learnharness/app/api/chats/[id]/stream/route.ts

/**
 * THE REATTACH STREAM (background-turn runner wave, owner ruling
 * 2026-09-25) — and, since CONNECTION DIET B (owner, 2026-10-10), THE
 * turn wire, period: POST /api/chat acknowledges and closes, so the
 * submitter too attaches here. One SSE stream per chat: a running turn →
 * subscribe to the live turn object: FULL replay of the event log, then
 * live chunks until settle ([DONE]). No running turn → the cheap terminal
 * ({"type":"turn-settled"} + [DONE]): the record is current, the client
 * refetches it.
 *
 * 404 mirrors the POST handler's unknown-chat. Framework route is a thin
 * wrapper over the server barrel (the import law); tests drive the seams
 * (turn-runs + ui-stream) directly.
 */
import { getChat, runningTurn, piTurnResponse, settledTurnResponse } from "@/src/server";

export async function GET(_req: Request, ctx: { params: Promise<{ id: string }> }): Promise<Response> {
	const { id } = await ctx.params;
	if (!getChat(id)) return Response.json({ error: "Unknown chat" }, { status: 404 });
	const handle = runningTurn(id);
	if (!handle) return settledTurnResponse();
	return piTurnResponse(handle);
}