fix(agent): strip thinking tags from text content

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

@@ -358,4 +358,84 @@ File contents here`,
     const result = extractAssistantText(msg);
     expect(result).toBe("Here's what I found:\nDone checking.");
   });
+
+  it("strips thinking tags from text content", () => {
+    const msg: AssistantMessage = {
+      role: "assistant",
+      content: [
+        {
+          type: "text",
+          text: "<think>El usuario quiere retomar una tarea...</think>Aquí está tu respuesta.",
+        },
+      ],
+      timestamp: Date.now(),
+    };
+
+    const result = extractAssistantText(msg);
+    expect(result).toBe("Aquí está tu respuesta.");
+  });
+
+  it("strips thinking tags without closing tag", () => {
+    const msg: AssistantMessage = {
+      role: "assistant",
+      content: [
+        {
+          type: "text",
+          text: "<think>Pensando sobre el problema...",
+        },
+      ],
+      timestamp: Date.now(),
+    };
+
+    const result = extractAssistantText(msg);
+    expect(result).toBe("");
+  });
+
+  it("strips thinking tags with various formats", () => {
+    const msg: AssistantMessage = {
+      role: "assistant",
+      content: [
+        {
+          type: "text",
+          text: "Before<thinking>internal reasoning</thinking>After",
+        },
+      ],
+      timestamp: Date.now(),
+    };
+
+    const result = extractAssistantText(msg);
+    expect(result).toBe("BeforeAfter");
+  });
+
+  it("strips antthinking tags", () => {
+    const msg: AssistantMessage = {
+      role: "assistant",
+      content: [
+        {
+          type: "text",
+          text: "<antthinking>Some reasoning</antthinking>The actual answer.",
+        },
+      ],
+      timestamp: Date.now(),
+    };
+
+    const result = extractAssistantText(msg);
+    expect(result).toBe("The actual answer.");
+  });
+
+  it("handles nested or multiple thinking blocks", () => {
+    const msg: AssistantMessage = {
+      role: "assistant",
+      content: [
+        {
+          type: "text",
+          text: "Start<think>first thought</think>Middle<think>second thought</think>End",
+        },
+      ],
+      timestamp: Date.now(),
+    };
+
+    const result = extractAssistantText(msg);
+    expect(result).toBe("StartMiddleEnd");
+  });
 });

src/agents/pi-embedded-utils.ts

@@ -47,6 +47,44 @@ function stripDowngradedToolCallText(text: string): string {
   return cleaned.trim();
 }
 
+/**
+ * Strip thinking tags and their content from text.
+ * This is a safety net for cases where the model outputs <think> tags
+ * that slip through other filtering mechanisms.
+ */
+function stripThinkingTagsFromText(text: string): string {
+  if (!text) return text;
+  // Quick check to avoid regex overhead when no tags present.
+  if (!/(?:think(?:ing)?|thought|antthinking)/i.test(text)) return text;
+
+  const tagRe = /<\s*(\/?)\s*(?:think(?:ing)?|thought|antthinking)\s*>/gi;
+  let result = "";
+  let lastIndex = 0;
+  let inThinking = false;
+
+  for (const match of text.matchAll(tagRe)) {
+    const idx = match.index ?? 0;
+    const isClose = match[1] === "/";
+
+    if (!inThinking && !isClose) {
+      // Opening tag - save text before it.
+      result += text.slice(lastIndex, idx);
+      inThinking = true;
+    } else if (inThinking && isClose) {
+      // Closing tag - skip content inside.
+      inThinking = false;
+    }
+    lastIndex = idx + match[0].length;
+  }
+
+  // Append remaining text if we're not inside thinking.
+  if (!inThinking) {
+    result += text.slice(lastIndex);
+  }
+
+  return result.trim();
+}
+
 export function extractAssistantText(msg: AssistantMessage): string {
   const isTextBlock = (block: unknown): block is { type: "text"; text: string } => {
     if (!block || typeof block !== "object") return false;
@@ -58,7 +96,9 @@ export function extractAssistantText(msg: AssistantMessage): string {
     ? msg.content
         .filter(isTextBlock)
         .map((c) =>
-          stripDowngradedToolCallText(stripMinimaxToolCallXml(c.text)).trim(),
+          stripThinkingTagsFromText(
+            stripDowngradedToolCallText(stripMinimaxToolCallXml(c.text)),
+          ).trim(),
         )
         .filter(Boolean)
     : [];