3 files changed, 239 insertions, 0 deletions
diff --git a/modules/by-name/di/direnv/landrun-fish.sh b/modules/by-name/di/direnv/landrun-fish.sh
new file mode 100755
index 00000000..2220db20
--- /dev/null
+++ b/modules/by-name/di/direnv/landrun-fish.sh
@@ -0,0 +1,44 @@
+#! /usr/bin/env sh
+
+_new_tmp="$(mktemp --directory -t landrun_fish_XXXXX)"
+trap 'rm --recursive "$_new_tmp"' EXIT
+
+# NOTE: We need to keep the XDG_RUNTIME_DIR, as pam_systemd sets it only once upon login. <2026-08-25>
+landrun \
+    --env XDG_RUNTIME_DIR \
+    --env NIX_SHELL_LEVEL \
+    --env TERM \
+    --env SHLVL \
+    --env IN_DIRENV_SANDBOX=true \
+    --env TMPDIR="$_new_tmp" \
+    --rox /nix/store \
+    --rox /run/wrappers/bin/sudo \
+    --rw "$_new_tmp" \
+    --ro /etc/ \
+    --ro /proc/ \
+    --rw /dev/ \
+    --rw "$XDG_RUNTIME_DIR" \
+    --rw "$HOME/.cache" \
+    --ro "$HOME/.local/share/nix/trusted-settings.json" \
+    --rw "$HOME/.local/share/nix/repl-history" \
+    --rw "$HOME/.local/share/ssh/known_hosts" \
+    --ro "$HOME/.local/share/ssh/id_ed25519.pub" \
+    --rw "$HOME/.local/share/task/" \
+    --rw "$HOME/.local/share/nvim/" \
+    --rw "$HOME/.local/state/nvim/" \
+    --rw "$HOME/.local/share/cargo/" \
+    --rw "$HOME/.local/share/ctpv/" \
+    --rw "$HOME/.local/share/direnv/" \
+    --rw "$HOME/.local/share/lf/" \
+    --ro "$HOME/.config/fish/" \
+    --ro "$HOME/.config/task/" \
+    --ro "$HOME/.config/nvim/" \
+    --ro "$HOME/.config/turtle/" \
+    --ro "$HOME/.config/git/" \
+    --rwx "$PWD" \
+    --connect-tcp 80 \
+    --connect-tcp 22 \
+    --connect-tcp 443 \
+    -- fish --login "$@"
+
+# vim: ft=sh
diff --git a/modules/by-name/di/direnv/module.nix b/modules/by-name/di/direnv/module.nix
new file mode 100644
index 00000000..fc800f35
--- /dev/null
+++ b/modules/by-name/di/direnv/module.nix
@@ -0,0 +1,106 @@
+# nixos-config - My current NixOS configuration
+#
+# Copyright (C) 2025 Benedikt Peetz <benedikt.peetz@b-peetz.de>
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+# This file is part of my nixos-config.
+#
+# You should have received a copy of the License along with this program.
+# If not, see <https://www.gnu.org/licenses/gpl-3.0.txt>.
+{
+  config,
+  lib,
+  pkgs,
+  sources,
+  ...
+}: let
+  cfg = config.soispha.programs.direnv;
+  direnvCfg = config.home-manager.users.soispha.programs.direnv;
+
+  inherit (sources) devshells nixpkgs;
+
+  pre-cache = pkgs.runCommand "pre-cache.sh" {} ''
+    cat "${./pre-cache.sh}" > $out
+
+    substituteInPlace $out \
+      --replace-fail "%DEVSHELLS_REPO%" "${devshells}" \
+      --replace-fail "%DEVSHELLS_REPO_REF%" "${devshells.sourceInfo.rev}.${builtins.readFile "${nixpkgs}/.git-revision"}"
+  '';
+
+  landrun-fish = pkgs.writeShellApplication {
+    name = "landrun-fish";
+    text = builtins.readFile ./landrun-fish.sh;
+    inheritPath = true;
+    runtimeInputs = [
+      pkgs.landrun
+    ];
+  };
+
+  direnvPkg = lib.getExe direnvCfg.package;
+in {
+  options.soispha.programs.direnv = {
+    enable = lib.mkEnableOption "direnv";
+  };
+
+  config = lib.mkIf cfg.enable {
+    soispha.programs.fish.integrations.direnv =
+      # fish
+      ''
+        set --global SHOULD_SANDBOX_DIRENV
+
+        function _direnv_export_eval
+          ${direnvPkg} export fish | source
+        end
+
+        function _direnv_hook --on-variable PWD
+          if not set --query IN_DIRENV_SANDBOX;
+            and set --query SHOULD_SANDBOX_DIRENV;
+            and ${direnvPkg} status | grep 'Found RC path' --quiet;
+            and ${direnvPkg} status | grep 'No .envrc or .env loaded' --quiet
+
+            # We found a RC path, but no RC file is loaded. So we can start our shell and
+            # load it.
