CATEGORICAL_BOUNDARY_LEDGER_2026 05 04

Categorical Boundary Validation Ledger

1. Audit Context

• Target Subsystems: moira.constants, moira.planets, moira.houses, moira.aspects
• Objective: Prove that astrological categories (signs, houses, aspects) are defined by absolute mathematical boundaries, and are immune to upstream float coercion, rounding errors, or fuzzy thresholding.
• Core Threat: Float-edge corruption, where a body at 29.9999999999° is prematurely coerced into the next sign/house due to loss of precision or silent rounding in the public interface.

2. Findings & Diagnostics

• The Absolute Threshold: Using 64-bit floating-point precision, a sequence of extreme limits was injected: 29.9999999999° (10 nines), 29.99999999999° (11 nines), and 29.999999999999° (12 nines), followed by exactly 30.000000000000°.
• Data Vessel Integrity: PlanetData inherently preserves the pure, unrounded longitude. Even the derived string-formatting helper longitude_dms correctly delegates to math.trunc style integer logic, avoiding the phenomenon where .9999 coerces to the next degree prior to sign assignment.
• Structural Purity: Neither the engine layer nor the presentation layer implements artificial "fuzzy" boundaries. A body is in Aries until it mathematically equals or crosses 30.0.

3. Validation Results

• Test Regimen: tests/unit/test_categorical_boundary.py
• Outcome:
  1. Sign Classification: moira.constants.sign_of strictly retained "Aries" for all 29.9... inputs.
  2. House Classification: moira.houses.assign_house placed 29.999999999999° in House 1, and only flipped to House 2 when exactly 30.0 was reached. It correctly toggled the exact_on_cusp flag only on the exact boundary.
  3. Aspect Engine: moira.aspects.aspects_between retains the exact float difference for its orb calculation, refusing to artificially round an 89.999999999999° square to an exact orb of 0.0.
  4. Data Vessel: PlanetData preserves the raw float.
• Status: Stable. The categorical layer is mathematically pure. No silent corruption exists at the threshold.