fix(metrics): skip unanchored step-metrics — no more empty bubbles at tail

Step-metrics are only shown when anchored to their tool content (inline
after the tool-call/result group). Steps whose chunks were trimmed (or
text-only steps with no tool chunks) are now SKIPPED instead of piling
up at the segment tail as empty 'step N · X tok' bubbles.

The turn-total metrics row still shows the aggregate (tokens, duration,
cache rate), so the conversation-level summary is preserved.

Updated place.test.ts + ui.test.ts to anchor steps with tool-call groups
where step-metrics are expected.

1 files changed, 36 insertions, 0 deletions

diff --git a/src/features/chat/ui.test.ts b/src/features/chat/ui.test.ts
index e541015..94db0ae 100644
--- a/src/features/chat/ui.test.ts
+++ b/src/features/chat/ui.test.ts
@@ -329,6 +329,18 @@ describe("ChatView", () => {
 				chunk: { type: "text", text: "Hello!" },
 				provisional: false,
 			},
+			{
+				seq: 3,
+				role: "assistant",
+				chunk: {
+					type: "tool-call",
+					toolCallId: "tc1",
+					toolName: "test",
+					input: {},
+					stepId: "t1#0" as StepId,
+				},
+				provisional: false,
+			},
 		];
 
 		const turnMetrics: TurnMetricsEntry[] = [
@@ -502,6 +514,18 @@ describe("ChatView", () => {
 				chunk: { type: "text", text: "Response" },
 				provisional: false,
 			},
+			{
+				seq: 3,
+				role: "assistant",
+				chunk: {
+					type: "tool-call",
+					toolCallId: "tc1",
+					toolName: "test",
+					input: {},
+					stepId: "t1#0" as StepId,
+				},
+				provisional: false,
+			},
 		];
 
 		const turnMetrics: TurnMetricsEntry[] = [
@@ -547,6 +571,18 @@ describe("ChatView", () => {
 				chunk: { type: "text", text: "Hello!" },
 				provisional: false,
 			},
+			{
+				seq: 3,
+				role: "assistant",
+				chunk: {
+					type: "tool-call",
+					toolCallId: "tc1",
+					toolName: "test",
+					input: {},
+					stepId: "t1#0" as StepId,
+				},
+				provisional: false,
+			},
 		];
 
 		const turnMetrics: TurnMetricsEntry[] = [