Protecting customers during a quota shock

This worked application uses explicit planning assumptions to demonstrate FIELD. Quantities below are inputs, calculated implications or proposed targets; they are not reported customer results. The engagement decision remains conditional on the evidence described.

Planning basis and engagement boundary

F — Frame the outcome

Preserve useful service for twenty customers when quota halves, with explicit fairness and degraded modes rather than a universal uptime promise.

Value measure: Verified task goodput and cost by tenant, including fallback escalation.

I — Investigate the workflow

Inspect tenant prompt/turn distributions, contracts and escalation burden. Determine whether the fallback's apparent token savings survive extra turns and review.

First evidence task: Halve provider quota while one tenant sends long prompts and retries.

E — Engineer the solution

Keep per-tenant admission, token/concurrency budgets and tested capability adapters; accepted demand must fit reduced quota including retries.

The implementation assessment below makes the authority, workload, resource and failure assumptions concrete. Its numbers are calculations from the stated scenario, not a vendor performance guarantee.

Contract

Define per-tenant service classes, quotas, completion deadlines and acceptable degraded tasks. The long-prompt tenant's resource share matters more than its request count. Fallback tool behavior requires evaluation before it is allowed to execute actions.

Implementation plan

Gateway authenticates and estimates input/output work; a scheduler applies per-tenant token and concurrency budgets plus interactive/batch classes. Model adapters normalize events, capability flags and errors. A durable task layer owns pending work and action state. Use bounded queues and one retry budget across layers.

Sizing

If normal offered load uses 80% of quota Q and quota falls to 0.5Q, excess is 0.3Q, or 37.5% of offered demand. That work must be reduced, deferred within deadlines, rerouted to evaluated capacity or rejected. Scaling API servers does not solve the deficit. Reserve output quota and account for token-length prediction error. Long prompts also affect connection occupancy and latency.

Fallback economics

Assume the primary costs $0.01/turn and averages two turns with 90% verified success: model-only cost/success≈$0.0222. A fallback costing $0.006/turn but averaging four turns with 80% success costs $0.03/success before review. Lower token price has not improved the workflow.

Failure behavior

Shed low-priority new work early, protect critical tenants under a declared fairness policy and expire jobs that can no longer meet their contract. Restrict a fallback with unproven tool semantics to read-only/clarification or human review. Show users an honest delayed/degraded status and communicate impact with measured scope.

Validation

Replay a mixed workload with a 50% quota reduction, one hot tenant, provider timeouts and slow outputs. Measure goodput by class, critical failures, token attempts, queue age, cost and review burden. Test recovery ramp-up rather than releasing the entire backlog at once.

L — Launch with evidence

Replay representative mixed traffic and compare verified outcomes, latency and cost per task across main/fallback modes. Restrict fallback where tool semantics differ.

Critical decision condition: An incompatible fallback cannot execute consequential tools merely to preserve availability.

Attach raw artifacts, the tested configuration, population, denominator, date and limitations to the release record. Missing or stale evidence holds the dependent decision. A favorable value forecast cannot offset a failed critical condition.

D — Develop ownership and reuse

The platform operator owns incident policy and customer communication; publish quota and compatibility changes through a versioned contract.

Candidate reusable asset: Tenant admission policy and capability regression suite.

Commercial decision and next commitment

Accountable decision owner: Service owner with customer workflow owners.

The initial commitment is the bounded journey above, with the stated exclusions. Confirm access, customer staffing and acceptance ownership during discovery; price and schedule unresolved dependencies explicitly. A new source, tenant class, language, action or operating envelope requires an impact review rather than silent scope growth.

Approve only the next exposure level supported by the evidence. The next useful investment is: halve provider quota while one tenant sends long prompts and retries.

Method and references

Apply the FIELD method, economic model and evidence rules. Methodological and technical influences are listed in the source register.