history
Thread history loader exposed as a Mastra custom API route.
Backed entirely by native Mastra: looks up the active agent by id,
asks its Memory instance to recall a page of MastraDBMessages,
and converts the result to AI SDK V5 UIMessages with the official
toAISdkV5Messages helper from @mastra/ai-sdk/ui. No direct
database reads.
The route is registered through historyRoute as a Mastra
registerApiRoute so it sits in the same dispatcher pipeline as
the standard agent routes. That means the MastraServer auth
middleware (in ./server.ts) has already populated RequestContext with
MASTRA_THREAD_ID_KEY and MASTRA_RESOURCE_ID_KEY by the time
the handler runs - no cookie or user lookups happen here, and the
session-cookie logic stays the single source of truth in server.ts.