feat(chat): live turn metrics — telemetry reducer + rendering

Consume wire/transport-contract 0.3.0 (step-complete event + timing
fields on usage/tool-result/done). Pure core/telemetry module:
foldMetricEvent (reducer) + derived selectors (stepTps, turnTps, etc).
TelemetryState is pure data, no active-turn tracking — consumers pass
turnId to selectors. ChatStore wires foldMetricEvent into handleDelta
and exposes telemetry + currentTurnId. ChatView shows step-metrics
footer (time/TPS/tokens) on assistant text bubbles and durationMs badge
on tool cards. New TurnSummary component renders turn-level stats
(wall-clock, tokens, steps, TPS) in a DaisyUI stats block. Extended
live-probe to verify telemetry events against bin/up (pending backend
restart). 336 tests, typecheck 0, biome clean, build ok.

1 files changed, 12 insertions, 0 deletions

diff --git a/src/features/chat/store.svelte.ts b/src/features/chat/store.svelte.ts
index 1d8ab17..58c165f 100644
--- a/src/features/chat/store.svelte.ts
+++ b/src/features/chat/store.svelte.ts
@@ -13,6 +13,8 @@ import {
 	selectChunks,
 	selectMessages,
 } from "../../core/chunks";
+import type { TelemetryState } from "../../core/telemetry";
+import { foldMetricEvent, initialState as telemetryInitialState } from "../../core/telemetry";
 import type { ConversationCache } from "../conversation-cache";
 import type { ChatTransport, HistorySync } from "./ports";
 
@@ -30,6 +32,8 @@ export interface ChatStore {
 	readonly pendingSync: boolean;
 	readonly error: string | null;
 	readonly model: string | undefined;
+	readonly telemetry: TelemetryState;
+	readonly currentTurnId: string | null;
 	handleDelta(msg: ChatDeltaMessage | ChatErrorMessage): void;
 	send(text: string): void;
 	setModel(model: string): void;
@@ -42,6 +46,7 @@ export function createChatStore(deps: ChatStoreDependencies): ChatStore {
 	let _pendingSync = $state(false);
 	let _error = $state<string | null>(null);
 	let _model = $state<string | undefined>(deps.model);
+	let telemetry = $state<TelemetryState>(telemetryInitialState());
 	let disposed = false;
 
 	async function syncTail(): Promise<void> {
@@ -76,6 +81,12 @@ export function createChatStore(deps: ChatStoreDependencies): ChatStore {
 		get model(): string | undefined {
 			return _model;
 		},
+		get telemetry(): TelemetryState {
+			return telemetry;
+		},
+		get currentTurnId(): string | null {
+			return transcript.currentTurnId;
+		},
 
 		handleDelta(msg: ChatDeltaMessage | ChatErrorMessage): void {
 			if (msg.type === "chat.error") {
@@ -89,6 +100,7 @@ export function createChatStore(deps: ChatStoreDependencies): ChatStore {
 				return;
 			}
 			transcript = foldEvent(transcript, msg.event);
+			telemetry = foldMetricEvent(telemetry, msg.event);
 			if (transcript.sealedTurnId !== null) {
 				void syncTail();
 			}