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Comprehensive guide to Output.ai Framework for building durable, LLM-powered workflows orchestrated by Temporal. Covers project structure, workflow patterns, steps, LLM integration, HTTP clients, CLI commands, and the full inventory of available agents and skills.

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Output.ai Framework - Complete Project Context

What is Output.ai?

Output.ai provides infrastructure for building production-grade AI workflows: fact checkers, content generators, data extractors, research assistants, and multi-step agents. Built on Temporal, it guarantees durable execution - if execution fails mid-run, it resumes from the last successful step.

Core Philosophy

Separation of orchestration from I/O:

  • Workflows orchestrate execution (must be deterministic - no I/O)
  • Steps/Evaluators handle all I/O operations (HTTP, LLM, database calls)

This separation enables automatic retries, resumption, and debugging.

Component Taxonomy

ComponentPurposeKey Rule
WorkflowOrchestrates step executionMust be deterministic (no I/O, no Date.now(), no Math.random())
StepHandles all I/O operationsWhere HTTP, LLM, DB calls happen
EvaluatorQuality assessmentReturns confidence-scored results for validation loops
ScenarioTest input dataJSON files matching workflow's inputSchema
PromptLLM templatesLiquid.js templating with YAML frontmatter config
Eval TestOffline quality testingDataset-driven verification with verify() from @outputai/evals

Project Structure

config/
├── credentials.yml.enc          # Global encrypted credentials
├── credentials.key              # Global decryption key (DO NOT COMMIT)
└── credentials/                 # Environment-specific credentials
    ├── production.yml.enc
    └── production.key
src/
├── shared/                      # Shared code across workflows
│   ├── clients/                 # API clients (e.g., jina.ts, stripe.ts)
│   └── utils/                   # Utility functions (e.g., string.ts)
└── workflows/                   # Workflow definitions
    └── {workflow_name}/
        ├── workflow.ts          # Orchestration logic (deterministic)
        ├── steps.ts             # I/O operations
        ├── types.ts             # Zod schemas (input, output, internal)
        ├── evaluators.ts        # Quality checks (optional)
        ├── utils.ts             # Local utilities (optional)
        ├── credentials.yml.enc  # Workflow-specific credentials (optional)
        ├── prompts/             # LLM templates (optional)
        │   └── generate@v1.prompt
        ├── scenarios/           # Test inputs (optional)
        │   └── happy_path.json
        └── tests/               # Offline eval tests (optional)
            ├── datasets/        # YAML test datasets
            │   └── happy_path.yml
            └── evals/           # Eval evaluators and workflow
                ├── evaluators.ts
                └── workflow.ts

Code Reuse Rules

Shared directory (src/shared/):

  • shared/clients/ - API clients using @outputai/http for external services
  • shared/utils/ - Helper functions and utilities

Allowed imports:

  • Workflows/steps can import from ../../shared/clients/*.js and ../../shared/utils/*.js
  • Workflows/steps can import from local files (./types.js, ./utils.js)

Forbidden:

  • Importing from sibling workflow folders (../other_workflow/steps.js)
  • Steps importing other steps (activity isolation requirement)

Critical Rules

RuleCorrectIncorrect
Zod importimport { z } from '@outputai/core'import { z } from 'zod'
HTTP clientimport { httpClient } from '@outputai/http'import axios from 'axios'
HTTP bodiesRead with .json()/.text() or cancel unused non-HEAD bodiesRead only response.url/status and leave body open
Credentialsimport { credentials } from '@outputai/credentials'process.env.SECRET
LLM callsimport { generateText, Output } from '@outputai/llm'Direct provider SDK
ES importsimport { fn } from './file.js'import { fn } from './file'
Workflow I/OCall steps for any I/ODirect fetch/http in workflow

Determinism violations (never in workflows):

  • Date.now(), new Date()
  • Math.random(), crypto.randomUUID()
  • Direct HTTP/fetch calls
  • File system operations
  • Environment variable reads

Available Tools Inventory

Agents

AgentPurpose
workflow-plannerDesigns workflow architecture, creates implementation blueprints
workflow-debuggerAnalyzes workflow execution traces, identifies issues
workflow-qualityReviews code quality, validates implementations
workflow-prompt-writerCreates and optimizes LLM prompt templates
workflow-context-fetcherGathers documentation and existing patterns

Skills

Workflow Authoring

SkillPurpose
output-plan-workflowPlan workflow architecture - ALWAYS FIRST, creates implementation blueprint
output-build-workflowBuild/implement workflows from a plan, or for modifications
output-debug-workflowDebug workflow issues when workflows fail or behave unexpectedly
output-migrateUpgrade a project between Output framework versions

