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

530 lines
25 KiB
TypeScript

/**
* THE concrete agent plugin: creates ReactLoopAgents, runs their loops, and
* registers them in ctx.agents. Deliberately thin — every behavior beyond
* "call the model, run the tools, repeat" belongs to plugins on the event
* taxonomy.
*
* @module @deepseek-ai/dsh-agent-loop
*/
import { Context, FiberState, Service } from 'cordis'
import { randomUUID } from 'node:crypto'
import z from 'schemastery'
import { createScope } from '@deepseek-ai/dsh-scope'
import type { Scope } from '@deepseek-ai/dsh-scope'
import { agentEvents } from '@deepseek-ai/dsh-agent'
import type { AgentFactory, AgentHandle, AgentId, AgentOptions, AgentRegistrationReservation, CreateAgentOptions, ResumeAgentOptions, SessionStartSource } from '@deepseek-ai/dsh-agent'
import type {} from '@deepseek-ai/dsh-llm'
import { SessionId, type SessionHeader } from '@deepseek-ai/dsh-session'
import type { Session, SessionRegistrationReservation } from '@deepseek-ai/dsh-session'
import type {} from '@deepseek-ai/dsh-system-prompt'
import type {} from '@deepseek-ai/dsh-tools'
import type { SessionPersistence } from '@deepseek-ai/dsh-session-persistence'
import { bindReactLoopAgentContext, prepareReactLoopAgent, ReactLoopAgent } from './agent.ts'
export { ReactLoopAgent } from './agent.ts'
/** Both unpublished identity capabilities held by one factory transaction. */
interface RegistrationReservations {
agent: AgentRegistrationReservation
session: SessionRegistrationReservation
release(): void
}
declare module 'cordis' {
interface Context {
agentLoop: AgentLoop
}
}
/**
* Plugin config: the agents to create — or resume, via `resumeSessionId` —
* declaratively at startup, so a cordis.yml deployment needs no code.
*/
export interface Config {
/** Agents created from configuration at startup. */
agents: (AgentOptions & {
/** Agent id to register under; also seeds the fresh per-run session id (`${id}-session-<uuid>`). */
id: AgentId
/** Optional workspace cwd for the config-created fresh session. */
cwd?: string
/**
* If set, the config agent RESUMES this persisted session id instead of
* starting a fresh `${id}-session-<uuid>`. Sourced from an env var in
* cordis.yml (`resumeSessionId: !!js process.env.RESUME_SESSION_ID`), so a
* demo can continue a prior conversation without code changes. Requires a
* `dsh-session-persistence` backend; the resume is deferred until that
* service is available (via `ctx.inject`) and the loaded session's events
* seed the live session so history continues.
*
* The schema accepts a plain string at runtime (cordis.yml values are
* untyped); the brand is compile-time only — the config format is the
* boundary where an id enters, so the TYPE declares the brand here.
*/
resumeSessionId?: SessionId
})[]
}
/**
* The agent-loop plugin (`ctx.agentLoop`): creates {@link ReactLoopAgent}s, runs
* their loops, and registers them in `ctx.agents`. Also implements the
* {@link AgentFactory} seam, so plugins create/resume agents through
* `ctx.agents` (the interface) without depending on this concrete package.
*
* The loop itself is deliberately thin — every behavior beyond "call the
* model, run the tools, repeat" belongs to plugins listening on the event
* taxonomy declared in @deepseek-ai/dsh-agent.
*/
export class AgentLoop extends Service implements AgentFactory {
static inject = ['agents', 'sessions', 'llm', 'tools', 'systemPrompt']
// The schema validates plain strings (cordis.yml config values are untyped at
// runtime); the {@link Config} TYPE declares the branded `id`/`resumeSessionId`
// because the config format is the boundary where an id enters. The brand is a
// zero-cost compile-time cast, so the runtime schema stays string-based and we
// assert the branded view once here — the single schema boundary.
static Config = z.object({
agents: z.array(z.object({
id: z.string().required(),
model: z.string(),
cwd: z.string(),
resumeSessionId: z.string(),
})).default([]),
}) as unknown as z<Config>
constructor(ctx: Context, public config: Config) {
super(ctx, 'agentLoop')
// Provide the agent-creation factory to the registry (effect-scoped: the
// slot is cleared on dispose).
