Tianyi Cui
513ba2716d
Cordis effect disposers are single-shot but not await-idempotent: when the owning fiber's unload invokes the raw wrapper first, a concurrent handle.dispose() got an immediate undefined and resolved before teardown finished — violating the driver's stated one-boundary contract (Codex implementation-review finding). The teardown chain's FIRST-yielded (so disposed-last) disposer now resolves a shared completion promise; the handle path awaits it after the wrapper, so tool-finally, parent-teardown, and owner-unload all observe the same fully-torn-down state. Regression test: owner unload begins first, concurrent handle.dispose still awaits unregistration + session detach.
396 lines
21 KiB
TypeScript
396 lines
21 KiB
TypeScript
/**
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* THE concrete agent plugin: creates ReactLoopAgents, runs their loops, and
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* registers them in ctx.agents. Deliberately thin — every behavior beyond
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* "call the model, run the tools, repeat" belongs to plugins on the event
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* taxonomy.
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*
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* @module @deepseek-ai/dsh-agent-loop
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*/
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import { Context, Service } from 'cordis'
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import { randomUUID } from 'node:crypto'
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import z from 'schemastery'
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import { createScope } from '@deepseek-ai/dsh-scope'
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import { agentEvents } from '@deepseek-ai/dsh-agent'
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import type { AgentFactory, AgentHandle, AgentId, AgentOptions, CreateAgentOptions, ResumeAgentOptions, SessionStartSource } from '@deepseek-ai/dsh-agent'
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import type {} from '@deepseek-ai/dsh-llm'
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import { SessionId } from '@deepseek-ai/dsh-session'
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import type { Session } from '@deepseek-ai/dsh-session'
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import type {} from '@deepseek-ai/dsh-system-prompt'
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import type {} from '@deepseek-ai/dsh-tools'
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import type { SessionPersistence } from '@deepseek-ai/dsh-session-persistence'
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import { ReactLoopAgent } from './agent.ts'
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export { ReactLoopAgent } from './agent.ts'
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export { Inbox, type InboxMessage } from './inbox.ts'
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export { runLoop } from './loop.ts'
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declare module 'cordis' {
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interface Context {
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agentLoop: AgentLoop
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}
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}
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/**
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* Plugin config: the agents to create — or resume, via `resumeSessionId` —
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* declaratively at startup, so a cordis.yml deployment needs no code.
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*/
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export interface Config {
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/** Agents created from configuration at startup. */
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agents: (AgentOptions & {
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/** Agent id to register under; also seeds the fresh per-run session id (`${id}-session-<uuid>`). */
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id: AgentId
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/**
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* If set, the config agent RESUMES this persisted session id instead of
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* starting a fresh `${id}-session-<uuid>`. Sourced from an env var in
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* cordis.yml (`resumeSessionId: !!js process.env.RESUME_SESSION_ID`), so a
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* demo can continue a prior conversation without code changes. Requires a
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* `dsh-session-persistence` backend; the resume is deferred until that
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* service is available (via `ctx.inject`) and the loaded session's events
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* seed the live session so history continues.
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*
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* The schema accepts a plain string at runtime (cordis.yml values are
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* untyped); the brand is compile-time only — the config format is the
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* boundary where an id enters, so the TYPE declares the brand here.
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*/
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resumeSessionId?: SessionId
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})[]
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}
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/**
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* The agent-loop plugin (`ctx.agentLoop`): creates {@link ReactLoopAgent}s, runs
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* their loops, and registers them in `ctx.agents`. Also implements the
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* {@link AgentFactory} seam, so plugins create/resume agents through
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* `ctx.agents` (the interface) without depending on this concrete package.
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*
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* The loop itself is deliberately thin — every behavior beyond "call the
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* model, run the tools, repeat" belongs to plugins listening on the event
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* taxonomy declared in @deepseek-ai/dsh-agent.
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*/
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export class AgentLoop extends Service implements AgentFactory {
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static inject = ['agents', 'sessions', 'llm', 'tools', 'systemPrompt']
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// The schema validates plain strings (cordis.yml config values are untyped at
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// runtime); the {@link Config} TYPE declares the branded `id`/`resumeSessionId`
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// because the config format is the boundary where an id enters. The brand is a
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// zero-cost compile-time cast, so the runtime schema stays string-based and we
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// assert the branded view once here — the single schema boundary.
