The bug: three persist sites accumulated cost instead of snapshotting
it like tokens. This caused cost to be inflated 1x-72x on multi-persist
sessions because the same cumulative usage was added repeatedly.
Root cause: persistSessionUsageUpdate, updateSessionStoreAfterAgentRun,
and the cron isolated-agent run path all used:
estimatedCostUsd = existingCost + runCost
But runCost was already computed from cumulative run usage, so this
added the same cost repeatedly on redundant persists.
Fix: snapshot cost directly like tokens already do:
estimatedCostUsd = runCost
Files affected:
- src/auto-reply/reply/session-usage.ts
- src/agents/command/session-store.ts
- src/cron/isolated-agent/run.ts
Tests added:
- session-store.test.ts: verify cost is snapshotted, not accumulated
- session.test.ts: updated existing test to verify snapshot behavior
Fixes#69347
47bb5ddece