Merge commit 'd803bfe2b1fe7f5e219e50ac20d6801a0a58ac75' as 'vendor/ruvector'

vendor/ruvector/crates/ruvector-attn-mincut/src/witness.rs

@@ -0,0 +1,64 @@
+use serde::{Deserialize, Serialize};
+use sha2::{Digest, Sha256};
+
+/// A single witness entry for determinism verification.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct WitnessEntry {
+    pub q_hash: String,
+    pub k_hash: String,
+    pub keep_mask: Vec<bool>,
+    pub cut_cost: f32,
+    pub lambda: f32,
+    pub tau: usize,
+    pub eps: f32,
+    pub timestamp: u64,
+}
+
+/// Serialize a witness entry to a single JSONL line.
+pub fn witness_log(entry: &WitnessEntry) -> String {
+    serde_json::to_string(entry).unwrap_or_else(|_| "{}".to_string())
+}
+
+/// SHA-256 hash of a float tensor (little-endian bytes), returned as hex.
+pub fn hash_tensor(data: &[f32]) -> String {
+    let mut h = Sha256::new();
+    for &v in data {
+        h.update(v.to_le_bytes());
+    }
+    h.finalize().iter().map(|b| format!("{:02x}", b)).collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_hash_deterministic() {
+        let d = vec![1.0f32, 2.0, 3.0];
+        assert_eq!(hash_tensor(&d), hash_tensor(&d));
+        assert_eq!(hash_tensor(&d).len(), 64);
+    }
+
+    #[test]
+    fn test_hash_differs() {
+        assert_ne!(hash_tensor(&[1.0, 2.0]), hash_tensor(&[1.0, 3.0]));
+    }
+
+    #[test]
+    fn test_witness_roundtrip() {
+        let e = WitnessEntry {
+            q_hash: "a".into(),
+            k_hash: "b".into(),
+            keep_mask: vec![true, false],
+            cut_cost: 1.5,
+            lambda: 0.5,
+            tau: 2,
+            eps: 0.01,
+            timestamp: 1000,
+        };
+        let json = witness_log(&e);
+        let r: WitnessEntry = serde_json::from_str(&json).unwrap();
+        assert_eq!(r.q_hash, "a");
+        assert!((r.cut_cost - 1.5).abs() < f32::EPSILON);
+    }
+}