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static Config = z.object({
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agents: z.array(z.object({
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id: z.string().required(),
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model: z.string(),
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resumeSessionId: z.string(),
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})).default([]),
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}) as unknown as z<Config>
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constructor(ctx: Context, public config: Config) {
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super(ctx, 'agentLoop')
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// Provide the agent-creation factory to the registry (effect-scoped: the
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// slot is cleared on dispose).
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ctx.effect(() => this.ctx.agents.setFactory(this), 'agentLoop.setFactory()')
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// The prompt variables the shipped loop provides, registered once. The
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// sections themselves (`harness:identity`, `deployment:persona`) belong to
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// dsh-system-prompt — they must survive a swapped loop plugin — but
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// `{{model}}`/`{{cwd}}` are runtime facts of the agents THIS loop drives:
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// it assembles with `{ agent }` each step (loop.ts), and the variables
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// project the agent's configured model and its session workspace from that
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// context. A provider returns undefined when the fact is absent
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// (renderPrompt then rejects a persona that claims it — fail loud).
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ctx.systemPrompt.variable('model', context => context.agent?.options.model)
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ctx.systemPrompt.variable('cwd', context => context.agent?.session.header.cwd)
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for (const { id, resumeSessionId, ...options } of config.agents) {
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if (resumeSessionId !== undefined && resumeSessionId !== '') {
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// Resume a prior session instead of starting fresh. resume() needs
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// `ctx.sessionPersistence`, which may load AFTER this plugin (cordis.yml
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// lists the backend later). `ctx.inject(['sessionPersistence'], cb)`
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// runs `cb` with a child ctx once the service exists; the child reads
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// the persistence and hands it to resumeWith (which uses this.ctx — the
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// parent — for sessions/registry, all in AgentLoop's static inject). A
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// failed resume is contained + logged: startup must not crash.
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ctx.effect(() => {
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const fiber = this.ctx.inject(['sessionPersistence'], (childCtx: Context) => {
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void this.resumeWith(childCtx.sessionPersistence, { agentId: id, resumeSessionId, agentOptions: options })
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.catch((error: unknown) => {
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this.ctx.logger.warn(`agent "${id}": config-driven resume of "${resumeSessionId}" failed: ${String(error)}`)
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})
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})
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return () => void fiber.dispose()
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}, `agentLoop.resume(${id})`)
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} else {
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this.create(id, options)
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}
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}
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}
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/**
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* Config-driven create: an agent on a FRESH, non-colliding session id per run
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* (`${id}-session-<uuid>`, no cwd). Used for `cordis.yml`-configured agents
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* and as the shared core for the programmatic factory {@link createAgent}.
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*
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* Why a per-run id, not a fixed `${id}-session`: once a durable persistence
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* backend is loaded, a fixed id collides on the second run — the backend
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* refuses to re-create an id whose log already exists on disk (the SessionId
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* is the identity). A fresh id means each run is a new session.
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*
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* TODO(demo): each run starting a brand-new session is fine for demos but is
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* NOT real conversation continuity. A production config-driven agent needs a
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* deliberate resume-or-create policy (resume the prior session if one exists,
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* else start fresh) or an explicit caller-chosen session id — revisit when the
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* UI/ACP path owns session selection.
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* @param id - the agent id; also seeds the generated session id.
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* @param options - loop options (model, limits, …); defaults applied per option.
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* @returns the running agent, owned by the calling fiber (no handle).
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*/
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create(id: AgentId, options: AgentOptions = {}): ReactLoopAgent {
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this.assertAgentIdFree(id)
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// Config/programmatic path: prepare the session and let start() fold its
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// lifecycle into the agent's composite effect (so a fiber unload tears the
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// session + agent down as one ordered chain, capturing the loop's closing
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// flush). The whole effect is owned by THIS fiber; no AgentHandle is needed.
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const session = this.ctx.sessions.prepare(SessionId(`${id}-session-${randomUUID()}`), { meta: {} })
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const { agent } = this.start(id, options, session, 'startup')
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return agent
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}
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/**
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* Programmatic factory create ({@link AgentFactory}): an agent on a
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* caller-supplied `sessionId` (NOT `${id}-session`), with optional session
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* metadata (validated `cwd`, lineage) and an optional `seed` event prefix. The
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* ACP bridge uses this so the client-generated session id becomes the
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* live/persisted session id; the in-process FORK subagent backend passes a
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* `seed` (a balanced completed-turn prefix of the parent's log) so the child
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* starts with the parent's context. Returns an {@link AgentHandle} the owner
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* disposes to tear down exactly this agent.
