Fix sqrt minor ticks: crowd toward low end via squared position

web/app.py

@@ -8,7 +8,7 @@ from fontTools.pens.svgPathPen import SVGPathPen
 
 app = Flask(__name__)
 
-VERSION = "0.78"
+VERSION = "0.79"
 
 _LOGO_PATH = pathlib.Path(__file__).parent / 'static' / 'logo.png'
 _LOGO_B64 = base64.b64encode(_LOGO_PATH.read_bytes()).decode()
@@ -444,14 +444,23 @@ def generate_svg(unit, min_val, max_val, range_label, big_ticks, small_ticks, la
             f' style="stroke:#1a1a1a;stroke-width:0.555;stroke-linecap:butt" />'
         )
 
-    # Minor ticks — evenly spaced in value, then positioned by the scale mapping.
-    # On a linear scale this is uniform; on a log scale they crowd toward the high end.
+    # Minor ticks — placement depends on scale type:
+    #   linear: uniform physical spacing (= uniform value spacing)
+    #   log:    linear value interpolation between geometric major values
+    #           (crowds toward high end of each interval)
+    #   sqrt:   sqrt of fractional position within each interval, giving
+    #           consistent high-end crowding across all intervals; using
+    #           value interpolation instead would concentrate the crowding
+    #           only near zero (where sqrt is steepest) and look linear elsewhere.
     if small_ticks > 0:
         sub = small_ticks + 1
         for i in range(big_ticks):
             for j in range(1, small_ticks + 1):
-                v = big_vals[i] + j * (big_vals[i + 1] - big_vals[i]) / sub
-                x = value_to_x(v)
+                if scale_type == 'sqrt':
+                    x = big_xs[i] + (j / sub) ** 2 * (big_xs[i + 1] - big_xs[i])
+                else:
+                    v = big_vals[i] + j * (big_vals[i + 1] - big_vals[i]) / sub
+                    x = value_to_x(v)
                 parts.append(
                     f'    <line x1="{x:.5f}" y1="{BAR_Y}" x2="{x:.5f}" y2="{BAR_Y - SMALL_H:.5f}"'
                     f' style="stroke:#1a1a1a;stroke-width:0.302;stroke-linecap:butt" />'