shardmap 0.3.0

//! Raw byte-oriented embedded sharded cache facade.
//!
//! [`SharedCache`] is the cloneable raw byte API. It wraps
//! [`SharedEmbeddedStore`], so callers get
//! a cheap handle they can move into many workers while still using the same
//! sharded storage core as server and owner-local embedded modes.

use bytes::Bytes as SharedBytes;

use crate::ShardCacheError;
use crate::config::EvictionPolicy;
use crate::storage::{
    EmbeddedKeyRoute, EmbeddedRouteMode, PreparedPointKey, SemanticCacheError, SemanticMatch,
    SharedEmbeddedConfig, SharedEmbeddedEntry, SharedEmbeddedLockPolicy, SharedEmbeddedRef,
    SharedEmbeddedRefMut, SharedEmbeddedStore, SharedEmbeddedVacantEntry,
};

/// Default number of stripes for [`crate::ShardMap`] and [`ShardCache`].
///
/// This intentionally over-stripes the common embedded shared-handle case. In
/// benchmarks, one stripe per worker leaves read-heavy shared access
/// under-striped compared with DashMap-style maps.
pub const DEFAULT_CACHE_SHARDS: usize = 64;

/// Configuration for [`crate::ShardMap`] and [`SharedCache`].
///
/// The shard count is a const generic on [`SharedCache`], keeping the hot path
/// monomorphized while [`crate::ShardMap`] gives users a simple default.
#[derive(Debug, Clone)]
pub struct CacheOptions {
    /// Total memory budget for all stripes. `None` disables memory-limit eviction.
    pub total_memory_bytes: Option<usize>,
    /// Eviction policy applied independently inside each stripe.
    pub eviction_policy: EvictionPolicy,
    /// Key routing mode used by point and session APIs.
    pub route_mode: EmbeddedRouteMode,
    /// Approximate total point-key capacity to reserve across all stripes.
    pub capacity_hint: Option<usize>,
    /// Default relative TTL, in milliseconds, applied by write APIs that do not
    /// pass an explicit TTL.
    pub default_ttl_ms: Option<u64>,
    /// Lock policy used by each stripe.
    pub lock_policy: SharedEmbeddedLockPolicy,
}

impl Default for CacheOptions {
    fn default() -> Self {
        let shared = SharedEmbeddedConfig::default();
        Self {
            total_memory_bytes: shared.total_memory_bytes,
            eviction_policy: shared.eviction_policy,
            route_mode: shared.route_mode,
            capacity_hint: shared.flat_map_capacity_hint,
            default_ttl_ms: None,
            lock_policy: shared.lock_policy,
        }
    }
}

impl From<CacheOptions> for SharedEmbeddedConfig {
    fn from(options: CacheOptions) -> Self {
        Self {
            total_memory_bytes: options.total_memory_bytes,
            eviction_policy: options.eviction_policy,
            route_mode: options.route_mode,
            flat_map_capacity_hint: options.capacity_hint,
            lock_policy: options.lock_policy,
        }
    }
}

impl From<SharedEmbeddedConfig> for CacheOptions {
    fn from(config: SharedEmbeddedConfig) -> Self {
        Self {
            total_memory_bytes: config.total_memory_bytes,
            eviction_policy: config.eviction_policy,
            route_mode: config.route_mode,
            capacity_hint: config.flat_map_capacity_hint,
            default_ttl_ms: None,
            lock_policy: config.lock_policy,
        }
    }
}

/// Borrowed read guard returned by [`SharedCache::get`].
pub type CacheRef<'a> = SharedEmbeddedRef<'a>;
/// Mutable point-key guard returned by [`SharedCache::get_mut`].
pub type CacheRefMut<'a> = SharedEmbeddedRefMut<'a>;
/// Entry API guard returned by [`SharedCache::entry`].
pub type CacheEntry<'a> = SharedEmbeddedEntry<'a>;
/// Vacant entry guard used by [`CacheEntry`].
pub type CacheVacantEntry<'a> = SharedEmbeddedVacantEntry<'a>;
/// Best-match result returned by semantic cache lookups.
pub type CacheSemanticMatch = SemanticMatch;
/// Error returned by semantic cache APIs.
pub type CacheSemanticError = SemanticCacheError;

