Module: LittleGhost

Defined in:
lib/little_ghost.rb,
lib/little_ghost/run.rb,
lib/little_ghost/tool.rb,
lib/little_ghost/agent.rb,
lib/little_ghost/model.rb,
lib/little_ghost/usage.rb,
lib/little_ghost/errors.rb,
lib/little_ghost/events.rb,
lib/little_ghost/lookup.rb,
lib/little_ghost/content.rb,
lib/little_ghost/message.rb,
lib/little_ghost/runtime.rb,
lib/little_ghost/sandbox.rb,
lib/little_ghost/session.rb,
lib/little_ghost/support.rb,
lib/little_ghost/version.rb,
lib/little_ghost/path_set.rb,
lib/little_ghost/workflow.rb,
lib/little_ghost/workspace.rb,
lib/little_ghost/invocation.rb,
lib/little_ghost/mcp/client.rb,
lib/little_ghost/run_result.rb,
lib/little_ghost/run_context.rb,
lib/little_ghost/tools/shell.rb,
lib/little_ghost/agent/skills.rb,
lib/little_ghost/runtime/hook.rb,
lib/little_ghost/skills/skill.rb,
lib/little_ghost/stream_event.rb,
lib/little_ghost/ag_ui/adapter.rb,
lib/little_ghost/agent_builder.rb,
lib/little_ghost/configuration.rb,
lib/little_ghost/model_request.rb,
lib/little_ghost/models/target.rb,
lib/little_ghost/session_store.rb,
lib/little_ghost/tool_registry.rb,
lib/little_ghost/model_resolver.rb,
lib/little_ghost/model_response.rb,
lib/little_ghost/models/catalog.rb,
lib/little_ghost/models/details.rb,
lib/little_ghost/providers/base.rb,
lib/little_ghost/skills/catalog.rb,
lib/little_ghost/support/loader.rb,
lib/little_ghost/tool_execution.rb,
lib/little_ghost/agent/tool_loop.rb,
lib/little_ghost/execution_state.rb,
lib/little_ghost/instrumentation.rb,
lib/little_ghost/prompt_resolver.rb,
lib/little_ghost/agent/delegation.rb,
lib/little_ghost/providers/gemini.rb,
lib/little_ghost/providers/openai.rb,
lib/little_ghost/support/executor.rb,
lib/little_ghost/support/redactor.rb,
lib/little_ghost/tools/filesystem.rb,
lib/little_ghost/provider_registry.rb,
lib/little_ghost/providers/bedrock.rb,
lib/little_ghost/structured_output.rb,
lib/little_ghost/subagents/manager.rb,
lib/little_ghost/support/callbacks.rb,
lib/little_ghost/tools/write_todos.rb,
lib/little_ghost/model_capabilities.rb,
lib/little_ghost/support/sse_parser.rb,
lib/little_ghost/agent_interruptions.rb,
lib/little_ghost/providers/anthropic.rb,
lib/little_ghost/providers/vertex_ai.rb,
lib/little_ghost/support/http_client.rb,
lib/little_ghost/models/configuration.rb,
lib/little_ghost/subagents/agent_path.rb,
lib/little_ghost/subagents/definition.rb,
lib/little_ghost/unrestricted_sandbox.rb,
lib/little_ghost/models/catalog/source.rb,
lib/little_ghost/providers/open_router.rb,
lib/little_ghost/session_stores/memory.rb,
lib/little_ghost/tracing/open_telemetry.rb,
lib/little_ghost/models/catalog_snapshot.rb,
lib/little_ghost/providers/configuration.rb,
lib/little_ghost/support/content_capture.rb,
lib/little_ghost/agent/context_management.rb,
lib/little_ghost/support/class_attributes.rb,
lib/little_ghost/support/output_truncation.rb,
lib/little_ghost/support/cancellation_token.rb,
lib/little_ghost/providers/openai_compatible.rb,
lib/little_ghost/support/interruptible_stream.rb,
lib/little_ghost/providers/bedrock/http_client.rb,
lib/little_ghost/providers/bedrock/aws_protocol.rb,
lib/little_ghost/providers/gemini/catalog_source.rb,
lib/little_ghost/models/catalog/models_dev_source.rb,
lib/little_ghost/providers/bedrock/catalog_source.rb,
lib/little_ghost/session_stores/agent_core_memory.rb,
lib/little_ghost/providers/anthropic/catalog_source.rb,
lib/little_ghost/providers/open_router/catalog_source.rb,
lib/little_ghost/providers/bedrock/credential_resolver.rb,
lib/little_ghost/providers/vertex_ai/credential_resolver.rb

