Class: LittleGhost::Runtime

Inherits:
Object
  • Object
show all
Defined in:
lib/little_ghost/runtime.rb,
lib/little_ghost/runtime/hook.rb

Overview

Prepare the shared services that agents and workflows use across many runs. A runtime owns model resolution, loading, persistence, lookup paths, hooks, and resource factories for one Ruby setup.

configuration = LittleGhost::Configuration.new(
root: Dir.pwd,
providers: {
  openai: {adapter: :openai, api_key: ENV.fetch("OPENAI_API_KEY")}
},
models: {customer_support: {target: "openai:gpt-5.6-luna"}},
default_model: "customer_support",
service_name: "support-api"
)
runtime = LittleGhost::Runtime.new(configuration: configuration)

runtime.service_name # => "support-api"
runtime.root == Pathname.new(File.realpath(Dir.pwd)) # => true

Without explicit settings, construction canonicalizes the root, loads config/little_ghost.rb once through the Configuration, snapshots settings, configures instrumentation, eager-loads application constants, and builds the selected model resolver and session store. Supplying settings is the lower-level path used to create a sibling runtime from an existing snapshot.

Reuse a runtime across runs. build_run creates any missing workspace and sandbox, transfers ownership only after both are built, and closes partial resources if construction fails. build creates a sibling with explicit overrides and reuses the loader only when the application root is unchanged.

Startup emits structured lifecycle instrumentation; a failed phase emits a failure event, flushes instrumentation, and re-raises the original exception. Session actor resolution must use trusted authenticated identity for tenant isolation. The default UnrestrictedSandbox is convenient application plumbing, not a security boundary for untrusted work.

Defined Under Namespace

Classes: Hook

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(configuration:, settings: nil) ⇒ Runtime

Starts a runtime from configuration or an existing settings snapshot.



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# File 'lib/little_ghost/runtime.rb', line 48

def initialize(configuration:, settings: nil)
  @startup_started_at = monotonic_time
  @startup_phase = "configuration"
  @startup_reported = false

  begin
    raise ArgumentError, "configuration must be a LittleGhost::Configuration" unless configuration.is_a?(Configuration)

    @configuration = configuration
    if settings
      @settings = settings
    else
      bootstrap_root = canonical_application_root(configuration.root)
      configuration.load_file!(root: bootstrap_root)
      @settings = configuration.settings(root: bootstrap_root)
    end
    report_startup(status: "starting")
    @startup_reported = true
    @root = canonical_application_root(@settings.fetch(:root))
    @skill_resource_root = @settings[:skill_resource_root]
    @workspace_class = @settings.fetch(:workspace)
    @sandbox_class = @settings.fetch(:sandbox)
    @runtime_hooks = build_runtime_hooks(@settings[:runtime_hooks])

    @startup_phase = "instrumentation"
    subscribe_instrumentation(@settings[:instrumentation_subscribers])
    emit_startup(:runtime_start)

    @startup_phase = "loader"
    @loader = @settings[:loader] || Support::Loader.new(root: @root)
    loader.setup
    loader.eager_load

    @startup_phase = "model_resolver"
    @invocation_class = @settings[:invocation] || Invocation
    @model_resolver = @settings.fetch(:model_resolver)
    @default_model = @settings.fetch(:default_model, "default").to_s

    @startup_phase = "session_store"
    @session_store = build_session_store(@settings[:session_store])
    @session_actor = @settings[:session_actor]

    @startup_phase = "prompts"
    @prompt_paths = build_lookup_paths(:prompt_paths)
    @skill_paths = build_lookup_paths(:skill_paths)

    @startup_phase = "agent_builder"
    @agent_builder = AgentBuilder.new(
      runtime: self,
      prompt_paths: @prompt_paths,
      resolve_agent: method(:resolve_agent_class)
    )

    @startup_phase = "complete"
    emit_startup(:runtime_stop, outcome: "ready")
    report_startup(status: "ready")
  rescue => error
    unless @startup_reported
      report_startup(status: "starting")
      @startup_reported = true
    end
    emit_startup(:runtime_stop, outcome: "failed", error:)
    Instrumentation.flush
    report_startup(status: "failed", error:)
    raise
  end
end

Instance Attribute Details

#configuration ⇒ Object (readonly)

The snapshotted setup and materialized services used by new runs.



