fix: make script help paths lightweight (#1937)

## Summary

Consolidate the script help/startup fixes so standalone helper commands
can show usage without requiring runtime-only dependencies or generating
files.

## Details

Several helper scripts imported optional packages, evaluated newer
annotations, or started generation before users could inspect CLI usage.
On a fresh checkout, this made common help paths fail on missing
packages such as `cairosvg`, `Pillow`, `freetype-py`, `fontTools`,
`pyphen`, `pyserial`, or on Python 3.9 annotation evaluation. A few
generators also treated `--help` as a normal output argument and wrote
files instead of printing usage.

This change keeps runtime dependencies on the code paths that need them,
handles lightweight help/list commands first, and adds explicit `--help`
handling for generator scripts that previously started work.

## Validation

- `python3 <script> --help` across tracked Python scripts, excluding
`scripts/patch_jpegdec.py` because it is a PlatformIO pre-build hook
rather than a standalone CLI
- `python3 scripts/convert_icon.py` still exits with usage for missing
required arguments
- `python3 lib/EpdFont/scripts/fontconvert_sdcard.py --list-presets`
- `python3 -m py_compile` for the changed scripts

lib/EpdFont/scripts/fontconvert.py

@@ -1,12 +1,10 @@
 #!python3
-import freetype
 import zlib
 import sys
 import re
 import math
 import argparse
 from collections import namedtuple
-from fontTools.ttLib import TTFont
 
 # Force UTF-8 stdout so that `python fontconvert.py … > foo.h` on Windows
 # (default cp1252) doesn't emit UTF-16 LE / replacement chars in the generated
@@ -27,6 +25,9 @@ parser.add_argument("--force-autohint", dest="force_autohint", action="store_tru
 parser.add_argument("--pnum", dest="pnum", action="store_true", help="Use proportional numerals (pnum OpenType feature) instead of default tabular figures. Reduces visual gaps between digits in running prose.")
 args = parser.parse_args()
 
+import freetype
+from fontTools.ttLib import TTFont
+
 GlyphProps = namedtuple("GlyphProps", ["width", "height", "advance_x", "left", "top", "data_length", "data_offset", "code_point"])
 
 font_stack = [freetype.Face(f) for f in args.fontstack]

lib/EpdFont/scripts/fontconvert_sdcard.py

@@ -22,7 +22,8 @@ Usage:
 
 """
 
-import freetype
+from __future__ import annotations
+
 import struct
 import sys
 import os
@@ -31,8 +32,6 @@ import math
 import argparse
 from collections import namedtuple
 
-from fontTools.ttLib import TTFont
-
 from cpfont_version import CPFONT_VERSION
 
 # --- Unicode interval presets ---
@@ -252,6 +251,8 @@ def extract_kerning_fonttools(font_path, codepoints, ppem):
     codepoints.  Values are scaled from font design units to integer
     pixels at ppem.
     """
+    from fontTools.ttLib import TTFont
+
     font = TTFont(font_path)
     units_per_em = font['head'].unitsPerEm
     cmap = font.getBestCmap() or {}
@@ -402,6 +403,8 @@ def extract_ligatures_fonttools(font_path, codepoints):
     Returns list of (packed_pair, ligature_codepoint) for the given codepoints.
     Multi-character ligatures are decomposed into chained pairs.
     """
+    from fontTools.ttLib import TTFont
+
     font = TTFont(font_path)
     cmap = font.getBestCmap() or {}
 
@@ -514,6 +517,8 @@ def extract_ligatures_fonttools(font_path, codepoints):
 
 def rasterize_font_style(fontfile, size, intervals, style_id=0, force_autohint=False):
     """Rasterize all glyphs for one font style. Returns StyleRasterData."""
+    import freetype
+
     style_names = {0: "regular", 1: "bold", 2: "italic", 3: "bolditalic"}
     style_label = style_names.get(style_id, str(style_id))
 

lib/EpdFont/scripts/verify_compression.py

@@ -234,6 +234,9 @@ def main():
     if len(sys.argv) < 2:
         print(f"Usage: {sys.argv[0]} <font_headers_directory>", file=sys.stderr)
         sys.exit(1)
+    if sys.argv[1] in ("-h", "--help"):
+        print(f"Usage: {sys.argv[0]} <font_headers_directory>")
+        sys.exit(0)
 
     font_dir = sys.argv[1]
     if not os.path.isdir(font_dir):

scripts/convert_icon.py

@@ -1,18 +1,21 @@
-import sys
 import os
-from PIL import Image
-import cairosvg
 import io
+import sys
 
 threshold = 128
+USAGE = 'Usage: python scripts/convert_icon.py input.png|input.svg output_name width height'
 
 def svg_to_png_bytes(svg_path, width, height):
+    import cairosvg
+
     with open(svg_path, 'rb') as f:
         svg_data = f.read()
     png_bytes = cairosvg.svg2png(bytestring=svg_data, output_width=width, output_height=height)
     return png_bytes
 
 def load_image(path, width, height):
+    from PIL import Image
+
     ext = os.path.splitext(path)[1].lower()
     if ext == '.svg':
         png_bytes = svg_to_png_bytes(path, width, height)
@@ -58,8 +61,11 @@ def image_to_c_array(img, array_name):
     return c
 
