fix(billing): stop the false unbilled-charge error on zero-cost runs

[waleedlatif1]

Problem

Every usage-gated (blocked) execution emitted an ERROR-level log:

Failed to record execution usage to usage_log ledger; charge may be unbilled

This is a 100% false positive on that path. It claims possible revenue loss on runs that never executed and have zero cost — exactly the line an engineer pages on. It misdirected a production investigation for hours. Across 5 days / 683 occurrences, sum(totalCost) = 0 and max(totalCost) = 0.

Mechanism (verified)

1. apps/sim/lib/execution/preprocessing.ts logPreprocessingError calls session.safeCompleteWithError({ skipCost: true }) and passes no billingAttribution.
2. skipCost: true makes logging-session.ts build an all-zero costSummary (no base charge, no models, no charges).
3. logger.ts recordExecutionUsage required a billing context before building targets[]:

   if (workflowRecord.workspaceId && !billingContext) {
     throw new Error('Billing attribution is required for workspace execution usage')
   }

   The throw was caught by the surrounding catch, which logs the unbilled-charge ERROR — even though targets[] would have been empty and recordUsage would never have been called.

Fix

Move the existing if (targets.length === 0) return 0 early return above the attribution requirement. Pure reordering — no new predicate.

No charge can be lost by this change. When targets.length === 0 there is nothing to insert into usage_log: both the old path (throw → catch → log → return 0) and the new path (return 0) record exactly zero. The only difference is the spurious ERROR. Every path with a non-zero target still requires billingContext and still throws when it is missing.

Genuine under-billing still alerts

The ERROR log is not silenced. Any real ledger failure — a recordUsage insert failure, a transaction/advisory-lock failure, or missing billing attribution on a run that does have cost — still reaches the same catch and still logs at ERROR with the full costSummary. Alerting on this line remains valid; it is now specific.

Tests

• a structurally zero-cost run without billing context logs no unbilled-charge error — fails without the fix (1 spurious ERROR call).
• a genuine ledger write failure still logs the unbilled-charge error — regression guard; fails if anyone downgrades or removes the ERROR (verified by temporarily switching it to warn).

The file's @sim/logger mock is overridden locally so withMetadata() children share one spy set, making log level assertable.

Verification

• bunx vitest run lib/logs/execution/logger.test.ts lib/logs/execution/logging-session.test.ts — 98 passed
• bunx tsc --noEmit -p apps/sim/tsconfig.json — clean
• bun run lint — clean

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
docs	Skipped		Aug 6, 2026 6:48pm

[cursor]

PR Summary

Low Risk
Pure reordering of guards in usage recording with no change to ledger writes when cost exists; billing attribution is still enforced before any insert when targets are non-empty.

Overview
Zero-cost workspace completions (e.g. usage-gated runs that never executed, with skipCost: true and no billing attribution) no longer hit the workspace billing-attribution throw and therefore no longer emit the ERROR Failed to record execution usage to usage_log ledger; charge may be unbilled.

In recordExecutionUsage, the existing targets.length === 0 early return is now evaluated before requiring billingContext for workspace workflows. Runs with nothing to ledger still return 0 and skip recordUsage; runs with billable targets still require attribution and still throw when it is missing, so real under-billing paths still reach the same catch and ERROR log.

Tests add a shared @sim/logger mock so ERROR calls are assertable, plus cases for zero-cost-without-context (no spurious ERROR) and genuine recordUsage failures (ERROR still logged).

^{Reviewed by Cursor Bugbot for commit 5235a4d. Configure here.}

[greptile-apps]

Greptile Summary

The PR prevents zero-target executions from emitting a false unbilled-charge error while preserving attribution validation and ledger error reporting whenever a billable target exists.

• Moves the empty-target return ahead of billing-context resolution.
• Adds regression coverage for zero-cost completions and genuine ledger-write failures.

Confidence Score: 5/5

The PR appears safe to merge because the new early return applies only when this path has no ledger entries to record.

Nonzero workflow-owned costs still require billing attribution and retain the existing ledger-write and error-reporting flow, while externally owned Mothership costs continue through their separate attributed ledger path.

Important Files Changed

Filename	Overview
apps/sim/lib/logs/execution/logger.ts	Reorders the existing empty-target return so no-charge executions bypass irrelevant billing-attribution validation without changing nonzero ledger writes.
apps/sim/lib/logs/execution/logger.test.ts	Adds shared logger spies and verifies both suppression of the false error and retention of error-level reporting for actual ledger failures.

_{Reviews (1): Last reviewed commit: "fix(billing): stop the false unbilled-ch..." | Re-trigger Greptile}