fix(agents): preserve kept-tail prompt during compaction transcript rotation (#93732)

Duplicate user-message detection ran over the full branch, so when a prompt
was re-sent within the 60s window its earlier copy in the summarized prefix
and the later copy in the kept tail were both removed: the summarized copy via
summarizedBranchIds and the kept copy as a duplicate. With
truncateAfterCompaction enabled the prompt then vanished from the successor
transcript entirely. Restrict dedup to the kept region so the first surviving
copy is preserved.

src/agents/embedded-agent-runner/compaction-successor-transcript.duplicate-prompt-loss.test.ts

@@ -0,0 +1,79 @@
+import fs from "node:fs/promises";
+import os from "node:os";
+import path from "node:path";
+import { SessionManager } from "openclaw/plugin-sdk/agent-sessions";
+import { afterEach, describe, expect, it } from "vitest";
+import { makeAgentAssistantMessage } from "../test-helpers/agent-message-fixtures.js";
+import { rotateTranscriptAfterCompaction } from "./compaction-successor-transcript.js";
+import { readTranscriptFileState } from "./transcript-file-state.js";
+
+let tmpDir: string | undefined;
+afterEach(async () => {
+  if (tmpDir) {
+    await fs.rm(tmpDir, { recursive: true, force: true }).catch(() => undefined);
+    tmpDir = undefined;
+  }
+});
+
+function makeAssistant(text: string, timestamp: number) {
+  return makeAgentAssistantMessage({ content: [{ type: "text", text }], timestamp });
+}
+
+function readUserTexts(entries: { type: string; message?: unknown }[]): string[] {
+  return entries
+    .filter(
+      (entry) =>
+        entry.type === "message" &&
+        (entry.message as { role?: unknown } | undefined)?.role === "user",
+    )
+    .map((entry) => {
+      const content = (entry.message as { content?: unknown } | undefined)?.content;
+      if (typeof content === "string") {
+        return content;
+      }
+      if (Array.isArray(content)) {
+        return content.map((block) => (block as { text?: string })?.text ?? "").join("");
+      }
+      return "";
+    });
+}
+
+const PROMPT = "Please refactor the authentication module right now";
+
+describe("rotateTranscriptAfterCompaction duplicate-prompt preservation", () => {
+  it("keeps a kept-tail prompt whose earlier copy was summarized away", async () => {
+    tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), "successor-dup-loss-"));
+    const manager = SessionManager.create(tmpDir, tmpDir);
+
+    manager.appendMessage({ role: "user", content: PROMPT, timestamp: 1000 });
+    manager.appendMessage(makeAssistant("Working on it.", 1001));
+    const firstKeptId = manager.appendMessage({
+      role: "user",
+      content: "go on",
+      timestamp: 1002,
+    });
+    manager.appendMessage(makeAssistant("Continuing.", 1003));
+    manager.appendCompaction("Summary of earlier turns.", firstKeptId, 5000);
+    manager.appendMessage({ role: "user", content: PROMPT, timestamp: 40000 });
+    manager.appendMessage(makeAssistant("On it again.", 40001));
+
+    const sessionFile = manager.getSessionFile();
+    if (!sessionFile) {
+      throw new Error("no session file");
+    }
+
+    const result = await rotateTranscriptAfterCompaction({ sessionManager: manager, sessionFile });
+    expect(result.rotated).toBe(true);
+    const successorFile = result.sessionFile;
+    if (!successorFile) {
+      throw new Error("no successor file");
+    }
+
+    const successor = await readTranscriptFileState(successorFile);
+    const userPromptTexts = readUserTexts(
+      successor.getEntries() as { type: string; message?: unknown }[],
+    );
+
+    expect(userPromptTexts.some((text) => text.includes(PROMPT))).toBe(true);
+  });
+});

src/agents/embedded-agent-runner/compaction-successor-transcript.ts

@@ -174,7 +174,9 @@ function buildSuccessorEntries(params: {
   }
 
   const removedIds = new Set<string>();
-  const duplicateUserMessageIds = collectDuplicateUserMessageEntryIdsForCompaction(branch);
+  const keptBranchEntries = branch.filter((entry) => !summarizedBranchIds.has(entry.id));
+  const duplicateUserMessageIds =
+    collectDuplicateUserMessageEntryIdsForCompaction(keptBranchEntries);
   for (const entry of allEntries) {
     if (
       (summarizedBranchIds.has(entry.id) && entry.type === "message") ||