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* @param options - agent id, caller-supplied session id, optional seed/meta,
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* and agent options.
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* @returns the handle whose dispose tears down exactly this agent.
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*/
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createAgent(options: CreateAgentOptions): AgentHandle {
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// Check the agent id BEFORE preparing the session: register() would reject a
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// duplicate id only AFTER the session enters the store, leaving an orphaned
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// live session (and lazy persistence state) that blocks reuse of that id.
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this.assertAgentIdFree(options.agentId)
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const session = this.ctx.sessions.prepare(options.sessionId, {
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...options.seed !== undefined ? { seed: options.seed } : {},
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meta: options.meta ?? {},
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})
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// A seeded (forked) create is still a fresh start, NOT a resume — `resume`
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// is reserved for reloading a PERSISTED session via resume()/resumeWith().
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return this.startOwned(options.agentId, options.agentOptions ?? {}, session, 'startup', options.setup)
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}
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/**
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* Resume an agent on a persisted session ({@link AgentFactory}). Loads the
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* session log + metadata via `ctx.sessionPersistence`, reconstructs the live
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* session with the loaded events (so `lastTurnNumber`/`deriveMessages`
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* continue), and starts a fresh agent on it. The live session id is the
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* resumed id, NOT `${agentId}-session`.
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*
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* Requires `ctx.sessionPersistence`; rejects with a clear error if it is not
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* configured. NOT hard-injected (that would make non-persistent demos pend
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* forever) — callers that need resume (ACP) inject `sessionPersistence`, so
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* by the time this runs the service exists.
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* @param options - the persisted session id to reload, plus agent id/options.
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* @returns the handle for the agent resumed on the reconstructed session.
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*/
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async resume(options: ResumeAgentOptions): Promise<AgentHandle> {
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// Read the service through `ctx.get('sessionPersistence')` — a direct
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// global-store lookup keyed by the isolate symbol — NOT
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// `this.ctx.sessionPersistence`. AgentLoop deliberately does NOT inject
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// `sessionPersistence` (injecting it would pend non-persistent demos
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// forever). The `ctx.<name>` property proxy resolves a service by an
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// ancestor-only walk of the current fiber's parent chain; from AgentLoop's
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// own fiber (which lacks the inject) that walk never reaches the sibling
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// backend fiber and throws "cannot get property … without inject". Worse,
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// when the call arrives via a traceable shadow (e.g. the ACP bridge child
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// fiber → `ctx.agents.resume()` → `this.factory.resume()`), the walk starts
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// at the shadow's origin fiber and fails the same way. `ctx.get(name)`
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// sidesteps the fiber walk entirely (a store lookup by the global isolate
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// key), so resume works from any caller fiber. It is strict by default: a
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// backend that is not ACTIVE (absent, or mid-teardown) reads as undefined
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// and we reject below, rather than handing back an unusable handle.
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const persistence = this.ctx.get('sessionPersistence')
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if (persistence === undefined) {
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throw new Error('cannot resume: session persistence is not configured (load a dsh-session-persistence backend)')
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}
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return this.resumeWith(persistence, options)
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}
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/**
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* Resume against an EXPLICIT persistence handle. Factored out of {@link resume}
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* so the config-driven path can pass the handle it obtained from a
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* `ctx.inject(['sessionPersistence'], …)` child context: `this.ctx` (the
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* service's own fiber) did not inject `sessionPersistence`, so reading it
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* there from inside the inject child trips the cordis inject guard. The
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* sessions store + registry are still read through `this.ctx` (both are in
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* AgentLoop's static inject, so they resolve fine).
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*/
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private async resumeWith(persistence: SessionPersistence, options: ResumeAgentOptions): Promise<AgentHandle> {
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this.assertAgentIdFree(options.agentId)
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const { meta, events } = await persistence.load(options.resumeSessionId)
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// Re-check the agent id AFTER the await: the pre-load check above can go
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// stale while load() is pending (a concurrent resume/create may register the
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// same id). Re-checking immediately before prepare()/start keeps the
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// "no orphaned session on a duplicate id" guarantee under concurrency.
