diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 1e29621..87e7232 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -357,6 +357,17 @@ repos:
         types_or: [c, c++]
         exclude: ^CPP/mini_browser/
 
+  # ===========================================================================
+  # CHECK PYTHON LOCATION - All Python files must be under python_pkg/
+  # ===========================================================================
+  - repo: local
+    hooks:
+      - id: check-python-location
+        name: check Python files are under python_pkg/
+        entry: scripts/check_python_location.sh
+        language: script
+        types: [python]
+
   # ===========================================================================
   # REMOVE EMPTY DIRECTORIES - Clean up empty folders in the repo
   # ===========================================================================
diff --git a/pyproject.toml b/pyproject.toml
index e51023d..c33aeb7 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -66,10 +66,10 @@ unfixable = []
 # Files using urlopen with validated URL schemes
 "python_pkg/geo_data/_common.py" = ["S310"]
 "python_pkg/steam_backlog_enforcer/library_hider.py" = ["S310"]
-"poker_modifier_app/poker_modifier_app.py" = [
+"python_pkg/poker_modifier_app/poker_modifier_app.py" = [
     "FBT003",  # Boolean positional values in tkinter API calls
 ]
-"poker_modifier_app/_poker_gui.py" = [
+"python_pkg/poker_modifier_app/_poker_gui.py" = [
     "FBT003",  # Boolean positional values in tkinter API calls
 ]
 "python_pkg/keyboard_coop/main.py" = [
@@ -102,12 +102,11 @@ unfixable = []
     "PLC0415", # Lazy imports of split helper modules
 ]
 # Moviepy showcase - lazy imports of split helpers
-"moviepy_showcase.py" = [
-    "INP001",
+"python_pkg/moviepy_showcase/moviepy_showcase.py" = [
     "PLC0415", # Lazy imports of split helper modules
 ]
 # Puzzle solver - late imports for CLI entry point
-"puzzle_solver/main.py" = [
+"python_pkg/puzzle_solver/main.py" = [
     "PLC0415", # Late imports in __main__ guard
 ]
 # Geo data admin helper
@@ -125,9 +124,7 @@ unfixable = []
 "python_pkg/praca_magisterska_video/visualize_q02.py" = [
     "PLC0415", # Late import for conditional dependency
 ]
-# Root-level helper scripts and test files outside packages
-"_moviepy_*.py" = ["INP001"]
-"tests/test_file_length.py" = ["INP001"]
+# Removed: root-level moviepy helper scripts and test files are now inside python_pkg
 "python_pkg/word_frequency/_translator_cli.py" = [
     "SLF001",  # Legitimately accesses translator module internals
 ]
@@ -251,7 +248,7 @@ exclude_dirs = ["tests", ".venv", "Bash/ffmpeg-build", "python_pkg/lichess_bot/.
 # PYTEST - Testing framework configuration
 # ============================================================================
 [tool.pytest.ini_options]
-testpaths = ["tests", "python_pkg", "articles"]
+testpaths = ["python_pkg"]
 python_files = ["test_*.py", "*_test.py"]
 python_classes = ["Test*"]
 python_functions = ["test_*"]
diff --git a/articles/.clang-format b/python_pkg/articles/.clang-format
similarity index 100%
rename from articles/.clang-format
rename to python_pkg/articles/.clang-format
diff --git a/articles/.gitignore b/python_pkg/articles/.gitignore
similarity index 100%
rename from articles/.gitignore
rename to python_pkg/articles/.gitignore
diff --git a/articles/Makefile b/python_pkg/articles/Makefile
similarity index 100%
rename from articles/Makefile
rename to python_pkg/articles/Makefile
diff --git a/articles/README.md b/python_pkg/articles/README.md
similarity index 100%
rename from articles/README.md
rename to python_pkg/articles/README.md
diff --git a/articles/__init__.py b/python_pkg/articles/__init__.py
similarity index 100%
rename from articles/__init__.py
rename to python_pkg/articles/__init__.py
diff --git a/articles/cppcheck.txt b/python_pkg/articles/cppcheck.txt
similarity index 100%
rename from articles/cppcheck.txt
rename to python_pkg/articles/cppcheck.txt
diff --git a/articles/data/articles.json b/python_pkg/articles/data/articles.json
similarity index 100%
rename from articles/data/articles.json
rename to python_pkg/articles/data/articles.json
diff --git a/articles/index.html b/python_pkg/articles/index.html
similarity index 100%
rename from articles/index.html
rename to python_pkg/articles/index.html
diff --git a/articles/run.sh b/python_pkg/articles/run.sh
similarity index 100%
rename from articles/run.sh
rename to python_pkg/articles/run.sh
diff --git a/articles/run_tests.sh b/python_pkg/articles/run_tests.sh
similarity index 100%
rename from articles/run_tests.sh
rename to python_pkg/articles/run_tests.sh
diff --git a/articles/server_c.c b/python_pkg/articles/server_c.c
similarity index 100%
rename from articles/server_c.c
rename to python_pkg/articles/server_c.c
diff --git a/articles/sw.js b/python_pkg/articles/sw.js
similarity index 100%
rename from articles/sw.js
rename to python_pkg/articles/sw.js
diff --git a/articles/test_server_api.py b/python_pkg/articles/test_server_api.py
similarity index 100%
rename from articles/test_server_api.py
rename to python_pkg/articles/test_server_api.py
diff --git a/articles/test_site_size.py b/python_pkg/articles/test_site_size.py
similarity index 100%
rename from articles/test_site_size.py
rename to python_pkg/articles/test_site_size.py
diff --git a/articles/tools/funcsize.awk b/python_pkg/articles/tools/funcsize.awk
similarity index 100%
rename from articles/tools/funcsize.awk
rename to python_pkg/articles/tools/funcsize.awk
diff --git a/python_pkg/moviepy_showcase/__init__.py b/python_pkg/moviepy_showcase/__init__.py
new file mode 100644
index 0000000..b113390
--- /dev/null
+++ b/python_pkg/moviepy_showcase/__init__.py
@@ -0,0 +1 @@
+"""MoviePy 2.x comprehensive showcase package."""
diff --git a/_moviepy_audio_output.py b/python_pkg/moviepy_showcase/_moviepy_audio_output.py
similarity index 99%
rename from _moviepy_audio_output.py
rename to python_pkg/moviepy_showcase/_moviepy_audio_output.py
index 1317fb8..b594f87 100644
--- a/_moviepy_audio_output.py
+++ b/python_pkg/moviepy_showcase/_moviepy_audio_output.py
@@ -31,7 +31,7 @@ from moviepy.video.tools.drawing import (
 )
 import numpy as np
 
