diff --git a/src/ariadne/.gitignore b/src/ariadne/.gitignore
new file mode 100644
index 0000000..f1cadcb
--- /dev/null
+++ b/src/ariadne/.gitignore
@@ -0,0 +1,2 @@
+# Local game-derived preparation output.
+/output/
diff --git a/src/ariadne/BUILD b/src/ariadne/BUILD
new file mode 100644
index 0000000..e40b023
--- /dev/null
+++ b/src/ariadne/BUILD
@@ -0,0 +1,5 @@
+sh_binary(
+    name = "extract_and_decompile",
+    srcs = ["extract-and-decompile.sh"],
+    data = ["extract-tools.nix"],
+)
diff --git a/src/ariadne/README.md b/src/ariadne/README.md
new file mode 100644
index 0000000..1d25d73
--- /dev/null
+++ b/src/ariadne/README.md
@@ -0,0 +1,25 @@
+# Ariadne
+
+Ariadne prepares Ren'Py game source for later analysis.
+
+## Bazel shape
+
+Keep project-owned source under `src/ariadne/`. Keep game-derived files local and ignored under
+`src/ariadne/output/`.
+
+The first target is a shell entry point:
+
+```sh
+bazel run //src/ariadne:extract_and_decompile -- \
+  --game-root /path/to/game-install
+```
+
+The script defaults to `<workspace>/src/ariadne/output`.
+This path stays stable when you run the command from inside `src/ariadne`.
+Use the game installation directory as the game root.
+One run processes all installed season directories.
+If `rpycdec` is not available, the script uses `extract-tools.nix` to enter a Nix shell.
+
+Keep the script as a thin orchestration layer.
+Bazel owns stable inputs and wrappers.
+Keep large game files and recovered output outside the build graph.
diff --git a/src/ariadne/extract-and-decompile.sh b/src/ariadne/extract-and-decompile.sh
new file mode 100755
index 0000000..0249baa
--- /dev/null
+++ b/src/ariadne/extract-and-decompile.sh
@@ -0,0 +1,224 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+usage() {
+  cat <<'USAGE'
+Usage: extract-and-decompile --game-root <path> [--output-root <path>] [--force]
+
+Prepare local game-owned source for Ariadne.
+
+Use the game installation directory as the game root to process all installed seasons.
+The utility writes recovered source under <output-root>/source/, transient work under <output-root>/work/, and local logs under <output-root>/logs/.
+The default output root is <workspace>/src/ariadne/output.
+Without --force, it refuses to run when any of those directories already exists.
+With --force, it deletes and recreates only source/, work/, and logs/ under the output root.
+The script enters a Nix shell for rpycdec when required tools are not already available.
+Game-derived preparation output must remain local and must not be committed.
+USAGE
+}
+
+fail() {
+  printf 'extract-and-decompile: %s\n' "$*" >&2
+  exit 2
+}
+
+require_tool() {
+  local name=$1
+  if ! command -v "$name" >/dev/null 2>&1; then
+    fail "missing required tool '$name'"
+  fi
+}
+
+tools_available() {
+  command -v python3 >/dev/null 2>&1 && command -v rpycdec >/dev/null 2>&1
+}
+
+enter_nix_shell_if_needed() {
+  if tools_available; then
+    return
+  fi
+
+  if [[ "${ARIADNE_NIX_SHELL:-}" == 1 ]]; then
+    require_tool python3
+    require_tool rpycdec
+    return
+  fi
+
+  require_tool nix
+
+  local tools_nix
+  if [[ -n "${BUILD_WORKSPACE_DIRECTORY:-}" ]]; then
+    tools_nix=$BUILD_WORKSPACE_DIRECTORY/src/ariadne/extract-tools.nix
+  else
+    tools_nix=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)/extract-tools.nix
+  fi
+
+  [[ -f "$tools_nix" ]] || fail "missing Ariadne tool definition: $tools_nix"
+
+  say "entering Nix shell for rpycdec"
+  export ARIADNE_NIX_SHELL=1
+  exec nix shell \
+    --extra-experimental-features 'nix-command flakes' \
+    --file "$tools_nix" \
+    --command bash "$0" "$@"
+}
+
+say() {
+  printf 'extract-and-decompile: %s\n' "$*" >&2
+}
+
+game_root=
+default_output_root=${BUILD_WORKSPACE_DIRECTORY:-$(pwd)}/src/ariadne/output
+output_root=$default_output_root
+force=false
+original_args=("$@")
+
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    --game-root)
+      [[ $# -ge 2 ]] || fail '--game-root requires a path'
+      game_root=$2
+      shift 2
+      ;;
+    --output-root)
+      [[ $# -ge 2 ]] || fail '--output-root requires a path'
+      output_root=$2
+      shift 2
+      ;;
+    --force)
+      force=true
+      shift
+      ;;
+    -h|--help)
+      usage
+      exit 0
+      ;;
+    *)
+      fail "unexpected argument: $1"
+      ;;
+  esac
+done
+
+[[ -n "$game_root" ]] || fail 'missing --game-root <path>'
+[[ -d "$game_root" ]] || fail "game root is not a directory: $game_root"
+
+enter_nix_shell_if_needed "${original_args[@]}"
+
