Preserve hidden context for extraction

tests/chat-history.mjs

@@ -0,0 +1,68 @@
+import assert from "node:assert/strict";
+import {
+  buildExtractionMessages,
+  getAssistantTurns,
+  isAssistantChatMessage,
+  isBmeManagedHiddenMessage,
+  isSystemMessageForExtraction,
+} from "../chat-history.js";
+
+const visibleAssistant = {
+  is_user: false,
+  is_system: false,
+  mes: "visible assistant",
+};
+assert.equal(isAssistantChatMessage(visibleAssistant), true);
+
+const managedHiddenAssistant = {
+  is_user: false,
+  is_system: true,
+  mes: "managed hidden assistant",
+  extra: { __st_bme_hide_managed: true },
+};
+assert.equal(isBmeManagedHiddenMessage(managedHiddenAssistant), true);
+assert.equal(isSystemMessageForExtraction(managedHiddenAssistant), false);
+assert.equal(isAssistantChatMessage(managedHiddenAssistant), true);
+
+const realSystemMessage = {
+  is_user: false,
+  is_system: true,
+  mes: "real system",
+};
+assert.equal(isSystemMessageForExtraction(realSystemMessage), true);
+assert.equal(isAssistantChatMessage(realSystemMessage), false);
+
+const chat = [
+  { is_user: false, is_system: true, mes: "greeting/system" },
+  { is_user: true, is_system: false, mes: "user-1" },
+  managedHiddenAssistant,
+  { is_user: true, is_system: false, mes: "user-2" },
+  visibleAssistant,
+  realSystemMessage,
+];
+
+assert.deepEqual(
+  getAssistantTurns(chat),
+  [2, 4],
+  "managed hidden assistant floors should still be extractable assistant turns",
+);
+
+const extractionMessages = buildExtractionMessages(chat, 4, 4, {
+  extractContextTurns: 2,
+});
+assert.deepEqual(
+  extractionMessages.map((message) => ({
+    seq: message.seq,
+    role: message.role,
+    content: message.content,
+  })),
+  [
+    { seq: 1, role: "user", content: "user-1" },
+    { seq: 2, role: "assistant", content: "managed hidden assistant" },
+    { seq: 3, role: "user", content: "user-2" },
+    { seq: 4, role: "assistant", content: "visible assistant" },
+  ],
+  "extraction should keep BME-managed hidden context but still skip real system messages",
+);
+
+console.log("chat-history tests passed");