From 82ab9dd2e34c58c8948ef3d80e9f76b145590965 Mon Sep 17 00:00:00 2001
From: Ollie Agent <ollie@example.com>
Date: Sat, 15 Aug 2026 13:43:04 +0200
Subject: [PATCH] version summary cache keys

---
 cmd/olliesrv/internal/agent/history.go            | 4 ++--
 cmd/olliesrv/internal/agent/summary_cache_test.go | 4 ++++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/cmd/olliesrv/internal/agent/history.go b/cmd/olliesrv/internal/agent/history.go
index 5e26660..6f0308e 100644
--- a/cmd/olliesrv/internal/agent/history.go
+++ b/cmd/olliesrv/internal/agent/history.go
@@ -104,8 +104,8 @@ func toolMessageID(m backend.Message) string {
 const coldSummaryCacheVersion = "v2"
 
 func toolSummaryHash(m backend.Message) string {
-	h := sha256.Sum256([]byte(coldSummaryCacheVersion + "\x00" + normalizeSummaryCacheContent(m.Content)))
-	return hex.EncodeToString(h[:])
+	h := sha256.Sum256([]byte(normalizeSummaryCacheContent(m.Content)))
+	return "cold-summary:" + coldSummaryCacheVersion + ":" + hex.EncodeToString(h[:])
 }
 
 func normalizeSummaryCacheContent(content string) string {
diff --git a/cmd/olliesrv/internal/agent/summary_cache_test.go b/cmd/olliesrv/internal/agent/summary_cache_test.go
index ba04853..d7be978 100644
--- a/cmd/olliesrv/internal/agent/summary_cache_test.go
+++ b/cmd/olliesrv/internal/agent/summary_cache_test.go
@@ -1,6 +1,7 @@
 package agent
 
 import (
+	"strings"
 	"testing"
 
 	"ollie/cmd/olliesrv/internal/backend"
@@ -30,6 +31,9 @@ func TestToolSummaryHashIgnoresToolCallID(t *testing.T) {
 	if first != second {
 		t.Fatalf("hashes differ for identical content: %q != %q", first, second)
 	}
+	if !strings.HasPrefix(first, "cold-summary:v2:") {
+		t.Fatalf("hash missing version prefix: %q", first)
+	}
 }
 
 func TestToolSummaryHashSeparatesContent(t *testing.T) {