feat: implement offline mode in data loader and pricing fetcher

- Add offline flag support to LoadOptions interface in data-loader
- Implement offline mode in PricingFetcher using pre-fetched macro data
- Add caching logic for offline pricing data to avoid repeated object creation
- Return cached pricing data when offline flag is enabled
- Provide graceful fallback when macro data is unavailable in offline mode
- Add proper error handling for offline mode edge cases

The pricing fetcher now supports both online (LiteLLM API) and offline
(build-time cached) modes, enabling usage without network connectivity.

Author: ryoppippi

src/data-loader.ts

@@ -464,6 +464,7 @@ export type LoadOptions = {
 	claudePath?: string; // Custom path to Claude data directory
 	mode?: CostMode; // Cost calculation mode
 	order?: SortOrder; // Sort order for dates
+	offline?: boolean; // Use offline mode for pricing
 } & DateFilter;
 
 export async function loadDailyUsageData(
@@ -487,7 +488,7 @@ export async function loadDailyUsageData(
 	const mode = options?.mode ?? 'auto';
 
 	// Use PricingFetcher with using statement for automatic cleanup
-	using fetcher = mode === 'display' ? null : new PricingFetcher();
+	using fetcher = mode === 'display' ? null : new PricingFetcher(options?.offline);
 
 	// Track processed message+request combinations for deduplication
 	const processedHashes = new Set<string>();
@@ -603,7 +604,7 @@ export async function loadSessionData(
 	const mode = options?.mode ?? 'auto';
 
 	// Use PricingFetcher with using statement for automatic cleanup
-	using fetcher = mode === 'display' ? null : new PricingFetcher();
+	using fetcher = mode === 'display' ? null : new PricingFetcher(options?.offline);
 
 	// Track processed message+request combinations for deduplication
 	const processedHashes = new Set<string>();

src/pricing-fetcher.ts

@@ -1,7 +1,9 @@
 import * as v from 'valibot';
+import { LITELLM_PRICING_URL } from './consts.internal.ts';
 import { logger } from './logger.ts';
+import { prefetchClaudePricing } from './macro.internal.ts' with { type: 'macro' };
 
-const ModelPricingSchema = v.object({
+export const ModelPricingSchema = v.object({
 	input_cost_per_token: v.optional(v.number()),
 	output_cost_per_token: v.optional(v.number()),
 	cache_creation_input_token_cost: v.optional(v.number()),
@@ -10,13 +12,13 @@ const ModelPricingSchema = v.object({
 
 export type ModelPricing = v.InferOutput<typeof ModelPricingSchema>;
 
-const LITELLM_PRICING_URL
-	= 'https://raw.githubusercontent.com/BerriAI/litellm/main/model_prices_and_context_window.json';
-
 export class PricingFetcher implements Disposable {
 	private cachedPricing: Map<string, ModelPricing> | null = null;
+	private readonly offline: boolean;
 
-	constructor() {}
+	constructor(offline = false) {
+		this.offline = offline;
+	}
 
 	[Symbol.dispose](): void {
 		this.clearCache();
@@ -31,6 +33,13 @@ export class PricingFetcher implements Disposable {
 			return this.cachedPricing;
 		}
 
+		// If we're in offline mode, return pre-fetched data
+		if (this.offline) {
+			const pricing = new Map(Object.entries(await prefetchClaudePricing()));
+			this.cachedPricing = pricing;
+			return pricing;
+		}
+
 		try {
 			logger.warn('Fetching latest model pricing from LiteLLM...');
 			const response = await fetch(LITELLM_PRICING_URL);