/// Cloneable raw byte-oriented embedded cache.
///
/// Use this lower-level surface when application code needs raw bytes, TTLs,
/// mutable byte guards, prepared keys, lock helpers, or semantic-cache APIs.
/// Use
/// [`embedded::ShardedEngine`](crate::embedded::ShardedEngine) and
/// [`embedded::LocalEmbeddedStore`](crate::embedded::LocalEmbeddedStore) when
/// you want the owner-local sharded performance model.
#[derive(Debug, Clone)]
pub struct SharedCache<const SHARDS: usize> {
    inner: SharedEmbeddedStore<SHARDS>,
    default_ttl_ms: Option<u64>,
}

/// Default raw byte-oriented embedded map.
pub type RawShardMap = SharedCache<DEFAULT_CACHE_SHARDS>;

/// Cache-flavored alias for users thinking in TTL/LRU/cache terms.
pub type ShardCache = RawShardMap;

/// Explicit-shard-count raw byte-oriented map alias.
pub type RawShardMapWithShards<const SHARDS: usize> = SharedCache<SHARDS>;

/// Explicit-shard-count cache-flavored alias.
pub type ShardCacheWithShards<const SHARDS: usize> = SharedCache<SHARDS>;

impl<const SHARDS: usize> Default for SharedCache<SHARDS> {
    fn default() -> Self {
        Self::new()
    }
}

impl<const SHARDS: usize> SharedCache<SHARDS> {
    /// Creates a cache with default options.
    #[inline(always)]
    pub fn new() -> Self {
        Self::with_options(CacheOptions::default())
    }

    /// Creates a cache with a total point-key capacity hint.
    #[inline(always)]
    pub fn with_capacity(capacity: usize) -> Self {
        Self::with_options(CacheOptions {
            capacity_hint: Some(capacity),
            ..CacheOptions::default()
        })
    }

    /// Creates a cache with explicit options.
    #[inline(always)]
    pub fn with_options(options: CacheOptions) -> Self {
        let default_ttl_ms = options.default_ttl_ms;
        Self {
            inner: SharedEmbeddedStore::new(options.into()),
            default_ttl_ms,
        }
    }

    /// Wraps an existing shared embedded store.
    #[inline(always)]
    pub fn from_shared_store(inner: SharedEmbeddedStore<SHARDS>) -> Self {
        Self {
            inner,
            default_ttl_ms: None,
        }
    }

    /// Returns the underlying shared embedded store.
    #[inline(always)]
    pub fn as_shared_store(&self) -> &SharedEmbeddedStore<SHARDS> {
        &self.inner
    }

    /// Consumes this facade and returns the underlying shared embedded store.
    #[inline(always)]
    pub fn into_shared_store(self) -> SharedEmbeddedStore<SHARDS> {
        self.inner
    }

    /// Returns the configured number of cache stripes.
    #[inline(always)]
    pub const fn shard_count(&self) -> usize {
        SHARDS
    }

    /// Returns the configured route mode.
    #[inline(always)]
    pub fn route_mode(&self) -> EmbeddedRouteMode {
        self.inner.route_mode()
    }

    /// Returns the default TTL applied by write APIs that do not pass an
    /// explicit TTL.
    #[inline(always)]
    pub const fn default_ttl_ms(&self) -> Option<u64> {
        self.default_ttl_ms
    }

    /// Computes the route for a key.
    #[inline(always)]
    pub fn route_key(&self, key: &[u8]) -> EmbeddedKeyRoute {
        self.inner.route_key(key)
    }

    /// Precomputes route and exact-match metadata for repeated point lookups.
    #[inline(always)]
    pub fn prepare_key(&self, key: &[u8]) -> PreparedPointKey {
        self.inner.prepare_point_key(key)
    }

    /// Returns a borrowed value guard for `key`.
    #[inline(always)]
    pub fn get(&self, key: &[u8]) -> Option<CacheRef<'_>> {
        self.inner.get_ref(key)
    }

    /// Returns a borrowed value guard for `key`.
    #[inline(always)]
    pub fn get_ref(&self, key: &[u8]) -> Option<CacheRef<'_>> {
        self.inner.get_ref(key)
    }

