fix(agent): preserve reasoning order in activity transcripts (#6546)

Format projected text entries in sequence instead of grouping replies ahead of their preceding reasoning. Timeline projection already owns fragment merging.

Co-authored-by: paseo-bot[bot] <266920839+paseo-bot[bot]@users.noreply.github.com>

packages/cli/src/commands/agent/logs.test.ts

@@ -15,6 +15,18 @@ function collect(items: readonly AgentTimelineItem[], turnId?: string): string {
 }
 
 describe("createFollowTranscriptWriter", () => {
+  it("matches one-shot logs when reasoning and assistant text alternate", () => {
+    const items: AgentTimelineItem[] = [
+      { type: "reasoning", text: "Check " },
+      { type: "reasoning", text: "the commands." },
+      { type: "assistant_message", text: "I will list the commands.", messageId: "msg_1" },
+      { type: "reasoning", text: "Then summarize." },
+      { type: "assistant_message", text: "Done.", messageId: "msg_2" },
+    ];
+
+    expect(collect(items).trimEnd()).toBe(formatAgentActivityTranscript(items));
+  });
+
   it("keeps a word that arrives split across fragments intact", () => {
     const output = collect([
       { type: "assistant_message", text: "the paseo-pr", messageId: "msg_1" },

packages/server/src/server/agent/activity-curator.test.ts

@@ -39,6 +39,45 @@ function row(seq: number, item: AgentTimelineItem): AgentTimelineRow {
 }
 
 describe("curateAgentActivity", () => {
+  it("keeps reasoning before the assistant text that followed it", () => {
+    const timeline: AgentTimelineItem[] = [
+      { type: "reasoning", text: "Check the commands first." },
+      { type: "assistant_message", text: "I will list the commands." },
+      toolCallItem({
+        callId: "shell-order",
+        name: "Bash",
+        detail: {
+          type: "shell",
+          command: "ls packages/cli/src/commands/agent/",
+          output: "",
+          exitCode: 0,
+        },
+      }),
+    ];
+
+    expect(curateAgentActivity(timeline)).toBe(
+      "[Thought] Check the commands first.\nI will list the commands.\n[Shell] ls packages/cli/src/commands/agent/",
+    );
+  });
+
+  it("preserves alternating text kinds, labels, and fragment concatenation", () => {
+    const timeline: AgentTimelineItem[] = [
+      { type: "assistant_message", text: "First message." },
+      { type: "reasoning", text: "First " },
+      { type: "reasoning", text: "thought." },
+      { type: "assistant_message", text: "Second " },
+      { type: "assistant_message", text: "message." },
+      { type: "reasoning", text: "Second thought." },
+    ];
+
+    expect(curateAgentActivity(timeline, { labelAssistantMessages: true })).toBe(
+      "[Assistant] First message.\n[Thought] First thought.\n[Assistant] Second message.\n[Thought] Second thought.",
+    );
+    expect(curateAgentActivity(timeline, { maxItems: 2 })).toBe(
+      "Second message.\n[Thought] Second thought.",
+    );
+  });
+
   it("renders user/assistant/reasoning entries", () => {
     const timeline: AgentTimelineItem[] = [
       { type: "user_message", text: "Hello" },

packages/server/src/server/agent/activity-curator.ts

@@ -25,36 +25,20 @@ interface ActivityEntry {
 
 type TextAgentAttachment = Extract<AgentAttachment, { type: "text" }>;
 
-function appendText(buffer: string, text: string): string {
-  const normalized = text.trim();
-  if (!normalized) {
-    return buffer;
-  }
-  if (!buffer) {
-    return normalized;
-  }
-  return `${buffer}\n${normalized}`;
-}
-
 function activityEntry(text: string): ActivityEntry {
   return { text };
 }
 
-function flushBuffers(
+function appendTextEntry(
   entries: ActivityEntry[],
-  buffers: { message: string; thought: string },
+  item: Extract<AgentTimelineItem, { type: "assistant_message" | "reasoning" }>,
   options?: ActivityCuratorOptions,
 ) {
-  if (buffers.message.trim()) {
-    const text = buffers.message.trim();
-    entries.push(activityEntry(options?.labelAssistantMessages ? `[Assistant] ${text}` : text));
-  }
-  if (buffers.thought.trim()) {
-    const text = buffers.thought.trim();
-    entries.push(activityEntry(`[Thought] ${text}`));
-  }
-  buffers.message = "";
-  buffers.thought = "";
+  const text = item.text.trim();
+  if (!text) return;
+  let prefix = options?.labelAssistantMessages ? "[Assistant] " : "";
+  if (item.type === "reasoning") prefix = "[Thought] ";
+  entries.push(activityEntry(`${prefix}${text}`));
 }
 
 function formatToolInputJson(input: unknown): string | null {
@@ -147,7 +131,6 @@ function curateProjectedActivityEntries(
   const recentItems = maxItems > 0 && items.length > maxItems ? items.slice(-maxItems) : items;
 
   const entries: ActivityEntry[] = [];
-  const buffers = { message: "", thought: "" };
 
   for (const item of recentItems) {
     if (!shouldIncludeItem(item, options)) {
@@ -156,17 +139,13 @@ function curateProjectedActivityEntries(
 
     switch (item.type) {
       case "user_message":
-        flushBuffers(entries, buffers, options);
         entries.push(activityEntry(`[User] ${item.text.trim()}`));
         break;
       case "assistant_message":
-        buffers.message = appendText(buffers.message, item.text);
-        break;
       case "reasoning":
-        buffers.thought = appendText(buffers.thought, item.text);
+        appendTextEntry(entries, item, options);
         break;
       case "tool_call": {
-        flushBuffers(entries, buffers, options);
         entries.push(formatToolCallEntry(item, options));
         if (item.detail.type === "sub_agent" && item.detail.log.trim()) {
           entries.push(activityEntry(item.detail.log.trim()));
@@ -174,7 +153,6 @@ function curateProjectedActivityEntries(
         break;
       }
       case "todo":
-        flushBuffers(entries, buffers, options);
         entries.push(activityEntry("[Tasks]"));
         for (const entry of item.items) {
           const checkbox = entry.completed ? "[x]" : "[ ]";
@@ -183,18 +161,14 @@ function curateProjectedActivityEntries(
         }
         break;
       case "error":
-        flushBuffers(entries, buffers, options);
         entries.push(activityEntry(`[Error] ${item.message}`));
         break;
       case "compaction":
-        flushBuffers(entries, buffers, options);
         entries.push(activityEntry("[Compacted]"));
         break;
     }
   }
 
-  flushBuffers(entries, buffers, options);
-
   return entries;
 }