F3 SLICE-5: live claude-code turn via applyAgentEdit seam + manual smoke (INV-8) (#6)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

test/liveTurn.test.ts

@@ -0,0 +1,18 @@
+import { describe, it, expect } from "vitest";
+import { extractReplacement } from "../src/liveTurn";
+
+describe("extractReplacement", () => {
+  it("returns plain text untouched", () => {
+    expect(extractReplacement("Hello world.")).toBe("Hello world.");
+  });
+  it("strips a wrapping fence", () => {
+    expect(extractReplacement("```\nHello world.\n```")).toBe("Hello world.");
+  });
+  it("strips a language-tagged fence", () => {
+    expect(extractReplacement("```markdown\nHello.\n```\n")).toBe("Hello.");
+  });
+  it("leaves inner fences alone", () => {
+    const inner = "before\n```js\ncode\n```\nafter";
+    expect(extractReplacement(inner)).toBe(inner);
+  });
+});