Model the system / 03

Context-based lazy assembly

An agent definition is a composition of resolvers. Each resolver can return immediately or asynchronously, and can use the current instance, conversation, request, Glove message, history, installations, or run controls.

One resolver shape

agents/analyst/agent.tstypescript

export default defineAgent({
  model: (_agent, ctx) => modelFor(ctx.agentInstance, ctx.message),
  store: ({ conversationId }) => storeFor(conversationId),
  systemPrompt: (_agent, ctx) => buildPrompt(ctx),
  compactionLimit: (_agent, ctx) => ctx.messageText.length > 2_000 ? 80_000 : 40_000,
  tools: (_agent, ctx) => toolsFor(ctx.installations, ctx.message),
  memory: (_agent, ctx) => memoryFor(ctx.agentInstance, ctx.message),
  inboxes: (_agent, ctx) => loadInboxes(ctx.agentId, ctx.message),
  subagents: (_agent, ctx) => specialistsFor(ctx.message),
  playbooks: (_agent, ctx) => composePlaybooks(ctx.agentInstance, ctx.message),
  workingEnvironment: (_agent, ctx) => workspaceFor(ctx.workspaceId),
  repl: (_agent, ctx) => replFor(ctx.agentId, ctx.message),
});

A literal value is shorthand for a resolver that always returns that value. Use literals for stable pieces and functions wherever capability should depend on policy or the current message.

Colocate what changes together

agents/brand-leadtext

agent.ts
composition.ts
tools/
  brief.tool.ts
apps/
  campaign-manager.app.ts
transmissions/
  campaign-events.transmission.ts
memory/
  brand-context.memory.ts
inboxes/
  approvals.inbox.ts
layers/
  request-context.layer.ts
subscribers/
  run-audit.subscriber.ts
workbench.ts

Project-level folders are also valid for truly shared primitives. Import the same imageReview tool into several agent compositions; Foundry assembles and names the definition from its route without requiring copied IDs.

Compose values, not registries

agents/brand-lead/composition.tstypescript

import { composeAgent } from "glove-foundry";
import imageReview from "../../tools/image-review.tool.js";
import brandMemory from "./memory/brand-context.memory.js";
import workspaceLayer from "./layers/workspace.layer.js";

export const components = composeAgent(
  imageReview,
  brandMemory,
  workspaceLayer,
);

Custom handlers and calls

Definitions are not required to assemble a model loop. A file may export a typed custom run handler for deterministic work, and agents can expose typed calls for other agents or application code. Zod infers inputs and outputs; ESLint and TypeScript enforce the framework conventions.

Effect at the runtime boundary

Discovery and authoring stay ergonomic TypeScript. Runtime services use Effect for typed failures, scoped resources, retries, concurrency, dependency layers, and interruption. Adapters can return Effects directly without leaking backend execution details into agent definitions.