HBit::harmony substrate-routed (D3 partial)

Replace the Euclidean `1/(1+|alpha-beta|)` harmony formula in
value::HBit::harmony with substrate-routed
`1/(1+attractor_distance(|alpha-beta|))`. Harmony now measures
coherence with the phi-pi-fibonacci attractor lattice — peaks at 1.0
when the band-diff lands on a Fibonacci attractor (0, 1, 2, 3, 5, 8,
13, 21, ..., 63245986). Decays with distance from the nearest.

Also delete the duplicate harmony formula in hbit::HBitProcessor —
it now delegates to value::HBit::harmony so both call sites share
one substrate-routed implementation.

Test coverage refreshed: HBitProcessor::harmony(5, 10) is no longer
asserted < 1.0 (diff 5 is on an attractor, so harmony = 1.0 is
correct under the new formula). New asserts pin off-attractor pairs
(harmony(4, 10) where diff 6 lands between attractors) and far-off
pairs (harmony(0, 1000) where diff 1000 lands distance 13 from
nearest attractor 987).

NOTE: this is D3-PARTIAL. The remaining work — wiring @hbit pragma
into a real codegen path (SL HBit architecture targets AVX-512 SIMD
intrinsics) — is a multi-session project tracked separately. This
commit is the substrate-alignment foundation that the codegen path
will build on top of.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: RandomCoder-lab

omnimcode-core/src/hbit.rs

@@ -37,11 +37,12 @@ impl HBitProcessor {
         self.track_harmony(harmony);
     }
 
-    /// Calculate harmony between two bands (from value.rs HBit)
-    /// Delegates to existing implementation to avoid duplication
+    /// Calculate harmony between two bands.
+    /// Delegates to the canonical substrate-routed formula in value.rs
+    /// (D3 substrate-fill — was a Euclidean duplicate here, now both
+    /// sites share the same attractor-distance computation).
     pub fn harmony(alpha: i64, beta: i64) -> f64 {
-        let diff = (alpha - beta).abs() as f64;
-        1.0 / (1.0 + diff)
+        crate::value::HBit::harmony(alpha, beta)
     }
 
     /// Calculate tension (complementary to harmony)
@@ -217,10 +218,24 @@ mod tests {
     use super::*;
 
     #[test]
-    fn test_hbit_harmony() {
-        assert_eq!(HBitProcessor::harmony(5, 5), 1.0); // Perfect harmony
-        assert!(HBitProcessor::harmony(5, 10) < 1.0); // Some discord
-        assert!(HBitProcessor::harmony(5, 10) > 0.0); // Still positive
+    fn test_hbit_harmony_substrate_routed() {
+        // Equal bands → diff 0 → on attractor 0 → perfect harmony.
+        assert_eq!(HBitProcessor::harmony(5, 5), 1.0);
+        // Diff lands ON a Fibonacci attractor → perfect harmony (this
+        // is the architecturally significant change vs the old
+        // Euclidean formula, where any nonzero diff dropped harmony).
+        // 10 - 5 = 5; 5 is an attractor; substrate-routed harmony = 1.0.
+        assert_eq!(HBitProcessor::harmony(5, 10), 1.0);
+        // Diff lands BETWEEN attractors → harmony < 1.0.
+        // 10 - 4 = 6; nearest attractor is 5 (dist 1) or 8 (dist 2);
+        // either way the distance is non-zero so harmony < 1.0.
+        let h = HBitProcessor::harmony(4, 10);
+        assert!(h < 1.0);
+        assert!(h > 0.0);
+        // Large off-attractor gap → very low harmony.
+        // 1000 - 0 = 1000; nearest attractor 987 (dist 13).
+        let h_far = HBitProcessor::harmony(0, 1000);
+        assert!(h_far < 0.1);
     }
 
     #[test]

omnimcode-core/src/value.rs

@@ -108,9 +108,22 @@ impl HBit {
         }
     }
 
+    /// Harmony — substrate-routed measure of how aligned α and β are
+    /// with OMC's φ-π-fibonacci attractor lattice. Equals
+    /// `1 / (1 + attractor_distance(|α - β|))`.
+    ///
+    /// Peak (1.0) when |α - β| is exactly on a Fibonacci attractor
+    /// (0, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, …, up to 63,245,986).
+    /// Decays with distance from the nearest attractor.
+    ///
+    /// Pre-substrate-fill this was Euclidean `1 / (1 + |α - β|)`. The
+    /// substrate routing makes harmony a *coherence with the
+    /// attractor grid*, not a coincidence-coincidence signal — see
+    /// SUBSTRATE_CHANGES.md (D3 substrate-routing of HBit harmony).
     pub fn harmony(alpha: i64, beta: i64) -> f64 {
-        let diff = (alpha - beta).abs() as f64;
-        1.0 / (1.0 + diff)
+        let diff = (alpha - beta).abs();
+        let (_, attractor_dist) = crate::phi_pi_fib::nearest_attractor_with_dist(diff);
+        1.0 / (1.0 + attractor_dist as f64)
     }
 }