    /// Returns a borrowed value guard for a prepared point key.
    #[inline(always)]
    pub fn get_prepared(&self, prepared: &PreparedPointKey) -> Option<CacheRef<'_>> {
        self.inner.get_prepared_ref(prepared)
    }

    /// Returns a refcount-only clone of the stored bytes for `key`.
    ///
    /// This releases the shard read lock before the caller inspects or copies
    /// the value.
    #[inline(always)]
    pub fn get_owned(&self, key: &[u8]) -> Option<SharedBytes> {
        self.inner.get_value_bytes(key)
    }

    /// Returns a refcount-only clone of the stored bytes for a prepared key.
    #[inline(always)]
    pub fn get_prepared_owned(&self, prepared: &PreparedPointKey) -> Option<SharedBytes> {
        self.inner.get_prepared_value_bytes(prepared)
    }

    /// Returns true when `key` is present in point-key storage.
    #[inline(always)]
    pub fn contains_key(&self, key: &[u8]) -> bool {
        self.inner.contains_key(key)
    }

    /// Returns true when `key` is present in point-key storage.
    #[inline(always)]
    pub fn exists(&self, key: &[u8]) -> bool {
        self.contains_key(key)
    }

    /// Returns a sorted snapshot of currently live point keys.
    #[inline(always)]
    pub fn key_snapshot(&self) -> Vec<SharedBytes> {
        self.inner.key_snapshot()
    }

    /// Visits currently live point keys without allocating a key snapshot.
    ///
    /// The visitor runs while each shard read lock is held. Keep callbacks
    /// lightweight, and return `false` to stop early.
    #[inline(always)]
    pub fn visit_keys(&self, visitor: impl FnMut(&[u8]) -> bool) {
        self.inner.visit_string_keys(visitor);
    }

    /// Visits currently live point entries without cloning keys or values.
    ///
    /// The visitor receives `(key, value, expire_at_ms)` while each shard read
    /// lock is held. Keep callbacks lightweight, and return `false` to stop
    /// early.
    #[inline(always)]
    pub fn visit_entries(&self, visitor: impl FnMut(&[u8], &[u8], Option<u64>) -> bool) {
        self.inner.visit_string_entries(visitor);
    }

    /// Inserts or replaces a point-key value without a TTL.
    #[inline(always)]
    pub fn insert<K, V>(&self, key: K, value: V)
    where
        K: Into<SharedBytes>,
        V: Into<SharedBytes>,
    {
        self.inner
            .insert_with_ttl(key.into(), value.into(), self.default_ttl_ms);
    }

    /// Inserts or replaces a point-key value from borrowed slices.
    #[inline(always)]
    pub fn insert_slice(&self, key: &[u8], value: &[u8]) {
        self.inner
            .insert_slice_with_ttl(key, value, self.default_ttl_ms);
    }

    /// Inserts or replaces a point-key value with an optional relative TTL.
    #[inline(always)]
    pub fn insert_with_ttl<K, V>(&self, key: K, value: V, ttl_ms: Option<u64>)
    where
        K: Into<SharedBytes>,
        V: Into<SharedBytes>,
    {
        self.inner.insert_with_ttl(key.into(), value.into(), ttl_ms);
    }

    /// Inserts or replaces a point-key value from borrowed bytes with a TTL.
    #[inline(always)]
    pub fn insert_slice_with_ttl(&self, key: &[u8], value: &[u8], ttl_ms: Option<u64>) {
        self.inner.insert_slice_with_ttl(key, value, ttl_ms);
    }

    /// Inserts or replaces a point-key value with an embedding for semantic lookup.
    #[inline(always)]
    pub fn insert_semantic_slice(
        &self,
        key: &[u8],
        value: &[u8],
        embedding: &[f32],
    ) -> Result<(), SemanticCacheError> {
        self.inner
            .insert_semantic_slice_with_ttl(key, value, embedding, self.default_ttl_ms)
    }

