feat(web): absorb intermediate agent text into tool groups

Intermediate agent text/thought rows between tool calls in the same
turn now render inside the collapsed tool group instead of after it,
preserving chronological order. The last agent text (no subsequent
tool) stays outside as the prominent final answer.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/src/structured.test.ts

@@ -413,6 +413,39 @@ describe("structured connection: data flow", () => {
     conn.dispose();
   });
 
+  it("absorbs intermediate agent text into tool group, keeps final text outside", () => {
+    const ws = new FakeSocket();
+    const conn = mount({ sockets: [ws] });
+    ws.open();
+    ws.emit({
+      type: "transcript_snapshot",
+      snapshot: {
+        cursor: 8,
+        rows: [
+          row("user:1", "user", { content: { type: "text", text: "do it" } }),
+          row("agent:1", "agent_text", { content: { type: "text", text: "Let me check" } }),
+          toolRow("tool:1", "one"),
+          toolRow("tool:2", "two"),
+          row("agent:2", "agent_text", { content: { type: "text", text: "Found issues, fixing" } }),
+          toolRow("tool:3", "three"),
+          toolRow("tool:4", "four"),
+          row("agent:3", "agent_text", { content: { type: "text", text: "All done" } }),
+        ],
+      },
+    });
+    const groups = conn.el.querySelectorAll<HTMLElement>(".st-tool-group");
+    expect(groups).toHaveLength(1);
+    // Header counts only tool rows, not intermediate text.
+    expect(groups[0].querySelector(".st-tool-group-head")!.textContent).toContain("4 tool calls");
+    // Intermediate text (agent:2) is inside the group.
+    expect(conn.el.querySelector('[data-row-id="agent:2"]')?.closest(".st-tool-group")).not.toBeNull();
+    // First text (agent:1) is outside — it precedes all tools.
+    expect(conn.el.querySelector('[data-row-id="agent:1"]')?.closest(".st-tool-group")).toBeNull();
+    // Final text (agent:3) is outside — no tool follows it.
+    expect(conn.el.querySelector('[data-row-id="agent:3"]')?.closest(".st-tool-group")).toBeNull();
+    conn.dispose();
+  });
+
   it("keeps an expanded running tool open without emitting a click when patched", () => {
     const ws = new FakeSocket();
     const conn = mount({ sockets: [ws] });