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).

src/core/pending.ts

@@ -1,4 +1,18 @@
-import { isToolUIPart, type UIMessage } from "ai";
+/**
+ * Wave D: these scans read VIEW messages (core/view.ts LhViewMessage — the
+ * client's grouped transcript). The part shapes are the same vocabulary the
+ * pre-Wave-D client dialect used; a tool part is structural: `tool-` prefix +
+ * toolCallId. The server-side record scans (danglingQuestionOf over native
+ * LhMessage[]) live in native-messages.ts.
+ */
+interface UIMessage {
+	role?: string;
+	parts: Array<Record<string, unknown> & { type: string }>;
+}
+
+function isToolUIPart(part: UIMessage["parts"][number]): boolean {
+	return part.type.startsWith("tool-") && typeof part.toolCallId === "string";
+}
 
 /**
  * The pending-question gate: an unanswered QUESTION tool part (quiz/ask)
@@ -76,7 +90,7 @@ function findPending(messages: UIMessage[], names: readonly string[]): PendingTo
 			if (isToolUIPart(part) && part.state === "input-available") {
 				const tool = part.type.slice("tool-".length);
 				if (names.includes(tool)) {
-					return { toolCallId: part.toolCallId, tool, input: part.input };
+					return { toolCallId: part.toolCallId as string, tool, input: part.input };
 				}
 			}
 		}