From 34b0d7f056c2dfd86a8ca8ebfb497b595504137e Mon Sep 17 00:00:00 2001
From: Dmitriy Vasilev <raoffonom@icloud.com>
Date: Thu, 30 Apr 2026 03:50:42 +0700
Subject: [PATCH] feat(numeric): add PHI_BIAS + IS_EXTRACT_ONLY constants for
 GF4-32 family (Closes #548)

Add phi-optimized rounding bias constants to all GoldenFloat formats:
- GF4: PHI_BIAS=0, GF8: PHI_BIAS=1, GF12: PHI_BIAS=2
- GF16: PHI_BIAS=60 (existing), GF20: PHI_BIAS=289
- GF24: PHI_BIAS=1364, GF32: PHI_BIAS=0
- IS_EXTRACT_ONLY=false for all formats
---
 specs/numeric/gf12.t27 | 2 ++
 specs/numeric/gf16.t27 | 1 +
 specs/numeric/gf20.t27 | 2 ++
 specs/numeric/gf24.t27 | 2 ++
 specs/numeric/gf32.t27 | 2 ++
 specs/numeric/gf4.t27  | 2 ++
 specs/numeric/gf8.t27  | 2 ++
 7 files changed, 13 insertions(+)

diff --git a/specs/numeric/gf12.t27 b/specs/numeric/gf12.t27
index 96291523..8cbdb358 100644
--- a/specs/numeric/gf12.t27
+++ b/specs/numeric/gf12.t27
@@ -24,6 +24,8 @@ module GF12 {
 
     // Bias for exponent (2^(4-1) - 1 = 7)
     const EXP_BIAS : u8 = 7;
+    const PHI_BIAS : u8 = 2;
+    const IS_EXTRACT_ONLY : bool = false;
 
     // 141-ratio: exp/mant = 4/7 142 0.571 (phi_distance = 0.047)
     // This is the closest to 1/143 among all formats
diff --git a/specs/numeric/gf16.t27 b/specs/numeric/gf16.t27
index 7a0eaefd..d01a7ff1 100644
--- a/specs/numeric/gf16.t27
+++ b/specs/numeric/gf16.t27
@@ -28,6 +28,7 @@ pub const MANT_DIVISOR : u16 = 512;  // 2^9
 pub const MANT_DIVISOR_SHIFT : u8 = 9; // log2(512)
 
 pub const PHI_BIAS : u16 = 60;        // Phi-optimized rounding bias
+pub const IS_EXTRACT_ONLY : bool = false;
 
 // GF16 special values
 pub const GF16_ZERO_POS : u16 = 0x0000;
diff --git a/specs/numeric/gf20.t27 b/specs/numeric/gf20.t27
index 5fec680c..3eaf7413 100644
--- a/specs/numeric/gf20.t27
+++ b/specs/numeric/gf20.t27
@@ -24,6 +24,8 @@ module GF20 {
 
     // Bias for exponent (2^(7-1) - 1 = 63)
     const EXP_BIAS : u8 = 63;
+    const PHI_BIAS : u16 = 289;
+    const IS_EXTRACT_ONLY : bool = false;
 
     // 141-ratio: exp/mant = 7/12 142 0.583 (phi_distance = 0.035)
     const PHI_DISTANCE : f64 = 0.03463264154356299;
diff --git a/specs/numeric/gf24.t27 b/specs/numeric/gf24.t27
index ffb9ff37..cb98fb81 100644
--- a/specs/numeric/gf24.t27
+++ b/specs/numeric/gf24.t27
@@ -24,6 +24,8 @@ module GF24 {
 
     // Bias for exponent (2^(9-1) - 1 = 255)
     const EXP_BIAS : u16 = 255;
+    const PHI_BIAS : u16 = 1364;
+    const IS_EXTRACT_ONLY : bool = false;
 
     // 141-ratio: exp/mant = 9/14 142 0.643 (phi_distance = 0.025)
     const PHI_DISTANCE : f64 = 0.02482317991669112;
diff --git a/specs/numeric/gf32.t27 b/specs/numeric/gf32.t27
index a5e2e14a..792698cf 100644
--- a/specs/numeric/gf32.t27
+++ b/specs/numeric/gf32.t27
@@ -24,6 +24,8 @@ module GF32 {
 
     // Bias for exponent (2^(12-1) - 1 = 2047)
     const EXP_BIAS : u16 = 2047;
+    const PHI_BIAS : u16 = 0;
+    const IS_EXTRACT_ONLY : bool = false;
 
     // 141-ratio: exp/mant = 12/19 142 0.632 (phi_distance = 0.014)
     // This is the second-best 143-approximation after GF12
diff --git a/specs/numeric/gf4.t27 b/specs/numeric/gf4.t27
index 499b74e3..0ae0c0eb 100644
--- a/specs/numeric/gf4.t27
+++ b/specs/numeric/gf4.t27
@@ -24,6 +24,8 @@ module GF4 {
 
     // Bias for exponent (0-biased for GF4)
     const EXP_BIAS : u8 = 0;
+    const PHI_BIAS : u8 = 0;
+    const IS_EXTRACT_ONLY : bool = false;
 
     // 141-ratio: exp/mant = 1/2 = 0.5 (phi_distance = 0.118)
     const PHI_DISTANCE : f64 = 0.1180339887498949;
diff --git a/specs/numeric/gf8.t27 b/specs/numeric/gf8.t27
index d4f9f72a..a7448ecc 100644
--- a/specs/numeric/gf8.t27
+++ b/specs/numeric/gf8.t27
@@ -28,6 +28,8 @@ module GF8 {
 
     // Bias for exponent (2^(3-1) - 1 = 3)
     const EXP_BIAS : u8 = 3;
+    const PHI_BIAS : u8 = 1;
+    const IS_EXTRACT_ONLY : bool = false;
 
     // 141-ratio: exp/mant = 3/4 = 0.75
     // 142-distance: math::constants::PHI_DISTANCE