Workflow Operations

SkillPurpose
output-workflow-runSynchronous workflow execution (waits for result)
output-workflow-startAsynchronous workflow execution (returns ID)
output-workflow-listList available workflows
output-workflow-statusCheck async workflow status
output-workflow-resultGet async workflow result
output-workflow-resetRerun a workflow from after a completed step

Monitoring & Debugging

SkillPurpose
output-workflow-stopStop running workflow
output-workflow-traceTrace workflow execution
output-workflow-trace-fileRender a local trace file as readable markdown
output-workflow-runs-listList workflow run history
output-dev-workflow-costCalculate cost of a workflow run
output-services-checkVerify Output services status

Error Diagnosis

SkillCatches
output-error-zod-importWrong zod import source
output-error-nondeterminismDate.now, Math.random in workflows
output-error-try-catchMissing error handling in steps
output-error-missing-schemasIncomplete Zod schema exports
output-error-direct-ioI/O operations in workflow files
output-error-http-clientUsing axios instead of @outputai/http

Meta/Lifecycle

SkillPurpose
output-meta-pre-flightPre-operation validation checks
output-meta-post-flightPost-operation verification
output-meta-project-contextLoad full project context (this skill)

Development

SkillPurpose
output-dev-folder-structureProject and workflow directory layout
output-dev-code-styleCode style conventions for workflow projects
output-dev-workflow-functionWriting deterministic workflow files
output-dev-step-functionWriting step functions for I/O
output-dev-agent-classBuild multi-step tool-loop agents with the Agent class
output-dev-types-fileZod schema definitions
output-dev-evaluator-functionQuality assessment functions
output-dev-eval-testingOffline eval tests with @outputai/evals
output-dev-prompt-fileLLM prompt templates with Liquid.js
output-dev-model-selectionPick a current LLM model via the AI Gateway listing
output-dev-upgrade-prompt-modelsBulk-upgrade model: fields across .prompt files
output-dev-scenario-fileTest input JSON files
output-dev-http-client-createShared HTTP API client patterns
output-dev-skill-fileAuthor .md skill files for the framework's lazy-loaded instructions
output-dev-create-skeletonGenerate workflow skeleton

Evals

SkillPurpose
output-eval-error-analysisReview traces to identify failure modes before building evaluators
output-eval-dataset-designDesign diverse eval datasets via dimension-based variation
output-eval-judge-promptDesign effective LLM judge .prompt files
output-eval-validate-judgeValidate LLM judges against human labels (TPR/TNR)
output-eval-auditAudit an existing eval suite for trustworthiness

Credentials

SkillPurpose
output-dev-credentialsFull credentials system reference (API, scopes, merging, custom providers)
output-credentials-initInitialize encrypted credentials files for the first time
output-credentials-editView and edit credential values with show/get/edit commands
output-credentials-env-varsWire credentials to env vars using the credential: convention

CLI Quick Reference

# Development
npx output dev                              # Start dev environment

# List & inspect
npx output workflow list                    # List available workflows

# Execute
npx output workflow run <name> --input '{}'  # Run synchronously (waits)
npx output workflow start <name> --input '{}' # Run async (returns ID)
npx output workflow status <id>              # Check async status
npx output workflow result <id>              # Get async result

# Debug
npx output workflow debug <id>               # Debug failed workflow
npx output workflow debug <id> --json # Machine-readable output

# Rerun from a step (replays up to <stepName>, re-executes everything after)
npx output workflow reset <id> --step <stepName>
npx output workflow reset <id> --step <stepName> --reason "why"

# Eval Testing
npx output workflow test <name>              # Run eval tests against datasets
npx output workflow test <name> --cached     # Use cached output (fast)
npx output workflow test <name> --save       # Run fresh and save results
npx output workflow dataset list <name>      # List datasets for a workflow
npx output workflow dataset generate <name> --input '{}'  # Generate dataset

# Credentials
npx output credentials init                  # Initialize encrypted credentials
npx output credentials edit                  # Edit credentials (decrypts, opens $EDITOR)
npx output credentials show                  # Show decrypted credentials
npx output credentials get <path>            # Get single credential value

Naming Conventions

ElementConventionExample
Workflow foldersnake_casefact_checker/
Workflow namesnake_casename: 'fact_checker'
Step functionscamelCasefetchArticle(), analyzeContent()
Schema namesPascalCaseInputSchema, ArticleData
Prompt filessnake_case@version.promptanalyze_claim@v1.prompt
Scenario filessnake_case.jsonhappy_path.json

Common Patterns

Workflow Pattern

import { workflow, z } from '@outputai/core';
import { fetchData, processData } from './steps.js';

export const inputSchema = z.object( { url: z.string().url() } );
export const outputSchema = z.object( { result: z.string() } );

export default workflow( {
  name: 'my_workflow',
  description: 'Processes data from URL',
  inputSchema,
  outputSchema,
  fn: async input => {
    const data = await fetchData( input.url );
    const result = await processData( data );
    return { result };
  }
} );

See output-dev-workflow-function for comprehensive patterns.