-from moviepy_showcase import (
+from python_pkg.moviepy_showcase.moviepy_showcase import (
     CLIP_DUR,
     FONT_B,
     FONT_R,
diff --git a/_moviepy_clip_types.py b/python_pkg/moviepy_showcase/_moviepy_clip_types.py
similarity index 99%
rename from _moviepy_clip_types.py
rename to python_pkg/moviepy_showcase/_moviepy_clip_types.py
index be9a735..46a2130 100644
--- a/_moviepy_clip_types.py
+++ b/python_pkg/moviepy_showcase/_moviepy_clip_types.py
@@ -18,7 +18,7 @@ from moviepy.video.fx import InvertColors
 from moviepy.video.tools.drawing import circle
 import numpy as np
 
-from moviepy_showcase import (
+from python_pkg.moviepy_showcase.moviepy_showcase import (
     CLIP_DUR,
     FONT_B,
     FONT_R,
diff --git a/_moviepy_video_effects.py b/python_pkg/moviepy_showcase/_moviepy_video_effects.py
similarity index 99%
rename from _moviepy_video_effects.py
rename to python_pkg/moviepy_showcase/_moviepy_video_effects.py
index b26ba9e..50a05fa 100644
--- a/_moviepy_video_effects.py
+++ b/python_pkg/moviepy_showcase/_moviepy_video_effects.py
@@ -45,7 +45,7 @@ from moviepy.video.fx import (
 from moviepy.video.tools.drawing import circle
 import numpy as np
 
-from moviepy_showcase import (
+from python_pkg.moviepy_showcase.moviepy_showcase import (
     CLIP_DUR,
     H,
     W,
diff --git a/moviepy_showcase.py b/python_pkg/moviepy_showcase/moviepy_showcase.py
similarity index 97%
rename from moviepy_showcase.py
rename to python_pkg/moviepy_showcase/moviepy_showcase.py
index 21814eb..58163cd 100644
--- a/moviepy_showcase.py
+++ b/python_pkg/moviepy_showcase/moviepy_showcase.py
@@ -197,18 +197,18 @@ def _build(tmpdir: str) -> None:
     # ── Lazy imports of moved part builders ───────────────────────
     from moviepy.audio.fx import MultiplyVolume
 
