Use descriptive names for generated resistor symbols (R0402_4.7K_1%)

Symbols are now named by value+tolerance instead of internal GLE P/N,
e.g. R0402_4.7K_1%, R0402_100_5%, R0402_10.0K_0.1%.

- Add make_symbol_name() to normalise value suffix (k→K) and extract
  tolerance via regex from the Description column
- Deduplicate by sym_name: where two GLE P/Ns share the same
  value+tolerance (alternate approved vendors), keep the first row
  and report the 10 skipped duplicates at runtime
- UMPN field still carries the GLE P/N of the primary vendor

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/gen_resistors_0402.py

@@ -6,13 +6,21 @@ Reads the approved parts list spreadsheet and generates KiCad 9 symbols
 for every 0402 resistor into kicad-lib/symbols/Res_0402.kicad_sym.
 
 The existing R_temp template symbol is kept in the file.  One new symbol
-is added per row, named by the internal part number (GLE P/N), with:
+is added per unique value+tolerance combination, named descriptively, e.g.:
+    R0402_4.7K_1%
+    R0402_100_5%
+    R0402_10.0K_0.1%
+
+Symbol fields:
     Value       ← Value1   (e.g. "10k", "4.7k", "100")
     Description ← Description column
-    UMPN        ← GLE P/N
+    UMPN        ← GLE P/N  (internal part number of first approved vendor)
     MFG         ← Mfg.1
     MPN         ← Mfg.1 P/N
 
+Where multiple approved vendors share the same value+tolerance, only the
+first row is used (the duplicate rows are reported and skipped).
+
 All geometry and pin definitions are copied verbatim from R_temp.
 
 Usage:
@@ -34,6 +42,24 @@ def kicad_str(value: str) -> str:
     return str(value).replace('\\', '\\\\').replace('"', '\\"')
 
 
+def make_symbol_name(value: str, description: str) -> str:
+    """
+    Build a descriptive KiCad symbol name, e.g. 'R0402_4.7K_1%'.
+
+    value       – the Value1 column (e.g. '4.7k', '100', '10.0k')
+    description – the Description column (e.g. 'Resistor, 0402, 1%, 4.7k')
+
+    The value suffix (k, m, g) is uppercased.  Tolerance is extracted
+    with a regex that matches patterns like '1%', '0.1%', '5%'.
+    """
+    # Uppercase trailing unit letter(s): 4.7k → 4.7K, 10.0k → 10.0K
+    value_norm = re.sub(r'([a-zA-Z]+)$', lambda m: m.group(1).upper(), value.strip())
+    # Extract tolerance from description
+    tol_match = re.search(r'(\d+(?:\.\d+)?%)', description)
+    tolerance = tol_match.group(1) if tol_match else 'X'
+    return f'R0402_{value_norm}_{tolerance}'
+
+
 def make_symbol(name: str, value: str, description: str,
                 umpn: str, mfg: str, mpn: str,
                 geometry_body: str) -> str:
@@ -206,6 +232,7 @@ def main(xlsx_path: Path, sym_path: Path):
     # ---- Build new symbols ----
     new_symbols = []
     skipped = []
+    seen_names: dict[str, str] = {}   # sym_name → GLE P/N of first occurrence
 
     for _, row in resistors.iterrows():
         gle_pn      = str(row['GLE P/N']).strip()
@@ -218,16 +245,25 @@ def main(xlsx_path: Path, sym_path: Path):
             skipped.append(('(no GLE P/N)', value))
             continue
 
+        # Build descriptive symbol name, e.g. "R0402_4.7K_1%"
+        sym_name = make_symbol_name(value, description)
+
+        # Skip duplicate value+tolerance combinations (alternate approved vendors)
+        if sym_name in seen_names:
+            skipped.append((sym_name, f'dup of GLE {seen_names[sym_name]} (this: {gle_pn})'))
+            continue
+        seen_names[sym_name] = gle_pn
+
         # Substitute R_temp → this symbol's name in the geometry block.
         # Also re-indent so sub-symbol opening parens align with the template.
-        geom = raw_geom.replace('R_temp_0_1', f'{gle_pn}_0_1') \
+        geom = raw_geom.replace('R_temp_0_1', f'{sym_name}_0_1') \
-                       .replace('R_temp_1_1', f'{gle_pn}_1_1')
+                       .replace('R_temp_1_1', f'{sym_name}_1_1')
         # Each sub-symbol block starts at column 0 after extract; add two tabs.
         geom = '\n'.join('\t\t' + line if line.startswith('(symbol ') else line
                          for line in geom.splitlines())
 
         sym = make_symbol(
-            name=gle_pn,
+            name=sym_name,
             value=value,
             description=description,
             umpn=gle_pn,
@@ -237,7 +273,14 @@ def main(xlsx_path: Path, sym_path: Path):
         )
         new_symbols.append(sym)
 
-    print(f"Generated {len(new_symbols)} symbols  ({len(skipped)} skipped)")
+    dups = [(n, r) for n, r in skipped if n != '(no GLE P/N)']
+    no_pn = [(n, r) for n, r in skipped if n == '(no GLE P/N)']
+    print(f"Generated {len(new_symbols)} symbols  "
+          f"({len(dups)} duplicate value/tol skipped, {len(no_pn)} missing GLE P/N)")
+    if dups:
+        print("  Skipped duplicates:")
+        for name, reason in dups:
+            print(f"    {name}: {reason}")
 
     # ---- Rebuild file from scratch (idempotent) ----
     # Extract the library header lines (everything before the first symbol)