Step Pattern

import { step, z } from '@outputai/core';
import { httpClient } from '@outputai/http';

export const fetchData = step(
  { name: 'fetchData', inputSchema: z.string(), outputSchema: z.any() },
  async url => {
    const client = httpClient( { prefixUrl: url } );
    const response = await client.get( '' );
    return response.json();
  }
);

See output-dev-step-function for comprehensive patterns.

HTTP Client Pattern (Shared)

Clients live in src/shared/clients/ and are shared across all workflows.

// src/shared/clients/example.ts
import { FatalError, ValidationError } from '@outputai/core';
import { httpClient } from '@outputai/http';
import { credentials } from '@outputai/credentials';

const API_KEY = credentials.require( 'example.api_key' );

const client = httpClient( {
  prefixUrl: 'https://api.example.com',
  headers: { Authorization: `Bearer ${API_KEY}` },
  timeout: 30000,
  retry: { limit: 3, statusCodes: [ 408, 429, 500, 502, 503, 504 ] }
} );

export async function fetchFromExample( query: string ): Promise<ExampleResponse> {

  try {
    const response = await client.get( 'endpoint', { searchParams: { q: query } } );
    return response.json();
  } catch ( error: unknown ) {
    const err = error as { status?: number; message?: string };
    if ( err.status === 401 || err.status === 403 ) {
      throw new FatalError( `Auth failed: ${err.message}` );
    }
    throw new ValidationError( `Request failed: ${err.message}` );
  }
}

Error type guidelines:

  • FatalError: 401, 403, 404 (won't succeed on retry)
  • ValidationError: 429, 5xx (may succeed on retry)

See output-dev-http-client-create for comprehensive patterns.

Evaluator Pattern

Evaluators return confidence-scored results. Three result types available:

import { evaluator, z, EvaluationBooleanResult, EvaluationNumberResult, EvaluationStringResult } from '@outputai/core';

// Boolean evaluator - pass/fail checks
export const evaluateCompleteness = evaluator( {
  name: 'evaluate_completeness',
  description: 'Check if content meets minimum length',
  inputSchema: z.object( { content: z.string(), minLength: z.number() } ),
  fn: async ( { content, minLength } ) => {
    return new EvaluationBooleanResult( {
      value: content.length >= minLength,
      confidence: 1.0,
      reasoning: `Content has ${content.length} chars (min: ${minLength})`
    } );
  }
} );

See output-dev-evaluator-function for comprehensive patterns.

Prompt File Pattern

Prompts use YAML frontmatter + Liquid.js templating. Location: src/workflows/{name}/prompts/

---
provider: anthropic
# current as of 2026-05-04 — run output-dev-model-selection for the latest
model: claude-sonnet-4-6
temperature: 0.7
maxTokens: 4096
---

<system>
You are an expert content analyzer.

{% if context %}
Additional context: {{ context }}
{% endif %}
</system>

<user>
Analyze the following content:

<content>
{{ content }}
</content>

Provide {{ numberOfPoints | default: 3 }} key insights.
</user>

Using in steps:

import { generateText, Output } from '@outputai/llm';
import { z } from '@outputai/core';

// Structured output
const { output } = await generateText( {
  prompt: 'analyze@v1',
  variables: { content: 'Article text...', numberOfPoints: 5 },
  output: Output.object( {
    schema: z.object( { insights: z.array( z.string() ) } )
  } )
} );

// Text output
const { result } = await generateText( {
  prompt: 'summarize@v1',
  variables: { content: 'Article text...' }
} );

Provider & model selection: the SDK supports anthropic, openai, vertex, bedrock, azure, and perplexity (the registered list lives in the SDK's model registry, sdk/llm/src/ai_model.js). Don't pin specific model IDs in docs — they drift. To pick a current model, run output-dev-model-selection, which queries the AI Gateway model index live.

See output-dev-prompt-file for comprehensive patterns.


Practical Tips

Docker & Services

  • Restart worker after adding workflows: docker restart <project>-worker-1
  • View worker logs: docker logs -f output-worker-1
  • Check services: Use output-services-check skill

Payload Limits

  • Temporal: ~2MB per workflow input/output
  • gRPC: ~4MB maximum
  • For larger data, use file storage and pass references

Debugging Workflow Failures

  1. Get the workflow ID from error output
  2. Run npx output workflow debug <id> --json
  3. Look for: failed step name, error message, input that caused failure
  4. Check if issue is determinism, schema validation, or external API