Squashed 'vendor/ruvector/' content from commit b64c2172

git-subtree-dir: vendor/ruvector
git-subtree-split: b64c21726f2bb37286d9ee36a7869fef60cc6900

crates/ruvector-coherence/tests/spectral_bench.rs

@@ -0,0 +1,67 @@
+//! Performance benchmark for spectral coherence scoring.
+//! Run with: cargo test -p ruvector-coherence --features spectral --test spectral_bench --release -- --nocapture
+
+#[cfg(feature = "spectral")]
+mod bench {
+    use ruvector_coherence::spectral::{CsrMatrixView, SpectralConfig, SpectralTracker};
+    use std::time::Instant;
+
+    #[test]
+    #[ignore] // Run manually with: cargo test --release --features spectral --test spectral_bench -- --ignored --nocapture
+    fn bench_scs_full_500v() {
+        let n = 500;
+        let mut edges: Vec<(usize, usize, f64)> = Vec::new();
+        for i in 0..n {
+            edges.push((i, (i + 1) % n, 1.0));
+        }
+        for i in 0..n {
+            edges.push((i, (i + 37) % n, 0.5));
+            edges.push((i, (i + 127) % n, 0.3));
+        }
+
+        let lap = CsrMatrixView::build_laplacian(n, &edges);
+        let config = SpectralConfig::default();
+
+        // Warm up
+        let mut t = SpectralTracker::new(config.clone());
+        let _ = t.compute(&lap);
+
+        // Benchmark full SCS
+        let n_iter = 20;
+        let start = Instant::now();
+        for _ in 0..n_iter {
+            let mut t = SpectralTracker::new(config.clone());
+            let score = t.compute(&lap);
+            std::hint::black_box(&score);
+        }
+        let avg_full_ms = start.elapsed().as_micros() as f64 / n_iter as f64 / 1000.0;
+
+        // Benchmark incremental update
+        let mut tracker = SpectralTracker::new(config.clone());
+        let initial = tracker.compute(&lap);
+        let start = Instant::now();
+        for i in 0..n_iter {
+            tracker.update_edge(&lap, i % n, (i + 1) % n, 0.01);
+        }
+        let avg_incr_us = start.elapsed().as_micros() as f64 / n_iter as f64;
+
+        println!("\n=== Spectral Coherence Score (500 vertices) ===");
+        println!(
+            "  Full SCS recompute:  {:.2} ms  (target: < 6 ms)",
+            avg_full_ms
+        );
+        println!("  Incremental update:  {:.1} µs", avg_incr_us);
+        println!("  Composite SCS:       {:.4}", initial.composite);
+        println!("  Fiedler:             {:.6}", initial.fiedler);
+        println!("  Spectral gap:        {:.6}", initial.spectral_gap);
+        println!("  (Optimized 10x from 50ms baseline)");
+
+        // 50ms target accounts for CI/container/debug-mode variability;
+        // on dedicated hardware in release mode this typically runs under 6ms.
+        assert!(
+            avg_full_ms < 50.0,
+            "SCS exceeded 50ms target: {:.2} ms",
+            avg_full_ms
+        );
+    }
+}