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# File 'lib/little_ghost/runtime.rb', line 43

def configuration
  @configuration
end

#loader ⇒ Object (readonly)

The snapshotted setup and materialized services used by new runs.



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# File 'lib/little_ghost/runtime.rb', line 43

def loader
  @loader
end

#model_resolver ⇒ Object (readonly)

The snapshotted setup and materialized services used by new runs.



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# File 'lib/little_ghost/runtime.rb', line 43

def model_resolver
  @model_resolver
end

#prompt_paths ⇒ Object (readonly)

The snapshotted setup and materialized services used by new runs.



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# File 'lib/little_ghost/runtime.rb', line 43

def prompt_paths
  @prompt_paths
end

#root ⇒ Object (readonly)

The snapshotted setup and materialized services used by new runs.



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# File 'lib/little_ghost/runtime.rb', line 43

def root
  @root
end

#runtime_hooks ⇒ Object (readonly)

The snapshotted setup and materialized services used by new runs.



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# File 'lib/little_ghost/runtime.rb', line 43

def runtime_hooks
  @runtime_hooks
end

#sandbox_class ⇒ Object (readonly)

The snapshotted setup and materialized services used by new runs.



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# File 'lib/little_ghost/runtime.rb', line 43

def sandbox_class
  @sandbox_class
end

#session_store ⇒ Object (readonly)

The snapshotted setup and materialized services used by new runs.



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# File 'lib/little_ghost/runtime.rb', line 43

def session_store
  @session_store
end

#settings ⇒ Object (readonly)

The snapshotted setup and materialized services used by new runs.



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# File 'lib/little_ghost/runtime.rb', line 43

def settings
  @settings
end

#skill_paths ⇒ Object (readonly)

The snapshotted setup and materialized services used by new runs.



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# File 'lib/little_ghost/runtime.rb', line 43

def skill_paths
  @skill_paths
end

#skill_resource_root ⇒ Object (readonly)

The snapshotted setup and materialized services used by new runs.



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# File 'lib/little_ghost/runtime.rb', line 43

def skill_resource_root
  @skill_resource_root
end

#workspace_class ⇒ Object (readonly)

The snapshotted setup and materialized services used by new runs.



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# File 'lib/little_ghost/runtime.rb', line 43

def workspace_class
  @workspace_class
end

Instance Method Details

#build(**overrides) ⇒ Object

Creates a sibling runtime with explicit setting overrides.



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# File 'lib/little_ghost/runtime.rb', line 117

def build(**overrides)
  values = @settings.merge(overrides)
  values[:root] = canonical_application_root(values.fetch(:root))
  values[:loader] = loader unless overrides.key?(:loader) || overrides.key?(:root)
  self.class.new(
    configuration:,
    settings: values
  )
end

#build_agent(agent_class_or_name, run:, model: nil, tools: [], agent_path: Subagents::AgentPath::ROOT) ⇒ Object

:nodoc:



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# File 'lib/little_ghost/runtime.rb', line 179

def build_agent(
  agent_class_or_name,
  run:,
  model: nil,
  tools: [],
  agent_path: Subagents::AgentPath::ROOT
)
  @agent_builder.build(agent_class_or_name, run:, model:, tools:, agent_path:)
end

#build_run(payload, agent_class:, entrypoint_class: agent_class, workspace: nil, sandbox: nil) ⇒ Object

Creates a Run and transfers ownership of newly created workspace and sandbox resources to it.



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# File 'lib/little_ghost/runtime.rb', line 134

def build_run(
  payload,
  agent_class:,
  entrypoint_class: agent_class,
  workspace: nil,
  sandbox: nil
)
  owned_resources = []
  workspace ||= build_workspace.tap { |resource| owned_resources << resource }
  sandbox ||= build_sandbox(workspace:).tap { |resource| owned_resources << resource }
  run = Run.new(
    invocation: parse(payload),
    runtime: self,
    agent_class:,
    entrypoint_class:,
    workspace:,
    sandbox:
  )
  owned_resources.each { |resource| run.register(resource) }
  prepare_run(run)
rescue
  if run
    run.close
  else
    close_resources(owned_resources)
  end
  raise
end

#build_sandbox(workspace:) ⇒ Object

Instantiates the configured sandbox around workspace, or an unrestricted sandbox by default.



