Fix adaptive barrel refinement and ambiguous decimal-comma inputs

- adaptive: barrel links could attach to coarse leaves (up to 1 mm),
  making the whole leaf equipotential and deleting the local spreading
  resistance - via-field results read up to ~13% low. Barrel attachment
  cells are now pinned into the keep-fine set before the quadtree is
  built; the guard ring grades around them.
- skin/dialog: the decimal-comma rewrite turned '1,500' into 1.5, a
  silent 1000x error in frequency, test current or cell size. Ambiguous
  comma patterns (thousands separators, multiple commas, mixed with a
  dot) now raise with a message; a real decimal comma ('1,5') still
  parses.
- dialog: Selection.adaptive default now matches the documented
  on-by-default; the adaptive accuracy claim is aligned to the measured
  0.03% quoted in README and config.

fill_resistance/adaptive.py

@@ -94,6 +94,7 @@ def run_solve_adaptive(problem: Problem, stack: RasterStack,
 
     # --- leaves per layer -------------------------------------------------
     t0 = time.perf_counter()
+    links, dead_barrels = sv._barrel_links(stack, problem)
     keep = e1 | e2
     if stack.chain is not None:
         keep |= stack.chain
@@ -101,6 +102,13 @@ def run_solve_adaptive(problem: Problem, stack: RasterStack,
         keep |= stack.buildup
     if stack.thick_scale is not None:
         keep |= stack.thick_scale != 1.0
+    # pin every barrel attachment cell fine: a point-like barrel
+    # injection into a coarse leaf makes the whole leaf equipotential
+    # and deletes the local spreading resistance (via fields read up
+    # to ~13% low otherwise); the guard ring then grades around it
+    for _vi, la, ia_, ja_, lb, ib_, jb_, _r in links:
+        keep[la, ia_, ja_] = True
+        keep[lb, ib_, jb_] = True
     mb = _max_block(stack.h_nm)
     grids = [quadtree.build_leaves(stack.masks[li], keep_fine=keep[li],
                                    max_block=mb,
@@ -181,7 +189,6 @@ def run_solve_adaptive(problem: Problem, stack: RasterStack,
             xx.append(np.full(k, -1, dtype=np.int8))
             ee.append(np.full(k, -1, dtype=np.int16))
 
-    links, dead_barrels = sv._barrel_links(stack, problem)
     for vi, la, ia_, ja_, lb, ib_, jb_, r_dc in links:
         na = offs[la] + grids[la].id_grid[ia_, ja_]
         nb = offs[lb] + grids[lb].id_grid[ib_, jb_]

fill_resistance/dialog.py

@@ -38,7 +38,7 @@ class Selection:
     include_tracks: bool = True
     vias_capped: bool = True
     cap_max_drill_mm: float = 0.5
-    adaptive: bool = False
+    adaptive: bool = True
 
 
 class _Dialog(QDialog):
@@ -81,7 +81,7 @@ class _Dialog(QDialog):
 
         self.adaptive_check = QCheckBox(
             "adaptive cells (coarsen plane interiors; faster on large "
-            "boards, corrected to ≲0.1 % of the uniform grid)")
+            "boards, corrected to ≲0.03 % of the uniform grid)")
         self.adaptive_check.setChecked(config.ADAPTIVE_CELLS)
         form.addRow("Grid:", self.adaptive_check)
 
@@ -187,10 +187,13 @@ class _Dialog(QDialog):
             raise ValueError("Check at least one layer.")
 
         def number(edit: QLineEdit, name: str) -> float:
+            text = edit.text().strip()
             try:
-                return float(edit.text().strip().replace(",", "."))
-            except ValueError:
-                raise ValueError(f"{name}: '{edit.text()}' is not a number.")
+                return float(skin.normalize_decimal(text))
+            except ValueError as exc:
+                if "separator" in str(exc):
+                    raise ValueError(f"{name}: {exc}")
+                raise ValueError(f"{name}: '{text}' is not a number.")
 
         current = number(self.current_edit, "Test current")
         if current <= 0:

fill_resistance/skin.py

@@ -21,6 +21,7 @@ from __future__ import annotations
 
 import cmath
 import math
+import re
 
 MU0 = 4e-7 * math.pi
 
@@ -58,11 +59,25 @@ def resistance_factor(thickness_m: float, freq_hz: float,
             / (rho_ohm_m / thickness_m))
 
 
+def normalize_decimal(text: str) -> str:
+    """Accept a European decimal comma ('1,5' -> '1.5'); reject
+    thousands-separator commas ('1,500' would silently become 1.5,
+    a 1000x error that propagates unnoticed into the result)."""
+    if "," in text:
+        if "." in text or text.count(",") > 1 \
+                or re.search(r",\d{3}(?=\D|$)", text):
+            raise ValueError(
+                f"ambiguous comma in '{text}': use '.' as the decimal "
+                "separator and no thousands separators")
+        text = text.replace(",", ".")
+    return text
+
+
 def parse_frequency(text: str) -> float:
     """'0', '100k', '1.5M', '142500' -> Hz; empty -> 0 (DC).
-    Raises ValueError on unparseable or negative input (a typo silently
-    becoming DC would mislabel the result)."""
-    t = text.strip().lower().replace(",", ".").removesuffix("hz").strip()
+    Raises ValueError on unparseable, ambiguous or negative input (a
+    typo silently becoming DC would mislabel the result)."""
+    t = normalize_decimal(text.strip().lower()).removesuffix("hz").strip()
     if not t:
         return 0.0
     mult = 1.0