tool-call id uniquifier: the Lacan fix (owner-approved 2026-10-04)

DeepSeek via OpenRouter returns tool-call ids that reset every response —
a one-call-per-turn session names every call call_0. Everything keys on
toolCallId (the fold's call↔result join, the pending gate, answer
routing, the option-shuffle seed), so the Lacan session corrupted: the
quiz answer overwrote the ask card, the ask question vanished, and the
order scrambled. Record itself was always intact.

- src/server/pi/call-ids.ts (new): ToolCallIdUniquifier at the wire
  boundary — colliding ids remint once (orig~2, ~3…), the same mints at
  settlement; tables key by message OBJECT IDENTITY (streaming messages
  carry no ids; the message_end object is reference-identical to the
  state object). History never rewrites; providers see paired ids, which
  is protocol-legal (pi synthesizes ids for providers that send none).
- ui-stream: runPiTurn remaps events + settles through the uniquifier
  (spec.usedToolCallIds, seeded by chat-handler from the record).
- view.ts: findToolPart scans newest-first — pre-fix duplicate-id
  records (the existing Lacan session) heal on next render.
- tests: 9 unit pins (call-ids.test.ts) + the two-call_0 e2e (chat-flow):
  ask answered as ask, quiz as quiz, ids unique in the record.

src/core/view.ts

@@ -129,7 +129,15 @@ export function projectView(messages: readonly LhMessage[], live?: LiveTurnState
 	};
 	const findToolPart = (toolCallId: string): LhViewPart | undefined => {
 		for (let i = out.length - 1; i >= 0; i--) {
-			for (const part of out[i]!.parts) {
+			// NEWEST-FIRST part scan within a group (the Lacan heal, 2026-10-04):
+			// a result pairs with the most RECENT call carrying its id. Unique
+			// ids (the uniquifier guarantees them for new turns) make scan order
+		// irrelevant; for legacy duplicate-id records (DeepSeek's per-response
+		// `call_0`) this routes each answer to its own call instead of letting
+		// a later result overwrite an earlier question's card.
+			const parts = out[i]!.parts;
+			for (let p = parts.length - 1; p >= 0; p--) {
+				const part = parts[p]!;
 				if (part.type.startsWith("tool-") && part.toolCallId === toolCallId) return part;
 			}
 		}