AI Denial-of-Service & Economic Abuse

Best time to learn: Immediately after implementing token budgets, truncation, retries, tool-call limits, queues, and rate limiting.

Prerequisites - Token counting and context budgets. - API rate limiting. - Async concurrency and queue basics. - Agent step and tool-call budgets.

### Threat model

AI workloads have variable and sometimes multiplicative costs. One user action may trigger retrieval, reranking, several model calls, tools, retries, and media processing.

Study: - Denial of wallet and cost amplification. - Context stuffing and oversized input. - Repeated tool invocation and recursive agent loops. - Retry storms and provider failure amplification. - Expensive retrieval/reranking patterns. - Per-user, per-tenant, and per-model quotas. - Concurrency limits, queue backpressure, and circuit breakers. - Abuse signals and anomaly detection.

### Labs

• Cost model (1h): Estimate cost per request across input/output tokens, retrieval, reranking, tools, and media.

• Adversarial load (1h): Simulate oversized prompts, repeated requests, and tool loops against your own local test system.

• Budget enforcement (2h): Add request, token, tool-call, wall-clock, and concurrency budgets with deterministic rejection behavior.

• Recovery test (1h): Simulate provider timeouts and retries; verify retry caps, jitter, circuit breaking, and queue recovery.

### Project integration

• Project 1: Token and conversation budgets, maximum response tokens, request timeout, and per-session limits.

• Project 3: Maximum steps, tool calls, parallel tasks, execution time, and approval waits.

• Production API: Per-user and per-tenant quotas, backpressure, and cost alerts.

### Measurable completion criteria

• Each request has a bounded token, time, and cost budget.

• Agent loops terminate at a deterministic limit.

• Retries cannot amplify an outage indefinitely.

• Load tests show controlled degradation and recovery.

• Cost and abuse metrics are available without logging sensitive prompt contents.

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