state, and inter-service dependencies. Use when evaluation and a system build cannot prove the requested runtime behavior.
+---
+
+# Test NixOS Runtime Behavior
+
+Prefer `pkgs.testers.runNixOSTest` for reusable NixOS behavior that can be
+proved without the user's physical machine. Do not activate the host
+configuration and do not substitute a live `nh os switch` for a deterministic
+test.
+
+## Define the observable contract
+
+List the runtime facts that must hold, such as:
+
+- a systemd unit reaches `active`;
+- a socket or port is listening;
+- a timer triggers its service;
+- a user can or cannot read a file;
+- a group membership grants access;
+- a firewall permits one path and blocks another;
+- state survives a reboot;
+- one service waits for another dependency.
+
+Exclude behavior that requires physical GPU, fingerprint, audio, display,
+Secure Boot, TPM, private credentials, or an external provider unless the test
+can model it explicitly.
+
+## Implement the smallest useful machine
+
+Create a test under `tests/` and expose it through `checks.<system>`. Import the
+owning module or Registry selection instead of copying its implementation into
+the test. Use only the packages, users, files, and network peers required by the
+contract.
+
+Typical shape:
+
+```nix
+pkgs.testers.runNixOSTest {
+  name = "service-name";
+
+  nodes.machine = {
+    # Enable the owning unit or import the module under test.
+  };
+
+  testScript = ''
+    machine.start()
+    machine.wait_for_unit("service-name.service")
+    machine.succeed("systemctl is-active service-name.service")
+  '';
+}
+```
+
+Use `wait_for_unit`, `wait_for_open_port`, `succeed`, `fail`, and explicit
+reboots to express outcomes. Avoid arbitrary sleeps when a readiness condition
+exists.
+
+## Validate and report
+
+Run the targeted test through its flake check, then run the repository
+validation app for the task paths. Report the test attribute and assertions
+that passed. State clearly which hardware or external behavior remains outside
+the VM/container model.

skills/update-flake-input/SKILL.md

@@ -0,0 +1,58 @@
+---
+name: update-flake-input
+description: Update one or more pinned flake inputs with bounded lock-file changes and non-activating Linux and Darwin validation. Use for dependency refreshes, input-specific updates, automated lock-file pull requests, or diagnosing a regression introduced by flake.lock.
+---
+
+# Update a Flake Input
+
+Keep the update scope explicit and treat `flake.lock` as generated dependency
+state. Never activate a host as part of this workflow; do not run `nh os switch`,
+`nixos-rebuild switch`, `darwin-rebuild switch`, `home-manager switch`, or an
+equivalent command.
+
+## Bound the update
+
+1. Read `AGENTS.md`, inspect `git status --short`, and preserve unrelated work.
+2. Record the input names and the behavior or version change being requested.
+3. Prefer an input-specific update:
+
+```sh
+nix flake update <input-name>
+```
+
+Use an unrestricted `nix flake update` only when the task explicitly requests a
+full refresh. Do not hand-edit lock nodes.
+
+## Audit the lock diff
+
+Inspect the complete `flake.lock` diff. Confirm that changed nodes are the
+requested inputs or unavoidable followers and that source owners, repositories,
+reference types, and hashes remain expected. Investigate unexpected node
+replacement, disappearing followers, or a large transitive graph rewrite before
+validation.
+
+## Validate without activation
+
+Run the common validation workflow against the lock file:
+
+```sh
+nix run .#check -- plan --paths flake.lock --json
+nix run .#check -- fast --paths flake.lock
+nix run .#check -- eval --paths flake.lock
+nix run .#check -- build --paths flake.lock
+```
+
+A lock-file change requires full evaluation and the complete native check set.
+Linux and Darwin builds must run on compatible runners. The scheduled update
+workflow uploads the candidate lock file, builds Linux and Darwin checks, and
+creates a pull request only after both pass.
+
+When a failure appears only after the update, invoke `debug-nix-failure`, compare
+the failing derivation or option with the base lock, and narrow the responsible
+input before adding an override or patch.
+
+## Report the result
+
+List requested and transitively changed inputs, validation commands and native
+platform results, any package or option migration, and remaining manual runtime
+checks. Evaluation or a native build is not activation.

