import type { OrchestrationThreadActivity, ThreadTokenUsageSnapshot } from "@t3tools/contracts"; type NullableContextWindowUsage = {  readonly [Key in keyof ThreadTokenUsageSnapshot]: undefined extends ThreadTokenUsageSnapshot[Key]    ? Exclude<ThreadTokenUsageSnapshot[Key], undefined> | null    : ThreadTokenUsageSnapshot[Key];}; export type ContextWindowSnapshot = NullableContextWindowUsage & {  readonly remainingTokens: number | null;  readonly usedPercentage: number | null;  readonly remainingPercentage: number | null;  readonly updatedAt: string;}; export function deriveLatestContextWindowSnapshot(  activities: ReadonlyArray<OrchestrationThreadActivity>,): ContextWindowSnapshot | null {  for (let index = activities.length - 1; index >= 0; index -= 1) {    const activity = activities[index];    if (!activity || activity.kind !== "context-window.updated") {      continue;    }     const {      payload: {        usedTokens,        totalProcessedTokens,        maxTokens,        inputTokens,        cachedInputTokens,        outputTokens,        reasoningOutputTokens,        lastUsedTokens,        lastInputTokens,        lastCachedInputTokens,        lastOutputTokens,        lastReasoningOutputTokens,        toolUses,        durationMs,        compactsAutomatically,      },    } = activity;    if (!Number.isFinite(usedTokens) || usedTokens <= 0) {      continue;    }     const usedPercentage =      maxTokens !== undefined && maxTokens > 0        ? Math.min(100, (usedTokens / maxTokens) * 100)        : null;    const remainingTokens =      maxTokens !== undefined ? Math.max(0, Math.round(maxTokens - usedTokens)) : null;    const remainingPercentage = usedPercentage !== null ? Math.max(0, 100 - usedPercentage) : null;     return {      usedTokens,      totalProcessedTokens: totalProcessedTokens ?? null,      maxTokens: maxTokens ?? null,      remainingTokens,      usedPercentage,      remainingPercentage,      inputTokens: inputTokens ?? null,      cachedInputTokens: cachedInputTokens ?? null,      outputTokens: outputTokens ?? null,      reasoningOutputTokens: reasoningOutputTokens ?? null,      lastUsedTokens: lastUsedTokens ?? null,      lastInputTokens: lastInputTokens ?? null,      lastCachedInputTokens: lastCachedInputTokens ?? null,      lastOutputTokens: lastOutputTokens ?? null,      lastReasoningOutputTokens: lastReasoningOutputTokens ?? null,      toolUses: toolUses ?? null,      durationMs: durationMs ?? null,      compactsAutomatically: compactsAutomatically ?? false,      updatedAt: activity.createdAt,    };  }   return null;} export function formatContextWindowTokens(value: number | null): string {  if (value === null || !Number.isFinite(value)) {    return "0";  }  if (value < 1_000) {    return `${Math.round(value)}`;  }  if (value < 10_000) {    return `${(value / 1_000).toFixed(1).replace(/\.0$/, "")}k`;  }  if (value < 1_000_000) {    return `${Math.round(value / 1_000)}k`;  }  return `${(value / 1_000_000).toFixed(1).replace(/\.0$/, "")}m`;}