fix: preserve steering stream boundaries

ui/src/e2e/chat-flow.active-run-follow-ups.e2e.test.ts

@@ -294,6 +294,22 @@ suite.define(() => {
         sessionKey: "main",
         state: "delta",
       });
+      const streamingBubble = page.locator(".chat-bubble.streaming", {
+        hasText: "Terminal response paragraph 1.",
+      });
+      await streamingBubble.waitFor();
+      const streamingRow = streamingBubble.locator(
+        "xpath=ancestor::div[contains(@class, 'chat-virtual-row')]",
+      );
+      await streamingRow.waitFor();
+      const steerBubble = page.locator(".chat-group.user", { hasText: steerText }).last();
+      const [steerBounds, streamingBounds] = await Promise.all([
+        steerBubble.boundingBox(),
+        streamingBubble.boundingBox(),
+      ]);
+      expect(steerBounds).not.toBeNull();
+      expect(streamingBounds).not.toBeNull();
+      expect(streamingBounds!.y).toBeGreaterThanOrEqual(steerBounds!.y + steerBounds!.height - 1);
       await gateway.emitGatewayEvent("session.message", {
         activeRunIds: [],
         clientRunId: runId,

ui/src/pages/chat/chat-state.test.ts

@@ -24,7 +24,7 @@ import {
 } from "./chat-state-refresh.ts";
 import { resolveChatAvatarUrl, selectedChatSessionRow } from "./chat-state-route.ts";
 import { buildChatItems } from "./chat-thread-build.ts";
-import { getChatSessionProjection } from "./history-merge.ts";
+import { getChatSessionProjection, reduceChatSessionProjection } from "./history-merge.ts";
 import { scheduleControlUiAfterPaint } from "./performance.ts";
 import { applySessionMessagePayload } from "./session-message-apply.ts";
 
@@ -269,6 +269,16 @@ describe("canonical session message recovery", () => {
     ]);
     expect(state.chatRunId).toBe(activeRunId);
     expect(state.chatQueue).toEqual([]);
+    reduceChatSessionProjection(state, {
+      type: "sendPending",
+      runId: steerRunId,
+      message: {
+        role: "user",
+        content: [{ type: "text", text: "Steer prompt" }],
+        timestamp: 50,
+        __openclaw: { idempotencyKey: `${steerRunId}:user` },
+      },
+    });
     state.chatRunId = steerRunId;
 
     const steerEvent = {
@@ -296,6 +306,7 @@ describe("canonical session message recovery", () => {
     handlePageGatewayEvent(state, steerEvent);
     expect(state.chatRunId).toBe(activeRunId);
     const segmentsAfterRequestBoundary = state.chatStreamSegments;
+    expect(segmentsAfterRequestBoundary.at(-1)?.boundaryRunId).toBe(steerRunId);
     expect(state.chatStreamSegments).toBe(segmentsAfterRequestBoundary);
     expect(
       state.chatMessages.filter((message) => extractText(message) === "Steer prompt"),

ui/src/pages/chat/session-message-apply.ts

@@ -12,7 +12,12 @@ import {
   readChatSessionProjectionScope,
   reduceChatSessionProjection,
 } from "./history-merge.ts";
-import { persistedSteerTargetRunId, rolloverChatStream } from "./stream-causal-boundary.ts";
+import {
+  latestPersistedSteerBoundary,
+  latestStreamBoundaryRunId,
+  persistedSteerTargetRunId,
+  rolloverChatStream,
+} from "./stream-causal-boundary.ts";
 import { maybeResetToolStream } from "./stream-reconciliation.ts";
 import { prunePersistedAssistantStreamSegments } from "./stream-segment-pruning.ts";
 
@@ -121,7 +126,6 @@ export function applySessionMessagePayload(
       ...(incoming.sequence !== null ? { seq: incoming.sequence } : {}),
     },
   };
-  const previousMessageCount = state.chatMessages.length;
   const projection = reduceChatSessionProjection(
     state,
     {
@@ -141,13 +145,17 @@ export function applySessionMessagePayload(
   }
   const steerTargetRunId = persistedSteerTargetRunId(message);
   const currentRunId = state.chatRunId;
+  const persistedSteerBoundary = steerTargetRunId
+    ? latestPersistedSteerBoundary(projection.messages, steerTargetRunId)
+    : null;
   if (
     incoming.role === "user" &&
     runActive === true &&
     incoming.runId &&
     steerTargetRunId &&
     (!currentRunId || currentRunId === steerTargetRunId || currentRunId === incoming.runId) &&
-    projection.messages.length > previousMessageCount
+    persistedSteerBoundary?.runId === incoming.runId &&
+    latestStreamBoundaryRunId(state) !== incoming.runId
   ) {
     state.chatRunId = steerTargetRunId;
     rolloverChatStream(state, {