Tianyi Cui
225ed051b1
Nominal string types via a unique-symbol brand (zero runtime cost): an AgentId can no longer be passed where a CallId is expected. Each core package brands the IDs it owns — CallId in dsh-llm (tool-call correlation across blocks, chunks, session events, and execution results), SessionId in dsh-session, AgentId in dsh-agent. Construction goes through same-named factory functions; public string-in APIs (sessions.create, agentLoop.create) keep accepting plain strings and brand internally. Policy note in the brand module: brand IDs that cross package boundaries, not every string.
dsh-agent
Agent interface, registry, and agent/* event vocabulary. Every plugin (UI,
hooks, orchestrators) programs against the Agent handle defined here — it has
zero loop dependency, so the loop is swappable.
Service: AgentRegistry (ctx key: agents)
Tracks live agents so UI, hook, and orchestrator plugins can find them without importing the concrete loop package.
Public API
ctx.agents.register(agent: Agent): () => voidRegister a live agent. Disposed with the calling fiber.ctx.agents.get(id: string): Agent | undefinedctx.agents.list(): Agent[]
Events
The full agent/* event taxonomy is declared via declaration merging in
dsh-agent (not dsh-agent-loop), so plugins depend only on this package.
Lifecycle (emit)
agent/created,agent/disposed— registration/deregistrationagent/status— idle / running / disposed transitionagent/queued— message entered inbox (source-resolved, steering flag)
Turn/step boundaries (emit)
agent/turn-start,agent/turn-end(carriesTurnEndReason)agent/step-start,agent/step-end
Interception seams (waterfall)
agent/request— mutateGenerateOptionsbefore the model call (hooks, compaction, model switching, tool filtering)agent/step-result— post-process the assembled assistant message before tool dispatch (validates what the log records)agent/turn-continuation— override the continue/stop decision (force-continue /loop, force-stop budget guard)
Streaming + tool (emit)
agent/stream-chunk— raw chunk from the model (token-level UI/log feed)agent/steering— steering content injected mid-turnagent/error— step/turn error
Agent interface (types.ts)
The handle every plugin programs against:
agent.send(content, options?)— queue a message; starts a turn when idleagent.steer(content, options?)— steer a running turn (inject between steps); behaves likesendwhen idleagent.inject(content, options?)— inject in-session context without triggering a turn (context/message event); next request sees itagent.abort(reason?)— abort the in-flight stepagent.session,agent.status,agent.options,agent.id
Extension points
- Agent creation:
AgentLoop.create()is the concrete implementation (indsh-agent-loop). Replace the loop by implementingAgentand registering viactx.agents.register(). - Event listeners: all
agent/*events are declared here — no dependency on the loop package needed.
What is NOT here (TODO)
- Sub-agent spawn/fork — seam on
AgentLoop.create(), semantics deferred.