Wave D: native AgentEvent wire + client session rewrite (SDK purged)

Server: ui-stream.ts is verbatim pi AgentEvent passthrough (SSE data
lines + [DONE]); only app-level events are the loop-level error and
turn-settled terminal; onError carries raw provider text (owner ruling).

Client: useChat + the AI-SDK transport replaced by components/session-core.ts
(SessionModel: 409 identity-retry, optimistic c_ appends, absorbed()
adoption, needsContinuation, shared consume for POST + reattach) and the
session.ts hook; the golden-master grouping canon moved client-side into
core/view.ts (projectView); scanners read the native record (phaseAt3Lh,
danglingQuestionOf, graph toolParts, plan-blocks, runner, extraction).

Coverage: the native message is the unit (fork 3) with the call+result
inseparability bond rule; view-line-less messages (markers, error
results) are invisible to coverage and never checkpointed.

Deletes: chat-transport, projection, ui-message, their tests (ported to
tests/session-core.test.ts), and the ai + @ai-sdk/react dependencies —
the Vercel SDK is fully out of the tree. Wire pins in chat-flow rewritten
onto the AgentEvent dialect (eventsOf parser).

Gates: tsc clean, 994/994 tests, eslint clean, build green; live smoke
on PORT=3004 (verbatim wire → native record).

app/chat/[id]/page.tsx

@@ -1,6 +1,6 @@
 import { notFound } from "next/navigation";
 import { Chat } from "@/components/chat";
-import { projectNative, slotsConfigured, type TeacherUIMessage } from "@/src/core";
+import { slotsConfigured } from "@/src/core";
 import { getChat, isTurnRunning, readSettingsRecord } from "@/src/server";
 
 export const dynamic = "force-dynamic";
@@ -24,9 +24,10 @@ export default async function ChatPage({
 			key={chat.id}
 			chatId={chat.id}
 			title={chat.title}
-			// Wave B: the record is native history — the client view is the
-				// one-way projection (GET /api/chats/[id] serves the same shape).
-				initialMessages={projectNative(chat.messages) as TeacherUIMessage[]}
+			// Wave D: the record IS native agent history — the client view is
+				// derived app-side (core/view.ts projectView; GET serves the same
+				// native messages).
+				initialMessages={chat.messages}
 			initialConfigured={slotsConfigured(record?.models)}
 			initialPrompt={prompt}
 			// A teacher turn that outlived its client: the remounted view must