 def main():
-    if len(sys.argv) < 5:
-        print('Usage: python convert_image.py input.png output_name width height')
+    if any(arg in ('-h', '--help') for arg in sys.argv[1:]):
+        print(USAGE)
+        sys.exit(0)
+    if len(sys.argv) != 5:
+        print(USAGE)
         sys.exit(1)
     input_path, output_name, width, height = sys.argv[1:5]
     array_name = output_name.capitalize() + 'Icon'
@@ -77,4 +83,4 @@ def main():
     print(f'Wrote {output_path}')
 
 if __name__ == '__main__':
-    main()
+    main()

scripts/debugging_monitor.py

@@ -35,6 +35,43 @@ import threading
 from collections import deque
 from datetime import datetime
 
+DEFAULT_BAUDRATE = 115200
+
+
+def build_arg_parser() -> argparse.ArgumentParser:
+    parser = argparse.ArgumentParser(
+        description="ESP32 Serial Monitor with Memory Graph - Real-time monitoring, graphing, and command interface"
+    )
+    parser.add_argument(
+        "port",
+        nargs="?",
+        default=None,
+        help="Serial port (leave empty for autodetection)",
+    )
+    parser.add_argument(
+        "--baud",
+        type=int,
+        default=DEFAULT_BAUDRATE,
+        help=f"Baud rate (default: {DEFAULT_BAUDRATE})",
+    )
+    parser.add_argument(
+        "--filter",
+        type=str,
+        default="",
+        help="Only display lines containing this keyword (case-insensitive)",
+    )
+    parser.add_argument(
+        "--suppress",
+        type=str,
+        default="",
+        help="Suppress lines containing this keyword (case-insensitive)",
+    )
+    return parser
+
+
+if any(arg in ("-h", "--help") for arg in sys.argv[1:]):
+    build_arg_parser().parse_args()
+
 # Try to import potentially missing packages
 PACKAGE_MAPPING: dict[str, str] = {
     "serial": "pyserial",
@@ -401,34 +438,7 @@ def main() -> None:
     - Screenshot capture capability
     - Graceful shutdown on Ctrl-C or window close
     """
-    parser = argparse.ArgumentParser(
-        description="ESP32 Serial Monitor with Memory Graph - Real-time monitoring, graphing, and command interface"
-    )
-    default_baudrate = 115200
-    parser.add_argument(
-        "port",
-        nargs="?",
-        default=None,
-        help="Serial port (leave empty for autodetection)",
-    )
-    parser.add_argument(
-        "--baud",
-        type=int,
-        default=default_baudrate,
-        help=f"Baud rate (default: {default_baudrate})",
-    )
-    parser.add_argument(
-        "--filter",
-        type=str,
-        default="",
-        help="Only display lines containing this keyword (case-insensitive)",
-    )
-    parser.add_argument(
-        "--suppress",
-        type=str,
-        default="",
-        help="Suppress lines containing this keyword (case-insensitive)",
-    )
+    parser = build_arg_parser()
     args = parser.parse_args()
     port = args.port
     if port is None:

scripts/generate-font-manifest.py

@@ -16,6 +16,8 @@ The input directory may be flat (all .cpfont files in one dir) or nested
 convention <FamilyName>_<size>.cpfont.
 """
 
+from __future__ import annotations
+
 import argparse
 import json
 import os

scripts/generate_kerning_ligature_epub.py

@@ -137,10 +137,15 @@ Also includes:
 
 import io
 import os
+import sys
 import zipfile
 import uuid
 from datetime import datetime
 
+if any(arg in ("-h", "--help") for arg in sys.argv[1:]):
+    print(__doc__.strip())
+    sys.exit(0)
+
 try:
     from PIL import Image, ImageDraw, ImageFont
 except ImportError:

scripts/generate_test_bmps.py

@@ -326,4 +326,7 @@ def main():
 
 
 if __name__ == '__main__':
+    if any(arg in ("-h", "--help") for arg in sys.argv[1:]):
+        print(__doc__.strip())
+        sys.exit(0)
     main()

scripts/generate_test_epub.py

@@ -11,9 +11,14 @@ Creates EPUBs with annotated JPEG and PNG images to verify:
 """
 
 import os
+import sys
 import zipfile
 from pathlib import Path
 
+if any(arg in ("-h", "--help") for arg in sys.argv[1:]):
+    print(__doc__.strip())
+    sys.exit(0)
+
 try:
     from PIL import Image, ImageDraw, ImageFont
 except ImportError:

test/hyphenation_eval/resources/generate_hyphenation_test_data.py

@@ -16,7 +16,6 @@ Requirements:
 import argparse
 import re
 from collections import Counter
-import pyphen
 from pathlib import Path
 import zipfile
 
@@ -75,6 +74,8 @@ def generate_hyphenation_data(
         min_prefix: Minimum characters allowed before the first hyphen (default: 2)
         min_suffix: Minimum characters allowed after the last hyphen (default: 2)
     """
+    import pyphen
+
     print(f"Reading from: {input_file}")
 
     # Read the input file