Class: SignalWire::Contexts::ContextBuilder

Inherits:
Object
  • Object
show all
Defined in:
lib/signalwire/contexts/context_builder.rb

Overview

Builder for multi-step, multi-context AI agent workflows.

A ContextBuilder owns one or more Contexts; each Context owns an ordered list of Steps. Only one context and one step is active at a time. Per chat turn, the runtime injects the current step’s instructions as a system message, then asks the LLM for a response.

Native tools auto-injected by the runtime

When a step (or its enclosing context) declares valid_steps or valid_contexts, the runtime auto-injects two native tools so the model can navigate the flow:

- +next_step(step: enum)+         — present when valid_steps is set
- +change_context(context: enum)+ — present when valid_contexts is set

Their enum schemas are rewritten on every turn to match whatever valid_steps / valid_contexts apply to the current step. You do NOT need to define these tools yourself; they appear automatically.

A third native tool — gather_submit — is injected during gather_info questioning (see Step#set_gather_info / Step#add_gather_question).

These three names — next_step, change_context, gather_submit — are reserved. validate! will reject any agent that defines a SWAIG tool with one of these names. See RESERVED_NATIVE_TOOL_NAMES.

Function whitelisting (Step#set_functions)

Each step may declare a functions whitelist. The whitelist is applied in-memory at the start of each LLM turn. CRITICALLY: if a step does NOT declare a functions field, it INHERITS the previous step’s active set. See Step#set_functions for details and examples.

Instance Method Summary collapse

Constructor Details

#initialize(agent = nil) ⇒ ContextBuilder

Python parity: “ContextBuilder.__init__(self, agent)“ accepts an owning agent so “validate!“ can introspect registered SWAIG tools when checking for reserved-name collisions. Ruby allows nil for standalone use (tests, idiom of building a builder before attaching).



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# File 'lib/signalwire/contexts/context_builder.rb', line 672

def initialize(agent = nil)
  @contexts      = {}   # name => Context
  @context_order = []
  @agent         = agent
end

Instance Method Details

#add_context(name) ⇒ Object

Add a new context. Returns the Context object.

Raises:

  • (ArgumentError) 


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# File 'lib/signalwire/contexts/context_builder.rb', line 696

def add_context(name)
  raise ArgumentError, "Context '#{name}' already exists" if @contexts.key?(name)
  raise ArgumentError, "Maximum number of contexts (#{MAX_CONTEXTS}) exceeded" if @contexts.size >= MAX_CONTEXTS

  ctx = Context.new(name)
  @contexts[name] = ctx
  @context_order << name
  ctx
end

#attach_agent(agent) ⇒ Object

Attach an agent reference so validate! can check user-defined tool names against RESERVED_NATIVE_TOOL_NAMES. Called internally by AgentBase#define_contexts.



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# File 'lib/signalwire/contexts/context_builder.rb', line 681

def attach_agent(agent)
  @agent = agent
  self
end

#get_context(name) ⇒ Object

Get an existing context by name. Returns Context or nil.



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# File 'lib/signalwire/contexts/context_builder.rb', line 707

def get_context(name)
  @contexts[name]
end

#reset ⇒ Object

Remove all contexts, returning the builder to its initial state. Use this in a dynamic config callback when you need to rebuild contexts from scratch for a specific request.



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# File 'lib/signalwire/contexts/context_builder.rb', line 689

def reset
  @contexts.clear
  @context_order.clear
  self
end

#to_h ⇒ Object 



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# File 'lib/signalwire/contexts/context_builder.rb', line 846

def to_h
  validate!
  result = {}
  @context_order.each do |name|
    result[name] = @contexts[name].to_h
  end
  result
end

#validate! ⇒ Object

Validate the full configuration. Raises ArgumentError on problems.

Raises:

  • (ArgumentError) 


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# File 'lib/signalwire/contexts/context_builder.rb', line 712

def validate!
  raise ArgumentError, "At least one context must be defined" if @contexts.empty?