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this.assertAgentIdFree(options.agentId)
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// Reconstruct the live session with the FULL persisted header (createdAt,
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// cwd, lineage) so resume preserves identity, not just the cwd. The seed
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// events make lastTurnNumber/deriveMessages continue; the backend already
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// has state (cursor) from the load above, so onCreated is a no-op and the
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// seed is not re-persisted. prepare() (not create()) so the session
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// lifecycle folds into the agent's composite effect (ordered teardown).
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const session = this.ctx.sessions.prepare(options.resumeSessionId, {
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seed: events,
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meta: {
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createdAt: meta.createdAt,
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...meta.cwd !== undefined ? { cwd: meta.cwd } : {},
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...meta.parentSession !== undefined ? { parentSession: meta.parentSession } : {},
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// Reconstruct the seed boundary from the persisted header, NOT from
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// `events.length` (the resume seeds the WHOLE stored log).
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...meta.seedLength !== undefined ? { seedLength: meta.seedLength } : {},
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},
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})
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return this.startOwned(options.agentId, options.agentOptions ?? {}, session, 'resume')
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}
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/**
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* Reject a duplicate agent id BEFORE the session is entered into the store, so
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* a failed factory call never leaves an orphaned live session (and lazy
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* persistence state) behind. `register()` enforces the same uniqueness, but
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* only after the session has already entered the store.
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*/
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private assertAgentIdFree(id: AgentId): void {
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if (this.ctx.agents.get(id) !== undefined) {
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throw new Error(`agent "${id}" is already registered`)
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}
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}
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/**
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* Shared: construct a ReactLoopAgent over a PREPARED (not-yet-entered)
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* session, then build the ONE composite effect that owns the whole agent
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* lifecycle — session entry, registry registration, and the loop. Keeping all
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* three in a SINGLE effect (not sibling effects) is load-bearing: a fiber
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* unload disposes sibling effects CONCURRENTLY (`Promise.all`), which would
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* race the session detach against the loop's closing flush and drop the
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* closing `turn/end`. Inside one effect the disposers run as an ORDERED LIFO
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* chain — the runtime awaits each disposer's returned promise before the next:
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*
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* yield session-detach (disposed LAST — detach onAppend + remove entry)
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* yield register (disposed 2nd — unregister)
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* yield stop-and-drain (disposed FIRST — request loop stop, await agent.done)
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*
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* So on teardown: the loop is stopped and AWAITED to exit (its final
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* `session/flush` + `turn/end` fire through the still-attached `onAppend`),
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* THEN the agent is unregistered, THEN the session is detached — capturing the
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* closing events before detach, whether the trigger is the handle's `dispose()`
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* OR a fiber unload. Rollback safety: each yield runs before the next mutation,
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* so a throwing `session/created`/`agent/created` listener unwinds the
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* already-yielded disposers instead of leaking.
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*
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* `source` says why the session began ({@link SessionStartSource}); it is
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* emitted as `agent/session-start` once, AFTER the agent is registered (so a
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* listener can resolve the agent via `ctx.agents.get(id)` and `inject()` into
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* it) and BEFORE the loop starts its first turn. The emit is contained: a
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* throwing session-start listener must not abort agent construction — it is
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* logged, and the agent still starts. (Unlike a turn-boundary throw, there is
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* no open turn here to balance; the durable evidence of a session-start hook
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* is whatever it `inject()`ed.)
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*
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* Returns the agent plus the composite effect's disposer (`disposeAgent`).
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*/
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private start(
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id: AgentId, options: AgentOptions, session: Session, source: SessionStartSource,
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setup?: (agentCtx: Context) => void,
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): { agent: ReactLoopAgent; disposeAgent: () => Promise<void> } {
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const agent = new ReactLoopAgent(this.ctx, id, options, session)
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// The ONE quiescence boundary every disposal path observes. Cordis effect
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// disposers are single-shot but not await-idempotent: when the OWNING
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// fiber's unload invokes the raw wrapper first, a concurrent
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// `handle.dispose()` calling the same wrapper gets an immediate undefined
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// (epoch already cleared) — so the handle path must await THIS promise,
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// resolved by the teardown chain's final disposer, not the wrapper's
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// return. Every disposer in the chain is deliberately infallible (stop()
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// is infallible by contract, unregister/detach contain their listeners,
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// the scope unwind is cordis-contained), so the final disposer always
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// runs — a throwing link would skip the rest of a cordis dispose chain.