+            ${lib.getExe landrun-fish} --init-command='_direnv_export_eval'
+
+            # After the user exists (via Ctrl+D), they probably want to change the
+            # directory.
+            ll
+          else
+            _direnv_export_eval
+          end
+        end
+      '';
+
+    home-manager.users.soispha = {
+      programs.direnv = {
+        enable = true;
+
+        package = pkgs.direnv-patched;
+
+        nix-direnv = {
+          enable = true;
+          package = pkgs.nix-direnv.override {nix = config.nix.package;};
+        };
+
+        # Handled by myself (and the script is overridden)
+        enableBashIntegration = true;
+        enableZshIntegration = true;
+        enableFishIntegration = false;
+
+        config = {
+          warn_timeout = 0;
+
+          # NOTE: Something variable is undeclared in the my default loaded stuff :/. <2026-08-18>
+          # strict_env = true;
+
+          # disable_stdin = true;
+        };
+      };
+      xdg.configFile = {
+        "direnv/lib/hm-pre-cache.sh" = {
+          source = pre-cache;
+        };
+      };
+    };
+  };
+}
diff --git a/modules/by-name/di/direnv/pre-cache.sh b/modules/by-name/di/direnv/pre-cache.sh
new file mode 100755
index 00000000..706dae61
--- /dev/null
+++ b/modules/by-name/di/direnv/pre-cache.sh
@@ -0,0 +1,89 @@
+#! /usr/bin/env sh
+
+_pre_cache_log() {
+    printf "pre-cache: %s\n" "$1"
+}
+_pre_cache_preflight() {
+    set -eu
+    _nix_direnv_preflight
+
+    REPO="%DEVSHELLS_REPO%"
+    system="x86_64-linux"
+    cache_dir="$XDG_CACHE_HOME/pre_cache"
+    [ -d "$cache_dir" ] || mkdir --parents "$cache_dir"
+
+    repo_ref="%DEVSHELLS_REPO_REF%"
+    final_cache="$cache_dir/$repo_ref"
+
+    if ! [ -d "$final_cache" ]; then
+        _pre_cache_log "Cache dir invalidated"
+
+        # There is not yet a final cache directory, so the ref must have changed.
+        # Therefore we delete the whole cache directory, so we invalidate old cached shells.
+        set -u
+        rm --recursive "$cache_dir"
+
+        mkdir --parents "$final_cache"
+    fi
+
+    # TODO: Direnv requires `-u` to be unset, for it's stdlib :/. <2026-08-22>
+    set +u
+}
+
+_pre_cache_load_shell() {
+    lang="$1"
+    lang_cache="$final_cache/$lang"
+
+    if ! [ -f "$lang_cache" ]; then
+        tmp_profile="$final_cache/__tmp_profile"
+        profile="$final_cache/__profile"
+
+        # It does not already exists, we need to evaluate it.
+        _nix print-dev-env --profile "$tmp_profile" "$REPO#$lang" >"$lang_cache"
+
+        _nix_add_gcroot "$tmp_profile" "$profile"
+        # rm "$tmp_profile" "$tmp_profile"* || true
+    fi
+
+    _pre_cache_log "Loaded dev-shell for $lang."
+    _nix_import_env "$lang_cache"
+}
+
+_pre_cache_build_shells() {
+    installables=""
+
+    for lang in "$@"; do
+        lang_cache="$final_cache/$lang"
+
+        if ! [ -f "$lang_cache" ]; then
+            new_part="$REPO#devShells.$system.$lang"
+
+            if [ -z "$installables" ]; then
+                installables="$new_part"
+            else
+                installables="$installables $new_part"
+            fi
+        fi
+    done
+
+    if [ -n "$installables" ]; then
+        _pre_cache_log "Building '$installables'..."
+
+        # We want shell-spliting
+        # shellcheck disable=SC2086
+        _nix build --no-link $installables
+    fi
+}
+
+pre_cache_load() {
+    _pre_cache_preflight
+
+    # Build all not-yet build shells concurrently. That speeds up the initial load.
+    _pre_cache_build_shells "$@"
+
+    for lan in "$@"; do
+        _pre_cache_load_shell "$lan"
+    done
+}
+
+# vim: ft=sh