diff --git a/ui/src/ui/format.test.ts b/ui/src/ui/format.test.ts
index dc785481c..d7acecebb 100644
--- a/ui/src/ui/format.test.ts
+++ b/ui/src/ui/format.test.ts
@@ -21,5 +21,22 @@ describe("stripThinkingTags", () => {
   it("returns original text when no tags exist", () => {
     expect(stripThinkingTags("Hello")).toBe("Hello");
   });
+
+  it("strips <final>…</final> segments", () => {
+    const input = "<final>\n\nHello there\n\n</final>";
+    expect(stripThinkingTags(input)).toBe("Hello there\n\n");
+  });
+
+  it("strips mixed <think> and <final> tags", () => {
+    const input = "<think>reasoning</think>\n\n<final>Hello</final>";
+    expect(stripThinkingTags(input)).toBe("Hello");
+  });
+
+  it("handles incomplete <final tag gracefully", () => {
+    // When streaming splits mid-tag, we may see "<final" without closing ">"
+    // This should not crash and should handle gracefully
+    expect(stripThinkingTags("<final\nHello")).toBe("<final\nHello");
+    expect(stripThinkingTags("Hello</final>")).toBe("Hello");
+  });
 });
 
diff --git a/ui/src/ui/format.ts b/ui/src/ui/format.ts
index 8e52af89a..e8f4e4991 100644
--- a/ui/src/ui/format.ts
+++ b/ui/src/ui/format.ts
@@ -67,9 +67,9 @@ export function parseList(input: string): string[] {
     .filter((v) => v.length > 0);
 }
 
-const THINKING_TAG_RE = /<\s*\/?\s*think(?:ing)?\s*>/gi;
-const THINKING_OPEN_RE = /<\s*think(?:ing)?\s*>/i;
-const THINKING_CLOSE_RE = /<\s*\/\s*think(?:ing)?\s*>/i;
+const THINKING_TAG_RE = /<\s*\/?\s*(?:think(?:ing)?|final)\s*>/gi;
+const THINKING_OPEN_RE = /<\s*(?:think(?:ing)?|final)\s*>/i;
+const THINKING_CLOSE_RE = /<\s*\/\s*(?:think(?:ing)?|final)\s*>/i;
 
 export function stripThinkingTags(value: string): string {
   if (!value) return value;