diff --git a/src/agents/pi-embedded-helpers.test.ts b/src/agents/pi-embedded-helpers.test.ts
index b88142c6a..df8c5c019 100644
--- a/src/agents/pi-embedded-helpers.test.ts
+++ b/src/agents/pi-embedded-helpers.test.ts
@@ -8,6 +8,7 @@ import {
   isMessagingToolDuplicate,
   normalizeTextForComparison,
   sanitizeGoogleTurnOrdering,
+  sanitizeSessionMessagesImages,
   validateGeminiTurns,
 } from "./pi-embedded-helpers.js";
 import {
@@ -250,6 +251,77 @@ describe("sanitizeGoogleTurnOrdering", () => {
   });
 });
 
+describe("sanitizeSessionMessagesImages", () => {
+  it("removes empty assistant text blocks but preserves tool calls", async () => {
+    const input = [
+      {
+        role: "assistant",
+        content: [
+          { type: "text", text: "" },
+          { type: "toolCall", id: "call_1", name: "read", arguments: {} },
+        ],
+      },
+    ] satisfies AgentMessage[];
+
+    const out = await sanitizeSessionMessagesImages(input, "test");
+
+    expect(out).toHaveLength(1);
+    const content = (out[0] as { content?: unknown }).content;
+    expect(Array.isArray(content)).toBe(true);
+    expect(content).toHaveLength(1);
+    expect((content as Array<{ type?: string }>)[0]?.type).toBe("toolCall");
+  });
+
+  it("filters whitespace-only assistant text blocks", async () => {
+    const input = [
+      {
+        role: "assistant",
+        content: [
+          { type: "text", text: "   " },
+          { type: "text", text: "ok" },
+        ],
+      },
+    ] satisfies AgentMessage[];
+
+    const out = await sanitizeSessionMessagesImages(input, "test");
+
+    expect(out).toHaveLength(1);
+    const content = (out[0] as { content?: unknown }).content;
+    expect(Array.isArray(content)).toBe(true);
+    expect(content).toHaveLength(1);
+    expect((content as Array<{ text?: string }>)[0]?.text).toBe("ok");
+  });
+
+  it("drops assistant messages that only contain empty text", async () => {
+    const input = [
+      { role: "user", content: "hello" },
+      { role: "assistant", content: [{ type: "text", text: "" }] },
+    ] satisfies AgentMessage[];
+
+    const out = await sanitizeSessionMessagesImages(input, "test");
+
+    expect(out).toHaveLength(1);
+    expect(out[0]?.role).toBe("user");
+  });
+
+  it("leaves non-assistant messages unchanged", async () => {
+    const input = [
+      { role: "user", content: "hello" },
+      {
+        role: "toolResult",
+        toolUseId: "tool-1",
+        content: [{ type: "text", text: "result" }],
+      },
+    ] satisfies AgentMessage[];
+
+    const out = await sanitizeSessionMessagesImages(input, "test");
+
+    expect(out).toHaveLength(2);
+    expect(out[0]?.role).toBe("user");
+    expect(out[1]?.role).toBe("toolResult");
+  });
+});
+
 describe("normalizeTextForComparison", () => {
   it("lowercases text", () => {
     expect(normalizeTextForComparison("Hello World")).toBe("hello world");
diff --git a/src/agents/pi-embedded-helpers.ts b/src/agents/pi-embedded-helpers.ts
index 2d3941006..bbfd8e0c4 100644
--- a/src/agents/pi-embedded-helpers.ts
+++ b/src/agents/pi-embedded-helpers.ts
@@ -99,6 +99,28 @@ export async function sanitizeSessionMessagesImages(
       }
     }
 
+    if (role === "assistant") {
+      const assistantMsg = msg as Extract<AgentMessage, { role: "assistant" }>;
+      const content = assistantMsg.content;
+      if (Array.isArray(content)) {
+        const filteredContent = content.filter((block) => {
+          if (!block || typeof block !== "object") return true;
+          const rec = block as { type?: unknown; text?: unknown };
+          if (rec.type !== "text" || typeof rec.text !== "string") return true;
+          return rec.text.trim().length > 0;
+        });
+        const sanitizedContent = (await sanitizeContentBlocksImages(
+          filteredContent as unknown as ContentBlock[],
+          label,
+        )) as unknown as typeof assistantMsg.content;
+        if (sanitizedContent.length === 0) {
+          continue;
+        }
+        out.push({ ...assistantMsg, content: sanitizedContent });
+        continue;
+      }
+    }
+
     out.push(msg);
   }
   return out;