@compose-market/core

Shared runtime primitives for Compose.Market SDKs.

This package contains the reusable, product-agnostic pieces used by higher-level Compose clients:

• typed Compose error classes
• a dependency-free Fetch-based HTTP client with retries and timeouts
• x402 PaymentRequired parsing
• session-budget and receipt helpers
• SSE parsing
• minimal pluggable storage helpers
• the single client-side decoder for the Compose agent/model domain event streams

Generated Speakeasy SDK output should remain generated. Higher-level SDKs can depend on this package as normal npm code without self-imports or generated-file patches.

Domain event stream contract

Both servers (the api gateway and the runtime) stream agent activity as a single typed event protocol. sse/stream parses the SSE transport and routes each frame to one of two decoders:

• activity.decode — ActivityEvent: { domain: "activity", type: "activity.*", id, ts, kind, status?, runId?, rootId?, parentId?, spanId?, target?, name?, delta?, payload? }
• model.decode — ModelEvent: { domain: "model", type: "model.*", id, ts, ... }

Event types:

• activity.run (terminal carries payload.usage once, plus payload.agent and optional payload.memory/payload.reason), activity.thinking, activity.tool (payload { toolCallId, input, output, message, error }), activity.selection, activity.plan, activity.connector, activity.child (tree via parentId/path), activity.conclave, activity.message, activity.error
• model.start, model.text.delta/model.text.done, model.reasoning.delta/model.reasoning.done, model.tool.delta/model.tool.done, model.asset (typed ModelAsset, never raw), model.status, model.done, model.error

target is an EventDisplay { kind?, id, name, target?, summary?, details? } — the server-owned, human-readable projection. Clients render from target, not from internal protocol fields.

The legacy runtime wire names (tool_start, swarm_child_*, plan.proposed, connector.connection_*, trace, timing, artifact.created, and friends) were removed with the runtime's hard cutover to domain events. The inference Responses wire (response.*, chat choices, text-delta, provider event names) is still decoded for /v1/responses streams.

Separation of concerns

• Servers (api, runtime) import nothing from packages/.
• core is the only client-side decoder; the SDK, web, and the Rust crates consume its contract. Rust parity is enforced by literal duplicated-frame tests in packages/sdk/rust/sdk/tests/parity.rs.
• raw payload fields are durable/server-side only and never appear on user-visible streams.