feat(documents): verbatim capture, chat prompt builder, budget, persistence documentId threading

src/app/api/insights/chat/[id]/route.ts

@@ -33,7 +33,11 @@ export const GET = apiHandler(async (_request: NextRequest, ctx: RouteCtx) => {
   const { id } = await ctx.params;
   if (!id) return apiError("coach.conversation.notFound", 404);
 
-  const detail = await fetchConversationWithMessages(auth.user.id, id);
+  // v1.27.33 — Coach detail is scoped to health threads (documentId null); a
+  // document chat is read through its own document-scoped route, not here.
+  const detail = await fetchConversationWithMessages(auth.user.id, id, {
+    documentId: null,
+  });
   if (!detail) {
     return apiError("coach.conversation.notFound", 404);
   }

src/app/api/insights/chat/route.ts

@@ -304,9 +304,12 @@ async function handleChatRequest(request: NextRequest): Promise<Response> {
   let priorSummary: string | null = null;
 
   if (conversationId) {
+    // v1.27.33 — scope to Coach threads (documentId null); a document chat can
+    // never be loaded through the Coach route.
     const existing = await fetchConversationWithMessages(
       userId,
       conversationId,
+      { documentId: null },
     );
     if (!existing) {
       // 404, not 403 — never reveal cross-user existence
@@ -1434,6 +1437,9 @@ export const GET = apiHandler(async (request: NextRequest) => {
     userId: auth.user.id,
     cursor,
     limit: Number.isFinite(limit) ? (limit as number) : undefined,
+    // v1.27.33 — the Coach rail shows only health threads; document chats
+    // (documentId set) live on the document sheet and are filtered out here.
+    documentId: null,
   });
 
   annotate({