feat(metrics): show turn number in metrics bubble (turn N · ...)

The turn number comes from the entry's position in the metrics array
(1-based), which is correct regardless of trimming since stepId matching
aligns segments to the right entry. Now displays 'turn 3 · 12k tok' instead
of just 'turn · 12k tok'.

3 files changed, 6 insertions, 1 deletions

diff --git a/src/core/metrics/format.ts b/src/core/metrics/format.ts
index 4d69f25..534277c 100644
--- a/src/core/metrics/format.ts
+++ b/src/core/metrics/format.ts
@@ -155,7 +155,7 @@ export function viewExpectedCache(current: Usage, prev: Usage | null): CacheRate
 }
 
 /** Build a formatted view of a turn's aggregate metrics. */
-export function viewTurnMetrics(turn: TurnMetrics): TurnMetricsView {
+export function viewTurnMetrics(turn: TurnMetrics, turnNumber?: number): TurnMetricsView {
 	const total = totalTokens(turn.usage);
 	let totalGenMs: number | undefined;
 	for (const step of turn.steps) {
@@ -166,6 +166,7 @@ export function viewTurnMetrics(turn: TurnMetrics): TurnMetricsView {
 	}
 	const tps = computeTps(turn.usage.outputTokens, totalGenMs);
 	return {
+		label: turnNumber !== undefined ? `turn ${turnNumber}` : "turn",
 		tokensLabel: `${formatTokens(total)} tok`,
 		breakdown: formatBreakdown(turn.usage),
 		tps: formatTps(tps),
diff --git a/src/core/metrics/place.ts b/src/core/metrics/place.ts
index cb16b30..1009b15 100644
--- a/src/core/metrics/place.ts
+++ b/src/core/metrics/place.ts
@@ -232,6 +232,7 @@ export function interleaveTurnMetrics(
 			rows.push({
 				kind: "turn-metrics",
 				turn: entry.total,
+				turnNumber: entryIdx + 1,
 				cumulativeUsage: cumulativeByEntry[entryIdx] ?? entry.total.usage,
 				prevTurnUsage: prevUsageByEntry[entryIdx] ?? null,
 			});
diff --git a/src/core/metrics/types.ts b/src/core/metrics/types.ts
index c22fd9f..5b96e0f 100644
--- a/src/core/metrics/types.ts
+++ b/src/core/metrics/types.ts
@@ -56,6 +56,8 @@ export type MetricsRow =
 	| {
 			readonly kind: "turn-metrics";
 			readonly turn: TurnMetrics;
+			/** 1-based turn number (the entry's position in the metrics array + 1). */
+			readonly turnNumber: number;
 			/** Cumulative usage across all finalized turns up to and including this one. */
 			readonly cumulativeUsage: Usage;
 			/**
@@ -87,6 +89,7 @@ export interface StepMetricsView {
 
 /** Formatted per-turn view for display. */
 export interface TurnMetricsView {
+	readonly label: string;
 	readonly tokensLabel: string;
 	readonly breakdown: string;
 	readonly tps: string | null;