diff --git a/src/agents/pi-embedded-runner/run/attempt.ts b/src/agents/pi-embedded-runner/run/attempt.ts
index 893bcbc6717..c010d5811d0 100644
--- a/src/agents/pi-embedded-runner/run/attempt.ts
+++ b/src/agents/pi-embedded-runner/run/attempt.ts
@@ -810,17 +810,6 @@ export async function runEmbeddedAttempt(
             note: `images: prompt=${imageResult.images.length} history=${imageResult.historyImagesByIndex.size}`,
           });
 
-          const shouldTrackCacheTtl =
-            params.config?.agents?.defaults?.contextPruning?.mode === "cache-ttl" &&
-            isCacheTtlEligibleProvider(params.provider, params.modelId);
-          if (shouldTrackCacheTtl) {
-            appendCacheTtlTimestamp(sessionManager, {
-              timestamp: Date.now(),
-              provider: params.provider,
-              modelId: params.modelId,
-            });
-          }
-
           // Only pass images option if there are actually images to pass
           // This avoids potential issues with models that don't expect the images parameter
           if (imageResult.images.length > 0) {
@@ -848,6 +837,22 @@ export async function runEmbeddedAttempt(
           }
         }
 
+        // Append cache-TTL timestamp AFTER prompt + compaction retry completes.
+        // Previously this was before the prompt, which caused a custom entry to be
+        // inserted between compaction and the next prompt — breaking the
+        // prepareCompaction() guard that checks the last entry type, leading to
+        // double-compaction. See: https://github.com/openclaw/openclaw/issues/9282
+        const shouldTrackCacheTtl =
+          params.config?.agents?.defaults?.contextPruning?.mode === "cache-ttl" &&
+          isCacheTtlEligibleProvider(params.provider, params.modelId);
+        if (shouldTrackCacheTtl) {
+          appendCacheTtlTimestamp(sessionManager, {
+            timestamp: Date.now(),
+            provider: params.provider,
+            modelId: params.modelId,
+          });
+        }
+
         messagesSnapshot = activeSession.messages.slice();
         sessionIdUsed = activeSession.sessionId;
         cacheTrace?.recordStage("session:after", {