Merge commit 'd803bfe2b1fe7f5e219e50ac20d6801a0a58ac75' as 'vendor/ruvector'

vendor/ruvector/crates/cognitum-gate-kernel/tests/canonical_witness_bench.rs

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+//! Performance benchmark for canonical witness fragments.
+//! Run with: cargo test -p cognitum-gate-kernel --features "std,canonical-witness" --test canonical_witness_bench --release -- --nocapture
+
+#[cfg(feature = "canonical-witness")]
+mod bench {
+    use cognitum_gate_kernel::canonical_witness::{ArenaCactus, CanonicalWitnessFragment};
+    use cognitum_gate_kernel::shard::CompactGraph;
+    use cognitum_gate_kernel::TileState;
+    use std::time::Instant;
+
+    #[test]
+    fn bench_witness_fragment_64v() {
+        // Build a CompactGraph with 64 vertices
+        let mut graph = CompactGraph::new();
+        for i in 0..64u16 {
+            graph.add_edge(i, (i + 1) % 64, 100);
+        }
+        for i in 0..64u16 {
+            graph.add_edge(i, (i + 13) % 64, 50);
+        }
+        graph.recompute_components();
+
+        // Warm up
+        let _ = ArenaCactus::build_from_compact_graph(&graph);
+
+        // Benchmark ArenaCactus construction
+        let n_iter = 1000;
+        let start = Instant::now();
+        for _ in 0..n_iter {
+            let cactus = ArenaCactus::build_from_compact_graph(&graph);
+            std::hint::black_box(&cactus);
+        }
+        let avg_cactus_us = start.elapsed().as_micros() as f64 / n_iter as f64;
+
+        // Benchmark canonical partition
+        let cactus = ArenaCactus::build_from_compact_graph(&graph);
+        let start = Instant::now();
+        for _ in 0..n_iter {
+            let p = cactus.canonical_partition();
+            std::hint::black_box(&p);
+        }
+        let avg_partition_us = start.elapsed().as_micros() as f64 / n_iter as f64;
+
+        // Full witness via TileState
+        let mut tile = TileState::new(42);
+        for i in 0..64u16 {
+            tile.graph.add_edge(i, (i + 1) % 64, 100);
+            tile.graph.add_edge(i, (i + 13) % 64, 50);
+        }
+        tile.graph.recompute_components();
+
+        let start = Instant::now();
+        for _ in 0..n_iter {
+            let f = tile.canonical_witness();
+            std::hint::black_box(&f);
+        }
+        let avg_witness_us = start.elapsed().as_micros() as f64 / n_iter as f64;
+
+        // Determinism check
+        let ref_f = tile.canonical_witness();
+        for _ in 0..100 {
+            let f = tile.canonical_witness();
+            assert_eq!(f.canonical_hash, ref_f.canonical_hash);
+            assert_eq!(f.cactus_digest, ref_f.cactus_digest);
+        }
+
+        println!("\n=== Canonical Witness Fragment (64 vertices) ===");
+        println!("  ArenaCactus build:    {:.1} µs", avg_cactus_us);
+        println!("  Partition extract:    {:.1} µs", avg_partition_us);
+        println!(
+            "  Full witness:         {:.1} µs  (target: < 50 µs)",
+            avg_witness_us
+        );
+        println!(
+            "  Fragment size:        {} bytes",
+            std::mem::size_of::<CanonicalWitnessFragment>()
+        );
+        println!("  Cut value:            {}", ref_f.cut_value);
+
+        assert!(
+            avg_witness_us < 50.0,
+            "Witness exceeded 50µs target: {:.1} µs",
+            avg_witness_us
+        );
+    }
+}