  # Single context must be named "default"
  if @contexts.size == 1
    ctx_name = @contexts.keys.first
    raise ArgumentError, "When using a single context, it must be named 'default'" if ctx_name != 'default'
  end

  # Each context must have at least one step
  @contexts.each do |ctx_name, ctx|
    raise ArgumentError, "Context '#{ctx_name}' must have at least one step" if ctx._steps.empty?
  end

  # Validate initial_step references a real step in the context
  @contexts.each do |ctx_name, ctx|
    is = ctx._initial_step
    if is && !ctx._steps.key?(is)
      available = ctx._steps.keys.sort
      raise ArgumentError,
            "Context '#{ctx_name}' has initial_step='#{is}' but that step does " \
            "not exist. Available steps: #{available.inspect}"
    end
  end

  # Validate step references in valid_steps
  @contexts.each do |ctx_name, ctx|
    ctx._steps.each do |step_name, step|
      step_h = step.to_h
      if step_h["valid_steps"]
        step_h["valid_steps"].each do |vs|
          next if vs == "next"
          unless ctx._steps.key?(vs)
            raise ArgumentError,
                  "Step '#{step_name}' in context '#{ctx_name}' references unknown step '#{vs}'"
          end
        end
      end
    end
  end

  # Validate context references at context level
  @contexts.each do |ctx_name, ctx|
    ctx_h = ctx.to_h
    if ctx_h["valid_contexts"]
      ctx_h["valid_contexts"].each do |vc|
        unless @contexts.key?(vc)
          raise ArgumentError,
                "Context '#{ctx_name}' references unknown context '#{vc}'"
        end
      end
    end
  end

  # Validate context references at step level
  @contexts.each do |ctx_name, ctx|
    ctx._steps.each do |step_name, step|
      step_h = step.to_h
      if step_h["valid_contexts"]
        step_h["valid_contexts"].each do |vc|
          unless @contexts.key?(vc)
            raise ArgumentError,
                  "Step '#{step_name}' in context '#{ctx_name}' references unknown context '#{vc}'"
          end
        end
      end
    end
  end

  # Validate gather_info configurations
  @contexts.each do |ctx_name, ctx|
    ctx._steps.each do |step_name, step|
      step_h = step.to_h
      next unless step_h.key?("gather_info")

      gi = step_h["gather_info"]
      questions = gi["questions"] || []
      raise ArgumentError,
            "Step '#{step_name}' in context '#{ctx_name}' has gather_info with no questions" if questions.empty?

      keys_seen = Set.new
      questions.each do |q|
        raise ArgumentError,
              "Step '#{step_name}' in context '#{ctx_name}' has duplicate gather_info question key '#{q['key']}'" if keys_seen.include?(q["key"])
        keys_seen << q["key"]
      end

      action = gi["completion_action"]
      if action
        if action == "next_step"
          idx = ctx._step_order.index(step_name)
          if idx >= ctx._step_order.size - 1
            raise ArgumentError,
                  "Step '#{step_name}' in context '#{ctx_name}' has gather_info " \
                  "completion_action='next_step' but it is the last step in the " \
                  "context. Either (1) add another step after '#{step_name}', " \
                  "(2) set completion_action to the name of an existing step in " \
                  "this context to jump to it, or (3) set completion_action=nil " \
                  "(default) to stay in '#{step_name}' after gathering completes."
          end
        elsif !ctx._steps.key?(action)
          available = ctx._steps.keys.sort
          raise ArgumentError,
                "Step '#{step_name}' in context '#{ctx_name}' has gather_info " \
                "completion_action='#{action}' but '#{action}' is not a step in " \
                "this context. Valid options: 'next_step' (advance to the next " \
                "sequential step), nil (stay in the current step), or one of " \
                "#{available.inspect}."
        end
      end
    end
  end

  # Validate that user-defined tools do not collide with reserved
  # native tool names. The runtime auto-injects next_step /
  # change_context / gather_submit when contexts/steps are
  # present, so user tools sharing those names would never be
  # called.
  if @agent && @agent.respond_to?(:list_tool_names)
    registered = @agent.list_tool_names.to_a
    colliding = registered.select { |n| RESERVED_NATIVE_TOOL_NAMES.include?(n) }.sort.uniq
    if colliding.any?
      raise ArgumentError,
            "Tool name(s) #{colliding.inspect} collide with reserved native " \
            "tools auto-injected by contexts/steps. The names " \
            "#{RESERVED_NATIVE_TOOL_NAMES.sort.inspect} are reserved and " \
            "cannot be used for user-defined SWAIG tools when contexts/steps " \
            "are in use. Rename your tool(s) to avoid the collision."
    end
  end

  true
end