> ## Documentation Index
> Fetch the complete documentation index at: https://docs.akua.dev/llms.txt
> Use this file to discover all available pages before exploring further.
# Limits and pricing
> Which limits and billing controls apply to hosted agents, retained runtimes, and provider usage
Hosted agents use the same workspace boundary as the rest of Akua. Sessions are cheap to keep open, but model usage, retained runtimes, filesystem storage, and automated triggers need explicit limits.
## Limits that apply to agents
| Limit | Scope | Canonical source |
| --------------------- | ------------------------------------ | -------------------------------------------------------------------- |
| Active agent sessions | Workspace quota | [Quotas →](/platform/quotas) |
| Running turns | Workspace concurrency limit | [Quotas → Concurrency limits →](/platform/quotas#concurrency-limits) |
| Retained runtimes | Workspace quota and retention policy | [Sessions and turns →](/agents/sessions-and-turns#retention) |
| Provider usage | Model budget and rate limit | [Configure an agent →](/agents/configure#model-policy) |
| API and MCP calls | Rate limit | [Quotas → Rate limits →](/platform/quotas#rate-limits) |
| Ambient triggers | Workspace policy and cooldown | [Ambient agents →](/agents/ambient-agents) |
Agent limits use per-workspace admission control before expensive work starts, so an agent cannot silently exceed runtime, provider, or automation limits.
When a limit blocks work before a turn is accepted, the API should return a structured error and create no turn. If work was accepted but a later runtime or budget gate blocks progress, the turn should expose a structured admission error that names the limit, scope, current usage, maximum, and retry timing when a retry is useful. Usage summaries should separate provider cost, retained runtime compute, retained filesystem storage, API/MCP calls, and ambient trigger runs.
## Pricing model
Agents support two billing paths:
| Billing path | How it works |
| -------------------- | ------------------------------------------------------------------------------------------- |
| Akua-managed billing | Akua routes provider calls and charges usage according to the workspace plan. |
| Workspace BYOK | The workspace supplies provider credentials through secrets and pays the provider directly. |
Retained runtimes are separate from model usage. A long-running coding task can consume compute, storage, and provider budget, while a read-only triage turn may only use platform tools and a small model budget.
## Usage dimensions
Agent usage is reported separately so teams can see what drove cost or limits:
| Dimension | What it measures |
| ---------------- | -------------------------------------------------------------------------------- |
| Provider tokens | Tokens sent to and returned from model providers. |
| Provider spend | Provider cost attributed to the workspace, agent, session, and turn. |
| Runtime compute | Seconds a retained sandbox spent running compute. |
| Retained storage | GB-hours for retained session filesystems. |
| API calls | Attributed platform API calls made by generated widgets, snippets, or Code Mode. |
| MCP calls | Tool calls made through MCP/Code Mode bridges. |
| Ambient triggers | Signal-triggered runs admitted by ambient policy. |
## Cost controls
Use agent policy to keep spend predictable:
* Set model budgets for agents that run automatically.
* Prefer Code Mode for platform operations that do not need files or shell access.
* Start retained runtimes only when repository, package manager, browser, or test work is required.
* Use cooldowns for ambient triggers.
* Expire retained filesystems unless the session is pinned.
* Require approval before shell commands, network egress, repository change request acceptance, or secret access.
Platform plans and included limits.
How resource, concurrency, and rate limits work.
Set model policy, runtime policy, grants, and triggers.
Review approvals, grants, and audit behavior.