    /// Inserts or replaces a point-key value with embedding and governance metadata.
    ///
    /// Governance metadata is returned with semantic matches so applications
    /// can validate cross-user cache hits against tenant, ACL, or document
    /// access policy before serving the cached value.
    #[inline(always)]
    pub fn insert_semantic_slice_with_governance(
        &self,
        key: &[u8],
        value: &[u8],
        embedding: &[f32],
        governance_metadata: &[u8],
    ) -> Result<(), SemanticCacheError> {
        self.inner.insert_semantic_slice_with_ttl_and_governance(
            key,
            value,
            embedding,
            self.default_ttl_ms,
            governance_metadata,
        )
    }

    /// Inserts or replaces a point-key value with an embedding and optional TTL.
    #[inline(always)]
    pub fn insert_semantic_slice_with_ttl(
        &self,
        key: &[u8],
        value: &[u8],
        embedding: &[f32],
        ttl_ms: Option<u64>,
    ) -> Result<(), SemanticCacheError> {
        self.inner
            .insert_semantic_slice_with_ttl(key, value, embedding, ttl_ms)
    }

    /// Inserts or replaces a point-key value with embedding, TTL, and governance metadata.
    #[inline(always)]
    pub fn insert_semantic_slice_with_ttl_and_governance(
        &self,
        key: &[u8],
        value: &[u8],
        embedding: &[f32],
        ttl_ms: Option<u64>,
        governance_metadata: &[u8],
    ) -> Result<(), SemanticCacheError> {
        self.inner.insert_semantic_slice_with_ttl_and_governance(
            key,
            value,
            embedding,
            ttl_ms,
            governance_metadata,
        )
    }

    /// Returns the best semantic match at or above `min_score`.
    #[inline(always)]
    pub fn semantic_search(
        &self,
        embedding: &[f32],
        min_score: f32,
    ) -> Result<Option<SemanticMatch>, SemanticCacheError> {
        self.inner.semantic_search(embedding, min_score)
    }

    /// Returns the best semantic match accepted by `governance_filter`.
    ///
    /// The filter receives the stored governance metadata, or `None` when the
    /// entry was written through the default semantic APIs, and must return
    /// true before the cached value is released. This path bypasses
    /// exact-query result caching because access policy is request-specific.
    #[inline(always)]
    pub fn semantic_search_with_governance_filter(
        &self,
        embedding: &[f32],
        min_score: f32,
        governance_filter: impl FnMut(Option<&[u8]>) -> bool,
    ) -> Result<Option<SemanticMatch>, SemanticCacheError> {
        self.inner
            .semantic_search_with_governance_filter(embedding, min_score, governance_filter)
    }

    /// Returns whether exact semantic query result caching is enabled.
    ///
    /// This cache accelerates repeated identical semantic queries. Disabling it
    /// is useful for cold-query benchmarks that should time the full vector
    /// search path on every lookup.
    #[inline(always)]
    pub fn semantic_query_cache_enabled(&self) -> bool {
        self.inner.semantic_query_cache_enabled()
    }

    /// Disables exact semantic query result caching for this shared cache.
    #[inline(always)]
    pub fn disable_semantic_query_cache(&self) {
        self.inner.disable_semantic_query_cache();
    }

    /// Inserts a point-key value only when the key is absent or expired.
    #[inline(always)]
    pub fn try_insert<K, V>(&self, key: K, value: V) -> bool
    where
        K: Into<SharedBytes>,
        V: Into<SharedBytes>,
    {
        let key = key.into();
        let value = value.into();
        self.inner
            .insert_slice_if_absent_with_ttl(&key, &value, self.default_ttl_ms)
    }

    /// Inserts borrowed bytes only when the key is absent or expired.
    #[inline(always)]
    pub fn try_insert_slice(&self, key: &[u8], value: &[u8]) -> bool {
        self.inner
            .insert_slice_if_absent_with_ttl(key, value, self.default_ttl_ms)
    }

    /// Inserts a point-key value with an optional TTL only when the key is
    /// absent or expired.
    #[inline(always)]
    pub fn try_insert_with_ttl<K, V>(&self, key: K, value: V, ttl_ms: Option<u64>) -> bool
    where
        K: Into<SharedBytes>,
        V: Into<SharedBytes>,
    {
        let key = key.into();
        let value = value.into();
        self.inner
            .insert_slice_if_absent_with_ttl(&key, &value, ttl_ms)
    }

