everruns/plugins/everruns-framework

Everruns Framework and advanced hosts

Start new Rust applications with the application-facing everruns Framework. The engine runs in process without a database, server, or worker. Enable the provider you intend to call and supply its credentials:

cargo add everruns --features openai

use everruns::{Agent, Engine, OpenAI};
 
# async fn example() -> Result<(), Box<dyn std::error::Error>> {
let agent = Agent::builder()
    .instructions("Answer in one short sentence.")
    .provider(OpenAI::from_env()?)
    .model("gpt-6.1-sol")
    .build()?;
let turn = Engine::new().create(agent).run("Say hello.").await?;
println!("{}", turn.response);
# Ok(())
# }

Choose the dependency path

• Ordinary applications use everruns for agents, models/providers, tools,

sessions, events, cancellation, workspaces, MCP, plugins, inspection, and opt-in local scheduling.

• Advanced system integrators combine everruns, everruns-core with the

host feature, and everruns-contracts. Select concrete providers and integrations through facade features or everruns::batteries.

everruns_core::host owns the low-level host boundary. The execution kernel lives in everruns_core::engine; do not add retired host, engine, or MCP crates.

Common Framework tasks

• Use Model::simulated or Model::simulated_with_config for deterministic,

credential-free tests. Examples and real workflows use a live provider.

• Pair a plain Framework Model with Provider, or use a provider

convenience, for real models.

• Add ordinary tools with #[everruns::tool] or FunctionTool; use the

curated everruns::capability API for reusable capability packages.

• Observe Session::events, cancel through RunOptions, and inspect the next

model context with Session::inspect.

• Seed files with AgentBuilder::file and readonly_file; attach one trusted

workspace and configure WorkspacePolicy where needed.

• Configure scoped MCP through McpServer and plugins through

AgentBuilder::plugin. Local-process MCP stays opt-in.

• Enable everruns/local for a real workspace plus local task/schedule state.

The same profile also provides crash-durable canonical event history.

Hosted agent applications

For an HTTP agent application with routes, tools, and approvals, see Everruns serve. Applications that only call a hosted Everruns agent use an SDK; the plugin's everruns-sdk guide covers Python, TypeScript, and Rust clients.

Advanced host boundary

Use low-level crates only when the application is itself an execution host and must replace stores, filesystem factories, platform definitions, phase adapters, durable scheduling lifecycle, or worker topology:

cargo add everruns everruns-contracts
cargo add everruns-core --features host

use everruns::Provider;
use everruns_core::host::{HostBackends, InProcessRuntimeBuilder};
use everruns_contracts::model_spec::ModelSpec;
# let _ = (HostBackends::in_memory, InProcessRuntimeBuilder::new);

Canonical events are the only maintained conversation write path. Advanced hosts use EventLog, EventHistory, EventSink, and EventReader; legacy mutable-history paths are not execution inputs.

References

• Everruns Framework
• Custom backends
• Framework API
• Host API
• Focused crate catalog
• Domain-language glossary