-    from _moviepy_audio_output import (
+    from python_pkg.moviepy_showcase._moviepy_audio_output import (
         _make_sine,
         part4_audio,
         part5_composition,
         part6_drawing_tools,
         part7_output,
     )
-    from _moviepy_clip_types import (
+    from python_pkg.moviepy_showcase._moviepy_clip_types import (
         part1_clip_types,
         part2_clip_methods,
     )
-    from _moviepy_video_effects import part3_video_effects
+    from python_pkg.moviepy_showcase._moviepy_video_effects import part3_video_effects
 
     # ── Render each part to its own temp file ─────────────────────
     # Title card
diff --git a/poker_modifier_app/README.md b/python_pkg/poker_modifier_app/README.md
similarity index 100%
rename from poker_modifier_app/README.md
rename to python_pkg/poker_modifier_app/README.md
diff --git a/poker_modifier_app/README_python.md b/python_pkg/poker_modifier_app/README_python.md
similarity index 100%
rename from poker_modifier_app/README_python.md
rename to python_pkg/poker_modifier_app/README_python.md
diff --git a/poker_modifier_app/__init__.py b/python_pkg/poker_modifier_app/__init__.py
similarity index 100%
rename from poker_modifier_app/__init__.py
rename to python_pkg/poker_modifier_app/__init__.py
diff --git a/poker_modifier_app/_poker_gui.py b/python_pkg/poker_modifier_app/_poker_gui.py
similarity index 99%
rename from poker_modifier_app/_poker_gui.py
rename to python_pkg/poker_modifier_app/_poker_gui.py
index b859295..07da909 100644
--- a/poker_modifier_app/_poker_gui.py
+++ b/python_pkg/poker_modifier_app/_poker_gui.py
@@ -7,7 +7,7 @@ from tkinter import ttk
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
-    from poker_modifier_app.poker_modifier_app import PokerModifierApp
+    from python_pkg.poker_modifier_app.poker_modifier_app import PokerModifierApp
 
 
 class PokerGuiMixin:
diff --git a/poker_modifier_app/_poker_modifiers.py b/python_pkg/poker_modifier_app/_poker_modifiers.py
similarity index 100%
rename from poker_modifier_app/_poker_modifiers.py
rename to python_pkg/poker_modifier_app/_poker_modifiers.py
diff --git a/poker_modifier_app/index.html b/python_pkg/poker_modifier_app/index.html
similarity index 100%
rename from poker_modifier_app/index.html
rename to python_pkg/poker_modifier_app/index.html
diff --git a/poker_modifier_app/poker_modifier_app.py b/python_pkg/poker_modifier_app/poker_modifier_app.py
similarity index 98%
rename from poker_modifier_app/poker_modifier_app.py
rename to python_pkg/poker_modifier_app/poker_modifier_app.py
index 61f3ab0..b1942af 100644
--- a/poker_modifier_app/poker_modifier_app.py
+++ b/python_pkg/poker_modifier_app/poker_modifier_app.py
@@ -4,8 +4,11 @@ import logging
 import secrets
 import tkinter as tk
 
-from poker_modifier_app._poker_gui import PokerGuiMixin
-from poker_modifier_app._poker_modifiers import ENDGAME_MODIFIERS, REGULAR_MODIFIERS
+from python_pkg.poker_modifier_app._poker_gui import PokerGuiMixin
+from python_pkg.poker_modifier_app._poker_modifiers import (
+    ENDGAME_MODIFIERS,
+    REGULAR_MODIFIERS,
+)
 
 _logger = logging.getLogger(__name__)
 
diff --git a/poker_modifier_app/script.js b/python_pkg/poker_modifier_app/script.js
similarity index 100%
rename from poker_modifier_app/script.js
rename to python_pkg/poker_modifier_app/script.js
diff --git a/poker_modifier_app/style.css b/python_pkg/poker_modifier_app/style.css
similarity index 100%
rename from poker_modifier_app/style.css
rename to python_pkg/poker_modifier_app/style.css
diff --git a/puzzle_solver/README.md b/python_pkg/puzzle_solver/README.md
similarity index 100%
rename from puzzle_solver/README.md
rename to python_pkg/puzzle_solver/README.md
diff --git a/puzzle_solver/__init__.py b/python_pkg/puzzle_solver/__init__.py
similarity index 100%
rename from puzzle_solver/__init__.py
rename to python_pkg/puzzle_solver/__init__.py
diff --git a/puzzle_solver/__main__.py b/python_pkg/puzzle_solver/__main__.py
similarity index 58%
rename from puzzle_solver/__main__.py
rename to python_pkg/puzzle_solver/__main__.py
index 41e0787..5b670fe 100644
--- a/puzzle_solver/__main__.py
+++ b/python_pkg/puzzle_solver/__main__.py
@@ -1,5 +1,5 @@
 """Allow ``python -m puzzle_solver …`` invocation."""
 