+preparation_dirs=(source work logs)
+
+for name in "${preparation_dirs[@]}"; do
+  path="$output_root/$name"
+  if [[ -e "$path" && "$force" != true ]]; then
+    fail "refusing to overwrite existing preparation path without --force: $path"
+  fi
+done
+
+if [[ "$force" == true ]]; then
+  say "removing existing preparation directories under $output_root"
+  for name in "${preparation_dirs[@]}"; do
+    rm -rf -- "${output_root:?}/$name"
+  done
+fi
+
+say "creating preparation directories under $output_root"
+for name in "${preparation_dirs[@]}"; do
+  mkdir -p -- "$output_root/$name"
+done
+
+source_dir=$output_root/source
+work_dir=$output_root/work
+logs_dir=$output_root/logs
+summary_log=$logs_dir/extract-and-decompile.log
+: > "$summary_log"
+
+log() {
+  printf '%s\n' "$*" >> "$summary_log"
+}
+
+record() {
+  say "$*"
+  log "$*"
+}
+
+relative_to_game_root() {
+  realpath --relative-to="$game_root" "$1"
+}
+
+is_renpy_runtime_path() {
+  local relative=$1
+  [[ "$relative" == renpy/* || "$relative" == */renpy/* ]]
+}
+
+copy_source_file() {
+  local input=$1
+  local input_root=$2
+  local label=$3
+  local relative output
+  relative=$(realpath --relative-to="$input_root" "$input")
+  if is_renpy_runtime_path "$relative"; then
+    log "skipped $label Ren'Py runtime source: $relative"
+    return
+  fi
+  output=$source_dir/$relative
+  mkdir -p -- "$(dirname -- "$output")"
+  cp -- "$input" "$output"
+  record "copied $label source: $relative"
+}
+
+copy_loose_source() {
+  copy_source_file "$1" "$game_root" loose
+}
+
+decompile_compiled_script() {
+  local input=$1
+  local input_root=$2
+  local relative output_dir log_file
+  relative=$(realpath --relative-to="$input_root" "$input")
+  if is_renpy_runtime_path "$relative"; then
+    log "skipped Ren'Py runtime compiled script: $relative"
+    return
+  fi
+  output_dir=$source_dir/$(dirname -- "$relative")
+  log_file=$logs_dir/decompile-${relative//\//__}.log
+  mkdir -p -- "$output_dir"
+  say "decompiling script: $relative"
+  RPYCDEC_NO_WARNING=1 rpycdec decompile --output "$output_dir" "$input" > "$log_file" 2>&1
+  log "decompiled script: $relative"
+}
+
+extract_archive() {
+  local archive=$1
+  local relative archive_output log_file
+  relative=$(relative_to_game_root "$archive")
+  archive_output=$work_dir/archives/${relative%.rpa}
+  log_file=$logs_dir/unrpa-${relative//\//__}.log
+  mkdir -p -- "$archive_output"
+  say "extracting archive: $relative"
+  RPYCDEC_NO_WARNING=1 rpycdec unrpa --output "$archive_output" "$archive" > "$log_file" 2>&1
+  log "extracted archive: $relative"
+
+  while IFS= read -r -d '' archived_source; do
+    copy_source_file "$archived_source" "$archive_output" archived
+  done < <(find "$archive_output" -type f -name '*.rpy' -print0 | sort -z)
+
+  while IFS= read -r -d '' compiled; do
+    decompile_compiled_script "$compiled" "$archive_output"
+  done < <(find "$archive_output" -type f \( -name '*.rpyc' -o -name '*.rpymc' \) -print0 | sort -z)
+}
+
+say "scanning loose source files"
+while IFS= read -r -d '' source_file; do
+  copy_loose_source "$source_file"
+done < <(find "$game_root" -type f -name '*.rpy' -print0 | sort -z)
+
+say "scanning archives"
+while IFS= read -r -d '' archive; do
+  extract_archive "$archive"
+done < <(find "$game_root" -type f -name '*.rpa' -print0 | sort -z)
+
+say "scanning loose compiled scripts"
+while IFS= read -r -d '' compiled; do
+  decompile_compiled_script "$compiled" "$game_root"
+done < <(find "$game_root" -type f \( -name '*.rpyc' -o -name '*.rpymc' \) -print0 | sort -z)
+
+say "done"
diff --git a/src/ariadne/extract-tools.nix b/src/ariadne/extract-tools.nix
new file mode 100644
index 0000000..70bd6b9
--- /dev/null
+++ b/src/ariadne/extract-tools.nix
@@ -0,0 +1,28 @@
+let
+  pkgs = import (builtins.getFlake "nixpkgs") { system = builtins.currentSystem; };
+  rpycdec = pkgs.python3Packages.buildPythonApplication {
+    pname = "rpycdec";
+    version = "0.0.0+1000bd1";
+    pyproject = true;
+    src = pkgs.fetchFromGitHub {
+      owner = "cnfatal";
+      repo = "rpycdec";
+      rev = "1000bd1da10ef07e82f6fa560c621e6a4b55d1b8";
+      hash = "sha256-VoVbIKs8xz5x2s0OGqdHbY55fWDruqMAX8YYjEQhwTQ=";
+    };
+    nativeBuildInputs = with pkgs.python3Packages; [
+      hatch-vcs
+      hatchling
+    ];
+    env.SETUPTOOLS_SCM_PRETEND_VERSION_FOR_RPYCDEC = "0.0.0+1000bd1";
+  };
+in
+pkgs.buildEnv {
+  name = "ariadne-extract-and-decompile-tools";
+  paths = [
+    pkgs.bash
+    pkgs.coreutils
+    pkgs.findutils
+    rpycdec
+  ];
+}