Files
deepseek-harness/packages/core/agent/src/dispatch.ts
T

123 lines
5.8 KiB
TypeScript

/**
* Agent-scoped dispatch and prompt assembly helpers. Ordinary events use the
* fused dispatcher so subject and scope key cannot diverge; registry lifecycle
* code instead captures one stable carrier for both edges.
* @module @deepseek-ai/dsh-agent/dispatch
*/
import type { Context, Events } from 'cordis'
import { scopeTarget } from '@deepseek-ai/dsh-scope'
import type { Scoped } from '@deepseek-ai/dsh-scope'
import type { AssembleContext } from '@deepseek-ai/dsh-system-prompt'
import type { Agent } from './types.ts'
/** Extract the parameter tuple from an event handler type (its `this` is not part of the tuple). */
type Params<F> = F extends (...args: infer P) => unknown ? P : never
/** Extract the return type from an event handler type. */
type Return<F> = F extends (...args: never[]) => infer R ? R : never
/**
* The event names whose subject is an agent: handler parameters start with an
* `Agent` AND the handler declares a `Scoped<Agent>` `this` (the scope-carrier
* contract). The `this` check keeps accidental first-parameter-happens-to-be-
* an-Agent events (or zero-arg events, whose parameter tuple would satisfy a
* bare rest-tuple check via callability) out of the fused-dispatch surface.
*/
export type AgentSubjectEvent = {
[K in keyof Events]: Events[K] extends (this: Scoped<Agent>, ...args: infer P) => unknown
? P extends [Agent, ...unknown[]] ? K : never
: never
}[keyof Events]
/** The event arguments AFTER the injected agent subject. */
type Tail<K extends AgentSubjectEvent> = Params<Events[K]> extends [Agent, ...infer R] ? R : never
/**
* The fused dispatcher {@link agentEvents} returns: each method dispatches the
* named agent-subject event with the agent's scope carrier as `thisArg` and
* the agent itself injected as the first event argument.
*/
export interface AgentEventDispatch {
/**
* Fire-and-forget notification in the agent's scope. Every listener is
* invoked; synchronous throws and returned-promise rejections are logged and
* contained per listener, so a notification cannot veto lifecycle progress
* or starve a later observer.
* @param name - the agent-subject event to emit.
* @param rest - the event's arguments after the injected agent.
*/
emit<K extends AgentSubjectEvent>(name: K, ...rest: Tail<K>): void
/**
* Awaited in-order dispatch (Cordis `serial`) in the agent's scope.
* @param name - the agent-subject event to dispatch.
* @param rest - the event's arguments after the injected agent.
* @returns the serial chain's result (the first bail value, if any).
*/
serial<K extends AgentSubjectEvent>(name: K, ...rest: Tail<K>): Promise<Awaited<Return<Events[K]>>>
/**
* Around-middleware dispatch (Cordis `waterfall`) in the agent's scope. The
* declared event parameters already end with the `next` callback, so `rest`
* is exactly the event's arguments after the injected agent — the final
* element being the innermost `next` (the default the listener chain wraps).
* @param name - the agent-subject event to dispatch.
* @param rest - the event's arguments after the injected agent.
* @returns the waterfall's composed result.
*/
waterfall<K extends AgentSubjectEvent>(name: K, ...rest: Tail<K>): Return<Events[K]>
}
/**
* Build a dispatcher that couples the agent subject to its scope carrier.
* @param ctx - the context to dispatch through (any context of the app).
* @param agent - the subject agent; also the scope-carrier key.
* @returns the fused dispatcher.
*/
export function agentEvents(ctx: Context, agent: Agent): AgentEventDispatch {
const carrier: Scoped<Agent> = scopeTarget(agent, agent)
// The ordinary dispatch methods forward through Cordis' variadic mixins. The
// fused (carrier, name, agent, ...rest) tuple is provably a valid argument
// list for the matching thisArg overload, but TypeScript cannot relate the
// generic Tail<K> spread back to that overload's conditional parameter
// tuple — hence one contained, shape-preserving cast per method.
return {
emit(name, ...rest) {
// Cordis emit invokes callbacks through Array.map: one synchronous throw
// starves later listeners, and returned promises are discarded. Agent
// notifications are non-vetoing, so resolve the same filtered callback
// set ourselves and contain both failure modes independently.
const args: unknown[] = [carrier, name, agent, ...rest]
const callbacks = ctx.events.dispatch('emit', args)
for (const callback of callbacks) {
try {
const returned: unknown = callback(...args)
void Promise.resolve(returned).catch((error: unknown) => {
ctx.logger.warn(`agent event "${name}" listener rejected: ${String(error)}`)
})
} catch (error: unknown) {
ctx.logger.warn(`agent event "${name}" listener threw: ${String(error)}`)
}
}
},
async serial(name, ...rest) {
// eslint-disable-next-line @typescript-eslint/unbound-method -- the events mixin accessor returns a pre-bound function
const serial = ctx.serial as (thisArg: Scoped<Agent>, name: string, ...args: unknown[]) => Promise<never>
return await serial(carrier, name, agent, ...rest)
},
waterfall(name, ...rest) {
// eslint-disable-next-line @typescript-eslint/unbound-method -- the events mixin accessor returns a pre-bound function
const waterfall = ctx.waterfall as (thisArg: Scoped<Agent>, name: string, ...args: unknown[]) => never
return waterfall(carrier, name, agent, ...rest)
},
}
}
/**
* Build the prompt assembly context with agent and scope set together, so
* agent-scoped prompt and tool contributions cannot be silently omitted.
* @param agent - the agent the assembly is for.
* @returns the context to pass to `assemble()`.
*/
export function assembleContextFor(agent: Agent): AssembleContext {
return { agent, scope: agent }
}