fix(acpx): preserve commentary across steering intervals

Project incremental assistant output as progress while keeping final snapshots authoritative. Verify frozen native steering intervals preserve their earlier commentary and record the failed native browser attempt and current validation scope.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

ui/src/components/transcript/native-run-events.test.ts

@@ -2,7 +2,12 @@ import { readFileSync } from "node:fs";
 import { describe, expect, it } from "vitest";
 import type { HeartbeatRunEvent } from "@paperclipai/shared";
 import { nativeRunEventsToTranscript } from "./native-run-events";
-import { transcriptToTaskChatItems } from "../task-chat/transcript-adapter";
+import {
+  paperclipRunnerTimelineItems,
+  settledRunChildren,
+  splitTranscriptAtAnchors,
+  transcriptToTaskChatItems,
+} from "../task-chat/transcript-adapter";
 
 const RUN_ID = "10000000-0000-4000-8000-000000000001";
 
@@ -74,6 +79,35 @@ function runResult(summary: string): Record<string, unknown> {
 }
 
 describe("provider notice presentation", () => {
+  it("keeps native ACPX commentary when steering freezes its earlier interval", () => {
+    const entries = nativeRunEventsToTranscript([
+      itemEvent(1, "item.delta", "reasoning-1", {
+        kind: "reasoning", channel: "summary", text: "Inspecting the current task.",
+      }),
+      itemEvent(2, "item.delta", "message-before-steer", {
+        kind: "agentMessage", channel: "progress", text: "I am starting the requested work.",
+      }),
+      itemEvent(3, "item.completed", "steering-ack", {
+        kind: "steering_acknowledgement", status: "acknowledged", text: "Steering acknowledged for the active turn.",
+      }),
+      itemEvent(4, "item.delta", "message-after-steer", {
+        kind: "agentMessage", channel: "progress", text: "The correction is now applied.",
+      }),
+    ]);
+    const [before, after] = splitTranscriptAtAnchors(
+      entries, Date.parse("2026-08-25T18:00:00.000Z"), [Date.parse("2026-08-25T18:00:03.000Z")],
+    );
+    const frozen = settledRunChildren(paperclipRunnerTimelineItems(transcriptToTaskChatItems(before.entries, {
+      runId: RUN_ID, running: false,
+    })));
+    expect(frozen.filter(item => item.kind === "activity_phase").map(item => item.interstitial?.text))
+      .toContain("I am starting the requested work.");
+    const continued = transcriptToTaskChatItems(after.entries, { runId: RUN_ID, running: true });
+    expect(continued.find(item => item.kind === "message")).toMatchObject({
+      text: "The correction is now applied.", channel: "progress",
+    });
+  });
+
   it("omits unrelated information from saved chat without removing warnings or responses", () => {
     const legacyNotice = {
       schema: "paperclip.provider.notice.v1",