diff --git a/src/agents/pi-extensions/compaction-safeguard.test.ts b/src/agents/pi-extensions/compaction-safeguard.test.ts
index 750eb2b4f38..1394f265f91 100644
--- a/src/agents/pi-extensions/compaction-safeguard.test.ts
+++ b/src/agents/pi-extensions/compaction-safeguard.test.ts
@@ -530,6 +530,22 @@ describe("compaction-safeguard recent-turn preservation", () => {
     expect(section).toContain("- Assistant: [non-text content: toolCall]");
   });
 
+  it("keeps non-text placeholders for mixed-content preserved messages", () => {
+    const section = formatPreservedTurnsSection([
+      {
+        role: "user",
+        content: [
+          { type: "text", text: "caption text" },
+          { type: "image", data: "abc", mimeType: "image/png" },
+        ],
+        timestamp: 1,
+      } as unknown as AgentMessage,
+    ]);
+
+    expect(section).toContain("- User: caption text");
+    expect(section).toContain("[non-text content: image]");
+  });
+
   it("clamps preserve count into a safe range", () => {
     expect(resolveRecentTurnsPreserve(undefined)).toBe(3);
     expect(resolveRecentTurnsPreserve(-1)).toBe(0);
diff --git a/src/agents/pi-extensions/compaction-safeguard.ts b/src/agents/pi-extensions/compaction-safeguard.ts
index df3889f5704..17714beed55 100644
--- a/src/agents/pi-extensions/compaction-safeguard.ts
+++ b/src/agents/pi-extensions/compaction-safeguard.ts
@@ -201,6 +201,9 @@ function formatNonTextPlaceholder(content: unknown): string | null {
   if (content === null || content === undefined) {
     return null;
   }
+  if (typeof content === "string") {
+    return null;
+  }
   if (!Array.isArray(content)) {
     return "[non-text content]";
   }
@@ -355,7 +358,8 @@ function formatPreservedTurnsSection(messages: AgentMessage[]): string {
       const nonTextPlaceholder = formatNonTextPlaceholder(
         (message as { content?: unknown }).content,
       );
-      const rendered = text || nonTextPlaceholder;
+      const rendered =
+        text && nonTextPlaceholder ? `${text}\n${nonTextPlaceholder}` : text || nonTextPlaceholder;
       if (!rendered) {
         return null;
       }