fix(agents): guard promoteThinkingTagsToBlocks against malformed content entries (#35143)

Merged via squash.

Prepared head SHA: 3971122f5f
Co-authored-by: Sid-Qin <201593046+Sid-Qin@users.noreply.github.com>
Co-authored-by: shakkernerd <165377636+shakkernerd@users.noreply.github.com>
Reviewed-by: @shakkernerd

src/agents/pi-embedded-utils.test.ts

@@ -3,6 +3,7 @@ import { describe, expect, it } from "vitest";
 import {
   extractAssistantText,
   formatReasoningMessage,
+  promoteThinkingTagsToBlocks,
   stripDowngradedToolCallText,
 } from "./pi-embedded-utils.js";
 
@@ -549,6 +550,39 @@ describe("stripDowngradedToolCallText", () => {
   });
 });
 
+describe("promoteThinkingTagsToBlocks", () => {
+  it("does not crash on malformed null content entries", () => {
+    const msg = makeAssistantMessage({
+      role: "assistant",
+      content: [null as never, { type: "text", text: "<thinking>hello</thinking>ok" }],
+      timestamp: Date.now(),
+    });
+    expect(() => promoteThinkingTagsToBlocks(msg)).not.toThrow();
+    const types = msg.content.map((b: { type?: string }) => b?.type);
+    expect(types).toContain("thinking");
+    expect(types).toContain("text");
+  });
+
+  it("does not crash on undefined content entries", () => {
+    const msg = makeAssistantMessage({
+      role: "assistant",
+      content: [undefined as never, { type: "text", text: "no tags here" }],
+      timestamp: Date.now(),
+    });
+    expect(() => promoteThinkingTagsToBlocks(msg)).not.toThrow();
+  });
+
+  it("passes through well-formed content unchanged when no thinking tags", () => {
+    const msg = makeAssistantMessage({
+      role: "assistant",
+      content: [{ type: "text", text: "hello world" }],
+      timestamp: Date.now(),
+    });
+    promoteThinkingTagsToBlocks(msg);
+    expect(msg.content).toEqual([{ type: "text", text: "hello world" }]);
+  });
+});
+
 describe("empty input handling", () => {
   it("returns empty string", () => {
     const helpers = [formatReasoningMessage, stripDowngradedToolCallText];

src/agents/pi-embedded-utils.ts

@@ -333,7 +333,9 @@ export function promoteThinkingTagsToBlocks(message: AssistantMessage): void {
   if (!Array.isArray(message.content)) {
     return;
   }
-  const hasThinkingBlock = message.content.some((block) => block.type === "thinking");
+  const hasThinkingBlock = message.content.some(
+    (block) => block && typeof block === "object" && block.type === "thinking",
+  );
   if (hasThinkingBlock) {
     return;
   }
@@ -342,6 +344,10 @@ export function promoteThinkingTagsToBlocks(message: AssistantMessage): void {
   let changed = false;
 
   for (const block of message.content) {
+    if (!block || typeof block !== "object" || !("type" in block)) {
+      next.push(block);
+      continue;
+    }
     if (block.type !== "text") {
       next.push(block);
       continue;