diff --git a/internal/cache/signature_cache.go b/internal/cache/signature_cache.go
index 12f19cf0..c1326629 100644
--- a/internal/cache/signature_cache.go
+++ b/internal/cache/signature_cache.go
@@ -3,6 +3,7 @@ package cache
 import (
 	"crypto/sha256"
 	"encoding/hex"
+	"sort"
 	"sync"
 	"time"
 )
@@ -89,20 +90,17 @@ func CacheSignature(sessionID, text, signature string) {
 					ts  time.Time
 				}{key, entry.Timestamp})
 			}
-			// Simple approach: remove first quarter of entries
+			// Sort by timestamp (oldest first) using sort.Slice
+			sort.Slice(oldest, func(i, j int) bool {
+				return oldest[i].ts.Before(oldest[j].ts)
+			})
+
 			toRemove := len(oldest) / 4
 			if toRemove < 1 {
 				toRemove = 1
 			}
-			// Sort by timestamp (oldest first) - simple bubble for small N
+
 			for i := 0; i < toRemove; i++ {
-				minIdx := i
-				for j := i + 1; j < len(oldest); j++ {
-					if oldest[j].ts.Before(oldest[minIdx].ts) {
-						minIdx = j
-					}
-				}
-				oldest[i], oldest[minIdx] = oldest[minIdx], oldest[i]
 				delete(sc.entries, oldest[i].key)
 			}
 		}
diff --git a/internal/translator/antigravity/claude/antigravity_claude_response.go b/internal/translator/antigravity/claude/antigravity_claude_response.go
index 939551ba..8f47b9bf 100644
--- a/internal/translator/antigravity/claude/antigravity_claude_response.go
+++ b/internal/translator/antigravity/claude/antigravity_claude_response.go
@@ -9,8 +9,6 @@ package claude
 import (
 	"bytes"
 	"context"
-	"crypto/sha256"
-	"encoding/hex"
 	"fmt"
 	"strings"
 	"sync/atomic"
@@ -46,27 +44,6 @@ type Params struct {
 	CurrentThinkingText strings.Builder // Accumulates thinking text for signature caching
 }
 
-// deriveSessionIDFromRequest generates a stable session ID from the request JSON.
-func deriveSessionIDFromRequest(rawJSON []byte) string {
-	messages := gjson.GetBytes(rawJSON, "messages")
-	if !messages.IsArray() {
-		return ""
-	}
-	for _, msg := range messages.Array() {
-		if msg.Get("role").String() == "user" {
-			content := msg.Get("content").String()
-			if content == "" {
-				content = msg.Get("content.0.text").String()
-			}
-			if content != "" {
-				h := sha256.Sum256([]byte(content))
-				return hex.EncodeToString(h[:16])
-			}
-		}
-	}
-	return ""
-}
-
 // toolUseIDCounter provides a process-wide unique counter for tool use identifiers.
 var toolUseIDCounter uint64
 
@@ -92,7 +69,7 @@ func ConvertAntigravityResponseToClaude(_ context.Context, _ string, originalReq
 			HasFirstResponse: false,
 			ResponseType:     0,
 			ResponseIndex:    0,
-			SessionID:        deriveSessionIDFromRequest(originalRequestRawJSON),
+			SessionID:        deriveSessionID(originalRequestRawJSON),
 		}
 	}