fix(cli): lazy settings fetch and full device erase

Download settings only for --show or when applying edits; skip upload
when unchanged; erase entire device root including settings.json.

Co-authored-by: Cursor <cursoragent@cursor.com>

README.md

@@ -27,11 +27,11 @@ Connection is always via **`-p` / `--port`** (default `/dev/ttyACM0`). There is
 | `--pause` | Sleep N seconds (for chained actions) |
 | `-u`, `--upload` | Recursive upload: `-u SRC [DEST]` |
 | `--src`, `--lib` | Upload `src/` or a tree to `/lib` |
-| `-e` | Erase device code (keeps `settings.json`) |
+| `-e`, `--erase` | Erase everything at device root (including `settings.json` and `presets.json`) |
 | `--rm` | Remove a path on the device |
 | `--flash` | Flash a firmware binary (uses **esptool** on the host) |
 
-**Default behaviour:** the tool always downloads `settings.json`, prints the merged view, and uploads again **only** when you pass setting edits (`--name`, `--leds`, …), **`--preset`**, or the relevant upload/flash/erase actions in order.
+**Settings I/O:** With no arguments, **`led-cli`** prints help (no device access). **`--show`** downloads `settings.json` and prints it (read-only). Setting fields (`--name`, `-b`, …) download once, merge, print, and **upload only when a value actually changed**. **`--preset`** alone only touches **`presets.json`** (no `settings.json` download). Ordered actions (`--reset`, `--upload`, `-e`, …) run without touching settings unless you also pass **`--show`** or setting / preset edits as above.
 
 Run **`python cli.py -h`** for the full epilog and argument list.
 

cli.py

@@ -2,8 +2,10 @@
 """
 LED Bar Configuration CLI Tool
 
-Command-line interface for downloading, editing, and uploading settings.json
+Command-line interface for editing settings.json on MicroPython devices via mpremote.
-to/from MicroPython devices via mpremote.
+Settings are downloaded from the device only when displaying (--show) or when applying
+setting changes; uploads occur only when something changed. Use --erase to clear the
+device filesystem (including settings).
 """
 
 import json
@@ -279,10 +281,13 @@ def main() -> None:
         formatter_class=argparse.RawDescriptionHelpFormatter,
         epilog="""
 Examples:
-  # Download and print current settings
+  # Show help (no device I/O)
   %(prog)s
 
-  # Download, edit device name and brightness, then upload
+  # Show current settings.json from device (read-only)
+  %(prog)s --show
+
+  # Edit device name and brightness, then upload only if values changed
   %(prog)s -n "LED-Strip-1" -b 128
 
   # Set multiple parameters
@@ -500,7 +505,7 @@ Examples:
         "-e", "--erase",
         dest="erase_all",
         action="store_true",
-        help="Erase all code on the device (delete all files except settings.json)"
+        help="Erase the device filesystem: delete all files and directories at device root (including settings.json and presets.json)",
     )
 
     parser.add_argument(
@@ -516,6 +521,9 @@ Examples:
     )
 
     try:
+        if len(sys.argv) <= 1:
+            parser.print_help()
+            return
         args = parser.parse_args()
         ordered_actions = _get_ordered_actions(sys.argv)
     except ValueError as e:
@@ -631,14 +639,12 @@ Examples:
 
         elif action_name == 'erase_all':
             try:
-                print(f"Erasing all code on device {port}...", file=sys.stderr)
+                print(f"Erasing device filesystem on {port}...", file=sys.stderr)
                 conn = DeviceConnection(port)
                 items = conn.list_files('')
                 for name, is_dir, size in items:
-                    if name == "settings.json":
-                        continue
                     conn.delete(name)
-                print("Erase complete.", file=sys.stderr)
+                print("Erase complete (device root is empty).", file=sys.stderr)
             except Exception as e:
                 print(f"Error erasing device: {e}", file=sys.stderr)
                 sys.exit(1)
@@ -735,25 +741,28 @@ Examples:
         # Clamp into single-byte range; store as int in settings.json
         edits["id"] = max(0, min(255, args.device_id))
 