    /// Inserts borrowed bytes with an optional TTL only when the key is absent
    /// or expired.
    #[inline(always)]
    pub fn try_insert_slice_with_ttl(&self, key: &[u8], value: &[u8], ttl_ms: Option<u64>) -> bool {
        self.inner
            .insert_slice_if_absent_with_ttl(key, value, ttl_ms)
    }

    /// Returns a mutable point-key guard for `key`.
    #[inline(always)]
    pub fn get_mut(&self, key: &[u8]) -> Option<CacheRefMut<'_>> {
        self.inner.get_mut(key)
    }

    /// Removes a point-key value and returns the stored bytes when present.
    #[inline(always)]
    pub fn remove(&self, key: &[u8]) -> Option<SharedBytes> {
        self.inner.remove(key)
    }

    /// Locks the routed stripe and returns an occupied or vacant entry.
    #[inline(always)]
    pub fn entry<K>(&self, key: K) -> CacheEntry<'_>
    where
        K: Into<SharedBytes>,
    {
        self.inner.entry(key.into())
    }

    /// Acquires a Redis-style token lock using `SET key token NX PX ttl`.
    ///
    /// This is process-local when used as an embedded cache. Use the server
    /// surface when multiple processes or machines need to coordinate through
    /// one lock table.
    #[inline(always)]
    pub fn try_acquire_lock(&self, key: &[u8], token: &[u8], ttl_ms: u64) -> crate::Result<bool> {
        if ttl_ms == 0 {
            return Err(ShardCacheError::Command(
                "lock ttl_ms must be greater than zero".into(),
            ));
        }
        Ok(self
            .inner
            .insert_slice_if_absent_with_ttl(key, token, Some(ttl_ms)))
    }

    /// Releases a token lock only when the stored token matches.
    #[inline(always)]
    pub fn release_lock(&self, key: &[u8], token: &[u8]) -> bool {
        self.inner.remove_if_value_eq(key, token)
    }

    /// Renews a token lock only when the stored token matches.
    #[inline(always)]
    pub fn renew_lock(&self, key: &[u8], token: &[u8], ttl_ms: u64) -> crate::Result<bool> {
        if ttl_ms == 0 {
            return Err(ShardCacheError::Command(
                "lock ttl_ms must be greater than zero".into(),
            ));
        }
        self.inner.update_ttl_if_value_eq(key, token, ttl_ms)
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    fn key_routed_away_from_semantic_shard<const SHARDS: usize>(
        cache: &SharedCache<SHARDS>,
    ) -> Vec<u8> {
        for index in 0..4096 {
            let key = format!("semantic-cross-shard-{index}").into_bytes();
            if cache.route_key(&key).shard_id != 0 {
                return key;
            }
        }
        panic!("could not find key routed away from semantic shard");
    }

    #[test]
    fn fast_map_round_trips_like_a_shared_map() {
        let cache = SharedCache::<4>::with_capacity(16);
        cache.insert_slice(b"alpha", b"one");

        assert_eq!(cache.get(b"alpha").unwrap().value(), b"one");
        assert_eq!(cache.get_owned(b"alpha").unwrap().as_ref(), b"one");
        assert!(cache.contains_key(b"alpha"));

        cache.get_mut(b"alpha").unwrap().set_slice(b"two");
        assert_eq!(cache.remove(b"alpha").unwrap().as_ref(), b"two");
        assert!(!cache.contains_key(b"alpha"));
    }

    #[test]
    fn fast_map_try_insert_only_writes_missing_keys() {
        let cache = SharedCache::<4>::new();

        assert!(cache.try_insert_slice(b"alpha", b"one"));
        assert!(!cache.try_insert_slice(b"alpha", b"two"));
        assert_eq!(cache.get(b"alpha").unwrap().value(), b"one");
    }

