feat(coding-agent): merge consecutive cache warming notices into one line

Back-to-back cache warms update a single 'Cache warmed: $<total>' line with the cumulative cost instead of adding one line per warm. Each warm is still persisted as its own usage entry.

packages/coding-agent/CHANGELOG.md

@@ -16,6 +16,7 @@
 
 - The default model for the `anthropic` provider is now Claude Opus 5.5 (`claude-opus-5-5`) instead of Claude Opus 4.8
 - Default models moved to newer models at the same or a lower price: `amazon-bedrock` Claude Opus 5.5, `azure` GPT-6.1 Sol, `google` and `google-vertex` Gemini 4 Argon, `vercel-ai-gateway` GLM 5.3, `baseten` GLM 5.3, `minimax` and `minimax-cn` MiniMax-M3, `qwen-token-plan` and `qwen-token-plan-cn` Qwen3.8 Max, `opencode-go` Kimi K3.1 Pro, and Kimi K2.7 Code instead of Kimi K2.6 for `moonshotai`, `moonshotai-cn`, `huggingface`, `opencode`, `openrouter`, `cloudflare-workers-ai` and `cloudflare-ai-gateway`
+- Consecutive cache warms now show as one `Cache warmed: $<total>` line with the cumulative cost instead of one line per warm
 
 ### Fixed
 

packages/coding-agent/src/core/cache-warmer.ts

@@ -447,9 +447,9 @@ export function formatCacheWarmingStatus(status: CacheWarmingStatus, now = Date.
 	return `${formatCacheWarmingDecisionTime(status.nextWarmAt, now)} (${details})`;
 }
 
-/** One-line transcript text for persisted cache-warming usage. */
-export function formatCacheWarmingUsage(entry: UsageEntry): string {
-	const note = entry.note ? ` (${entry.note})` : "";
-	const cost = entry.usage.cost.total.toFixed(6).replace(/(\.\d{3}\d*?)0+$/, "$1");
-	return `Cache warmed${note}: $${cost}`;
+/** One-line transcript text for the total cost of one or more consecutive cache warms. */
+export function formatCacheWarmingUsage(totalCost: number, note?: string): string {
+	const noteText = note ? ` (${note})` : "";
+	const cost = totalCost.toFixed(6).replace(/(\.\d{3}\d*?)0+$/, "$1");
+	return `Cache warmed${noteText}: $${cost}`;
 }

packages/coding-agent/src/modes/interactive/interactive-mode.ts

@@ -504,6 +504,8 @@ export class InteractiveMode {
 	private changelogMarkdown: string | undefined = undefined;
 	private extensionChangelogUpdates: ExtensionChangelogUpdate[] = [];
 	private startupNoticesShown = false;
+	/** Last cache-warming notice, extended in place while it is the last chat line. */
+	private cacheWarmingNotice: { component: ThemedText; total: { cost: number }; note: string | undefined } | undefined;
 	private anthropicSubscriptionWarningShown = false;
 
 	// Status line tracking (for mutating immediately-sequential status updates)
@@ -4239,9 +4241,18 @@ export class InteractiveMode {
 
 	private addCacheWarmingUsage(entry: UsageEntry): void {
 		if (!this.settingsManager.getShowCacheMissNotices()) return;
+		// Back-to-back warms collapse into one line with the cumulative cost.
+		const previous = this.cacheWarmingNotice;
+		if (previous && this.chatContainer.children.at(-1) === previous.component && previous.note === entry.note) {
+			previous.total.cost += entry.usage.cost.total;
+			previous.component.invalidate();
+			return;
+		}
+		const total = { cost: entry.usage.cost.total };
+		const component = new ThemedText(() => theme.fg("dim", formatCacheWarmingUsage(total.cost, entry.note)), 1, 0);
+		this.cacheWarmingNotice = { component, total, note: entry.note };
 		this.chatContainer.addChild(new Spacer(1));
-		const usage = formatCacheWarmingUsage(entry);
-		this.chatContainer.addChild(new ThemedText(() => theme.fg("dim", usage), 1, 0));
+		this.chatContainer.addChild(component);
 	}
 
 	/**

packages/coding-agent/test/cache-warmer.test.ts

@@ -338,7 +338,9 @@ describe("cache warming", () => {
 			usage,
 			"extension override",
 		);
-		expect(formatCacheWarmingUsage(entry)).toBe("Cache warmed (extension override): $0.029497");
+		expect(formatCacheWarmingUsage(entry.usage.cost.total, entry.note)).toBe(
+			"Cache warmed (extension override): $0.029497",
+		);
 	});
 });