feat(ai): use Luna as the default conversation model

packages/ai/src/ai/config/models.ts

@@ -15,7 +15,7 @@ const gateway = createGateway({
 export const modelNames = {
 	tiny: "openai/gpt-oss-120b",
 	quick: "google/gemini-2.5-flash-lite",
-	balanced: "openai/gpt-5.6-terra",
+	balanced: "openai/gpt-5.6-luna",
 	deep: "deepseek/deepseek-v4-flash",
 } as const;
 

packages/ai/src/lib/usage-telemetry.test.ts

@@ -47,4 +47,25 @@ describe("summarizeAgentUsage", () => {
 		expect(summary.cost_total_usd).toBe(20.875);
 		expect(summary.agent_credits_used).toBe(417.5);
 	});
+
+	test("bills Luna input, output, and cached tokens at its own rates", () => {
+		const summary = summarizeAgentUsage("openai/gpt-5.6-luna", {
+			inputTokens: 30_000,
+			outputTokens: 10_000,
+			inputTokenDetails: {
+				cacheReadTokens: 10_000,
+				cacheWriteTokens: 10_000,
+			},
+		});
+
+		expect(summary.cost_fallback).toBe(false);
+		expect(summary.cost_model_id).toBe("openai/gpt-5.6-luna");
+		expect(summary.fresh_input_tokens).toBe(10_000);
+		expect(summary.cost_input_usd).toBeCloseTo(0.002, 8);
+		expect(summary.cost_cache_read_usd).toBeCloseTo(0.0002, 8);
+		expect(summary.cost_cache_write_usd).toBeCloseTo(0.0025, 8);
+		expect(summary.cost_output_usd).toBeCloseTo(0.012, 8);
+		expect(summary.cost_total_usd).toBeCloseTo(0.0167, 8);
+		expect(summary.agent_credits_used).toBeCloseTo(0.334, 8);
+	});
 });

packages/shared/src/agent-credits.ts

@@ -51,6 +51,12 @@ export const AGENT_MODEL_COSTS_USD_PER_MILLION: Record<
 		cache_read: 0.25,
 		cache_write: 3.125,
 	},
+	"openai/gpt-5.6-luna": {
+		input: 0.2,
+		output: 1.2,
+		cache_read: 0.02,
+		cache_write: 0.25,
+	},
 };
 
 export const AGENT_PRICING_BASELINE_MODEL_ID =