    #[cfg(not(feature = "no-ttl"))]
    #[test]
    fn default_ttl_applies_to_plain_cache_writes_and_can_be_overridden() {
        let cache = SharedCache::<4>::with_options(CacheOptions {
            default_ttl_ms: Some(20),
            ..CacheOptions::default()
        });

        assert_eq!(cache.default_ttl_ms(), Some(20));
        cache.insert_slice(b"default", b"expires");
        assert_eq!(cache.get(b"default").unwrap().value(), b"expires");

        std::thread::sleep(std::time::Duration::from_millis(30));
        assert!(cache.get(b"default").is_none());

        cache.insert_slice_with_ttl(b"durable", b"stays", None);
        std::thread::sleep(std::time::Duration::from_millis(30));
        assert_eq!(cache.get(b"durable").unwrap().value(), b"stays");

        cache.insert_slice_with_ttl(b"explicit", b"short", Some(10));
        std::thread::sleep(std::time::Duration::from_millis(20));
        assert!(cache.get(b"explicit").is_none());
    }

    #[test]
    fn semantic_cache_returns_best_live_match() {
        let cache = SharedCache::<4>::new();
        cache
            .insert_semantic_slice(b"cat", b"meow", &[1.0, 0.0])
            .unwrap();
        cache
            .insert_semantic_slice(b"dog", b"woof", &[0.0, 1.0])
            .unwrap();

        let matched = cache.semantic_search(&[0.9, 0.1], 0.75).unwrap().unwrap();

        assert_eq!(matched.key.as_slice(), b"cat");
        assert_eq!(matched.value.as_ref(), b"meow");
        assert!(matched.governance.is_none());
        assert!(matched.score > 0.99);
    }

    #[test]
    fn semantic_cache_returns_governance_metadata() {
        let cache = SharedCache::<4>::new();
        cache
            .insert_semantic_slice_with_governance(
                b"cat",
                b"meow",
                &[1.0, 0.0],
                b"tenant=acme;doc=cat-faq;policy=v1",
            )
            .unwrap();

        let matched = cache.semantic_search(&[1.0, 0.0], 0.75).unwrap().unwrap();

        assert_eq!(matched.key.as_slice(), b"cat");
        assert_eq!(matched.value.as_ref(), b"meow");
        assert_eq!(
            matched.governance.as_deref(),
            Some(b"tenant=acme;doc=cat-faq;policy=v1".as_slice())
        );
    }

    #[test]
    fn semantic_governance_defaults_to_none() {
        let cache = SharedCache::<4>::new();
        cache
            .insert_semantic_slice(b"default", b"value", &[1.0, 0.0])
            .unwrap();

        let matched = cache
            .semantic_search_with_governance_filter(&[1.0, 0.0], 0.75, |metadata| {
                metadata.is_none()
            })
            .unwrap()
            .unwrap();

        assert_eq!(matched.key.as_slice(), b"default");
        assert!(matched.governance.is_none());
    }

    #[test]
    fn semantic_governance_filter_runs_before_value_release() {
        let cache = SharedCache::<4>::new();
        cache
            .insert_semantic_slice_with_governance(
                b"restricted",
                b"secret",
                &[1.0, 0.0],
                b"tenant=internal",
            )
            .unwrap();
        cache
            .insert_semantic_slice_with_governance(
                b"allowed",
                b"public",
                &[0.8, 0.2],
                b"tenant=acme",
            )
            .unwrap();

        let unfiltered = cache.semantic_search(&[1.0, 0.0], 0.0).unwrap().unwrap();
        assert_eq!(unfiltered.key.as_slice(), b"restricted");

        let filtered = cache
            .semantic_search_with_governance_filter(&[1.0, 0.0], 0.0, |metadata| {
                metadata == Some(b"tenant=acme".as_slice())
            })
            .unwrap()
            .unwrap();

        assert_eq!(filtered.key.as_slice(), b"allowed");
        assert_eq!(filtered.value.as_ref(), b"public");
        assert_eq!(
            filtered.governance.as_deref(),
            Some(b"tenant=acme".as_slice())
        );

        assert!(
            cache
                .semantic_search_with_governance_filter(&[1.0, 0.0], 0.0, |metadata| {
                    metadata == Some(b"tenant=missing".as_slice())
                })
                .unwrap()
                .is_none()
        );
    }