skills/validate-nix-change/SKILL.md

@@ -0,0 +1,128 @@
+---
+name: validate-nix-change
+description: Plan and run efficient, non-activating validation for edits to this NixOS, nix-darwin, and Home Manager flake. Use after changing Nix modules, hosts, profiles, overlays, flake outputs, tests, scripts, CI, or agent configuration; before handing off a task; or when deciding which real hosts must be evaluated or built.
+---
+
+# Validate a Nix Change
+
+Use the repository validation app as the source of truth for change impact and
+validation commands. It derives affected hosts from Registry ownership,
+`meta.includes`, host selections, fragment class, and host-local paths.
+
+Never activate a live configuration as part of this workflow. Do not run
+`nh os switch`, `nixos-rebuild switch`, `darwin-rebuild switch`,
+`home-manager switch`, or an equivalent activation command. The user owns live
+activation separately.
+
+## Establish the validation scope
+
+1. Read `AGENTS.md` and run `git status --short` before editing.
+2. Preserve unrelated user changes. Track the paths owned by the current task,
+   including newly created untracked files.
+3. Inspect the plan before expensive checks:
+
+```sh
+nix run .#check -- plan --paths <task-path>... --json
+```
+
+When validating a committed pull-request range, use:
+
+```sh
+nix run .#check -- plan --base <base-sha> --json
+```
+
+The app automatically uses a `path:` flake reference when task paths are
+untracked, so newly created Registry fragments are visible to Nix without
+staging them.
+
+## Run checks in increasing cost order
+
+### Fast edit loop
+
+After each coherent edit, parse Nix files, validate project JSON, TOML, and
+skill frontmatter, check whitespace, and run the configured hooks only for
+task-owned files:
+
+```sh
+nix run .#check -- fast --paths <task-path>...
+```
+
+Do not replace this with `pre-commit run --all-files` during the edit loop.
+Unrelated repository files must not become part of the task merely because an
+existing check fails elsewhere.
+
+### Evaluation
+
+After the implementation is structurally complete, evaluate every affected
+NixOS and Darwin derivation plus the supporting checks without realizing or
+activating them. Flake-wide paths additionally evaluate every flake system:
+
+```sh
+nix run .#check -- eval --paths <task-path>...
+```
+
+This proves module evaluation, option types, assertions, Registry selection,
+and derivation instantiation. It does not prove a successful build or runtime
+behavior.
+
+### Compatible builds
+
+Build affected configurations for the current platform with no result link:
+
+```sh
+nix run .#check -- build --paths <task-path>...
+```
+
+The app reports incompatible targets as evaluated but skipped for native build.
+A Darwin target must be built by a compatible Darwin runner or builder; a Linux
+evaluation is not a Darwin build.
+
+### Final task validation
+
+Before handoff, run the cumulative task check. It applies file checks only to
+task-owned paths, evaluates every flake system, and builds affected native
+targets:
+
+```sh
+nix run .#check -- all --paths <task-path>...
+```
+
+Use `--all-hosts` only when a deliberate audit must report every registered
+host as affected. Use the exhaustive command for CI, scheduled maintenance, or
+an explicit repository-wide audit:
+
+```sh
+nix run .#check -- full
+```
+
+`full` runs hooks over every tracked file and builds every check for the current
+platform through `nix-fast-build`.
+
+## Add runtime tests when needed
+
+Evaluation and builds do not prove service startup, socket behavior, firewall
+rules, users and groups, permissions, reboot behavior, or network interaction.
+For reusable NixOS behavior, invoke the `test-nixos-service` skill and add a
+`pkgs.testers.runNixOSTest` check. Hardware, credentials, GUI appearance, and
+external services may still require a precisely described manual check after
+the user activates the configuration.
+
+## Diagnose failures by layer
+
+Invoke the `debug-nix-failure` skill when a stage fails. Fix the first failing
+layer before running a more expensive one. Do not hide a pre-existing failure,
+weaken an assertion, add `lib.mkForce`, or skip a required host merely to make
+the task appear green.
+
+## Report evidence precisely
+
+Conclude with:
+
+- task-owned paths;
+- affected units and hosts reported by `plan`;
+- each command run and its result;
+- which targets were parsed, evaluated, built, or runtime-tested;
+- any compatible-platform or manual-runtime gap.
+
+Never describe evaluation as a build, a build as activation, or a VM test as
+proof of hardware-specific behavior.