ctx.effect(() => this.ctx.agents.setFactory(this), 'agentLoop.setFactory()')
// The prompt variables the shipped loop provides, registered once. The
// sections themselves (`harness:identity`, `deployment:persona`) belong to
// dsh-system-prompt — they must survive a swapped loop plugin — but
// `{{model}}`/`{{cwd}}` are runtime facts of the agents THIS loop drives:
// it assembles with `{ agent }` each step (loop.ts), and the variables
// project the agent's configured model and its session workspace from that
// context. A provider returns undefined when the fact is absent
// (renderPrompt then rejects a persona that claims it — fail loud).
ctx.systemPrompt.variable('model', context => context.agent?.options.model)
ctx.systemPrompt.variable('cwd', context => context.agent?.session.header.cwd)
for (const { id, cwd, resumeSessionId, ...options } of config.agents) {
if (resumeSessionId !== undefined && resumeSessionId !== '') {
// Resume a prior session instead of starting fresh. resume() needs
// `ctx.sessionPersistence`, which may load AFTER this plugin (cordis.yml
// lists the backend later). `ctx.inject(['sessionPersistence'], cb)`
// runs `cb` with a child ctx once the service exists; the child reads
// the persistence and hands it to resumeWith (which uses this.ctx — the
// parent — for sessions/registry, all in AgentLoop's static inject). A
// failed resume is contained + logged: startup must not crash.
ctx.effect(() => {
const fiber = this.ctx.inject(['sessionPersistence'], (childCtx: Context) => {
void this.resumeWith(childCtx.sessionPersistence, { agentId: id, resumeSessionId, agentOptions: options })
.catch((error: unknown) => {
this.ctx.logger.warn(`agent "${id}": config-driven resume of "${resumeSessionId}" failed: ${String(error)}`)
})
})
// Return the EXACT child-fiber disposer. Cordis moves a returned
// effect into this labeled owner's teardown tree by function
// identity; a wrapper would leave the child as a concurrent sibling
// and could discard its async quiescence promise.
return fiber.dispose
}, `agentLoop.resume(${id})`)
} else {
this.create(id, options, cwd === undefined ? {} : { cwd })
}
}
}
/**
* Config-driven create: an agent on a FRESH, non-colliding session id per run
* (`${id}-session-<uuid>`). Used for `cordis.yml`-configured agents and as
* the shared core for the programmatic factory {@link createAgent}.
*
* Why a per-run id, not a fixed `${id}-session`: once a durable persistence
* backend is loaded, a fixed id collides on the second run — the backend
* refuses to re-create an id whose log already exists on disk (the SessionId
* is the identity). A fresh id means each run is a new session.
*
* TODO(demo): each run starting a brand-new session is fine for demos but is
* NOT real conversation continuity. A production config-driven agent needs a
* deliberate resume-or-create policy (resume the prior session if one exists,
* else start fresh) or an explicit caller-chosen session id — revisit when the
* UI/ACP path owns session selection.
* @param id - the agent id; also seeds the generated session id.
* @param options - loop options (model, limits, …); defaults applied per option.
* @param meta - optional session metadata for the fresh session.
* @returns the running agent, owned by the calling fiber (no handle).
*/
create(id: AgentId, options: AgentOptions = {}, meta: Pick<SessionHeader, 'cwd'> = {}): ReactLoopAgent {
const sessionId = SessionId(`${id}-session-${randomUUID()}`)
const reservations = this.reserve(id, sessionId)
// Config/programmatic path: prepare the session and let start() fold its
// lifecycle into the agent's composite effect (so a fiber unload tears the
// session + agent down as one ordered chain, capturing the loop's closing
// flush). The whole effect is owned by THIS fiber; no AgentHandle is needed.
try {
const session = reservations.session.prepare({ meta })
const { agent } = this.start(id, options, session, 'startup', reservations)
return agent
} finally {
reservations.release()
}
}
/**
* Programmatic factory create ({@link AgentFactory}): an agent on a
* caller-supplied `sessionId` (NOT `${id}-session`), with optional session
* metadata (validated `cwd`, lineage) and an optional `seed` event prefix. The
* ACP bridge uses this so the client-generated session id becomes the
* live/persisted session id; the in-process FORK subagent backend passes a
* `seed` (a balanced completed-turn prefix of the parent's log) so the child
* starts with the parent's context. Returns an {@link AgentHandle} the owner
* disposes to tear down exactly this agent.
* @param options - agent id, caller-supplied session id, optional seed/meta,
* and agent options.
* @returns the handle whose dispose tears down exactly this agent.
