fix(sam3_image): prevent unwrap panic caused by LruCache eviction during mixed queries (#254)

* fix(sam3): prevent unwrap panic caused by LRU cache eviction

* fix: use get instead of contains to promote LRU items and prevent eviction

* fmt & clippy

---------

Co-authored-by: jamjamjon <xxyydzml@outlook.com>

Author: darkSuperman

src/models/vlm/sam3_image/impl.rs

@@ -348,12 +348,30 @@ impl Sam3Image {
             let mut uncached = Vec::new();
             let mut seen = HashSet::new();
             for p in prompts {
-                if seen.insert(&p.text) && !self.text_cache.contains(&p.text) {
+                if seen.insert(&p.text) && self.text_cache.get(&p.text).is_none() {
                     uncached.push(p.text.as_str());
                 }
             }
+
+            let unique_prompts_count = seen.len();
+            if unique_prompts_count > self.text_cache.cap().get() {
+                // If the number of unique prompts in the current batch exceeds the cache capacity, force an expansion.
+                self.text_cache
+                    .resize(NonZeroUsize::new(unique_prompts_count).unwrap());
+            }
+
             if !uncached.is_empty() {
-                for (text, feat) in uncached.iter().zip(self.encode_texts(engines, &uncached)?) {
+                let encoded_feats = self.encode_texts(engines, &uncached)?;
+
+                if encoded_feats.len() != uncached.len() {
+                    bail!(
+                        "Encoded features length mismatch: expected {}, got {}",
+                        uncached.len(),
+                        encoded_feats.len()
+                    );
+                }
+
+                for (text, feat) in uncached.iter().zip(encoded_feats) {
                     self.text_cache.put(text.to_string(), feat);
                 }
             }