Get the conversation an email belongs to

Returns the full conversation the given inbound email belongs to, as ordered, ready-to-prompt turns WITH bodies. It resolves the thread from the email and returns every message oldest-first, so an agent that received an email can pass messages straight to a chat model in one call instead of walking /threads/{id} plus /emails/{id} and /sent-emails/{id} per message.

Each message carries a direction (inbound | outbound) and a derived role: inbound -> user, outbound -> assistant (your own prior replies). The role mapping assumes the caller owns the outbound side, which is the agent-reply case this exists for. If the email has no thread yet (a brand-new message), the conversation is just that one message as a single user turn.

The message list is capped; check truncated to detect when older messages were omitted. Consecutive same-role turns are not merged here; that normalization is model-specific and left to the caller.