-from puzzle_solver.main import main
+from python_pkg.puzzle_solver.main import main
 
 main()
diff --git a/puzzle_solver/main.py b/python_pkg/puzzle_solver/main.py
similarity index 95%
rename from puzzle_solver/main.py
rename to python_pkg/puzzle_solver/main.py
index 1ed011b..6e7b08e 100644
--- a/puzzle_solver/main.py
+++ b/python_pkg/puzzle_solver/main.py
@@ -22,8 +22,8 @@ import json
 from pathlib import Path
 import sys
 
-from puzzle_solver.parse_image import draw_debug, parse_image, save_puzzle
-from puzzle_solver.solver import Puzzle, print_puzzle, print_solution, solve
+from python_pkg.puzzle_solver.parse_image import draw_debug, parse_image, save_puzzle
+from python_pkg.puzzle_solver.solver import Puzzle, print_puzzle, print_solution, solve
 
 
 def cmd_parse(args: argparse.Namespace) -> None:
diff --git a/puzzle_solver/parse_image.py b/python_pkg/puzzle_solver/parse_image.py
similarity index 100%
rename from puzzle_solver/parse_image.py
rename to python_pkg/puzzle_solver/parse_image.py
diff --git a/puzzle_solver/solver.py b/python_pkg/puzzle_solver/solver.py
similarity index 100%
rename from puzzle_solver/solver.py
rename to python_pkg/puzzle_solver/solver.py
diff --git a/python_pkg/tests/__init__.py b/python_pkg/tests/__init__.py
new file mode 100644
index 0000000..f44a9a5
--- /dev/null
+++ b/python_pkg/tests/__init__.py
@@ -0,0 +1 @@
+"""Repository-wide tests package."""
diff --git a/tests/test_file_length.py b/python_pkg/tests/test_file_length.py
similarity index 96%
rename from tests/test_file_length.py
rename to python_pkg/tests/test_file_length.py
index 716d53f..1abab19 100644
--- a/tests/test_file_length.py
+++ b/python_pkg/tests/test_file_length.py
@@ -20,7 +20,7 @@ _SKIP_DIRS = frozenset(
     }
 )
 
-_ROOT = Path(__file__).resolve().parents[1]
+_ROOT = Path(__file__).resolve().parents[2]
 
 
 def _python_files() -> list[Path]:
diff --git a/scripts/check_python_location.sh b/scripts/check_python_location.sh
new file mode 100755
index 0000000..aa5897f
--- /dev/null
+++ b/scripts/check_python_location.sh
@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+# Check that all Python files are under python_pkg/.
+# Exceptions: linux_configuration/, pomodoro_app/, sonic_pi/, Bash/,
+#             and vendored/generated directories.
+# Used as a pre-commit hook; receives staged file paths as arguments.
+
+set -uo pipefail
+
+# Directories allowed to contain Python files outside python_pkg/
+ALLOWED_DIRS="linux_configuration/|pomodoro_app/|sonic_pi/"
+
+errors=()
+
+for file in "$@"; do
+    # Only check .py files
+    [[ "$file" != *.py ]] && continue
+
+    # Skip files already under python_pkg/
+    [[ "$file" == python_pkg/* ]] && continue
+
+    # Skip allowed directories (non-Python projects with some Python scripts)
+    if echo "$file" | grep -qE "^($ALLOWED_DIRS)"; then
+        continue
+    fi
+
+    # Skip vendored/generated directories
+    if echo "$file" | grep -qE '(^|/)(\.venv|venv|__pycache__|build|dist|node_modules|\.git)/'; then
+        continue
+    fi
+
+    errors+=("$file")
+done
+
+if [[ ${#errors[@]} -gt 0 ]]; then
+    echo "ERROR: Python files must be under python_pkg/."
+    echo "The following files are in the wrong location:"
+    for err in "${errors[@]}"; do
+        echo "  $err"
+    done
+    echo ""
+    echo "Move them with: git mv <file> python_pkg/<file>"
+    exit 1
+fi