This document provides an order-of-magnitude cost model for the platform. Cost efficiency is a first-class design principle (see ARCHITECTURE.md). The model covers infrastructure baseline costs, per-task variable costs, and cost attribution guidance.
Detailed cost management (per-user budgets, cost attribution dashboards, token budget enforcement) builds on this baseline analysis and focuses on the dominant cost drivers.
These costs are incurred regardless of task volume:
| Component | Estimated cost | Notes |
|---|---|---|
| NAT Gateway (1×) | ~$32/month | Fixed hourly cost + data processing. Single AZ (see COMPUTE.md - Network architecture). |
| VPC Interface Endpoints (7×, 2 AZs) | ~$102/month | $0.01/hr × 7 endpoints × 2 AZs × 730 hrs. |
| VPC Flow Logs | ~$3/month | CloudWatch ingestion. |
| DynamoDB (on-demand, idle) | ~$0/month | Pay-per-request; 6 tables (Tasks, Events, Nudges, UserConcurrency, Webhooks, Repo). No cost when idle. |
| S3 Trace Artifacts bucket (idle) | ~$0/month | 7-day lifecycle auto-expires objects; no cost when no traces are stored. |
| EventBridge reconciler rule | <$0.01/month | Invokes Lambda every 5 min (288/day). Rule itself is free; Lambda invocation is the cost (see below). |
| Stranded task reconciler Lambda (idle) | <$0.01/month | 288 invocations/day × 256 MB × ~100 ms avg (early exit when no stranded tasks). ~$0.005/month total (requests + duration). |
| CloudWatch Logs retention | ~$1–5/month | Depends on log volume. 90-day retention. |
| API Gateway (idle) | ~$0/month | Pay-per-request. |
| Total baseline | ~$140–150/month | Reconciler adds negligible cost; VPC networking remains dominant. |
Most platform components are fully serverless and incur zero cost when idle: DynamoDB (PAY_PER_REQUEST, 6 tables), Lambda, API Gateway, S3 (trace artifacts auto-expire in 7 days), SQS (fanout DLQ), ECS Fargate (cluster is free, when enabled), AgentCore Runtime (per-session), Bedrock (per-token), and Cognito (free tier). The stranded task reconciler adds <$0.01/month even when idle (288 Lambda invocations/day, early-exit). The always-on cost floor (~$140–150/month) is dominated by VPC networking infrastructure (NAT Gateway + 7 interface endpoints across 2 AZs) which is required for private subnet connectivity to AWS services and GitHub. See the Deployment guide for the full scale-to-zero breakdown.
Each task incurs costs proportional to its duration, token consumption, and compute usage. The dominant cost driver is Bedrock model invocation (token cost), not infrastructure.
Assuming a typical task: 1–2 hours, Claude Sonnet, ~100K input tokens, ~20K output tokens per turn, ~50 turns:
| Component | Estimated cost per task | Calculation basis |
|---|---|---|
| Bedrock tokens (dominant) | $2–15 | Varies widely by model, task complexity, and turn count. Claude Sonnet: ~$3/M input tokens, ~$15/M output tokens. A 50-turn task with 100K input + 20K output per turn ≈ 5M input + 1M output ≈ $15 + $15 = $30 at list price. Prompt caching reduces this significantly (up to 90% for cache hits). Typical range: $2–15 after caching. |
| AgentCore Runtime compute | $0.10–0.50 | 2 vCPU / 8 GB for 1–2 hours. Pricing model is per-session based on vCPU-hours and GB-hours. |
| Lambda orchestrator | <$0.01 | ~10 invocations per task (admission, hydration, polling, finalization). Negligible. |
| Lambda fanout consumer | <$0.01 | Triggered per batch of task events (batch size 100, 5 s window). Typically 5–20 invocations per task at 256 MB. Negligible. |
| Lambda nudge / trace / events | <$0.01 | On-demand per user request. Negligible unless heavily polled. |
| DynamoDB reads/writes | <$0.01 | ~30–80 operations per task (task CRUD, events, nudges, counter updates). Negligible. |
| DynamoDB Streams (fanout) | <$0.01 | Stream reads charged per 25 KB. Typical task: ~20–50 event records. Negligible. |
S3 trace upload (if --trace) |
<$0.01 | One PUT per task + storage (gzipped NDJSON, typically 50–500 KB, auto-expires in 7 days). |
| NAT Gateway data | <$0.01 | GitHub API traffic: clone + push. Small repos: <10 MB. |
| Custom step Lambdas | $0–0.05 | Only if configured. Per-invocation: ~$0.01 per step. |
| Total per task | $2–15 | Bedrock tokens dominate (>90% of per-task cost). New interactive features add <$0.01 per task. |
| Factor | Impact on cost | Mitigation |
|---|---|---|
| Model choice | 5–10× between Haiku and Opus | Default to Claude Sonnet; allow per-repo override. |
| Turn count | Linear with turns | max_turns cap (default 100, configurable 1–500). |
| Cost budget | Hard stop at budget | max_budget_usd cap (configurable $0.01–$100). Agent stops when budget is reached regardless of remaining turns. |
| Task duration | Sub-linear (compute is cheap; tokens dominate) | AgentCore: 8-hour service limit; orchestrator: 9-hour executionTimeout. |
| Prompt caching | 50–90% token cost reduction | Enable by default; cache system prompts and repo context. |
| Concurrency | Linear with parallel tasks | Per-user and system-wide concurrency limits. |
| Scale | Tasks/month | Estimated monthly cost (infra + tasks) |
|---|---|---|
| Low (1 developer) | 30–60 | $200–550 |
| Medium (small team) | 200–500 | $550–3,000 |
| High (org-wide) | 2,000–5,000 | $5,000–30,000 |
These estimates assume Claude Sonnet with prompt caching enabled and average task complexity.
For multi-user deployments, cost should be attributable to individual users and repositories:
- Per-task: Token usage and compute duration are captured in task metadata (
agent.cost_usd,agent.turns- see OBSERVABILITY.md). - Per-user: Aggregate task costs by
user_id. - Per-repo: Aggregate task costs by
repo. - Dashboard: Cost attribution dashboards should be built from the same task-level metrics.
| Guardrail | Mechanism | Default |
|---|---|---|
| Turn limit | max_turns per task |
100 |
| Cost budget | max_budget_usd per task |
None (unlimited) |
| Session timeout | Orchestrator timeout | 9 hours |
| Concurrency limit | Per-user atomic counter | 3 concurrent tasks |
| System concurrency | System-wide counter | Account-level AgentCore quota |
- Per-user monthly token budgets with alerts at 80% and hard stop at 100%.
- Per-team monthly cost budgets.
- Cost attribution dashboard in the control panel.
- Automated model downgrade (e.g. Sonnet -> Haiku) when approaching budget limits.
- COMPUTE.md -- Compute option billing models and network architecture.
- ORCHESTRATOR.md -- Polling cost analysis.
- OBSERVABILITY.md -- Cost-related metrics (
agent.cost_usd, token usage). - Deployment guide -- Deployment choices, scale-to-zero analysis, AWS services inventory.
- DEPLOYMENT_ROLES.md -- Least-privilege IAM policies for deployment.