Activity kinds reference

cli

Runs a shell command or external binary.

Template:

import { step } from '@cori-do/sdk';
import { z } from 'zod';

export const input = z.object({
  // define step inputs
});

export const output = z.object({
  // define step outputs
});

export default step.cli({
  description: 'What this step does',
  command: ({ input }) => `your-binary --flag ${input.some_value}`,
  parse_output: (stdout) => ({
    // parse stdout into output shape
  }),
});

Rules:

• Declare the binary in the manifest's tools_required. Validated at cori check time.
• If the binary is not found on PATH, run cori status to check the worker's environment.
• Default retry: 1 attempt (transient failures are not automatically retried).
• Default per-attempt timeout: 60 seconds.

mcp_tool

Calls a tool on an MCP server.

Template:

import { step } from '@cori-do/sdk';
import { z } from 'zod';

export const input = z.object({
  // define step inputs
});

export const output = z.object({
  // define step outputs
});

export default step.mcp_tool({
  description: 'What this step does',
  server: 'server-name',   // must match mcp_servers in manifest
  tool: 'tool_name',
  args: ({ input }) => ({
    // tool arguments
  }),
  parse_output: (result) => ({
    // parse MCP result into output shape
  }),
});

Rules:

• Declare the MCP server in the manifest's mcp_servers. Validated at cori check time.
• Default retry: 1 attempt.
• Default per-attempt timeout: 60 seconds.

code

Pure TypeScript computation with no I/O.

Template:

import { step } from '@cori-do/sdk';
import { z } from 'zod';

export const input = z.object({
  // define step inputs
});

export const output = z.object({
  // define step outputs
});

export default step.code({
  description: 'What this step does',
  run: ({ input }) => {
    // pure computation — no network, no filesystem, no shell
    return {
      // output shape
    };
  },
});

Rules:

• Default retry: 3 attempts.
• Default per-attempt timeout: 30 seconds.

What a code step may import. Steps run in a Deno subprocess launched with a fixed import map containing exactly two entries — @cori-do/sdk and zod — resolved against that map, never against any node_modules.

• Default: import only @cori-do/sdk, zod, and JS/Web/Deno globals that need no import (JSON, Intl, Date, Math, Map/Set, structuredClone, TextEncoder, crypto.subtle, URL, …). Most pure transforms need nothing more.
• node:* imports are forbidden — cori check rejects them with a hard error, and the sandbox lacks the permissions those modules want.
• Need a third-party library? Use an explicit registry specifier, not a bare name: npm:<pkg>@<ver>, jsr:<scope>/<pkg>, or https://esm.sh/<pkg>@<ver>. The package must be pure JS/Wasm — native addons or anything touching node:fs/net/child_process fails under the sandbox. A bare import _ from 'lodash' does not work; it must be import _ from 'npm:lodash@4'. Testing with deno test catches a bad bare import before runtime, because tests resolve against the same import map.

llm

Calls a language model with a prompt and parses the typed output.

Template:

import { step } from '@cori-do/sdk';
import { z } from 'zod';

export const input = z.object({
  // define step inputs
});

export const output = z.object({
  // define step outputs — required for llm steps
});

export default step.llm({
  description: 'What this step does',
  model: 'gpt-4o-mini',
  prompt: ({ input }) => `Your prompt here. Data: ${JSON.stringify(input)}`,
  output_schema: output,
  // optional:
  system: 'You are a helpful assistant.',
});

Rules:

• output_schema is required. LLM steps must declare a typed output.
• Use llm only for content that varies at runtime (translation, classification, extraction).
• Provider credentials are configured at the worker level, not in the step file.
• Default retry: 3 attempts.
• Default per-attempt timeout: 300 seconds.

builtin — deferred in v1

The builtin constructors provide workflow-level control flow:

These will be executable in a future version of Cori.