Overview

Build AI features with reusable agents and agentic workflows. LittleGhost can sit inside an existing Ruby system or support a dedicated AI service, keeping models, prompts, tools, sessions, streaming, and instrumentation behind a cohesive set of Ruby conventions.

A customer support agent can answer directly, use an application tool, or ask a specialist for research while the caller observes one run:

class ResearchAgent < LittleGhost::Agent
description "Researches difficult support questions"
model "openai:gpt-5.6-luna"
end

class CustomerSupportAgent < LittleGhost::Agent
description "Handles support requests"
model "openai:gpt-5.6-luna"
tools AccountTool
subagent ResearchAgent, kind: "research"
end

run = CustomerSupportAgent.ask("Why is transfer 481 still pending?")
run.completed? # => true
run.response   # => "Transfer 481 is waiting for the receiving bank."

Agent subclasses hold reusable behavior; Invocation objects carry one request, and Run objects own execution and cleanup. Workflow subclasses can compose several agents when ordinary Ruby branching is clearer than one agent loop.

LittleGhost.configuration is process-wide unless LittleGhost.with_configuration supplies an execution-scoped replacement. Configuration is loaded lazily and snapshotted into a Runtime, so make application changes before the first agent runtime is built.

Defined Under Namespace

Modules: AGUI, Content, Events, ExecutionState, Instrumentation, Lookup, MCP, ModelInterface, Models, Providers, SessionStores, Skills, StructuredOutput, Subagents, Support, Tools, Tracing Classes: AbstractMethodError, AdapterLoadError, Agent, AgentBuilder, AgentInterruptError, AgentInterruptions, CancelledError, CleanupError, Configuration, ConfigurationError, ContextWindowOverflowError, CredentialError, DeadlineExceededError, Error, InvalidPromptTemplateError, Invocation, InvocationError, MalformedToolCallError, Message, MissingPromptLocalError, MissingPromptTemplateError, Model, ModelCapabilities, ModelRequest, ModelResolver, ModelResponse, OutputLimitError, PathSet, PromptResolver, PromptTemplateError, ProtocolError, ProviderError, ProviderRegistry, Run, RunContext, RunResult, Runtime, Sandbox, Session, SessionStore, StreamEvent, StructuredResult, StructuredResultError, Tool, ToolError, ToolExecution, ToolLoopError, ToolRegistry, TrustedPath, UnrestrictedSandbox, UnsupportedInputError, Usage, Workflow, Workspace

Constant Summary collapse

VERSION =

Current LittleGhost gem version.

"0.2.1"

Class Method Summary collapse

Class Method Details

.configuration ⇒ Object

The configuration active in the current execution context, falling back to the process-wide default.



103
104
105
 
# File 'lib/little_ghost.rb', line 103

def configuration
  ExecutionState[:configuration] || (@configuration ||= Configuration.new)
end

.configure(&block) ⇒ Object

Opens the active Configuration for application setup and returns it.

Configuration files are loaded lazily when a runtime is first built, so make application-level changes before invoking an agent.



111
112
113
 
# File 'lib/little_ghost.rb', line 111

def configure(&block)
  configuration.configure(&block)
end

.model_resolver ⇒ Object

Returns the model resolver owned by the active process configuration.



116
 
# File 'lib/little_ghost.rb', line 116

def model_resolver = configuration.model_resolver

.with_configuration(configuration) ⇒ Object

Makes configuration current only while the block runs.

Execution state restores the previous configuration even when the block raises. Other execution contexts continue to see their own configuration.



122
123
124
 
# File 'lib/little_ghost.rb', line 122

def with_configuration(configuration)
  ExecutionState.with(configuration:) { yield }
end