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const { promise: torndown, resolve: markTorndown } = Promise.withResolvers<void>()
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const dispose = this.ctx.effect(function* (this: AgentLoop) {
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// First-yielded ⇒ disposed LAST: marks true teardown completion.
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yield () => { markTorndown() }
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// Mint the agent's scope (key = the agent) and wire the two-phase
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// reference: the scope context tags registrations + filters dispatch;
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// the extend adds the `ctx.agent` DX own-property on top. The raw
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// disposer is yielded IMMEDIATELY (exact function identity nests the
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// scope fiber out of the loop fiber's concurrent sibling list), so
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// there is no window in which a throw leaves the scope un-nested.
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//
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// Yield order is the REVERSE of teardown (LIFO). Teardown runs:
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// stop/drain → unregister → detach session → unwind scope
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// Detach BEFORE the scope unwind is deliberate: the scope fiber's
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// unload is asynchronous (fiber inertia), and every disposer chained
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// after an async one waits for it — detaching first keeps the
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// store/registry rollback SYNCHRONOUS on every failure path (a caller
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// that catches a throwing create() observes no half-created agent or
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// session, and the ids are immediately reusable), at the cost that a
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// scoped listener's own disposer runs after the session left the store
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// (it heard the final stop/drain flush while still attached, so
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// nothing durable is lost).
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const scope = createScope(this.ctx, agent)
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agent.ctx = scope.ctx.extend({ agent })
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yield scope.rawDispose
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// Enter the session THROUGH agent.ctx so the store captures the agent's
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// scope as the session's dispatch carrier.
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yield agent.ctx.sessions.enter(session)
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this.ctx.sessions.announce(session)
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yield this.ctx.agents.register(agent)
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// The creator's scoped composition, inside the rollback boundary: a
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// throwing setup unwinds LIFO through register → scope → detach, so a
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// half-created agent never leaks. Setup REGISTERS (through agent.ctx),
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// it never drives — see CreateAgentOptions.setup.
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setup?.(agent.ctx)
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// Fire AFTER register (a listener can ctx.agents.get(id) + inject()) and
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// BEFORE the loop's first turn. Contained: a throwing listener is logged,
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// never aborts construction (no open turn to balance here).
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try {
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agentEvents(this.ctx, agent).emit('agent/session-start', source)
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} catch (error: unknown) {
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this.ctx.logger.warn(`agent "${id}": agent/session-start listener threw: ${String(error)}`)
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}
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const stop = agent.start()
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// Disposed FIRST (LIFO): request loop stop (sync), then AWAIT the loop's
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// actual exit so its closing flush lands while onAppend (yielded above,
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// disposed later) is still attached.
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yield async () => { stop(); await agent.done }
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}.bind(this), 'agentLoop.start()')
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return { agent, disposeAgent: async () => { await dispose(); await torndown } }
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}
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/**
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* Build an {@link AgentHandle} for a PREPARED session + a fresh agent. The
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* handle's `dispose()` runs the composite effect's disposer (see
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* {@link start}) — which stops the loop, awaits its exit (final flush
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* captured), unregisters the agent, and detaches the session, in that order.
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* The same composite effect is what a fiber unload disposes, so both teardown
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* triggers honor the ordering identically.
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*
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* `dispose()` is MEMOIZED: the underlying cordis effect disposer is
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* single-shot (a second call returns immediately because the effect's epoch is
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* already cleared, NOT awaiting the in-flight teardown), so concurrent/repeated
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* `dispose()` calls would otherwise resolve before the first call's
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* `await agent.done` + final flush completed. Memoizing the promise makes every
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* caller observe the SAME quiescence boundary, honoring the
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|
* `AgentHandle.dispose(): Promise<void>` contract (mirrors the ACP `quiesce()`
|
|
* helper).
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|
*/
|
|
private startOwned(
|
|
id: AgentId, options: AgentOptions, session: Session, source: SessionStartSource,
|
|
setup?: (agentCtx: Context) => void,
|
|
): AgentHandle {
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|
const { agent, disposeAgent } = this.start(id, options, session, source, setup)
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|
let disposing: Promise<void> | undefined
|
|
return { agent, dispose: () => (disposing ??= disposeAgent()) }
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|
}
|
|
}
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|
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export default AgentLoop
|