fix(cnn_v3/training): fix defaults and help strings across py tools

- train_cnn_v3.py: enc-channels 4,8→8,16; checkpoint-every 50→100;
  add help strings for epochs/batch-size/lr/checkpoint-dir
- gen_test_vectors.py: add help strings for --W/--H/--seed
- export_cnn_v3_weights.py: fix --output help string (export/→export)

3 files changed, 20 insertions, 12 deletions

diff --git a/cnn_v3/training/export_cnn_v3_weights.py b/cnn_v3/training/export_cnn_v3_weights.py
index 2fa83d1..67330a6 100644
--- a/cnn_v3/training/export_cnn_v3_weights.py
+++ b/cnn_v3/training/export_cnn_v3_weights.py
@@ -189,7 +189,7 @@ def main() -> None:
     p = argparse.ArgumentParser(description='Export CNN v3 trained weights to .bin')
     p.add_argument('checkpoint', help='Path to .pth checkpoint file')
     p.add_argument('--output', default='export',
-                   help='Output directory (default: export/)')
+                   help='Output directory (default: export)')
     p.add_argument('--html', action='store_true',
                    help=f'Also update {_WEIGHTS_JS_DEFAULT} with base64-encoded weights')
     p.add_argument('--html-output', default=None, metavar='PATH',
diff --git a/cnn_v3/training/gen_test_vectors.py b/cnn_v3/training/gen_test_vectors.py
index cdda5a5..3f81247 100644
--- a/cnn_v3/training/gen_test_vectors.py
+++ b/cnn_v3/training/gen_test_vectors.py
@@ -405,9 +405,12 @@ def main():
     parser = argparse.ArgumentParser(description="CNN v3 parity test vector generator")
     parser.add_argument('--header', action='store_true',
                         help='Emit C header to stdout')
-    parser.add_argument('--W', type=int, default=8)
-    parser.add_argument('--H', type=int, default=8)
-    parser.add_argument('--seed', type=int, default=42)
+    parser.add_argument('--W', type=int, default=8,
+                        help='Test image width (default 8)')
+    parser.add_argument('--H', type=int, default=8,
+                        help='Test image height (default 8)')
+    parser.add_argument('--seed', type=int, default=42,
+                        help='Random seed (default 42)')
     args = parser.parse_args()
 
     # Send self-test output to stderr so --header stdout stays clean
diff --git a/cnn_v3/training/train_cnn_v3.py b/cnn_v3/training/train_cnn_v3.py
index 5b6a0be..e48f684 100644
--- a/cnn_v3/training/train_cnn_v3.py
+++ b/cnn_v3/training/train_cnn_v3.py
@@ -21,6 +21,7 @@ Weight budget: ~15.3 KB conv f16 (7828 f16); total with MLP ~17.9 KB
 Training improvements:
   --edge-loss-weight   Sobel edge loss alongside MSE (default 0.1)
   --film-warmup-epochs Train U-Net only for N epochs before unfreezing FiLM MLP (default 50)
+  --checkpoint-every   Save checkpoint every N epochs (default 100)
 """
 
 import argparse
@@ -309,18 +310,22 @@ def main():
                    help='Search ±N px in target to minimise grayscale MSE (default 0=disabled)')
 
     # Model
-    p.add_argument('--enc-channels', default='4,8',
-                   help='Encoder channels, comma-separated (default 4,8)')
+    p.add_argument('--enc-channels', default='8,16',
+                   help='Encoder channels, comma-separated (default 8,16)')
     p.add_argument('--film-cond-dim', type=int, default=5,
                    help='FiLM conditioning input dim (default 5)')
 
     # Training
-    p.add_argument('--epochs',           type=int,   default=200)
-    p.add_argument('--batch-size',       type=int,   default=16)
-    p.add_argument('--lr',               type=float, default=1e-3)
-    p.add_argument('--checkpoint-dir',   default='checkpoints')
-    p.add_argument('--checkpoint-every', type=int,   default=50,
-                   help='Save checkpoint every N epochs (0=disable)')
+    p.add_argument('--epochs',           type=int,   default=200,
+                   help='Total training epochs (default 200)')
+    p.add_argument('--batch-size',       type=int,   default=16,
+                   help='Batch size (default 16)')
+    p.add_argument('--lr',               type=float, default=1e-3,
+                   help='Learning rate (default 1e-3)')
+    p.add_argument('--checkpoint-dir',   default='checkpoints',
+                   help='Directory to save checkpoints (default checkpoints)')
+    p.add_argument('--checkpoint-every', type=int,   default=100,
+                   help='Save checkpoint every N epochs (default 100; 0=disable)')
     p.add_argument('--resume', default='', metavar='CKPT',
                    help='Resume from checkpoint path; if path missing, use latest in --checkpoint-dir')
     p.add_argument('--edge-loss-weight', type=float, default=0.1,