fix(ahbg): stop reconstructing UCNS centers in presentation geometry

Author: erinepshovel-code

ahbg/presentation/geometry.py

@@ -1,43 +1,58 @@
-"""Seed of Life presentation geometry.
-
-The tile is the centerpoint. Each circle has radius equal to the distance
-between adjacent centers. This module renders geometry; it does not define game
-movement or adjacency authority.
+# === MODULE_BUILD ===
+# id: ahbg_presentation_display_transform
+#   module_name: geometry
+#   module_kind: adapter
+#   summary: scales already-supplied UCNS source coordinates into SVG display coordinates without reconstructing or selecting geometry
+#   owner: AHBG presentation
+#   public_surface: source_to_display, center_distance
+#   internal_surface: none
+#   auth_boundary: none
+#   storage_boundary: none
+#   network_boundary: none
+#   user_data_boundary: none
+#   admin_only: false
+#   tests: ahbg/presentation/tests/test_presentation.py
+#   rollout: used only by presentation tests and equivalent browser transform
+#   rollback: inline display scaling or remove presentation package; no mechanics effect
+#   requires: caller-supplied UCNS-derived x/y source coordinates
+#   since: 2026-08-31
+#   unresolved: none
+# === END MODULE_BUILD ===
+
+"""Presentation-only transform of source-backed center coordinates.
+
+This module does not derive Seed-of-Life centers, adjacency, orientation, or
+nesting. It only scales coordinates already supplied by the declared UCNS source
+into display pixels; optional y inversion is the SVG screen-coordinate transform.
+
+Usage guidance:
+    ``source_to_display(x, y, scale=64.0)`` after validating the snapshot.
 """
 
 from __future__ import annotations
 
 import math
-from typing import Sequence
 
 
-def axial_to_xy(q: int, r: int, radius: float) -> tuple[float, float]:
-    """Map already-supplied axial coordinates into presentation pixels."""
+def source_to_display(
+    x: float,
+    y: float,
+    scale: float,
+    *,
+    invert_y: bool = True,
+) -> tuple[float, float]:
+    """Scale source coordinates for display without changing their topology."""
 
-    if radius <= 0:
-        raise ValueError("radius must be positive")
-    return (radius * (q + r / 2), radius * (math.sqrt(3) / 2) * r)
+    if isinstance(x, bool) or not isinstance(x, (int, float)):
+        raise ValueError("x must be numeric and nonboolean")
+    if isinstance(y, bool) or not isinstance(y, (int, float)):
+        raise ValueError("y must be numeric and nonboolean")
+    if isinstance(scale, bool) or not isinstance(scale, (int, float)) or scale <= 0:
+        raise ValueError("scale must be positive numeric and nonboolean")
+    return float(x) * float(scale), (-float(y) if invert_y else float(y)) * float(scale)
 
 
 def center_distance(left: tuple[float, float], right: tuple[float, float]) -> float:
-    return math.hypot(left[0] - right[0], left[1] - right[1])
+    """Measure distance between already-supplied source/display points."""
 
-
-def visual_one_radius_pairs(
-    tiles: Sequence[tuple[int, int]], radius: float
-) -> tuple[tuple[tuple[int, int], tuple[int, int]], ...]:
-    """Return center pairs one display radius apart; presentation use only."""
-
-    points = {item: axial_to_xy(item[0], item[1], radius) for item in tiles}
-    pairs = []
-    items = list(tiles)
-    for index, left in enumerate(items):
-        for right in items[index + 1 :]:
-            if math.isclose(
-                center_distance(points[left], points[right]),
-                radius,
-                rel_tol=1e-9,
-                abs_tol=1e-9,
-            ):
-                pairs.append((left, right))
-    return tuple(pairs)
+    return math.hypot(left[0] - right[0], left[1] - right[1])