chatruntime

Chat Runtime

Run(ctx, Input) (*sol.RunResult, error) is the shared hosted-chat entrypoint. This package imports neither the SDK root nor Airlock. The host owns run creation, completion, durable permission checkpoints, and conversation serialization.

Required input:

• Model stream.Model and explicit ModelLimits session.ModelLimits.
• SessionStore session.SessionStore, scoped to the conversation.
• MaxSteps, a positive run budget.
• Sink eventstream.Sink, receiving Sol text, tool, permission, compaction, and suspension events. Completion is represented by the returned sol.RunResult.
• Backend, implementing Invoke(context.Context, Invocation) (tool.Result, error).
• Capabilities []capability.Definition, the authorized subset of the canonical catalog. Authorization remains mandatory in the backend on every invocation.
• ExecutorFactory for JS mode. Direct mode never allocates an executor.

Invocation contains CapabilityID, ToolCallID, and JSON Input. The backend binds run/user/job attribution independently of script input. App capabilities use wire.RuntimeInvokePath; platform capabilities execute in the host broker. Backend output must be redacted before crossing the JS/model/event boundaries. Attachments carry storage references resolved by the host model adapter. Definition.TextOutput distinguishes plain-text file results from encoded JSON; the invoker preserves their string type even for JSON-looking file contents.

ExecutorFactory is func(context.Context, []capability.Definition) (jsexec.Session, error). Bind each non-executor definition using its canonical Path.ID() as jsexec.Binding.Name and Path.JSParts() as the JS path. Each JS function takes one object argument matching Definition.InputSchema; the invoker receives a positional JSON array containing that object. Console methods and air.log are executor intrinsics, not backend invocations. The host factory supplies optional jsexec.Options.User from its authenticated run scope. Only id, email, and displayName enter the realm; no grants or credentials do. JavaScript receives a frozen lexical user object, or null. For local tests, set agenttest.ExecutorConfig.User to the same identity as Env.Chat's wire.RuntimeContext. This display context never authorizes calls.

JS executes as an async function body: return await tools.lookup({id: "123"});. Model tool calls are serial. A script may await bounded concurrent callbacks. Explicit globalThis data can persist across scripts in one uninterrupted run; it does not survive suspension, completion, cancellation, or replica movement. The whole run_js approval gate runs before lazy executor allocation. Run closes its executor on all exits. Execution and callback limits are enforced by the supplied jsexec.Session outside the untrusted realm.

Instructions is host-composed prompt text. RenderPrompt and RenderTypeScript use the same catalog as execution, including canonical schemas and examples. Both return (string, error); Run rejects schema-rendering errors before model execution. Raw MCP schemas support unions, local acyclic $refs, and typed additionalProperties. Unrestricted schemas render as unknown; unsupported references and malformed type-bearing keywords fail explicitly. TypeScript is a description, not a replacement for the backend's JSON Schema validation. DirectTools selects individual model tools instead of run_js. AutoConfirm is an explicit host policy for noninteractive runs.

Resume uses Resume *sol.SuspensionContext and required Approved *bool. Only permission suspension is accepted. The host must reject incompatible checkpoints before constructing Input. Internal A2A, sibling discovery, and delegated checkpoint orchestration are not part of this runtime. External MCP servers declared in the manifest are ordinary broker capabilities.