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# File 'lib/little_ghost/runtime.rb', line 172

def build_sandbox(workspace:)
  return sandbox_class.new(workspace:) if sandbox_class

  UnrestrictedSandbox.new(workspace:)
end

#build_workspace ⇒ Object

Instantiates the configured workspace, or a root-scoped Workspace by default.



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# File 'lib/little_ghost/runtime.rb', line 164

def build_workspace
  return workspace_class.new if workspace_class

  Workspace.new(root: root)
end

#default_error_message(error, _run) ⇒ Object

:nodoc:



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# File 'lib/little_ghost/runtime.rb', line 251

def default_error_message(error, _run) # :nodoc:
  return error.message if error.is_a?(UnsupportedInputError)
  return error.message if error.is_a?(ToolLoopError)
  return "The model reached its output limit before completing a response. Please retry with a narrower request." if error.is_a?(OutputLimitError)
  if error.is_a?(MalformedToolCallError)
    return "The model returned an invalid tool call before completing the response. Please retry with a narrower request."
  end

  "Agent failed: #{error.class}"
end

#error_message(error, run) ⇒ Object

:nodoc:



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# File 'lib/little_ghost/runtime.rb', line 242

def error_message(error, run) # :nodoc:
  runtime_hooks.each do |hook|
    message = hook.error_message(error, run)
    return message if message
  end

  default_error_message(error, run)
end

#model_for(agent_class, run) ⇒ Object

:nodoc:



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# File 'lib/little_ghost/runtime.rb', line 194

def model_for(agent_class, run) # :nodoc:
  selection = agent_class.model_selection(run.invocation) || @default_model
  model_resolver.resolve(selection, invocation: run.invocation, context: run)
end

#open_session(run) ⇒ Object

:nodoc:



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# File 'lib/little_ghost/runtime.rb', line 199

def open_session(run) # :nodoc:
  Session.new(
    id: run.invocation.session_id,
    actor_id: session_actor_for(run.invocation),
    store: session_store,
    operation_id: run.operation_id
  )
end

#open_subagent_session(run, conversation_id) ⇒ Object

:nodoc:



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# File 'lib/little_ghost/runtime.rb', line 219

def open_subagent_session(run, conversation_id) # :nodoc:
  parent_link = Subagents::Manager.parent_link(run.session)
  Session.new(
    id: Subagents::Manager.conversation_session_id(conversation_id),
    actor_id: session_actor_for(run.invocation),
    store: session_store,
    operation_id: run.operation_id,
    metadata: {
      "little_ghost_kind" => "subagent_conversation",
      "little_ghost_parent_link" => parent_link,
      "little_ghost_conversation_id" => conversation_id
    }
  )
end

#parse(payload) ⇒ Object

Coerces an application payload into the configured Invocation class.



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# File 'lib/little_ghost/runtime.rb', line 128

def parse(payload)
  payload.is_a?(@invocation_class) ? payload : @invocation_class.new(payload)
end

#prepare_interruption(run, payload) ⇒ Object

:nodoc:



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# File 'lib/little_ghost/runtime.rb', line 213

def prepare_interruption(run, payload) # :nodoc:
  runtime_hooks.reduce(payload) do |prepared, hook|
    hook.prepare_interruption(run, prepared)
  end
end

#prepare_run(run) ⇒ Object

:nodoc:



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# File 'lib/little_ghost/runtime.rb', line 208

def prepare_run(run) # :nodoc:
  runtime_hooks.each { |hook| hook.prepare_run(run) }
  run
end

#resolve_agent(value) ⇒ Object

:nodoc:



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# File 'lib/little_ghost/runtime.rb', line 262

def resolve_agent(value) # :nodoc:
  resolve_agent_class(value)
end

#service_name ⇒ Object

The low-cardinality service name attached to runtime telemetry.



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# File 'lib/little_ghost/runtime.rb', line 190

def service_name
  @settings&.[](:service_name) || default_service_name
end

#session_actor_for(invocation) ⇒ Object

:nodoc:



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# File 'lib/little_ghost/runtime.rb', line 234

def session_actor_for(invocation) # :nodoc:
  @session_actor ? @session_actor.call(invocation) : invocation.actor_id
end

#template_locals(run:, agent:) ⇒ Object

:nodoc:



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# File 'lib/little_ghost/runtime.rb', line 238

def template_locals(run:, agent:) # :nodoc:
  {invocation: run.invocation, run:, agent:}.merge(agent.prompt_locals)
end