fix: restore Anthropic token accounting

src/cron/isolated-agent.ts

@@ -14,6 +14,7 @@ import {
 import { runEmbeddedPiAgent } from "../agents/pi-embedded.js";
 import { buildWorkspaceSkillSnapshot } from "../agents/skills.js";
 import { resolveAgentTimeoutMs } from "../agents/timeout.js";
+import { hasNonzeroUsage } from "../agents/usage.js";
 import {
   DEFAULT_AGENT_WORKSPACE_DIR,
   ensureAgentWorkspace,
@@ -357,7 +358,7 @@ export async function runCronIsolatedAgentTurn(params: {
     cronSession.sessionEntry.modelProvider = providerUsed;
     cronSession.sessionEntry.model = modelUsed;
     cronSession.sessionEntry.contextTokens = contextTokens;
-    if (usage) {
+    if (hasNonzeroUsage(usage)) {
       const input = usage.input ?? 0;
       const output = usage.output ?? 0;
       const promptTokens =