API reference

This reference is generated from spec/api.json, the contract both implementations follow. Members that exist in the contract but are not built yet are left out; members built in one language only say so.

Naming

Functions and methods are lowerCamelCase in TypeScript and snake_case in Python: openThread and open_thread.
Types have the same PascalCase name in both.
Required inputs are positional. Everything else is one trailing options object in TypeScript and keyword-only arguments in Python, with the same names and defaults.
Expected failures are values, not exceptions: TypeScript returns { ok: true, value } or { ok: false, error: { code, message } }, Python returns Ok[T] or Err[Failure]. Only ConfigError, for a definition that can't run, is thrown.

Packages

Package	TypeScript	Python
core	`@threads/core`	`threads`
host	`@threads/host`	`threads.host`
mcp	`@threads/mcp`	`threads.mcp`

Model, sandbox, channel and memory providers live in their own packages (@threads/anthropic, threads.anthropic, ...). See Models, Sandboxes, Host server and Memory.

Functions

TypeScript	Python	What it does
`agent`	`agent`	Describe an agent.
`tool`	`tool`	Define an app tool.
`extension`	`extension`	The one extension primitive: tools, trusted instructions and hooks.
`mcp`	`mcp`	An MCP server in one line.
`secret`	`secret`	A reference to a host secret, resolved only in the host.
`openThread`	`open_thread`	A handle for inspection and control, independent of any in-memory run.
`sqlite`	`sqlite`	The one log and artifact store.
`localMemory`	`local_memory`	Built-in memory: SQLite FTS5 in the run's store.
`localKnowledge`	`local_knowledge`	Built-in knowledge: SQLite FTS5 over admitted versions stored as artifacts.
`scriptedModel`	`scripted_model`	Test kit.
`fakeSandbox`	`fake_sandbox`	Test kit.
`host`	`host`	Bind agents to a store, channels and schedules.

Types

Agents and runs: Agent, RunResult, RunStream, RunContext, Tool, McpServer, Extension, Hooks, Skill, Secret, Store, ConfigError, ConfigErrorCode

Threads and evals: Thread, CaseExpectation, SavedCase

Host: Host, Schedule

Model adapters: Model, ModelContext, ModelInfo, ModelRequest, ModelResponse, ModelChunk, LookupResult, LookupCapability

Sandbox adapters: Sandbox, SandboxAuthority, SandboxContext, SandboxInfo, SandboxSession, ExecOutput, ExecResult

Memory and knowledge adapters: MemoryProvider, KnowledgeProvider, Scope, Binding, MemoryRecord, RecordRef, MemoryHit, KnowledgeSource, DocVersion, KnowledgeHit, Doc, SearchBackend, SearchHit

Channel adapters: ChannelAdapter, ChannelCapabilities, RawRequest, RawResponse, VerifiedDelivery, Inbound, DeliveryOutcome

HTTP API

The host's HTTP API is documented from its OpenAPI file in the HTTP API reference.

Naming

Packages

Functions

Types

HTTP API

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