*/
async createAgent(options: CreateAgentOptions): Promise<AgentHandle> {
// Snapshot every caller-owned field before the first async setup boundary.
// The callback itself is an identity capability. Agent options detach here;
// seed and metadata stay raw only until sessions.prepare() synchronously
// reads, validates, and detaches them, so structuredClone cannot erase an
// exotic prototype before the session boundary sees it.
const agentId = options.agentId
const sessionId = options.sessionId
const setup = options.setup
const agentOptions = structuredClone(options.agentOptions ?? {})
const seed = options.seed
const meta = options.meta
const reservations = this.reserve(agentId, sessionId)
try {
const session = reservations.session.prepare({
...seed !== undefined ? { seed } : {},
...meta !== undefined ? { meta } : {},
})
// A seeded (forked) create is still a fresh start, NOT a resume.
return await this.startOwned(agentId, agentOptions, session, 'startup', reservations, setup)
} finally {
reservations.release()
}
}
/**
* Resume an agent on a persisted session ({@link AgentFactory}). Loads the
* session log + metadata via `ctx.sessionPersistence`, reconstructs the live
* session with the loaded events (so `lastTurnNumber`/`deriveMessages`
* continue), and starts a fresh agent on it. The live session id is the
* resumed id, NOT `${agentId}-session`.
*
* Requires `ctx.sessionPersistence`; rejects with a clear error if it is not
* configured. NOT hard-injected (that would make non-persistent demos pend
* forever) — callers that need resume (ACP) inject `sessionPersistence`, so
* by the time this runs the service exists.
* @param options - the persisted session id to reload, plus agent id/options.
* @returns the handle for the agent resumed on the reconstructed session.
*/
async resume(options: ResumeAgentOptions): Promise<AgentHandle> {
// Read the service through `ctx.get('sessionPersistence')` — a direct
// global-store lookup keyed by the isolate symbol — NOT
// `this.ctx.sessionPersistence`. AgentLoop deliberately does NOT inject
// `sessionPersistence` (injecting it would pend non-persistent demos
// forever). The `ctx.<name>` property proxy resolves a service by an
// ancestor-only walk of the current fiber's parent chain; from AgentLoop's
// own fiber (which lacks the inject) that walk never reaches the sibling
// backend fiber and throws "cannot get property … without inject". Worse,
// when the call arrives via a traceable shadow (e.g. the ACP bridge child
// fiber → `ctx.agents.resume()` → `this.factory.resume()`), the walk starts
// at the shadow's origin fiber and fails the same way. `ctx.get(name)`
// sidesteps the fiber walk entirely (a store lookup by the global isolate
// key), so resume works from any caller fiber. It is strict by default: a
// backend that is not ACTIVE (absent, or mid-teardown) reads as undefined
// and we reject below, rather than handing back an unusable handle.
const persistence = this.ctx.get('sessionPersistence')
if (persistence === undefined) {
throw new Error('cannot resume: session persistence is not configured (load a dsh-session-persistence backend)')
}
return this.resumeWith(persistence, options)
}
/**
* Resume against an EXPLICIT persistence handle. Factored out of {@link resume}
* so the config-driven path can pass the handle it obtained from a
* `ctx.inject(['sessionPersistence'], …)` child context: `this.ctx` (the
* service's own fiber) did not inject `sessionPersistence`, so reading it
* there from inside the inject child trips the cordis inject guard. The
* sessions store + registry are still read through `this.ctx` (both are in
* AgentLoop's static inject, so they resolve fine).
*/
private async resumeWith(persistence: SessionPersistence, options: ResumeAgentOptions): Promise<AgentHandle> {
// Persistence is an async trust boundary. Reserve, load, reconstruct, and
// publish only the identities/options accepted at entry—never fields
// reread from a caller-owned object after the await.
const agentId = options.agentId
const sessionId = options.resumeSessionId
const agentOptions = structuredClone(options.agentOptions ?? {})
const setup = options.setup
const { promise: ownerDisposed, resolve: markOwnerDisposed } = Promise.withResolvers<void>()
const { promise: transactionSettled, resolve: markTransactionSettled } = Promise.withResolvers<void>()
let observingOwner = true
// Resume must observe its caller from BEFORE persistence I/O begins. The
// full agent lifecycle does not exist until load returns, so without this
// sentinel a never-settling backend outlives owner disposal and holds both
// public identities forever. `this.ctx.effect` retains the traceable caller
// ownership used by startOwned's lifecycle effect. Install it before even
// reserving the ids: an inactive owner cannot leak a reservation if effect
// registration fails.
