Add dashboard token usage history (#240)

electron/utils/token-usage-core.ts

@@ -0,0 +1,89 @@
+export interface TokenUsageHistoryEntry {
+  timestamp: string;
+  sessionId: string;
+  agentId: string;
+  model?: string;
+  provider?: string;
+  inputTokens: number;
+  outputTokens: number;
+  cacheReadTokens: number;
+  cacheWriteTokens: number;
+  totalTokens: number;
+  costUsd?: number;
+}
+
+interface TranscriptUsageShape {
+  input?: number;
+  output?: number;
+  total?: number;
+  cacheRead?: number;
+  cacheWrite?: number;
+  promptTokens?: number;
+  completionTokens?: number;
+  totalTokens?: number;
+  cost?: {
+    total?: number;
+  };
+}
+
+interface TranscriptLineShape {
+  type?: string;
+  timestamp?: string;
+  message?: {
+    role?: string;
+    model?: string;
+    modelRef?: string;
+    provider?: string;
+    usage?: TranscriptUsageShape;
+  };
+}
+
+export function parseUsageEntriesFromJsonl(
+  content: string,
+  context: { sessionId: string; agentId: string },
+  limit = 20,
+): TokenUsageHistoryEntry[] {
+  const entries: TokenUsageHistoryEntry[] = [];
+  const lines = content.split(/\r?\n/).filter(Boolean);
+
+  for (let i = lines.length - 1; i >= 0 && entries.length < limit; i -= 1) {
+    let parsed: TranscriptLineShape;
+    try {
+      parsed = JSON.parse(lines[i]) as TranscriptLineShape;
+    } catch {
+      continue;
+    }
+
+    const message = parsed.message;
+    if (!message || message.role !== 'assistant' || !message.usage || !parsed.timestamp) {
+      continue;
+    }
+
+    const usage = message.usage;
+    const inputTokens = usage.input ?? usage.promptTokens ?? 0;
+    const outputTokens = usage.output ?? usage.completionTokens ?? 0;
+    const cacheReadTokens = usage.cacheRead ?? 0;
+    const cacheWriteTokens = usage.cacheWrite ?? 0;
+    const totalTokens = usage.total ?? usage.totalTokens ?? inputTokens + outputTokens + cacheReadTokens + cacheWriteTokens;
+
+    if (totalTokens <= 0 && !usage.cost?.total) {
+      continue;
+    }
+
+    entries.push({
+      timestamp: parsed.timestamp,
+      sessionId: context.sessionId,
+      agentId: context.agentId,
+      model: message.model ?? message.modelRef,
+      provider: message.provider,
+      inputTokens,
+      outputTokens,
+      cacheReadTokens,
+      cacheWriteTokens,
+      totalTokens,
+      costUsd: usage.cost?.total,
+    });
+  }
+
+  return entries;
+}