## Summary
Implements a ClickHouse-backed polling system to enforce metered-credit
caps for workflow executions, replacing reliance on Stripe billing
alerts. The system re-evaluates tier caps against live pricing on every
poll cycle, allowing price/tier changes to propagate immediately without
recreating Stripe alert objects.
## Key Changes
- **BillingUsageCapService**: New service that queries ClickHouse for
current-period credit usage and evaluates whether a subscription has
reached its metered-credit allowance (tier cap + credit balance)
- `isClickHouseEnabled()`: Checks if ClickHouse is configured
- `getCurrentPeriodCreditsUsed()`: Sums creditsUsedMicro from usageEvent
table for a workspace within a billing period
- `evaluateCap()`: Determines if usage has reached the allowance by
reading live pricing from the subscription
- **EnforceUsageCapJob**: Cron job that polls all active subscriptions
and updates `hasReachedCurrentPeriodCap` on metered items
- Runs every 2 minutes to keep cap enforcement in sync with live usage
- Supports shadow mode (log-only) via
`BILLING_USAGE_CAP_CLICKHOUSE_ENABLED` flag for safe rollout
- Continues processing after per-subscription errors with detailed
logging
- **EnforceUsageCapCronCommand**: CLI command to register the
enforcement cron job
- **MeteredCreditService**: Extracted
`extractMeteredPricingInfoFromSubscription()` as a pure function for
callers that already hold the subscription with pricing loaded, avoiding
redundant DB queries
- **Configuration**: Added `BILLING_USAGE_CAP_CLICKHOUSE_ENABLED` flag
to control enforcement mode (active vs. shadow)
- **Constants**: Added `METERED_OPERATION_TYPES` to define which
operation types count toward the metered product's credit cap
## Implementation Details
- The service queries ClickHouse for the sum of `creditsUsedMicro` in
the current billing period, matching Stripe meter semantics
- Pricing is re-read on every evaluation, so tier changes propagate
within one poll cycle without Stripe alert recreation
- The cron job only updates the database when the cap state actually
changes (no-op if already in the correct state)
- Shadow mode allows safe validation before enabling enforcement;
transitions are logged but not persisted
- Comprehensive test coverage for both the service and cron job,
including error handling and state transitions
https://claude.ai/code/session_01VksTSrYLXJVCPVBQhQdBTe
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Co-authored-by: Claude <noreply@anthropic.com>
Félix Malfait
455022f652