const disposeLoadSentinel = this.ctx.effect(() => () => {
if (!observingOwner) return
markOwnerDisposed()
// Owner-triggered teardown does not reach quiescence until the resume
// transaction has observed disposal and released both reservations.
return transactionSettled
}, `agentLoop.resumeLoad(${agentId})`)
try {
const reservations = this.reserve(agentId, sessionId)
try {
const loadTask = persistence.load(sessionId)
const { meta, events } = await Promise.race([
loadTask,
ownerDisposed.then(() => {
throw new Error(`agent "${agentId}" resume aborted: owner disposed during persistence load`)
}),
])
// The backend is an async boundary too. Read each loaded header field
// once so a stateful implementation cannot pass a valid presence check
// and then substitute a different value during reconstruction.
const createdAt = meta.createdAt
const cwd = meta.cwd
const parentSession = meta.parentSession
const seedLength = meta.seedLength
// An out-of-band direct registry/session insertion can still race this
// service's reservation, so the public enter primitives re-check exact
// liveness at publication.
const session = reservations.session.prepare({
seed: events,
meta: {
createdAt,
...cwd !== undefined ? { cwd } : {},
...parentSession !== undefined ? { parentSession } : {},
...seedLength !== undefined ? { seedLength } : {},
},
})
// Calling startOwned synchronously installs the complete lifecycle
// effect before it reaches its first setup await. Only then disarm the
// load sentinel: ownership passes directly from one effect to the other
// with no disposal gap.
const starting = this.startOwned(agentId, agentOptions, session, 'resume', reservations, setup)
observingOwner = false
await disposeLoadSentinel()
return await starting
} finally {
reservations.release()
}
} finally {
try {
// Manual handoff/removal must not return transactionSettled: awaiting
// that promise from inside this transaction would deadlock it. If the
// owner already triggered cleanup, this idempotent second disposal is a
// no-op and the owner's first cleanup remains parked on the shared
// settlement promise.
observingOwner = false
await disposeLoadSentinel()
} finally {
markTransactionSettled()
}
}
}
/** Reserve both public identities in their owning registries. */
private reserve(agentId: AgentId, sessionId: SessionId): RegistrationReservations {
const agent = this.ctx.agents.reserve(agentId)
try {
const session = this.ctx.sessions.reserve(sessionId)
return {
agent,
session,
release() {
// Both owner capabilities are independently idempotent, so the
// composite needs no second state machine of its own.
session.release()
agent.release()
},
}
} catch (error: unknown) {
agent.release()
throw error
}
}
/**
* Construct an unpublished agent and synchronously install its complete
* teardown skeleton before any setup await. The closures are assigned their
* session/registry/loop disposers only at publication, while the exact scope
* disposer is nested immediately. Therefore owner unload during setup flips
* `active`, unwinds the scope, and wins the race without any late Cordis
* effect collection.
*/
private prepareLifecycle(
id: AgentId,
options: AgentOptions,
session: Session,
reservations: RegistrationReservations,
): {
agent: ReactLoopAgent
active: () => boolean
deactivated: Promise<void>
publish: (source: SessionStartSource) => void
disposeAgent: () => Promise<void>
} {
// When creation is invoked through an agent scope (subagents), the owner
// agent's disposed status flips synchronously at handle teardown—earlier
// than Cordis reaches nested scope effects. Include that signal in the
// pre-publication liveness check so a same-turn parent dispose cannot race
// an already-fulfilled setup promise into briefly publishing a child.
const ownerAgent = this.ctx.agent
const ownerFiber = this.ctx.fiber
const driver = prepareReactLoopAgent(this.ctx, id, options, session)
const { agent } = driver
const scope: Scope = createScope(this.ctx, agent)
bindReactLoopAgentContext(agent, scope.ctx.extend({ agent }))
let active = true
let detachSession: (() => void) | undefined
let detachAgent: (() => void) | undefined
let stop: (() => Promise<void>) | undefined
const { promise: deactivated, resolve: markDeactivated } = Promise.withResolvers<void>()
const { promise: torndown, resolve: markTorndown } = Promise.withResolvers<void>()
const dispose = this.ctx.effect(function* () {
// First yielded, disposed last: every preceding teardown stage settled.
yield () => { markTorndown() }
// Exact identity moves the scope fiber out of the owner's concurrent
// sibling list and into this ordered transaction.