    #[test]
    fn semantic_insert_preserves_routed_point_lookup() {
        let cache = SharedCache::<4>::new();
        let key = key_routed_away_from_semantic_shard(&cache);

        cache
            .insert_semantic_slice(&key, b"value", &[1.0, 0.0])
            .unwrap();

        assert_eq!(cache.get(&key).unwrap().value(), b"value");
        assert_eq!(cache.get_owned(&key).unwrap().as_ref(), b"value");
        let matched = cache.semantic_search(&[1.0, 0.0], 0.5).unwrap().unwrap();
        assert_eq!(matched.key.as_slice(), key.as_slice());
        assert_eq!(matched.value.as_ref(), b"value");
    }

    #[test]
    fn ordinary_write_invalidates_semantic_embedding() {
        let cache = SharedCache::<4>::new();
        let key = key_routed_away_from_semantic_shard(&cache);
        cache
            .insert_semantic_slice(&key, b"meow", &[1.0, 0.0])
            .unwrap();

        cache.insert_slice(&key, b"purr");

        assert!(cache.semantic_search(&[1.0, 0.0], 0.5).unwrap().is_none());
        assert_eq!(cache.get(&key).unwrap().value(), b"purr");
    }

    #[test]
    fn mutable_guard_invalidates_semantic_embedding() {
        let cache = SharedCache::<4>::new();
        let key = key_routed_away_from_semantic_shard(&cache);
        cache
            .insert_semantic_slice(&key, b"meow", &[1.0, 0.0])
            .unwrap();

        cache.get_mut(&key).unwrap().set_slice(b"purr");

        assert!(cache.semantic_search(&[1.0, 0.0], 0.5).unwrap().is_none());
        assert_eq!(cache.get(&key).unwrap().value(), b"purr");
    }

    #[test]
    fn ordinary_remove_invalidates_semantic_embedding() {
        let cache = SharedCache::<4>::new();
        let key = key_routed_away_from_semantic_shard(&cache);
        cache
            .insert_semantic_slice(&key, b"meow", &[1.0, 0.0])
            .unwrap();

        assert_eq!(cache.remove(&key).unwrap().as_ref(), b"meow");

        assert!(cache.semantic_search(&[1.0, 0.0], 0.5).unwrap().is_none());
        assert!(cache.get(&key).is_none());
    }

    #[cfg(not(feature = "no-ttl"))]
    #[test]
    fn semantic_cache_does_not_replay_expired_ttl_hit() {
        let cache = SharedCache::<4>::new();
        cache
            .insert_semantic_slice_with_ttl(b"cat", b"meow", &[1.0, 0.0], Some(50))
            .unwrap();

        assert!(cache.semantic_search(&[1.0, 0.0], 0.5).unwrap().is_some());
        std::thread::sleep(std::time::Duration::from_millis(60));
        assert!(cache.semantic_search(&[1.0, 0.0], 0.5).unwrap().is_none());
    }

    #[test]
    fn semantic_cache_rejects_invalid_embeddings() {
        let cache = SharedCache::<4>::new();

        assert_eq!(
            cache.insert_semantic_slice(b"empty", b"value", &[]),
            Err(SemanticCacheError::EmptyEmbedding)
        );
        assert_eq!(
            cache.insert_semantic_slice(b"zero", b"value", &[0.0, 0.0]),
            Err(SemanticCacheError::ZeroMagnitude)
        );
        assert_eq!(
            cache.semantic_search(&[f32::NAN], 0.5),
            Err(SemanticCacheError::NonFinite)
        );
    }

    #[cfg(not(feature = "no-ttl"))]
    #[test]
    fn fast_map_token_locks_are_compare_and_delete() {
        let cache = SharedCache::<4>::new();

        assert!(
            cache
                .try_acquire_lock(b"lock:alpha", b"token-1", 60_000)
                .unwrap()
        );
        assert!(
            !cache
                .try_acquire_lock(b"lock:alpha", b"token-2", 60_000)
                .unwrap()
        );
        assert!(!cache.release_lock(b"lock:alpha", b"token-2"));
        assert!(cache.renew_lock(b"lock:alpha", b"token-1", 60_000).unwrap());
        assert!(cache.release_lock(b"lock:alpha", b"token-1"));
        assert!(
            cache
                .try_acquire_lock(b"lock:alpha", b"token-2", 60_000)
                .unwrap()
        );
    }
}