-    # 1. Download: get current settings from device
+    settings_work = args.show or bool(edits)
+
+    if settings_work:
         try:
             print(f"Downloading settings from {args.port}...", file=sys.stderr)
             settings = download_settings(args.port)
             print("Settings downloaded successfully.", file=sys.stderr)
         except Exception as e:
             if "timeout" in str(e).lower() or "connection" in str(e).lower():
-            print(f"Error: Connection timeout. Check device connection on {args.port}", file=sys.stderr)
+                print(
+                    f"Error: Connection timeout. Check device connection on {args.port}",
+                    file=sys.stderr,
+                )
             else:
                 print(f"Error downloading settings: {e}", file=sys.stderr)
             sys.exit(1)
 
-    # If --show only, print and exit (unless presets or settings are being written)
         if args.show:
             print_settings(settings)
             if not edits and args.preset is None:
                 return
 
-    # 2. Edit: only apply/upload settings when values actually change
         changed_edits: Dict[str, Any] = {}
         for key, value in edits.items():
             if settings.get(key) != value:
@@ -768,7 +777,6 @@ Examples:
 
         print_settings(settings)
 
-    # 3a. Presets file (led-driver presets.json)
         if args.preset is not None:
             pattern = args.pattern if args.pattern is not None else "on"
             try:
@@ -789,12 +797,14 @@ Examples:
                     print("Device will reset.", file=sys.stderr)
             except Exception as e:
                 if "timeout" in str(e).lower() or "connection" in str(e).lower():
-                print(f"Error: Connection timeout. Check device connection on {args.port}", file=sys.stderr)
+                    print(
+                        f"Error: Connection timeout. Check device connection on {args.port}",
+                        file=sys.stderr,
+                    )
                 else:
                     print(f"Error uploading presets: {e}", file=sys.stderr)
                 sys.exit(1)
 
-    # 3b. Settings upload (resets device)
         if changed_edits:
             try:
                 print(f"\nUploading settings to {args.port}...", file=sys.stderr)
@@ -802,10 +812,47 @@ Examples:
                 print("Settings uploaded successfully. Device will reset.", file=sys.stderr)
             except Exception as e:
                 if "timeout" in str(e).lower() or "connection" in str(e).lower():
-                print(f"Error: Connection timeout. Check device connection on {args.port}", file=sys.stderr)
+                    print(
+                        f"Error: Connection timeout. Check device connection on {args.port}",
+                        file=sys.stderr,
+                    )
                 else:
                     print(f"Error uploading settings: {e}", file=sys.stderr)
                 sys.exit(1)
+        return
+
+    if args.preset is not None:
+        pattern = args.pattern if args.pattern is not None else "on"
+        try:
+            print(f"Downloading presets from {args.port}...", file=sys.stderr)
+            presets_data = download_presets(args.port)
+            entry = presets_data.get(args.preset)
+            if not isinstance(entry, dict):
+                entry = {}
+            entry["p"] = pattern
+            presets_data[args.preset] = entry
+            print(
+                f"Writing preset {args.preset!r} (pattern={pattern}) to {PRESETS_REMOTE}...",
+                file=sys.stderr,
+            )
+            upload_presets(args.port, presets_data, reset=True)
+            print("Presets uploaded successfully.", file=sys.stderr)
+            print("Device will reset.", file=sys.stderr)
+        except Exception as e:
+            if "timeout" in str(e).lower() or "connection" in str(e).lower():
+                print(
+                    f"Error: Connection timeout. Check device connection on {args.port}",
+                    file=sys.stderr,
+                )
+            else:
+                print(f"Error uploading presets: {e}", file=sys.stderr)
+            sys.exit(1)
+        return
+
+    if ordered_actions:
+        return
+
+    parser.print_help()
 
 
 if __name__ == "__main__":

device.py

@@ -137,7 +137,8 @@ class DeviceConnection:
             dirs_created = 0
             
             for root, dirs, files in os.walk(local_dir):
-                # Calculate relative path from local_dir
+                # Never upload Python bytecode trees (MicroPython does not use them).
+                dirs[:] = [d for d in dirs if d != "__pycache__"]
                 rel_path = os.path.relpath(root, local_dir)
                 
                 # Build remote path
@@ -156,8 +157,10 @@ class DeviceConnection:
                     self.transport.fs_mkdir(remote_base)
                     dirs_created += 1
                 
-                # Copy files
+                # Copy files (skip bytecode; __pycache__ dirs are pruned above)
                 for file in files:
+                    if file.endswith((".pyc", ".pyo")):
+                        continue
                     local_file = os.path.join(root, file)
                     # Handle root directory case properly
                     if remote_base == '/':