yield scope.rawDispose
yield () => {
detachSession?.()
detachSession = undefined
}
yield () => {
detachAgent?.()
detachAgent = undefined
}
// Last yielded, disposed first. Keep the pre-publication path
// synchronous: returning a Promise only after the loop actually began
// lets a failed announcement roll back registry/store before create's
// rejection is observed.
yield () => {
active = false
markDeactivated()
if (stop === undefined) return
return stop()
}
}, 'agentLoop.lifecycle()')
let disposing: Promise<void> | undefined
const disposeAgent = (): Promise<void> => (disposing ??= (async () => {
await dispose()
await torndown
})())
const publish = (source: SessionStartSource): void => {
// Publication is one synchronous, rollback-covered sequence. Setup has
// already completed, so its scoped listeners observe both announcements.
detachSession = agent.ctx.sessions.enter(session, reservations.session)
detachAgent = this.ctx.agents.enter(agent, reservations.agent)
this.ctx.sessions.announce(session)
this.ctx.agents.announce(agent)
// Setup is over and both entries are live. Open the driving surface just
// before session-start so its listeners retain their supported ability to
// inject/queue, while setup itself can never drive an unpublished agent.
driver.enableDrive()
agentEvents(this.ctx, agent).emit('agent/session-start', source)
stop = driver.startDriver()
}
return {
agent,
active: () => active
&& ownerFiber.state !== FiberState.UNLOADING
&& ownerFiber.state !== FiberState.DISPOSED
&& ownerFiber.state !== FiberState.FAILED
&& ownerAgent?.status !== 'disposed',
deactivated,
publish,
disposeAgent,
}
}
/** Publish a no-setup config agent synchronously. */
private start(
id: AgentId,
options: AgentOptions,
session: Session,
source: SessionStartSource,
reservations: RegistrationReservations,
): { agent: ReactLoopAgent; disposeAgent: () => Promise<void> } {
const lifecycle = this.prepareLifecycle(id, options, session, reservations)
try {
lifecycle.publish(source)
return { agent: lifecycle.agent, disposeAgent: lifecycle.disposeAgent }
} catch (error: unknown) {
void lifecycle.disposeAgent()
throw error
}
}
/**
* Build an {@link AgentHandle} for a PREPARED session + a fresh agent. The
* handle's `dispose()` runs the composite effect's disposer (see
* {@link start}) — which stops the loop, awaits its exit and outstanding
* idle-injection flushes, unregisters the agent, and detaches the session, in
* that order.
* The same composite effect is what a fiber unload disposes, so both teardown
* triggers honor the ordering identically.
*
* `dispose()` is MEMOIZED: the underlying cordis effect disposer is
* single-shot (a second call returns immediately because the effect's epoch is
* already cleared, NOT awaiting the in-flight teardown), so concurrent/repeated
* `dispose()` calls would otherwise resolve before the first call's
* loop + flush quiescence boundary completed. Memoizing the promise makes
* every caller observe that SAME boundary, honoring the
* `AgentHandle.dispose(): Promise<void>` contract (mirrors the ACP `quiesce()`
* helper).
*/
private async startOwned(
id: AgentId, options: AgentOptions, session: Session, source: SessionStartSource,
reservations: RegistrationReservations,
setup?: (agentCtx: Context) => Promise<void> | void,
): Promise<AgentHandle> {
const lifecycle = this.prepareLifecycle(id, options, session, reservations)
try {
// The owner-disposal branch makes a never-settling setup unable to hold
// the transaction or its ID reservations forever. Promise.race installs
// rejection observation on setup even if owner disposal wins first.
const setupTask = Promise.resolve(setup?.(lifecycle.agent.ctx))
await Promise.race([
setupTask,
lifecycle.deactivated.then(() => {
throw new Error(`agent "${id}" setup aborted: owner disposed during setup`)
}),
])
// Cordis begins a fiber unload synchronously but invokes nested effect
// disposers from its next microtask. Give that already-started unload one
// checkpoint to deactivate this lifecycle before publication; otherwise
// an immediately fulfilled setup continuation can outrun its owner's
// same-turn dispose and briefly publish an already-doomed child.
await Promise.resolve()
if (!lifecycle.active()) {
throw new Error(`agent "${id}" setup aborted: owner disposed during setup`)
}
lifecycle.publish(source)
return { agent: lifecycle.agent, dispose: lifecycle.disposeAgent }
} catch (error: unknown) {
await lifecycle.disposeAgent()
throw error
}
}
}
export default AgentLoop