fix: preserve cancel prompt after event checkpoints (#2154)

Co-authored-by: root <root@lyon.remote>

internal/cloud/workbench-projection-writer.test.ts

@@ -715,6 +715,20 @@ test("workbench projection writer does not replace prior user prompt with cancel
     },
     session: { sessionStatus: "running", lastTraceId: traceId }
   });
+  await writeWorkbenchProjectionEvent({
+    runtimeStore,
+    event: {
+      traceId,
+      sessionId: "ses_writer_canceled_prompt_preserved",
+      source: "agentrun",
+      sourceSeq: 1,
+      type: "backend",
+      eventType: "backend",
+      status: "running",
+      label: "agentrun:request:accepted",
+      createdAt: "2026-06-20T11:04:10.000Z"
+    }
+  });
   await writeWorkbenchProjectionSession({
     accessController,
     runtimeStore,

internal/cloud/workbench-projection-writer.ts

@@ -677,17 +677,19 @@ function workbenchProjectionUserMessage({ payload = {}, params = {}, traceId = n
 }
 
 function preserveTerminalUserMessage(messages = [], { terminal = false, traceId = null, previousCheckpoint = null } = {}) {
-  if (!terminal || !traceId || !previousCheckpoint?.userMessage) return messages;
-  const previousUserMessage = previousCheckpoint.userMessage;
-  const previousText = textValue(previousUserMessage.text ?? previousUserMessage.content ?? previousUserMessage.message);
-  if (!previousText) return messages;
-  let replaced = false;
+  if (!terminal || !traceId) return messages;
+  const previousUserMessage = previousCheckpoint?.userMessage ?? null;
+  const previousText = textValue(previousUserMessage?.text ?? previousUserMessage?.content ?? previousUserMessage?.message);
+  let handledUser = false;
   const normalizedTraceId = safeTraceId(traceId) ?? traceId;
   const preserved = messages.map((message) => {
     const role = textValue(message?.role) || "agent";
     const messageTraceId = safeTraceId(message?.traceId ?? message?.turnId ?? normalizedTraceId) ?? normalizedTraceId;
     if (role !== "user" || messageTraceId !== normalizedTraceId) return message;
-    replaced = true;
+    handledUser = true;
+    const messageText = textValue(message?.text ?? message?.content ?? message?.message);
+    if (!previousText && isSyntheticTerminalUserNotice(messageText)) return null;
+    if (!previousText) return message;
     return {
       ...message,
       ...previousUserMessage,
@@ -700,11 +702,17 @@ function preserveTerminalUserMessage(messages = [], { terminal = false, traceId
       terminal: false,
       sealed: false
     };
-  });
-  if (replaced) return preserved;
+  }).filter(Boolean);
+  if (handledUser) return preserved;
+  if (!previousText) return preserved;
   return [previousUserMessage, ...messages];
 }
 
+function isSyntheticTerminalUserNotice(text) {
+  const value = textValue(text);
+  return /当前\s*AgentRun\s*请求已取消|请求已取消|hwlab-user-cancel/u.test(value);
+}
+
 function normalizeMessages(messages, context) {
   const normalized = Array.isArray(messages) ? messages.map((message, index) => normalizeMessageFact(message, index, context)).filter(Boolean) : [];
   if (context?.terminal && context?.finalText && context?.traceId && !normalized.some((message) => message.role !== "user" && message.traceId === context.traceId)) {