refactor(chat): split stream helpers

src/routes/chat.ts

@@ -35,9 +35,11 @@ import {
   isPressureTrendDemoPrompt,
 } from "./pressureTrendDemo.js";
 import {
+  buildForkedSessionUiState,
   buildPromptWithLearningContext,
   extractLatestFrontendTurn,
   generateSessionTitle,
+  resolveRequestedStreamSessionId,
   shouldGenerateSessionTitle,
   shouldRestoreConversationForRuntime,
 } from "./chatSession.js";
@@ -98,20 +100,6 @@ const toSessionUiStateContext = (sessionRecord: SessionRecord) => ({
   sessionId: sessionRecord.sessionId,
 });
 
-export const buildForkedSessionUiState = (
-  sourceState: { messages?: unknown[] } | null | undefined,
-  input: {
-    keepMessageCount: number;
-    targetSessionId: string;
-  },
-) => ({
-  sessionId: input.targetSessionId,
-  isTitleManuallyEdited: false,
-  messages: Array.isArray(sourceState?.messages)
-    ? sourceState.messages.slice(0, input.keepMessageCount)
-    : [],
-});
-
 const getSessionRunStatus = (sessionId: string) =>
   activeRuns.get(sessionId)?.status ?? lastRunStatuses.get(sessionId);
 
@@ -193,21 +181,6 @@ const pipeUiChunk = (
   }
 };
 
-export const resolveRequestedStreamSessionId = (input: {
-  sessionId?: string;
-  promptText: string;
-  createClientSessionId: () => string;
-}) => {
-  const sessionId = input.sessionId?.trim();
-  if (sessionId) {
-    return sessionId;
-  }
-  if (isPressureTrendDemoPrompt(input.promptText)) {
-    return input.createClientSessionId();
-  }
-  return undefined;
-};
-
 export const buildChatRouter = (
   sessionBridge: ChatSessionBridge,
   runtime: OpencodeRuntimeAdapter,